From 9f5948650eeb10bec3a26f942c1a738bc54a8aca Mon Sep 17 00:00:00 2001 From: clssck Date: Sun, 30 Nov 2025 20:14:52 +0100 Subject: [PATCH] chore(lightrag): add wikipedia test dataset for evaluation Add comprehensive test dataset with 7 domain-specific Wikipedia documents (climate, finance, medical, sports) and corresponding test cases in JSON format. Total of 2292 lines of test data across 8 files for RAG quality evaluation and end-to-end testing infrastructure. --- .../wiki_documents/climate_climate_change.txt | 291 ++++++++++++ .../climate_renewable_energy.txt | 394 ++++++++++++++++ .../wiki_documents/finance_cryptocurrency.txt | 432 ++++++++++++++++++ .../wiki_documents/finance_stock_market.txt | 235 ++++++++++ .../wiki_documents/medical_covid-19.txt | 424 +++++++++++++++++ .../wiki_documents/medical_diabetes.txt | 239 ++++++++++ .../wiki_documents/sports_fifa_world_cup.txt | 228 +++++++++ lightrag/evaluation/wiki_test_dataset.json | 49 ++ 8 files changed, 2292 insertions(+) create mode 100644 lightrag/evaluation/wiki_documents/climate_climate_change.txt create mode 100644 lightrag/evaluation/wiki_documents/climate_renewable_energy.txt create mode 100644 lightrag/evaluation/wiki_documents/finance_cryptocurrency.txt create mode 100644 lightrag/evaluation/wiki_documents/finance_stock_market.txt create mode 100644 lightrag/evaluation/wiki_documents/medical_covid-19.txt create mode 100644 lightrag/evaluation/wiki_documents/medical_diabetes.txt create mode 100644 lightrag/evaluation/wiki_documents/sports_fifa_world_cup.txt create mode 100644 lightrag/evaluation/wiki_test_dataset.json diff --git a/lightrag/evaluation/wiki_documents/climate_climate_change.txt b/lightrag/evaluation/wiki_documents/climate_climate_change.txt new file mode 100644 index 00000000..b52b1bc5 --- /dev/null +++ b/lightrag/evaluation/wiki_documents/climate_climate_change.txt @@ -0,0 +1,291 @@ +Present-day climate change includes both global warming—the ongoing increase in global average temperature—and its wider effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to Earth's climate. The modern-day rise in global temperatures is driven by human activities, especially fossil fuel (coal, oil and natural gas) burning since the Industrial Revolution. Fossil fuel use, deforestation, and some agricultural and industrial practices release greenhouse gases. These gases absorb some of the heat that the Earth radiates after it warms from sunlight, warming the lower atmosphere. Carbon dioxide, the primary gas driving global warming, has increased in concentration by about 50% since the pre-industrial era to levels not seen for millions of years. +Climate change has an increasingly large impact on the environment. Deserts are expanding, while heat waves and wildfires are becoming more common. Amplified warming in the Arctic has contributed to thawing permafrost, retreat of glaciers and sea ice decline. Higher temperatures are also causing more intense storms, droughts, and other weather extremes. Rapid environmental change in mountains, coral reefs, and the Arctic is forcing many species to relocate or become extinct. Even if efforts to minimize future warming are successful, some effects will continue for centuries. These include ocean heating, ocean acidification and sea level rise. +Climate change threatens people with increased flooding, extreme heat, increased food and water scarcity, more disease, and economic loss. Human migration and conflict can also be a result. The World Health Organization calls climate change one of the biggest threats to global health in the 21st century. Societies and ecosystems will experience more severe risks without action to limit warming. Adapting to climate change through efforts like flood control measures or drought-resistant crops partially reduces climate change risks, although some limits to adaptation have already been reached. Poorer communities are responsible for a small share of global emissions, yet have the least ability to adapt and are most vulnerable to climate change. + +Many climate change impacts have been observed in the first decades of the 21st century, with 2024 the warmest on record at +1.60 °C (2.88 °F) since regular tracking began in 1850. Additional warming will increase these impacts and can trigger tipping points, such as melting all of the Greenland ice sheet. Under the 2015 Paris Agreement, nations collectively agreed to keep warming "well under 2 °C". However, with pledges made under the Agreement, global warming would still reach about 2.8 °C (5.0 °F) by the end of the century. +There is widespread support for climate action worldwide, and most countries aim to stop emitting carbon dioxide. Fossil fuels can be phased out by stopping subsidising them, conserving energy and switching to energy sources that do not produce significant carbon pollution. These energy sources include wind, solar, hydro, and nuclear power. Cleanly generated electricity can replace fossil fuels for powering transportation, heating buildings, and running industrial processes. Carbon can also be removed from the atmosphere, for instance by increasing forest cover and farming with methods that store carbon in soil. + + + + +== Terminology == +Before the 1980s, it was unclear whether the warming effect of increased greenhouse gases was stronger than the cooling effect of airborne particulates in air pollution. Scientists used the term inadvertent climate modification to refer to human impacts on the climate at this time. In the 1980s, the terms global warming and climate change became more common, often being used interchangeably. Scientifically, global warming refers only to increased global average surface temperature, while climate change describes both global warming and its effects on Earth's climate system, such as precipitation changes. +Climate change can also be used more broadly to include changes to the climate that have happened throughout Earth's history. Global warming—used as early as 1975—became the more popular term after NASA climate scientist James Hansen used it in his 1988 testimony in the U.S. Senate. Since the 2000s, usage of climate change has increased. Various scientists, politicians and media may use the terms climate crisis or climate emergency to talk about climate change, and may use the term global heating instead of global warming. + + +== Global temperature rise == + + +=== Temperatures prior to present-day global warming === + +Over the last few million years the climate cycled through ice ages. One of the hotter periods was the Last Interglacial, around 125,000 years ago, where temperatures were between 0.5 °C and 1.5 °C warmer than before the start of global warming. This period saw sea levels 5 to 10 metres higher than today. The most recent glacial maximum 20,000 years ago was some 5–7 °C colder. This period has sea levels that were over 125 metres (410 ft) lower than today. +Temperatures stabilized in the current interglacial period beginning 11,700 years ago. This period also saw the start of agriculture. Historical patterns of warming and cooling, like the Medieval Warm Period and the Little Ice Age, did not occur at the same time across different regions. Temperatures may have reached as high as those of the late 20th century in a limited set of regions. Climate information for that period comes from climate proxies, such as trees and ice cores. + + +=== Warming since the Industrial Revolution === + +Around 1850 thermometer records began to provide global coverage. +Between the 18th century and 1970 there was little net warming, as the warming impact of greenhouse gas emissions was offset by cooling from sulfur dioxide emissions. Sulfur dioxide causes acid rain, but it also produces sulfate aerosols in the atmosphere, which reflect sunlight and cause global dimming. After 1970, the increasing accumulation of greenhouse gases and controls on sulfur pollution led to a marked increase in temperature. + +Ongoing changes in climate have had no precedent for several thousand years. Multiple datasets all show worldwide increases in surface temperature, at a rate of around 0.2 °C per decade. The 2014–2023 decade warmed to an average 1.19 °C [1.06–1.30 °C] compared to the pre-industrial baseline (1850–1900). Not every single year was warmer than the last: internal climate variability processes can make any year 0.2 °C warmer or colder than the average. From 1998 to 2013, negative phases of two such processes, Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO) caused a short slower period of warming called the "global warming hiatus". After the "hiatus", the opposite occurred, with 2024 well above the recent average at more than +1.5 °C. This is why the temperature change is defined in terms of a 20-year average, which reduces the noise of hot and cold years and decadal climate patterns, and detects the long-term signal. +A wide range of other observations reinforce the evidence of warming. The upper atmosphere is cooling, because greenhouse gases are trapping heat near the Earth's surface, and so less heat is radiating into space. Warming reduces average snow cover and forces the retreat of glaciers. At the same time, warming also causes greater evaporation from the oceans, leading to more atmospheric humidity, more and heavier precipitation. Plants are flowering earlier in spring, and thousands of animal species have been permanently moving to cooler areas. + + +==== Differences by region ==== +Different regions of the world warm at different rates. The pattern is independent of where greenhouse gases are emitted, because the gases persist long enough to diffuse across the planet. Since the pre-industrial period, the average surface temperature over land regions has increased almost twice as fast as the global average surface temperature. This is because oceans lose more heat by evaporation and oceans can store a lot of heat. The thermal energy in the global climate system has grown with only brief pauses since at least 1970, and over 90% of this extra energy has been stored in the ocean. The rest has heated the atmosphere, melted ice, and warmed the continents. +The Northern Hemisphere and the North Pole have warmed much faster than the South Pole and Southern Hemisphere. The Northern Hemisphere not only has much more land, but also more seasonal snow cover and sea ice. As these surfaces flip from reflecting a lot of light to being dark after the ice has melted, they start absorbing more heat. Local black carbon deposits on snow and ice also contribute to Arctic warming. Arctic surface temperatures are increasing between three and four times faster than in the rest of the world. Melting of ice sheets near the poles weakens both the Atlantic and the Antarctic limb of thermohaline circulation, which further changes the distribution of heat and precipitation around the globe. + + +=== Future global temperatures === + +The World Meteorological Organization estimates there is almost a 50% chance of the five-year average global temperature exceeding +1.5 °C between 2024 and 2028. The IPCC expects the 20-year average to exceed +1.5 °C in the early 2030s. +The IPCC Sixth Assessment Report (2021) included projections that by 2100 global warming is very likely to reach 1.0–1.8 °C under a scenario with very low emissions of greenhouse gases, 2.1–3.5 °C under an intermediate emissions scenario, +or 3.3–5.7 °C under a very high emissions scenario. The warming will continue past 2100 in the intermediate and high emission scenarios, with future projections of global surface temperatures by year 2300 being similar to millions of years ago. +The remaining carbon budget for staying beneath certain temperature increases is determined by modelling the carbon cycle and climate sensitivity to greenhouse gases. According to UNEP, global warming can be kept below 2.0 °C with a 50% chance if emissions after 2023 do not exceed 900 gigatonnes of CO2. This carbon budget corresponds to around 16 years of current emissions. + + +== Causes of recent global temperature rise == + +The climate system experiences various cycles on its own which can last for years, decades or even centuries. For example, El Niño events cause short-term spikes in surface temperature while La Niña events cause short term cooling. Their relative frequency can affect global temperature trends on a decadal timescale. Other changes are caused by an imbalance of energy from external forcings. Examples of these include changes in the concentrations of greenhouse gases, solar luminosity, volcanic eruptions, and variations in the Earth's orbit around the Sun. +To determine the human contribution to climate change, unique "fingerprints" for all potential causes are developed and compared with both observed patterns and known internal climate variability. For example, solar forcing—whose fingerprint involves warming the entire atmosphere—is ruled out because only the lower atmosphere has warmed. Atmospheric aerosols produce a smaller, cooling effect. Other drivers, such as changes in albedo, are less impactful. + + +=== Greenhouse gases === + +Greenhouse gases are transparent to sunlight, and thus allow it to pass through the atmosphere to heat the Earth's surface. The Earth radiates it as heat, and greenhouse gases absorb a portion of it. This absorption slows the rate at which heat escapes into space, trapping heat near the Earth's surface and warming it over time. +While water vapour (≈50%) and clouds (≈25%) are the biggest contributors to the greenhouse effect, they primarily change as a function of temperature and are therefore mostly considered to be feedbacks that change climate sensitivity. On the other hand, concentrations of gases such as CO2 (≈20%), tropospheric ozone, CFCs and nitrous oxide are added or removed independently from temperature, and are therefore considered to be external forcings that change global temperatures. +Before the Industrial Revolution, naturally occurring amounts of greenhouse gases caused the air near the surface to be about 33 °C warmer than it would have been in their absence. Human activity since the Industrial Revolution, mainly extracting and burning fossil fuels (coal, oil, and natural gas), has increased the amount of greenhouse gases in the atmosphere. In 2022, the concentrations of CO2 and methane had increased by about 50% and 164%, respectively, since 1750. These CO2 levels are higher than they have been at any time during the last 14 million years. Concentrations of methane are far higher than they were over the last 800,000 years. + +Global human-caused greenhouse gas emissions in 2019 were equivalent to 59 billion tonnes of CO2. Of these emissions, 75% was CO2, 18% was methane, 4% was nitrous oxide, and 2% was fluorinated gases. CO2 emissions primarily come from burning fossil fuels to provide energy for transport, manufacturing, heating, and electricity. Additional CO2 emissions come from deforestation and industrial processes, which include the CO2 released by the chemical reactions for making cement, steel, aluminium, and fertilizer. Methane emissions come from livestock, manure, rice cultivation, landfills, wastewater, and coal mining, as well as oil and gas extraction. Nitrous oxide emissions largely come from the microbial decomposition of fertilizer. +While methane only lasts in the atmosphere for an average of 12 years, CO2 lasts much longer. The Earth's surface absorbs CO2 as part of the carbon cycle. While plants on land and in the ocean absorb most excess emissions of CO2 every year, that CO2 is returned to the atmosphere when biological matter is digested, burns, or decays. Land-surface carbon sink processes, such as carbon fixation in the soil and photosynthesis, remove about 29% of annual global CO2 emissions. The ocean has absorbed 20 to 30% of emitted CO2 over the last two decades. CO2 is only removed from the atmosphere for the long term when it is stored in the Earth's crust, which is a process that can take millions of years to complete. + + +=== Land surface changes === + +Around 30% of Earth's land area is largely unusable for humans (glaciers, deserts, etc.), 26% is forests, 10% is shrubland and 34% is agricultural land. Deforestation is the main land use change contributor to global warming, as the destroyed trees release CO2, and are not replaced by new trees, removing that carbon sink. Between 2001 and 2018, 27% of deforestation was from permanent clearing to enable agricultural expansion for crops and livestock. Another 24% has been lost to temporary clearing under the shifting cultivation agricultural systems. 26% was due to logging for wood and derived products, and wildfires have accounted for the remaining 23%. Some forests have not been fully cleared, but were already degraded by these impacts. Restoring these forests also recovers their potential as a carbon sink. +Local vegetation cover impacts how much of the sunlight gets reflected back into space (albedo), and how much heat is lost by evaporation. For instance, the change from a dark forest to grassland makes the surface lighter, causing it to reflect more sunlight. Deforestation can also modify the release of chemical compounds that influence clouds, and by changing wind patterns. In tropic and temperate areas the net effect is to produce significant warming, and forest restoration can make local temperatures cooler. At latitudes closer to the poles, there is a cooling effect as forest is replaced by snow-covered (and more reflective) plains. Globally, these increases in surface albedo have been the dominant direct influence on temperature from land use change. Thus, land use change to date is estimated to have a slight cooling effect. + + +=== Other factors === + + +==== Aerosols and clouds ==== +Air pollution, in the form of aerosols, affects the climate on a large scale. Aerosols scatter and absorb solar radiation. From 1961 to 1990, a gradual reduction in the amount of sunlight reaching the Earth's surface was observed. This phenomenon is popularly known as global dimming, and is primarily attributed to sulfate aerosols produced by the combustion of fossil fuels with heavy sulfur concentrations like coal and bunker fuel. Smaller contributions come from black carbon (from combustion of fossil fuels and biomass), and from dust. Globally, aerosols have been declining since 1990 due to pollution controls, meaning that they no longer mask greenhouse gas warming as much. +Aerosols also have indirect effects on the Earth's energy budget. Sulfate aerosols act as cloud condensation nuclei and lead to clouds that have more and smaller cloud droplets. These clouds reflect solar radiation more efficiently than clouds with fewer and larger droplets. They also reduce the growth of raindrops, which makes clouds more reflective to incoming sunlight. Indirect effects of aerosols are the largest uncertainty in radiative forcing. +While aerosols typically limit global warming by reflecting sunlight, black carbon in soot that falls on snow or ice can contribute to global warming. Not only does this increase the absorption of sunlight, it also increases melting and sea-level rise. Limiting new black carbon deposits in the Arctic could reduce global warming by 0.2 °C by 2050. The effect of decreasing sulfur content of fuel oil for ships since 2020 is estimated to cause an additional 0.05 °C increase in global mean temperature by 2050. + + +==== Solar and volcanic activity ==== + +As the Sun is the Earth's primary energy source, changes in incoming sunlight directly affect the climate system. Solar irradiance has been measured directly by satellites, and indirect measurements are available from the early 1600s onwards. Since 1880, there has been no upward trend in the amount of the Sun's energy reaching the Earth, in contrast to the warming of the lower atmosphere (the troposphere). The upper atmosphere (the stratosphere) would also be warming if the Sun was sending more energy to Earth, but instead, it has been cooling. +This is consistent with greenhouse gases preventing heat from leaving the Earth's atmosphere. +Explosive volcanic eruptions can release gases, dust and ash that partially block sunlight and reduce temperatures, or they can send water vapour into the atmosphere, which adds to greenhouse gases and increases temperatures. These impacts on temperature only last for several years, because both water vapour and volcanic material have low persistence in the atmosphere. volcanic CO2 emissions are more persistent, but they are equivalent to less than 1% of current human-caused CO2 emissions. Volcanic activity still represents the single largest natural impact (forcing) on temperature in the industrial era. Yet, like the other natural forcings, it has had negligible impacts on global temperature trends since the Industrial Revolution. + + +==== Climate change feedbacks ==== + +The climate system's response to an initial forcing is shaped by feedbacks, which either amplify or dampen the change. Self-reinforcing or positive feedbacks increase the response, while balancing or negative feedbacks reduce it. The main reinforcing feedbacks are the water-vapour feedback, the ice–albedo feedback, and the net cloud feedback. The primary balancing mechanism is radiative cooling, as Earth's surface gives off more heat to space in response to rising temperature. In addition to temperature feedbacks, there are feedbacks in the carbon cycle, such as the fertilizing effect of CO2 on plant growth. Feedbacks are expected to trend in a positive direction as greenhouse gas emissions continue, raising climate sensitivity. +These feedback processes alter the pace of global warming. For instance, warmer air can hold more moisture in the form of water vapour, which is itself a potent greenhouse gas. Warmer air can also make clouds higher and thinner, and therefore more insulating, increasing climate warming. The reduction of snow cover and sea ice in the Arctic is another major feedback, this reduces the reflectivity of the Earth's surface in the region and accelerates Arctic warming. This additional warming also contributes to permafrost thawing, which releases methane and CO2 into the atmosphere. +Around half of human-caused CO2 emissions have been absorbed by land plants and by the oceans. This fraction is not static and if future CO2 emissions decrease, the Earth will be able to absorb up to around 70%. If they increase substantially, it'll still absorb more carbon than now, but the overall fraction will decrease to below 40%. This is because climate change increases droughts and heat waves that eventually inhibit plant growth on land, and soils will release more carbon from dead plants when they are warmer. The rate at which oceans absorb atmospheric carbon will be lowered as they become more acidic and experience changes in thermohaline circulation and phytoplankton distribution. Uncertainty over feedbacks, particularly cloud cover, is the major reason why different climate models project different magnitudes of warming for a given amount of emissions. + + +== Modelling == + +A climate model is a representation of the physical, chemical and biological processes that affect the climate system. Models include natural processes like changes in the Earth's orbit, historical changes in the Sun's activity, and volcanic forcing. Models are used to estimate the degree of warming future emissions will cause when accounting for the strength of climate feedbacks. Models also predict the circulation of the oceans, the annual cycle of the seasons, and the flows of carbon between the land surface and the atmosphere. +The physical realism of models is tested by examining their ability to simulate current or past climates. Past models have underestimated the rate of Arctic shrinkage and underestimated the rate of precipitation increase. Sea level rise since 1990 was underestimated in older models, but more recent models agree well with observations. The 2017 United States-published National Climate Assessment notes that "climate models may still be underestimating or missing relevant feedback processes". Additionally, climate models may be unable to adequately predict short-term regional climatic shifts. +A subset of climate models add societal factors to a physical climate model. These models simulate how population, economic growth, and energy use affect—and interact with—the physical climate. With this information, these models can produce scenarios of future greenhouse gas emissions. This is then used as input for physical climate models and carbon cycle models to predict how atmospheric concentrations of greenhouse gases might change. Depending on the socioeconomic scenario and the mitigation scenario, models produce atmospheric CO2 concentrations that range widely between 380 and 1400 ppm. + + +== Impacts == + + +=== Environmental effects === + +The environmental effects of climate change are broad and far-reaching, affecting oceans, ice, and weather. Changes may occur gradually or rapidly. Evidence for these effects comes from studying climate change in the past, from modelling, and from modern observations. Since the 1950s, droughts and heat waves have appeared simultaneously with increasing frequency. Extremely wet or dry events within the monsoon period have increased in India and East Asia. Monsoonal precipitation over the Northern Hemisphere has increased since 1980. The rainfall rate and intensity of hurricanes and typhoons is likely increasing, and the geographic range likely expanding poleward in response to climate warming. The frequency of tropical cyclones has not increased as a result of climate change. + +Global sea level is rising as a consequence of thermal expansion and the melting of glaciers and ice sheets. Sea level rise has increased over time, reaching 4.8 cm per decade between 2014 and 2023. Over the 21st century, the IPCC projects 32–62 cm of sea level rise under a low emission scenario, 44–76 cm under an intermediate one and 65–101 cm under a very high emission scenario. Marine ice sheet instability processes in Antarctica may add substantially to these values, including the possibility of a 2-meter sea level rise by 2100 under high emissions. +Climate change has led to decades of shrinking and thinning of the Arctic sea ice. While ice-free summers are expected to be rare at 1.5 °C degrees of warming, they are set to occur once every three to ten years at a warming level of 2 °C. Higher atmospheric CO2 concentrations cause more CO2 to dissolve in the oceans, which is making them more acidic. Because oxygen is less soluble in warmer water, its concentrations in the ocean are decreasing, and dead zones are expanding. + + +=== Tipping points and long-term impacts === + +Greater degrees of global warming increase the risk of passing through 'tipping points'—thresholds beyond which certain major impacts can no longer be avoided even if temperatures return to their previous state. For instance, the Greenland ice sheet is already melting, but if global warming reaches levels between 1.7 °C and 2.3 °C, its melting will continue until it fully disappears. If the warming is later reduced to 1.5 °C or less, it will still lose a lot more ice than if the warming was never allowed to reach the threshold in the first place. While the ice sheets would melt over millennia, other tipping points would occur faster and give societies less time to respond. The collapse of major ocean currents like the Atlantic meridional overturning circulation (AMOC), and irreversible damage to key ecosystems like the Amazon rainforest and coral reefs can unfold in a matter of decades. The collapse of the AMOC would be a severe climate catastrophe, resulting in a cooling of the Northern Hemisphere. +The long-term effects of climate change on oceans include further ice melt, ocean warming, sea level rise, ocean acidification and ocean deoxygenation. The timescale of long-term impacts are centuries to millennia due to CO2's long atmospheric lifetime. The result is an estimated total sea level rise of 2.3 metres per degree Celsius (4.2 ft/°F) after 2000 years. Oceanic CO2 uptake is slow enough that ocean acidification will also continue for hundreds to thousands of years. Deep oceans (below 2,000 metres (6,600 ft)) are also already committed to losing over 10% of their dissolved oxygen by the warming which occurred to date. Further, the West Antarctic ice sheet appears committed to practically irreversible melting, which would increase the sea levels by at least 3.3 m (10 ft 10 in) over approximately 2000 years. + + +=== Nature and wildlife === + +Recent warming has driven many terrestrial and freshwater species poleward and towards higher altitudes. For instance, the range of hundreds of North American birds has shifted northward at an average rate of 1.5 km/year over the past 55 years. Higher atmospheric CO2 levels and an extended growing season have resulted in global greening. However, heatwaves and drought have reduced ecosystem productivity in some regions. The future balance of these opposing effects is unclear. A related phenomenon driven by climate change is woody plant encroachment, affecting up to 500 million hectares globally. Climate change has contributed to the expansion of drier climate zones, such as the expansion of deserts in the subtropics. The size and speed of global warming is making abrupt changes in ecosystems more likely. Overall, it is expected that climate change will result in the extinction of many species. +The oceans have heated more slowly than the land, but plants and animals in the ocean have migrated towards the colder poles faster than species on land. Just as on land, heat waves in the ocean occur more frequently due to climate change, harming a wide range of organisms such as corals, kelp, and seabirds. Ocean acidification makes it harder for marine calcifying organisms such as mussels, barnacles and corals to produce shells and skeletons; and heatwaves have bleached coral reefs. Harmful algal blooms enhanced by climate change and eutrophication lower oxygen levels, disrupt food webs and cause great loss of marine life. Coastal ecosystems are under particular stress. Almost half of global wetlands have disappeared due to climate change and other human impacts. Plants have come under increased stress from damage by insects. + + +=== Humans === + +The effects of climate change are impacting humans everywhere in the world. Impacts can be observed on all continents and ocean regions, with low-latitude, less developed areas facing the greatest risk. Continued warming has potentially "severe, pervasive and irreversible impacts" for people and ecosystems. The risks are unevenly distributed, but are generally greater for disadvantaged people in developing and developed countries. + + +==== Health and food ==== + +The World Health Organization calls climate change one of the biggest threats to global health in the 21st century. Scientists have warned about the irreversible harms it poses. Extreme weather events affect public health, and food and water security. Temperature extremes lead to increased illness and death. Climate change increases the intensity and frequency of extreme weather events. It can affect transmission of infectious diseases, such as dengue fever and malaria. According to the World Economic Forum, 14.5 million more deaths are expected due to climate change by 2050. 30% of the global population currently live in areas where extreme heat and humidity are already associated with excess deaths. By 2100, 50% to 75% of the global population would live in such areas. +While total crop yields have been increasing in the past 50 years due to agricultural improvements, climate change has already decreased the rate of yield growth. Fisheries have been negatively affected in multiple regions. While agricultural productivity has been positively affected in some high latitude areas, mid- and low-latitude areas have been negatively affected. According to the World Economic Forum, an increase in drought in certain regions could cause 3.2 million deaths from malnutrition by 2050 and stunting in children. With 2 °C warming, global livestock headcounts could decline by 7–10% by 2050, as less animal feed will be available. If the emissions continue to increase for the rest of century, then over 9 million climate-related deaths would occur annually by 2100. + + +==== Livelihoods and inequality ==== + +Economic damages due to climate change may be severe and there is a chance of disastrous consequences. Severe impacts are expected in South-East Asia and sub-Saharan Africa, where most of the local inhabitants are dependent upon natural and agricultural resources. Heat stress can prevent outdoor labourers from working. If warming reaches 4 °C then labour capacity in those regions could be reduced by 30 to 50%. The World Bank estimates that between 2016 and 2030, climate change could drive over 120 million people into extreme poverty without adaptation. +Inequalities based on wealth and social status have worsened due to climate change. Major difficulties in mitigating, adapting to, and recovering from climate shocks are faced by marginalized people who have less control over resources. Indigenous people, who are subsistent on their land and ecosystems, will face endangerment to their wellness and lifestyles due to climate change. An expert elicitation concluded that the role of climate change in armed conflict has been small compared to factors such as socio-economic inequality and state capabilities. +While women are not inherently more at risk from climate change and shocks, limits on women's resources and discriminatory gender norms constrain their adaptive capacity and resilience. For example, women's work burdens, including hours worked in agriculture, tend to decline less than men's during climate shocks such as heat stress. + + +==== Climate migration ==== + +Low-lying islands and coastal communities are threatened by sea level rise, which makes urban flooding more common. Sometimes, land is permanently lost to the sea. This could lead to statelessness for people in island nations, such as the Maldives and Tuvalu. In some regions, the rise in temperature and humidity may be too severe for humans to adapt to. With worst-case climate change, models project that areas almost one-third of humanity live in might become Sahara-like uninhabitable and extremely hot climates. +These factors can drive climate or environmental migration, within and between countries. More people are expected to be displaced because of sea level rise, extreme weather and conflict from increased competition over natural resources. Climate change may also increase vulnerability, leading to "trapped populations" who are not able to move due to a lack of resources. + + +== Reducing and recapturing emissions == + +Climate change can be mitigated by reducing the rate at which greenhouse gases are emitted into the atmosphere, and by increasing the rate at which carbon dioxide is removed from the atmosphere. To limit global warming to less than 2 °C global greenhouse gas emissions need to be net-zero by 2070. This requires far-reaching, systemic changes on an unprecedented scale in energy, land, cities, transport, buildings, and industry. +The United Nations Environment Programme estimates that countries need to triple their pledges under the Paris Agreement within the next decade to limit global warming to 2 °C. With pledges made under the Paris Agreement as of 2024, there would be a 66% chance that global warming is kept under 2.8 °C by the end of the century (range: 1.9–3.7 °C, depending on exact implementation and technological progress). When only considering current policies, this raises to 3.1 °C. Globally, limiting warming to 2 °C may result in higher economic benefits than economic costs. +Although there is no single pathway to limit global warming to 2 °C, most scenarios and strategies see a major increase in the use of renewable energy in combination with increased energy efficiency measures to generate the needed greenhouse gas reductions. To reduce pressures on ecosystems and enhance their carbon sequestration capabilities, changes would also be necessary in agriculture and forestry, such as preventing deforestation and restoring natural ecosystems by reforestation. +Other approaches to mitigating climate change have a higher level of risk. Scenarios that limit global warming to 1.5 °C typically project the large-scale use of carbon dioxide removal methods over the 21st century. There are concerns, though, about over-reliance on these technologies, and environmental impacts. +Solar radiation modification (SRM) is a proposal for reducing global warming by reflecting some sunlight away from Earth and back into space. Because it does not reduce greenhouse gas concentrations, it would not address ocean acidification and is not considered mitigation. SRM should be considered only as a supplement to mitigation, not a replacement for it, due to risks such as rapid warming if it were abruptly stopped and not restarted. The most-studied approach is stratospheric aerosol injection. SRM could reduce global warming and some of its impacts, though imperfectly. It poses environmental risks, such as changes to rainfall patterns, as well as political challenges, such as who would decide whether to use it. + + +=== Clean energy === + +Renewable energy is key to limiting climate change. For decades, fossil fuels have accounted for roughly 80% of the world's energy use. The remaining share has been split between nuclear power and renewables (including hydropower, bioenergy, wind and solar power and geothermal energy). Fossil fuel use is expected to peak in absolute terms prior to 2030 and then to decline, with coal use experiencing the sharpest reductions. Renewables represented 86% of all new electricity generation installed in 2023. Other forms of clean energy, such as nuclear and hydropower, currently have a larger share of the energy supply. However, their future growth forecasts appear limited in comparison. +While solar panels and onshore wind are now among the cheapest forms of adding new power generation capacity in many locations, green energy policies are needed to achieve a rapid transition from fossil fuels to renewables. To achieve carbon neutrality by 2050, renewable energy would become the dominant form of electricity generation, rising to 85% or more by 2050 in some scenarios. Investment in coal would be eliminated and coal use nearly phased out by 2050. +Electricity generated from renewable sources would also need to become the main energy source for heating and transport. Transport can switch away from internal combustion engine vehicles and towards electric vehicles, public transit, and active transport (cycling and walking). For shipping and flying, low-carbon fuels would reduce emissions. Heating could be increasingly decarbonized with technologies like heat pumps. +There are obstacles to the continued rapid growth of clean energy, including renewables. Wind and solar produce energy intermittently and with seasonal variability. Traditionally, hydro dams with reservoirs and fossil fuel power plants have been used when variable energy production is low. Going forward, battery storage can be expanded, energy demand and supply can be matched, and long-distance transmission can smooth variability of renewable outputs. Bioenergy is often not carbon-neutral and may have negative consequences for food security. The growth of nuclear power is constrained by controversy around radioactive waste, nuclear weapon proliferation, and accidents. Hydropower growth is limited by the fact that the best sites have been developed, and new projects are confronting increased social and environmental concerns. +Low-carbon energy improves human health by minimizing climate change as well as reducing air pollution deaths, which were estimated at 7 million annually in 2016. Meeting the Paris Agreement goals that limit warming to a 2 °C increase could save about a million of those lives per year by 2050, whereas limiting global warming to 1.5 °C could save millions and simultaneously increase energy security and reduce poverty. Improving air quality also has economic benefits which may be larger than mitigation costs. + + +=== Energy conservation === + +Reducing energy demand is another major aspect of reducing emissions. If less energy is needed, there is more flexibility for clean energy development. It also makes it easier to manage the electricity grid, and minimizes carbon-intensive infrastructure development. Major increases in energy efficiency investment will be required to achieve climate goals, comparable to the level of investment in renewable energy. Several COVID-19 related changes in energy use patterns, energy efficiency investments, and funding have made forecasts for this decade more difficult and uncertain. +Strategies to reduce energy demand vary by sector. In the transport sector, passengers and freight can switch to more efficient travel modes, such as buses and trains, or use electric vehicles. Industrial strategies to reduce energy demand include improving heating systems and motors, designing less energy-intensive products, and increasing product lifetimes. In the building sector the focus is on better design of new buildings, and higher levels of energy efficiency in retrofitting. The use of technologies like heat pumps can also increase building energy efficiency. + + +=== Agriculture and industry === + + Agriculture and forestry face a triple challenge of limiting greenhouse gas emissions, preventing the further conversion of forests to agricultural land, and meeting increases in world food demand. A set of actions could reduce agriculture and forestry-based emissions by two-thirds from 2010 levels. These include reducing growth in demand for food and other agricultural products, increasing land productivity, protecting and restoring forests, and reducing greenhouse gas emissions from agricultural production. +On the demand side, a key component of reducing emissions is shifting people towards plant-based diets. Eliminating the production of livestock for meat and dairy would eliminate about 3/4ths of all emissions from agriculture and other land use. Livestock also occupy 37% of ice-free land area on Earth and consume feed from the 12% of land area used for crops, driving deforestation and land degradation. +Steel and cement production are responsible for about 13% of industrial CO2 emissions. In these industries, carbon-intensive materials such as coke and lime play an integral role in the production, so that reducing CO2 emissions requires research into alternative chemistries. Where energy production or CO2-intensive heavy industries continue to produce waste CO2, technology can sometimes be used to capture and store most of the gas instead of releasing it to the atmosphere. This technology, carbon capture and storage (CCS), could have a critical but limited role in reducing emissions. It is relatively expensive and has been deployed only to an extent that removes around 0.1% of annual greenhouse gas emissions. + + +=== Carbon dioxide removal === + +Natural carbon sinks can be enhanced to sequester significantly larger amounts of CO2 beyond naturally occurring levels. Reforestation and afforestation (planting forests where there were none before) are among the most mature sequestration techniques, although the latter raises food security concerns. Farmers can promote sequestration of carbon in soils through practices such as use of winter cover crops, reducing the intensity and frequency of tillage, and using compost and manure as soil amendments. Forest and landscape restoration yields many benefits for the climate, including greenhouse gas emissions sequestration and reduction. Restoration/recreation of coastal wetlands, prairie plots and seagrass meadows increases the uptake of carbon into organic matter. When carbon is sequestered in soils and in organic matter such as trees, there is a risk of the carbon being re-released into the atmosphere later through changes in land use, fire, or other changes in ecosystems. +The use of bioenergy in conjunction with carbon capture and storage (BECCS) can result in net negative emissions as CO2 is drawn from the atmosphere. It remains highly uncertain whether carbon dioxide removal techniques will be able to play a large role in limiting warming to 1.5 °C. Policy decisions that rely on carbon dioxide removal increase the risk of global warming rising beyond international goals. + + +== Adaptation == + +Adaptation is "the process of adjustment to current or expected changes in climate and its effects". Without additional mitigation, adaptation cannot avert the risk of "severe, widespread and irreversible" impacts. More severe climate change requires more transformative adaptation, which can be prohibitively expensive. The capacity and potential for humans to adapt is unevenly distributed across different regions and populations, and developing countries generally have less. The first two decades of the 21st century saw an increase in adaptive capacity in most low- and middle-income countries with improved access to basic sanitation and electricity, but progress is slow. Many countries have implemented adaptation policies. However, there is a considerable gap between necessary and available finance. +Adaptation to sea level rise consists of avoiding at-risk areas, learning to live with increased flooding, and building flood controls. If that fails, managed retreat may be needed. There are economic barriers for tackling dangerous heat impact. Avoiding strenuous work or having air conditioning is not possible for everybody. In agriculture, adaptation options include a switch to more sustainable diets, diversification, erosion control, and genetic improvements for increased tolerance to a changing climate. Insurance allows for risk-sharing, but is often difficult to get for people on lower incomes. Education, migration and early warning systems can reduce climate vulnerability. Planting mangroves or encouraging other coastal vegetation can buffer storms. +Ecosystems adapt to climate change, a process that can be supported by human intervention. By increasing connectivity between ecosystems, species can migrate to more favourable climate conditions. Species can also be introduced to areas acquiring a favourable climate. Protection and restoration of natural and semi-natural areas helps build resilience, making it easier for ecosystems to adapt. Many of the actions that promote adaptation in ecosystems, also help humans adapt via ecosystem-based adaptation. For instance, restoration of natural fire regimes makes catastrophic fires less likely, and reduces human exposure. Giving rivers more space allows for more water storage in the natural system, reducing flood risk. Restored forest acts as a carbon sink, but planting trees in unsuitable regions can exacerbate climate impacts. +There are synergies but also trade-offs between adaptation and mitigation. An example for synergy is increased food productivity, which has large benefits for both adaptation and mitigation. An example of a trade-off is that increased use of air conditioning allows people to better cope with heat, but increases energy demand. Another trade-off example is that more compact urban development may reduce emissions from transport and construction, but may also increase the urban heat island effect, exposing people to heat-related health risks. + + +== Policies and politics == + +Countries that are most vulnerable to climate change have typically been responsible for a small share of global emissions. This raises questions about justice and fairness. Limiting global warming makes it much easier to achieve the UN's Sustainable Development Goals, such as eradicating poverty and reducing inequalities. The connection is recognized in Sustainable Development Goal 13 which is to "take urgent action to combat climate change and its impacts". The goals on food, clean water and ecosystem protection have synergies with climate mitigation. +The geopolitics of climate change is complex. It has often been framed as a free-rider problem, in which all countries benefit from mitigation done by other countries, but individual countries would lose from switching to a low-carbon economy themselves. Sometimes mitigation also has localized benefits though. For instance, the benefits of a coal phase-out to public health and local environments exceed the costs in almost all regions. Furthermore, net importers of fossil fuels win economically from switching to clean energy, causing net exporters to face stranded assets: fossil fuels they cannot sell. + + +=== Policy options === + +A wide range of policies, regulations, and laws are being used to reduce emissions. As of 2019, carbon pricing covers about 20% of global greenhouse gas emissions. Carbon can be priced with carbon taxes and emissions trading systems. Direct global fossil fuel subsidies reached $319 billion in 2017, and $5.2 trillion when indirect costs such as air pollution are priced in. Ending these can cause a 28% reduction in global carbon emissions and a 46% reduction in air pollution deaths. Money saved on fossil subsidies could be used to support the transition to clean energy instead. More direct methods to reduce greenhouse gases include vehicle efficiency standards, renewable fuel standards, and air pollution regulations on heavy industry. Several countries require utilities to increase the share of renewables in power production. A global carbon market coalition proposed at COP30 (2025) was estimated to increase emissions reduction seven-fold over current policies, while delivering $200 billion per year for clean-energy and social programs. + + +==== Climate justice ==== +Policy designed through the lens of climate justice tries to address human rights issues and social inequality. According to proponents of climate justice, the costs of climate adaptation should be paid by those most responsible for climate change, while the beneficiaries of payments should be those suffering impacts. One way this can be addressed in practice is to have wealthy nations pay poorer countries to adapt. +Oxfam found that in 2023 the wealthiest 10% of people were responsible for 50% of global emissions, while the bottom 50% were responsible for just 8%. Production of emissions is another way to look at responsibility: under that approach, the top 21 fossil fuel companies would owe cumulative climate reparations of $5.4 trillion over the period 2025–2050. To achieve a just transition, people working in the fossil fuel sector would also need other jobs, and their communities would need investments. + + +=== International climate agreements === + +Nearly all countries in the world are parties to the 1994 United Nations Framework Convention on Climate Change (UNFCCC). The goal of the UNFCCC is to prevent dangerous human interference with the climate system. As stated in the convention, this requires that greenhouse gas concentrations are stabilized in the atmosphere at a level where ecosystems can adapt naturally to climate change, food production is not threatened, and economic development can be sustained. The UNFCCC does not itself restrict emissions but rather provides a framework for protocols that do. Global emissions have risen since the UNFCCC was signed. Its yearly conferences are the stage of global negotiations. +The 1997 Kyoto Protocol extended the UNFCCC and included legally binding commitments for most developed countries to limit their emissions. During the negotiations, the G77 (representing developing countries) pushed for a mandate requiring developed countries to "[take] the lead" in reducing their emissions, since developed countries contributed most to the accumulation of greenhouse gases in the atmosphere. Per-capita emissions were also still relatively low in developing countries and developing countries would need to emit more to meet their development needs. +The 2009 Copenhagen Accord has been widely portrayed as disappointing because of its low goals, and was rejected by poorer nations including the G77. Associated parties aimed to limit the global temperature rise to below 2 °C. The accord set the goal of sending $100 billion per year to developing countries for mitigation and adaptation by 2020, and proposed the founding of the Green Climate Fund. As of 2020, only 83.3 billion were delivered. Only in 2023 the target is expected to be achieved. +In 2015 all UN countries negotiated the Paris Agreement, which aims to keep global warming well below 2.0 °C and contains an aspirational goal of keeping warming under 1.5 °C. The agreement replaced the Kyoto Protocol. Unlike Kyoto, no binding emission targets were set in the Paris Agreement. Instead, a set of procedures was made binding. Countries have to regularly set ever more ambitious goals and reevaluate these goals every five years. The Paris Agreement restated that developing countries must be financially supported. As of March 2025, 194 states and the European Union have acceded to or ratified the agreement. +The 1987 Montreal Protocol, an international agreement to phase out production of ozone-depleting gases, has had benefits for climate change mitigation. Several ozone-depleting gases like chlorofluorocarbons are powerful greenhouse gases, so banning their production and usage may have avoided a temperature rise of 0.5 °C–1.0 °C, as well as additional warming by preventing damage to vegetation from ultraviolet radiation. It is estimated that the agreement has been more effective at curbing greenhouse gas emissions than the Kyoto Protocol specifically designed to do so. The most recent amendment to the Montreal Protocol, the 2016 Kigali Amendment, committed to reducing the emissions of hydrofluorocarbons, which served as a replacement for banned ozone-depleting gases and are also potent greenhouse gases. Should countries comply with the amendment, a warming of 0.3 °C–0.5 °C is estimated to be avoided. + + +=== National responses === + +In 2019, the United Kingdom parliament became the first national government to declare a climate emergency. Other countries and jurisdictions followed suit. That same year, the European Parliament declared a "climate and environmental emergency". The European Commission presented its European Green Deal with the goal of making the EU carbon-neutral by 2050. In 2021, the European Commission released its "Fit for 55" legislation package, which contains guidelines for the car industry; all new cars on the European market must be zero-emission vehicles from 2035. +Major countries in Asia have made similar pledges: South Korea and Japan have committed to become carbon-neutral by 2050, and China by 2060. While India has strong incentives for renewables, it also plans a significant expansion of coal in the country. Vietnam is among very few coal-dependent, fast-developing countries that pledged to phase out unabated coal power by the 2040s or as soon as possible thereafter. +As of 2021, based on information from 48 national climate plans, which represent 40% of the parties to the Paris Agreement, estimated total greenhouse gas emissions will be 0.5% lower compared to 2010 levels, below the 45% or 25% reduction goals to limit global warming to 1.5 °C or 2 °C, respectively. + + +== Society and culture == + + +=== Denial and misinformation === + +Public debate about climate change has been strongly affected by climate change denial and misinformation, which first emerged in the United States and has since spread to other countries, particularly Canada and Australia. It originated from fossil fuel companies, industry groups, conservative think tanks, and contrarian scientists. Like the tobacco industry, the main strategy of these groups has been to manufacture doubt about climate-change related scientific data and results. People who hold unwarranted doubt about climate change are sometimes called climate change "skeptics", although "contrarians" or "deniers" are more appropriate terms. +There are different variants of climate denial: some deny that warming takes place at all, some acknowledge warming but attribute it to natural influences, and some minimize the negative impacts of climate change. Manufacturing uncertainty about the science later developed into a manufactured controversy: creating the belief that there is significant uncertainty about climate change within the scientific community to delay policy changes. Strategies to promote these ideas include criticism of scientific institutions, and questioning the motives of individual scientists. An echo chamber of climate-denying blogs and media has further fomented misunderstanding of climate change. + + +=== Public awareness and opinion === + +Climate change came to international public attention in the late 1980s. Due to media coverage in the early 1990s, people often confused climate change with other environmental issues like ozone depletion. In popular culture, the climate fiction movie The Day After Tomorrow (2004) and the Al Gore documentary An Inconvenient Truth (2006) focused on climate change. +Significant regional, gender, age and political differences exist in both public concern for, and understanding of, climate change. More highly educated people, and in some countries, women and younger people, were more likely to see climate change as a serious threat. College biology textbooks from the 2010s featured less content on climate change compared to those from the preceding decade, with decreasing emphasis on solutions. Partisan gaps also exist in many countries, and countries with high CO2 emissions tend to be less concerned. Views on causes of climate change vary widely between countries. Media coverage linked to protests has had impacts on public sentiment as well as on which aspects of climate change are focused upon. Higher levels of worry are associated with stronger public support for policies that address climate change. Concern has increased over time, and in 2021 a majority of citizens in 30 countries expressed a high level of worry about climate change, or view it as a global emergency. A 2024 survey across 125 countries found that 89% of the global population demanded intensified political action, but systematically underestimated other peoples' willingness to act. + + +==== Climate movement ==== + +Climate protests demand that political leaders take action to prevent climate change. They can take the form of public demonstrations, fossil fuel divestment, lawsuits and other activities. Prominent demonstrations include the School Strike for Climate. In this initiative, young people across the globe have been protesting since 2018 by skipping school on Fridays, inspired by Swedish activist and then-teenager Greta Thunberg. Mass civil disobedience actions by groups like Extinction Rebellion have protested by disrupting roads and public transport. +Litigation is increasingly used as a tool to strengthen climate action from public institutions and companies. Activists also initiate lawsuits which target governments and demand that they take ambitious action or enforce existing laws on climate change. Lawsuits against fossil-fuel companies generally seek compensation for loss and damage. On 23 July 2025, the UN's International Court of Justice issued its advisory opinion, saying explicitly that states must act to stop climate change, and if they fail to accomplish that duty, other states can sue them. This obligation includes implementing their commitments in international agreements they are parties to, such as the 2015 Paris Climate Accord. + + +== History == + + +=== Early discoveries === + +Scientists in the 19th century such as Alexander von Humboldt began to foresee the effects of climate change. In the 1820s, Joseph Fourier proposed the greenhouse effect to explain why Earth's temperature was higher than the Sun's energy alone could explain. Earth's atmosphere is transparent to sunlight, so sunlight reaches the surface where it is converted to heat. However, the atmosphere is not transparent to heat radiating from the surface, and captures some of that heat, which in turn warms the planet. +In 1856 Eunice Newton Foote demonstrated that the warming effect of the Sun is greater for air with water vapour than for dry air, and that the effect is even greater with carbon dioxide (CO2). In "Circumstances Affecting the Heat of the Sun's Rays" she concluded that "[a]n atmosphere of that gas would give to our earth a high temperature". + +Starting in 1859, John Tyndall established that nitrogen and oxygen—together totalling 99% of dry air—are transparent to radiated heat. However, water vapour and gases such as methane and carbon dioxide absorb radiated heat and re-radiate that heat into the atmosphere. Tyndall proposed that changes in the concentrations of these gases may have caused climatic changes in the past, including ice ages. +Svante Arrhenius noted that water vapour in air continuously varied, but the CO2 concentration in air was influenced by long-term geological processes. Warming from increased CO2 levels would increase the amount of water vapour, amplifying warming in a positive feedback loop. In 1896, he published the first climate model of its kind, projecting that halving CO2 levels could have produced a drop in temperature initiating an ice age. Arrhenius calculated the temperature increase expected from doubling CO2 to be around 5–6 °C. Other scientists were initially sceptical and believed that the greenhouse effect was saturated so that adding more CO2 would make no difference, and that the climate would be self-regulating. Beginning in 1938, Guy Stewart Callendar published evidence that climate was warming and CO2 levels were rising, but his calculations met the same objections. + + +=== Development of a scientific consensus === + +In the 1950s, Gilbert Plass created a detailed computer model that included different atmospheric layers and the infrared spectrum. This model predicted that increasing CO2 levels would cause warming. Around the same time, Hans Suess found evidence that CO2 levels had been rising, and Roger Revelle showed that the oceans would not absorb the increase. The two scientists subsequently helped Charles Keeling to begin a record of continued increase—the "Keeling Curve"—which was part of continued scientific investigation through the 1960s into possible human causation of global warming. Studies such as the National Research Council's 1979 Charney Report supported the accuracy of climate models that forecast significant warming. Human causation of observed global warming and dangers of unmitigated warming were publicly presented in James Hansen's 1988 testimony before a US Senate committee. The Intergovernmental Panel on Climate Change (IPCC), set up in 1988 to provide formal advice to the world's governments, spurred interdisciplinary research. As part of the IPCC reports, scientists assess the scientific discussion that takes place in peer-reviewed journal articles. +There is a nearly unanimous scientific consensus that the climate is warming and that this is caused by human activities. No scientific body of national or international standing disagrees with this view. As of 2019, agreement in recent literature reached over 99%. The 2021 IPCC Assessment Report stated that it is "unequivocal" that climate change is caused by humans. Consensus has further developed that action should be taken to protect people against the impacts of climate change. National science academies have called on world leaders to cut global emissions. + + +=== Recent developments === +Extreme event attribution (EEA), also known as attribution science, was developed in the early decades of the 21st century. EEA uses climate models to identify and quantify the role that human-caused climate change plays in the frequency, intensity, duration, and impacts of specific individual extreme weather events. Results of attribution studies allow scientists and journalists to make statements such as, "this weather event was made at least n times more likely by human-caused climate change" or "this heatwave was made m degrees hotter than it would have been in a world without global warming" or "this event was effectively impossible without climate change". Greater computing power in the 2000s and conceptual breakthroughs in the early to mid 2010s enabled attribution science to detect the effects of climate change on some events with high confidence. Scientists use attribution methods and climate simulations that have already been peer reviewed, allowing "rapid attribution studies" to be published within a "news cycle" time frame after weather events. + + +== References == + + +=== Sources === + This article incorporates text from a free content work. Licensed under CC BY-SA 3.0. Text taken from The status of women in agrifood systems – Overview​, FAO, FAO. + + +==== IPCC reports ==== + + +==== Other peer-reviewed sources ==== + + +==== Books, reports and legal documents ==== + + +==== Non-technical sources ==== + + +== External links == + +Intergovernmental Panel on Climate Change: IPCC (IPCC) +UN: Climate Change (UN) +Met Office: Climate Guide (Met Office) +National Oceanic and Atmospheric Administration: Climate (NOAA) +Royal Society. Climate change: Evidence and causes (Royal Society) \ No newline at end of file diff --git a/lightrag/evaluation/wiki_documents/climate_renewable_energy.txt b/lightrag/evaluation/wiki_documents/climate_renewable_energy.txt new file mode 100644 index 00000000..ec1f358c --- /dev/null +++ b/lightrag/evaluation/wiki_documents/climate_renewable_energy.txt @@ -0,0 +1,394 @@ +Renewable energy (also called green energy) is energy made from renewable natural resources that are replenished on a human timescale. The most widely used renewable energy types are solar energy, wind power, and hydropower. Bioenergy and geothermal power are also significant in some countries. Some also consider nuclear power a renewable power source, although this is controversial, as nuclear energy requires mining uranium, a nonrenewable resource. Renewable energy installations can be large or small and are suited for both urban and rural areas. Renewable energy is often deployed together with further electrification. This has several benefits: electricity can move heat and vehicles efficiently and is clean at the point of consumption. Variable renewable energy sources are those that have a fluctuating nature, such as wind power and solar power. In contrast, controllable renewable energy sources include dammed hydroelectricity, bioenergy, or geothermal power. + +Renewable energy systems have rapidly become more efficient and cheaper over the past 30 years. A large majority of worldwide newly installed worldwide electricity capacity is now renewable. Renewable energy sources, such as solar and wind power, have seen significant cost reductions over the past decade, making them more competitive with traditional fossil fuels. In some geographic localities, photovoltaic solar or onshore wind is the cheapest new-build electricity. From 2011 to 2021, renewable energy grew from 20% to 28% of the global electricity supply. Power from the sun and wind accounted for most of this increase, growing from a combined 2% to 10%. Use of fossil energy shrank from 68% to 62%. In 2024, renewables accounted for over 30% of global electricity generation and are projected to reach over 45% by 2030. Many countries already have renewables contributing more than 20% of their total energy supply, with some generating over half or even all their electricity from renewable sources. +The main motivation to use renewable energy instead of fossil fuels is to slow and eventually stop climate change, which is mostly caused by their greenhouse gas emissions. In general, renewable energy sources pollute much less than fossil fuels. The International Energy Agency estimates that to achieve net zero emissions by 2050, 90% of global electricity will need to be generated by renewables. Renewables also cause much less air pollution than fossil fuels, improving public health, and are less noisy. + +The deployment of renewable energy still faces obstacles, especially fossil fuel subsidies, lobbying by incumbent power providers, and local opposition to the use of land for renewable installations. Like all mining, the extraction of minerals required for many renewable energy technologies also results in environmental damage. In addition, although most renewable energy sources are sustainable, some are not. + + +== Overview == + + +=== Definition === +Renewable energy is usually understood as energy harnessed from continuously occurring natural phenomena. The International Energy Agency defines it as "energy derived from natural processes that are replenished at a faster rate than they are consumed". Solar power, wind power, hydroelectricity, geothermal energy, and biomass are widely agreed to be the main types of renewable energy. Renewable energy often displaces conventional fuels in four areas: electricity generation, hot water/space heating, transportation, and rural (off-grid) energy services. +Although almost all forms of renewable energy cause much fewer carbon emissions than fossil fuels, the term is not synonymous with low-carbon energy. Some non-renewable sources of energy, such as nuclear power,generate almost no emissions, while some renewable energy sources can be very carbon-intensive, such as the burning of biomass if it is not offset by planting new plants. Renewable energy is also distinct from sustainable energy, a more abstract concept that seeks to group energy sources based on their overall permanent impact on future generations of humans. For example, biomass is often associated with unsustainable deforestation. + + +=== Role in addressing climate change === +As part of the global effort to limit climate change, most countries have committed to net zero greenhouse gas emissions. In practice, this means phasing out fossil fuels and replacing them with low-emissions energy sources. This much needed process, coined as "low-carbon substitutions" in contrast to other transition processes including energy additions, needs to be accelerated multiple times in order to successfully mitigate climate change. At the 2023 United Nations Climate Change Conference, around three-quarters of the world's countries set a goal of tripling renewable energy capacity by 2030. The European Union aims to generate 40% of its electricity from renewables by the same year. + + +=== Other benefits === + +Renewable energy is more evenly distributed around the world than fossil fuels, which are concentrated in a limited number of countries. It also brings health benefits by reducing air pollution caused by the burning of fossil fuels. The potential worldwide savings in health care costs have been estimated at trillions of dollars annually. + + +=== Intermittency === + +The two most important forms of renewable energy, solar and wind, are intermittent energy sources: they are not available constantly, resulting in lower capacity factors. In contrast, fossil fuel power plants, nuclear power plants and hydropower are usually able to produce precisely the amount of energy an electricity grid requires at a given time. Solar energy can only be captured during the day, and ideally in cloudless conditions. Wind power generation can vary significantly not only day-to-day, but even month-to-month. This poses a challenge when transitioning away from fossil fuels: energy demand will often be higher or lower than what renewables can provide. +In the medium-term, this variability may require keeping some gas-fired power plants or other dispatchable generation on standby until there is enough energy storage, demand response, grid improvement, or base load power from non-intermittent sources. In the long-term, energy storage is an important way of dealing with intermittency. Using diversified renewable energy sources and smart grids can also help flatten supply and demand. +Sector coupling of the power generation sector with other sectors may increase flexibility: for example the transport sector can be coupled by charging electric vehicles and sending electricity from vehicle to grid. Similarly the industry sector can be coupled by hydrogen produced by electrolysis, and the buildings sector by thermal energy storage for space heating and cooling. +Building overcapacity for wind and solar generation can help ensure sufficient electricity production even during poor weather. In optimal weather, it may be necessary to curtail energy generation if it is not possible to use or store excess electricity. + + +==== Electrical energy storage ==== + +Electrical energy storage is a collection of methods used to store electrical energy. Electrical energy is stored during times when production (especially from intermittent sources such as wind power, tidal power, solar power) exceeds consumption, and returned to the grid when production falls below consumption. Pumped-storage hydroelectricity accounts for more than 85% of all grid power storage. Batteries are increasingly being deployed for storage and grid ancillary services and for domestic storage. Green hydrogen is a more economical means of long-term renewable energy storage, in terms of capital expenditures compared to pumped hydroelectric or batteries. + + +==== Energy supply security ==== +Two main renewable energy sources - solar power and wind power - are usually deployed in distributed generation architecture, which offers specific benefits and comes with specific risks. Notable risks are associated with centralisation of 90% of the supply chains in a single country (China) in the photovoltaic sector. Mass-scale installation of photovoltaic power inverters with remote control, security vulnerabilities and backdoors results in cyberattacks that can disable generation from millions of physically decentralised panels, resulting in disappearance of hundreds of gigawatts of installed power from the grid in one moment. Similar attacks have targeted wind power farms through vulnerabilities in their remote control and monitoring systems. The European NIS2 directive partially responds to these challenges by extending the scope of cybersecurity regulations to the energy generation market.Recent analyses indicate that global solar photovoltaic capacity surpassed 1 terawatt in 2024, providing about 6–7% of global electricity supply. Renewable energy infrastructure is also increasingly vulnerable to extreme weather events linked to climate change, such as heat waves, wildfires, severe storms, and flooding. Solar farms can experience reduced output during prolonged heat or smoke conditions, while wind turbines may require shutdowns during high-wind events or face damage from icing or wave action. These climate-related stresses can threaten the continuity of electricity supply in regions with high shares of variable renewables. As a result, governments and grid operators are adopting climate-resilience standards, hardening infrastructure, and developing emergency-response protocols to maintain energy security under more frequent and severe weather conditions. + + +== Mainstream technologies == + + +=== Solar energy === + +Solar power produced around 1.3 terrawatt-hours (TWh) worldwide in 2022, representing 4.6% of the world's electricity. Almost all of this growth has happened since 2010. Solar energy can be harnessed anywhere that receives sunlight; however, the amount of solar energy that can be harnessed for electricity generation is influenced by weather conditions, geographic location and time of day. +There are two mainstream ways of harnessing solar energy: solar thermal, which converts solar energy into heat; and photovoltaics (PV), which converts it into electricity. PV is far more widespread, accounting for around two thirds of the global solar energy capacity as of 2022. It is also growing at a much faster rate, with 170 GW newly installed capacity in 2021, compared to 25 GW of solar thermal. +Passive solar refers to a range of construction strategies and technologies that aim to optimize the distribution of solar heat in a building. Examples include solar chimneys, orienting a building to the sun, using construction materials that can store heat, and designing spaces that naturally circulate air. +From 2020 to 2022, solar technology investments almost doubled from USD 162 billion to USD 308 billion, driven by the sector's increasing maturity and cost reductions, particularly in solar photovoltaic (PV), which accounted for 90% of total investments. China and the United States were the main recipients, collectively making up about half of all solar investments since 2013. Despite reductions in Japan and India due to policy changes and COVID-19, growth in China, the United States, and a significant increase from Vietnam's feed-in tariff program offset these declines. Globally, the solar sector added 714 gigawatts (GW) of solar PV and concentrated solar power (CSP) capacity between 2013 and 2021, with a notable rise in large-scale solar heating installations in 2021, especially in China, Europe, Turkey, and Mexico. In 2023, global solar power capacity grew by nearly 30%, driven by falling panel prices and expanded government incentives worldwide. + + +==== Photovoltaics ==== + +A photovoltaic system, consisting of solar cells assembled into panels, converts light into electrical direct current via the photoelectric effect. PV has several advantages that make it by far the fastest-growing renewable energy technology. It is cheap, low-maintenance and scalable; adding to an existing PV installation as demanded arises is simple. Its main disadvantage is its poor performance in cloudy weather. +PV systems range from small, residential and commercial rooftop or building integrated installations, to large utility-scale photovoltaic power station. A household's solar panels can either be used for just that household or, if connected to an electrical grid, can be aggregated with millions of others. +The first utility-scale solar power plant was built in 1982 in Hesperia, California by ARCO. The plant was not profitable and was sold eight years later. However, over the following decades, PV cells became significantly more efficient and cheaper. As a result, PV adoption has grown exponentially since 2010. Global capacity increased from 230 GW at the end of 2015 to 890 GW in 2021. PV grew fastest in China between 2016 and 2021, adding 560 GW, more than all advanced economies combined. Four of the ten biggest solar power stations are in China, including the biggest, Golmud Solar Park in China. +Solar panels are recycled to reduce electronic waste and create a source for materials that would otherwise need to be mined, but such business is still small and work is ongoing to improve and scale-up the process. + + +==== Solar thermal ==== + +Unlike photovoltaic cells that convert sunlight directly into electricity, solar thermal systems convert it into heat. They use mirrors or lenses to concentrate sunlight onto a receiver, which in turn heats a water reservoir. The heated water can then be used in homes. The advantage of solar thermal is that the heated water can be stored until it is needed, eliminating the need for a separate energy storage system. Solar thermal power can also be converted to electricity by using the steam generated from the heated water to drive a turbine connected to a generator. However, because generating electricity this way is much more expensive than photovoltaic power plants, there are very few in use today. + + +==== Floatovoltaics ==== + +Floatovoltiacs, or floating solar panels, are solar panels floating on bodies of water. There are both positive and negative points to this. Some positive points are increased efficiency and price decrease of water space compared to land space. A negative point is that making floating solar panels could be more expensive. + + +==== Agrivoltaics ==== + +Agrivoltaics is where there is simultaneous use of land for energy production and agriculture. There are again both positive and negative points. A positive viewpoint is there is a better use of land, which leads to lower land costs. A negative viewpoint is it the plants grown underneath would have to be plants that can grow well under shade, such as Polka Dot Plant, Pineapple Sage, and Begonia. Agrivoltaics not only optimizes land use and reduces costs by enabling dual revenue streams from both energy production and agriculture, but it can also help moderate temperatures beneath the panels, potentially reducing water loss and improving microclimates for crop growth. However, careful design and crop selection are crucial, as the shading effect may limit the types of plants that can thrive, necessitating the use of shade-tolerant species and innovative management practices. + + +=== Wind power === + +Humans have harnessed wind energy since at least 3500 BC. Until the 20th century, it was primarily used to power ships, windmills and water pumps. Today, the vast majority of wind power is used to generate electricity using wind turbines. Modern utility-scale wind turbines range from around 600 kW to 9 MW of rated power. The power available from the wind is a function of the cube of the wind speed, so as wind speed increases, power output increases up to the maximum output for the particular turbine. Areas where winds are stronger and more constant, such as offshore and high-altitude sites, are preferred locations for wind farms. +Wind-generated electricity met nearly 4% of global electricity demand in 2015, with nearly 63 GW of new wind power capacity installed. Wind energy was the leading source of new capacity in Europe, the US and Canada, and the second largest in China. In Denmark, wind energy met more than 40% of its electricity demand while Ireland, Portugal and Spain each met nearly 20%. +Globally, the long-term technical potential of wind energy is believed to be five times total current global energy production, or 40 times current electricity demand, assuming all practical barriers needed were overcome. This would require wind turbines to be installed over large areas, particularly in areas of higher wind resources, such as offshore, and likely also industrial use of new types of VAWT turbines in addition to the horizontal axis units currently in use. As offshore wind speeds average ~90% greater than that of land, offshore resources can contribute substantially more energy than land-stationed turbines. +Investments in wind technologies reached USD 161 billion in 2020, with onshore wind dominating at 80% of total investments from 2013 to 2022. Offshore wind investments nearly doubled to USD 41 billion between 2019 and 2020, primarily due to policy incentives in China and expansion in Europe. Global wind capacity increased by 557 GW between 2013 and 2021, with capacity additions increasing by an average of 19% each year. + + +=== Hydropower === + +Since water is about 800 times denser than air, even a slow flowing stream of water, or moderate sea swell, can yield considerable amounts of energy. Water can generate electricity with a conversion efficiency of about 90%, which is the highest rate in renewable energy. There are many forms of water energy: + +Historically, hydroelectric power came from constructing large hydroelectric dams and reservoirs, which are still popular in developing countries. The largest of them are the Three Gorges Dam (2003) in China and the Itaipu Dam (1984) built by Brazil and Paraguay. +Small hydro systems are hydroelectric power installations that typically produce up to 50 MW of power. They are often used on small rivers or as a low-impact development on larger rivers. China is the largest producer of hydroelectricity in the world and has more than 45,000 small hydro installations. +Run-of-the-river hydroelectricity plants derive energy from rivers without the creation of a large reservoir. The water is typically conveyed along the side of the river valley (using channels, pipes or tunnels) until it is high above the valley floor, whereupon it can be allowed to fall through a penstock to drive a turbine. A run-of-river plant may still produce a large amount of electricity, such as the Chief Joseph Dam on the Columbia River in the United States. However many run-of-the-river hydro power plants are micro hydro or pico hydro plants. +Much hydropower is flexible, thus complementing wind and solar, as it not intermittent. In 2021, the world renewable hydropower capacity was 1,360 GW. Only a third of the world's estimated hydroelectric potential of 14,000 TWh/year has been developed. New hydropower projects face opposition from local communities due to their large impact, including relocation of communities and flooding of wildlife habitats and farming land. High cost and lead times from permission process, including environmental and risk assessments, with lack of environmental and social acceptance are therefore the primary challenges for new developments. It is popular to repower old dams thereby increasing their efficiency and capacity as well as quicker responsiveness on the grid. Where circumstances permit existing dams such as the Russell Dam built in 1985 may be updated with "pump back" facilities for pumped-storage which is useful for peak loads or to support intermittent wind and solar power. Because dispatchable power is more valuable than VRE countries with large hydroelectric developments such as Canada and Norway are spending billions to expand their grids to trade with neighboring countries having limited hydro. + + +=== Bioenergy === + +Biomass is biological material derived from living, or recently living organisms. Most commonly, it refers to plants or plant-derived materials. As an energy source, biomass can either be used directly via combustion to produce heat, or converted to a more energy-dense biofuel like ethanol. Wood is the most significant biomass energy source as of 2012 and is usually sourced from a trees cleared for silvicultural reasons or fire prevention. Municipal wood waste – for instance, construction materials or sawdust – is also often burned for energy. The biggest per-capita producers of wood-based bioenergy are heavily forested countries like Finland, Sweden, Estonia, Austria, and Denmark. +Bioenergy can be environmentally destructive if old-growth forests are cleared to make way for crop production. In particular, demand for palm oil to produce biodiesel has contributed to the deforestation of tropical rainforests in Brazil and Indonesia. In addition, burning biomass still produces carbon emissions, although much less than fossil fuels (39 grams of CO2 per megajoule of energy, compared to 75 g/MJ for fossil fuels). + +Some biomass sources are unsustainable at current rates of exploitation (as of 2017). + + +==== Biofuel ==== + +Biofuels are primarily used in transportation, providing 3.5% of the world's transport energy demand in 2022, up from 2.7% in 2010. Biojet is expected to be important for short-term reduction of carbon dioxide emissions from long-haul flights. +Aside from wood, the major sources of bioenergy are bioethanol and biodiesel. Bioethanol is usually produced by fermenting the sugar components of crops like sugarcane and maize, while biodiesel is mostly made from oils extracted from plants, such as soybean oil and corn oil. Most of the crops used to produce bioethanol and biodiesel are grown specifically for this purpose, although used cooking oil accounted for 14% of the oil used to produce biodiesel as of 2015. The biomass used to produce biofuels varies by region. Maize is the major feedstock in the United States, while sugarcane dominates in Brazil. In the European Union, where biodiesel is more common than bioethanol, rapeseed oil and palm oil are the main feedstocks. China, although it produces comparatively much less biofuel, uses mostly corn and wheat. In many countries, biofuels are either subsidized or mandated to be included in fuel mixtures. + +There are many other sources of bioenergy that are more niche, or not yet viable at large scales. For instance, bioethanol could be produced from the cellulosic parts of crops, rather than only the seed as is common today. Sweet sorghum may be a promising alternative source of bioethanol, due to its tolerance of a wide range of climates. Cow dung can be converted into methane. There is also a great deal of research involving algal fuel, which is attractive because algae is a non-food resource, grows around 20 times faster than most food crops, and can be grown almost anywhere. + + +=== Geothermal energy === + +Geothermal energy is thermal energy (heat) extracted from the Earth's crust. It originates from several different sources, of which the most significant is slow radioactive decay of minerals contained in the Earth's interior, as well as some leftover heat from the formation of the Earth. Some of the heat is generated near the Earth's surface in the crust, but some also flows from deep within the Earth from the mantle and core. Geothermal energy extraction is viable mostly in countries located on tectonic plate edges, where the Earth's hot mantle is more exposed. As of 2023, the United States has by far the most geothermal capacity (2.7 GW, or less than 0.2% of the country's total energy capacity), followed by Indonesia and the Philippines. Global capacity in 2022 was 15 GW. +Geothermal energy can be either used directly to heat homes, as is common in Iceland where almost all of its energy is renewable, or to generate electricity. Iceland is a global leader in renewable energy, relying almost entirely on its abundant geothermal and hydroelectric resources derived from volcanic activity and glaciers. At smaller scales, geothermal power can be generated with geothermal heat pumps, which can extract heat from ground temperatures of under 30 °C (86 °F), allowing them to be used at relatively shallow depths of a few meters. Electricity generation requires large plants and ground temperatures of at least 150 °C (302 °F). In some countries, electricity produced from geothermal energy accounts for a large portion of the total, such as Kenya (43%) and Indonesia (5%). +Technical advances may eventually make geothermal power more widely available. For example, enhanced geothermal systems involve drilling around 10 kilometres (6.2 mi) into the Earth, breaking apart hot rocks and extracting the heat using water. In theory, this type of geothermal energy extraction could be done anywhere on Earth. + + +== Emerging technologies == +There are also other renewable energy technologies that are still under development, including enhanced geothermal systems, concentrated solar power, cellulosic ethanol, piezoelectricity, and marine energy. These technologies are not yet widely demonstrated or have limited commercialization. Some may have potential comparable to other renewable energy technologies, but still depend on further breakthroughs from research, development and engineering. + + +=== Enhanced geothermal systems === + +Enhanced geothermal systems (EGS) are a new type of geothermal power which does not require natural hot water reservoirs or steam to generate power. Most of the underground heat within drilling reach is trapped in solid rocks, not in water. EGS technologies use hydraulic fracturing to break apart these rocks and release the heat they contain, which is then harvested by pumping water into the ground. The process is sometimes known as "hot dry rock" (HDR). Unlike conventional geothermal energy extraction, EGS may be feasible anywhere in the world, depending on the cost of drilling. EGS projects have so far primarily been limited to demonstration plants, as the technology is capital-intensive due to the high cost of drilling. + + +=== Sand battery === +Sand batteries are large tanks filled with soapstone that absorb heat. Excess heat energy from renewable energy is piped into the tank and then energy is discharged as boiling water, steam, or heated air. Finland is using this technology in Pornainen as Polar Night Energy built a 1MW sand battery that can store up to 100 MWh that went online in 2025. + + +=== Piezoelectricity === +Piezoelectricity is the conversion of existing mechanical stress or vibration (classical mechanics) into an electrical charge without consuming or depleting a fuel source. Piezotronics enables the interaction of piezoelectric and semiconducting behaviors to modulate energy barriers at contact surface, thereby controlling charge carrier transport. Since the introduction of nanogenerators, the efficiency of microscale energy harvesting has improved. For instance, nanogenerators typically consist of piezoelectric nanowires; as these wires bend or compress, the applied mechanical stress causes the ions within the material's crystal lattice to shift their positions. This shift disrupts the nanowire's charge symmetry which causes an instantaneous charge polarization (separation of positive and negative charges) across the nanowire's ends. Once polarized, electrons are freed from the attached electrode which generates usable alternating current (AC) electricity that can energize low-power sensors. Piezoelectric microelectromechanical systems (piezoMEMS), such as actuators for artificial organs and pacemakers or micropumps for drug delivery and reagent transfers, are vital for medical purposes and energy harvesting. Furthermore, specialized components like piezoelectric resonators and quartz crystal oscillators are used to regulate electrical circuit frequencies. + + +=== Marine energy === + +Marine energy (also sometimes referred to as ocean energy) is the energy carried by ocean waves, tides, salinity, and ocean temperature differences. Technologies to harness the energy of moving water include wave power, marine current power, and tidal power. Reverse electrodialysis (RED) is a technology for generating electricity by mixing fresh water and salty sea water in large power cells. Most marine energy harvesting technologies are still at low technology readiness levels and not used at large scales. Tidal energy is generally considered the most mature, but has not seen wide deployment. The world's largest tidal power station is on Sihwa Lake, South Korea, which produces around 550 gigawatt-hours of electricity per year. + + +=== Earth infrared thermal radiation === +Earth emits roughly 1017 W of infrared thermal radiation that flows toward the cold outer space. Solar energy hits the surface and atmosphere of the earth and produces heat. Using various theorized devices like emissive energy harvester (EEH) or thermoradiative diode, this energy flow can be converted into electricity. In theory, this technology can be used during nighttime. + + +=== Others === + + +==== Algae fuels ==== + +Producing liquid fuels from oil-rich (fat-rich) varieties of algae is an ongoing research topic. Various microalgae grown in open or closed systems are being tried including some systems that can be set up in brownfield and desert lands. + + +==== Space-based solar power ==== + +There have been numerous proposals for space-based solar power, in which very large satellites with photovoltaic panels would be equipped with microwave transmitters to beam power back to terrestrial receivers. A 2024 study by the NASA Office of Science and Technology Policy examined the concept and concluded that with current and near-future technologies it would be economically uncompetitive. + + +==== Water vapor ==== +Collection of static electricity charges from water droplets on metal surfaces is an experimental technology that would be especially useful in low-income countries with relative air humidity over 60%. + + +==== Nuclear energy ==== +Breeder reactors could, in principle, depending on the fuel cycle employed, extract almost all of the energy contained in uranium or thorium, decreasing fuel requirements by a factor of 100 compared to widely used once-through light water reactors, which extract less than 1% of the energy in the actinide metal (uranium or thorium) mined from the earth. The high fuel-efficiency of breeder reactors could greatly reduce concerns about fuel supply, energy used in mining, and storage of radioactive waste. With seawater uranium extraction (currently too expensive to be economical), there is enough fuel for breeder reactors to satisfy the world's energy needs for 5 billion years at 1983's total energy consumption rate, thus making nuclear energy effectively a renewable energy. In addition to seawater the average crustal granite rocks contain significant quantities of uranium and thorium with which breeder reactors can supply abundant energy for the remaining lifespan of the sun on the main sequence of stellar evolution. + + +==== Artificial photosynthesis ==== + +Artificial photosynthesis uses techniques including nanotechnology to store solar electromagnetic energy in chemical bonds by splitting water to produce hydrogen and then using carbon dioxide to make methanol. Researchers in this field strived to design molecular mimics of photosynthesis that use a wider region of the solar spectrum, employ catalytic systems made from abundant, inexpensive materials that are robust, readily repaired, non-toxic, stable in a variety of environmental conditions and perform more efficiently allowing a greater proportion of photon energy to end up in the storage compounds, i.e., carbohydrates (rather than building and sustaining living cells). However, prominent research faces hurdles, Sun Catalytix a MIT spin-off stopped scaling up their prototype fuel-cell in 2012 because it offers few savings over other ways to make hydrogen from sunlight. +Recent research emphasizes that while artificial photosynthesis shows promise in splitting water to generate hydrogen, its broader significance lies in the ability to produce dense, carbon-based solar fuels suitable for transport applications, such as aviation and long-haul shipping. These fuels, if derived from carbon dioxide and water using sunlight, could close the carbon loop and reduce reliance on fossil-based hydrocarbons. However, realizing this potential requires overcoming major technical hurdles, including the development of efficient, durable catalysts for water oxidation and CO2 reduction, and careful attention to land use and public perception. + + +== Comparison of the theoretical and practical potentials of different renewable energy technologies == +Global energy consumption in 2019 was approximately 65 petawatt-hours (PWh) per year or 65,000 terawatt-hours (TWh) annually. + + +=== Technical Potential by Technology === +According to a comprehensive peer-reviewed study published in 2023, the technical potentials for utility-scale solar photovoltaic, concentrated solar power, onshore wind, and offshore wind each exceed 100 PWh/year, and thus each of them is capable of meeting the Humankind's total demand in theory. + + +==== Solar Photovoltaic (PV) ==== +Technical Potential: Over 5,800 PWh per year from solar PV alone using current technology This represents approximately 89 times current global energy demand. Thus, utilizing only 2% of the solar power can solve Humankind's energy problems, in principle. + + +==== Wind Energy (Onshore + Offshore) ==== +Technical Potential: Nearly 900 PWh per year from onshore and offshore wind combined https://carbontracker.org/solar-and-wind-can-meet-world-energy-demand-100-times-over-renewables/ +In kilowatts: 900,000,000,000,000 kWh/year (900 trillion kWh/year) +This represents approximately 14 times current global energy demand. However, it is highly intermittent, and it is not feasible to cover most of the earth surface to collect all wind. + + +==== Combined Solar and Wind ==== +With current technology, at least 6,700 PWh per year can be captured from solar and wind, which is more than 100 times global energy demand.. + + +==== Hydropower ==== +Gross Theoretical Potential: Approximately 52 PWh/year distributed over 11.8 million potential locations worldwide. +In kilowatts: 52,000,000,000,000 kWh/year (52 trillion kWh/year). +This equals to about 33% of annually required energy. + + +==== Geothermal Energy ==== +Conventional Geothermal: Technical potential above 10 PWh/year. +Enhanced Geothermal Systems (EGS): About 600 terawatts (TW) of geothermal capacity using thermal resources within 8 km of depth, equivalent to about 4,000 PWh of technical potential for annual generation. +The full technical potential of next-generation geothermal systems is sufficient to meet global electricity demand 140 times over and is second only to solar PV among renewable technologies. + + +==== Other Ocean Technologies ==== +Rooftop Solar PV, Wave, and Tidal: Technical potentials above 1 PWh/year each. +Ocean Thermal Energy Conversion (OTEC): Technical potential above 10 PWh/year. +Salinity Gradient: Technical potential above 0.1 PWh/year. + + +==== Overall Technical Potential ==== +When including all renewable energy sources, the global technical potential ranges from 164 to 27,200 PWh/year, which is 6.6 to 1,101 times the 2021 electricity consumption of 24.7 PWh/year. + + +==== Economic Potential ==== +The literature assessing the global economic potential of renewables shows that the economic potential is higher than current and near-future electricity demand. More specifically: +Around 60% of the world's solar resource and 15% of its wind resource is already economically competitive compared with local fossil fuel generation. + + +== Market and industry trends == + +Most new renewables are solar, followed by wind then hydro then bioenergy. Investment in renewables, especially solar, tends to be more effective in creating jobs than coal, gas or oil. Worldwide, renewables employ about 12 million people as of 2020, with solar PV being the technology employing the most at almost 4 million. However, as of February 2024, the world's supply of workforce for solar energy is lagging greatly behind demand as universities worldwide still produce more workforce for fossil fuels than for renewable energy industries. +In 2021, China accounted for almost half of the global increase in renewable electricity. +There are 3,146 gigawatts installed in 135 countries, while 156 countries have laws regulating the renewable energy sector. +Globally in 2020 there are over 10 million jobs associated with the renewable energy industries, with solar photovoltaics being the largest renewable employer. The clean energy sectors added about 4.7 million jobs globally between 2019 and 2022, totaling 35 million jobs by 2022. + + +=== Usage by sector or application === +Some studies say that a global transition to 100% renewable energy across all sectors – power, heat, transport and industry – is feasible and economically viable. +One of the efforts to decarbonize transportation is the increased use of electric vehicles (EVs). Despite that and the use of biofuels, such as biojet, less than 4% of transport energy is from renewables. Occasionally hydrogen fuel cells are used for heavy transport. Meanwhile, in the future electrofuels may also play a greater role in decarbonizing hard-to-abate sectors like aviation and maritime shipping. +Solar water heating makes an important contribution to renewable heat in many countries, most notably in China, which now has 70% of the global total (180 GWth). Most of these systems are installed on multi-family apartment buildings and meet a portion of the hot water needs of an estimated 50–60 million households in China. Worldwide, total installed solar water heating systems meet a portion of the water heating needs of over 70 million households. +Heat pumps provide both heating and cooling, and also flatten the electric demand curve and are thus an increasing priority. Renewable thermal energy is also growing rapidly. About 10% of heating and cooling energy is from renewables. + + +=== Cost comparison === +The International Renewable Energy Agency (IRENA) stated that ~86% (187 GW) of renewable capacity added in 2022 had lower costs than electricity generated from fossil fuels. IRENA also stated that capacity added since 2000 reduced electricity bills in 2022 by at least $520 billion, and that in non-OECD countries, the lifetime savings of 2022 capacity additions will reduce costs by up to $580 billion. + +* = 2018. All other values for 2019. + + +=== Growth of renewables === + +The results of a recent review of the literature concluded that as greenhouse gas (GHG) emitters begin to be held liable for damages resulting from GHG emissions resulting in climate change, a high value for liability mitigation would provide powerful incentives for deployment of renewable energy technologies. +In the decade of 2010–2019, worldwide investment in renewable energy capacity excluding large hydropower amounted to US$2.7 trillion, of which the top countries China contributed US$818 billion, the United States contributed US$392.3 billion, Japan contributed US$210.9 billion, Germany contributed US$183.4 billion, and the United Kingdom contributed US$126.5 billion. This was an increase of over three and possibly four times the equivalent amount invested in the decade of 2000–2009 (no data is available for 2000–2003). +As of 2022, an estimated 28% of the world's electricity was generated by renewables. This is up from 19% in 1990. By the end of 2024, global renewable power capacity reached 4,300 gigawatts (GW), with solar photovoltaics accounting for over 60% of annual additions. + + +==== Future projections ==== + +A December 2022 report by the IEA forecasts that over 2022-2027, renewables are seen growing by almost 2,400 GW in its main forecast, equal to the entire installed power capacity of China in 2021. This is an 85% acceleration from the previous five years, and almost 30% higher than what the IEA forecast in its 2021 report, making its largest ever upward revision. Renewables are set to account for over 90% of global electricity capacity expansion over the forecast period. To achieve net zero emissions by 2050, IEA believes that 90% of global electricity generation will need to be produced from renewable sources. +In June 2022, IEA Executive Director Fatih Birol said that countries should invest more in renewables to "ease the pressure on consumers from high fossil fuel prices, make our energy systems more secure, and get the world on track to reach our climate goals." +China's five year plan to 2025 includes increasing direct heating by renewables such as geothermal and solar thermal. +REPowerEU, the EU plan to escape dependence on fossil Russian gas, is expected to call for much more green hydrogen. +After a transitional period, renewable energy production is expected to make up most of the world's energy production. In 2018, the risk management firm, DNV GL, forecasts that the world's primary energy mix will be split equally between fossil and non-fossil sources by 2050. +Middle eastern nations are also planning on reducing their reliance fossil fuel. Many planned green projects will contribute in 26% of energy supply for the region by 2050 achieving emission reductions equal to 1.1 Gt CO2/year. +Massive Renewable Energy Projects in the Middle East: + +Mohammed bin Rashid Al Maktoum Solar Park in Dubai, UAE +Shuaibah Two (2) Solar Facility in Mecca Province, Saudi Arabia +NEOM Green Hydrogen Project in NEOM, Saudi Arabia +Gulf of Suez Wind Power Project in Suez, Egypt +Al-Ajban Solar Park in Abu Dhabi, UAE + + +=== Demand === +In July 2014, WWF and the World Resources Institute convened a discussion among a number of major US companies who had declared their intention to increase their use of renewable energy. These discussions identified a number of "principles" which companies seeking greater access to renewable energy considered important market deliverables. These principles included choice (between suppliers and between products), cost competitiveness, longer term fixed price supplies, access to third-party financing vehicles, and collaboration. +UK statistics released in September 2020 noted that "the proportion of demand met from renewables varies from a low of 3.4 per cent (for transport, mainly from biofuels) to highs of over 20 per cent for 'other final users', which is largely the service and commercial sectors that consume relatively large quantities of electricity, and industry". +In some locations, individual households can opt to purchase renewable energy through a consumer green energy program. + + +=== Developing countries === + +In Kenya, the Olkaria V Geothermal Power Station is one of the largest in the world. The Grand Ethiopia Renaissance Dam project incorporates wind turbines. Once completed, Morocco's Ouarzazate Solar Power Station is projected to provide power to over a million people. + + +== Policy == + +Policies to support renewable energy have been vital in their expansion. Where Europe dominated in establishing energy policy in the early 2000s, most countries around the world now have some form of energy policy. +The International Renewable Energy Agency (IRENA) is an intergovernmental organization for promoting the adoption of renewable energy worldwide. It aims to provide concrete policy advice and facilitate capacity building and technology transfer. IRENA was formed in 2009, with 75 countries signing the charter of IRENA. As of April 2019, IRENA has 160 member states. The then United Nations Secretary-General Ban Ki-moon has said that renewable energy can lift the poorest nations to new levels of prosperity, and in September 2011 he launched the UN Sustainable Energy for All initiative to improve energy access, efficiency and the deployment of renewable energy. +The 2015 Paris Agreement on climate change motivated many countries to develop or improve renewable energy policies. In 2017, a total of 121 countries adopted some form of renewable energy policy. National targets that year existed in 176 countries. In addition, there is also a wide range of policies at the state/provincial, and local levels. Some public utilities help plan or install residential energy upgrades. +Many national, state and local governments have created green banks. A green bank is a quasi-public financial institution that uses public capital to leverage private investment in clean energy technologies. Green banks use a variety of financial tools to bridge market gaps that hinder the deployment of clean energy. +Global and national policies related to renewable energy can be divided based on sectors, such as agriculture, transport, buildings, industry: +Climate neutrality (net zero emissions) by the year 2050 is the main goal of the European Green Deal. For the European Union to reach their target of climate neutrality, one goal is to decarbonise its energy system by aiming to achieve "net-zero greenhouse gas emissions by 2050." + + +== Finance == + +The International Renewable Energy Agency's (IRENA) 2023 report on renewable energy finance highlights steady investment growth since 2018: USD 348 billion in 2020 (a 5.6% increase from 2019), USD 430 billion in 2021 (24% up from 2020), and USD 499 billion in 2022 (16% higher). This trend is driven by increasing recognition of renewable energy's role in mitigating climate change and enhancing energy security, along with investor interest in alternatives to fossil fuels. Policies such as feed-in tariffs in China and Vietnam have significantly increased renewable adoption. Furthermore, from 2013 to 2022, installation costs for solar photovoltaic (PV), onshore wind, and offshore wind fell by 69%, 33%, and 45%, respectively, making renewables more cost-effective. +Between 2013 and 2022, the renewable energy sector underwent a significant realignment of investment priorities. Investment in solar and wind energy technologies markedly increased. In contrast, other renewable technologies such as hydropower (including pumped storage hydropower), biomass, biofuels, geothermal, and marine energy experienced a substantial decrease in financial investment. Notably, from 2017 to 2022, investment in these alternative renewable technologies declined by 45%, falling from USD 35 billion to USD 17 billion. +In 2023, the renewable energy sector experienced a significant surge in investments, particularly in solar and wind technologies, totaling approximately USD 200 billion—a 75% increase from the previous year. The increased investments in 2023 contributed between 1% and 4% to the GDP in key regions including the United States, China, the European Union, and India. +The energy sector receives investments of approximately USD 3 trillion each year, with USD 1.9 trillion directed towards clean energy technologies and infrastructure. To meet the targets set in the Net Zero Emissions (NZE) Scenario by 2035, this investment must increase to USD 5.3 trillion per year. + + +== Debates == + + +=== Nuclear power proposed as renewable energy === + + +=== Geopolitics === + +The geopolitical impact of the growing use of renewable energy is a subject of ongoing debate and research. Many fossil-fuel producing countries, such as Qatar, Russia, Saudi Arabia and Norway, are currently able to exert diplomatic or geopolitical influence as a result of their oil wealth. Most of these countries are expected to be among the geopolitical "losers" of the energy transition, although some, like Norway, are also significant producers and exporters of renewable energy. Fossil fuels and the infrastructure to extract them may, in the long term, become stranded assets. It has been speculated that countries dependent on fossil fuel revenue may one day find it in their interests to quickly sell off their remaining fossil fuels. +Conversely, nations abundant in renewable resources, and the minerals required for renewables technology, are expected to gain influence. In particular, China has become the world's dominant manufacturer of the technology needed to produce or store renewable energy, especially solar panels, wind turbines, and lithium-ion batteries. Nations rich in solar and wind energy could become major energy exporters. Some may produce and export green hydrogen, although electricity is projected to be the dominant energy carrier in 2050, accounting for almost 50% of total energy consumption (up from 22% in 2015). Countries with large uninhabited areas such as Australia, China, and many African and Middle Eastern countries have a potential for huge installations of renewable energy. The production of renewable energy technologies requires rare-earth elements with new supply chains. +Countries with already weak governments that rely on fossil fuel revenue may face even higher political instability or popular unrest. Analysts consider Nigeria, Angola, Chad, Gabon, and Sudan, all countries with a history of military coups, to be at risk of instability due to dwindling oil income. +A study found that transition from fossil fuels to renewable energy systems reduces risks from mining, trade and political dependence because renewable energy systems don't need fuel – they depend on trade only for the acquisition of materials and components during construction. +In October 2021, European Commissioner for Climate Action Frans Timmermans suggested "the best answer" to the 2021 global energy crisis is "to reduce our reliance on fossil fuels." He said those blaming the European Green Deal were doing so "for perhaps ideological reasons or sometimes economic reasons in protecting their vested interests." Some critics blamed the European Union Emissions Trading System (EU ETS) and closure of nuclear plants for contributing to the energy crisis. European Commission President Ursula von der Leyen said that Europe is "too reliant" on natural gas and too dependent on natural gas imports. According to Von der Leyen, "The answer has to do with diversifying our suppliers ... and, crucially, with speeding up the transition to clean energy." + + +=== Metal and mineral extraction === + +The transition to renewable energy requires increased extraction of certain metals and minerals. Like all mining, this impacts the environment and can lead to environmental conflict. For example, lithium mining uses around 65% of the water in the Salar de Atamaca desert forcing farmers and llama herders to abandon their ancestral settlements and creating environment degradation, in several African countries, the green energy transition has created a mining boom, causing deforestation, and threatening already endangered species. Wind power requires large amounts of copper and zinc, as well as smaller amounts of the rarer metal neodymium. Solar power is less resource-intensive, but still requires significant amounts of aluminum. The expansion of electrical grids requires both copper and aluminum. Batteries, which are critical to enable storage of renewable energy, use large quantities of copper, nickel, aluminum and graphite. Demand for lithium is expected to grow 42-fold from 2020 to 2040. Demand for nickel, cobalt and graphite is expected to grow by a factor of about 20–25. For each of the most relevant minerals and metals, its mining is dominated by a single country: copper in Chile, nickel in Indonesia, rare earths in China, cobalt in the Democratic Republic of the Congo (DRC), and lithium in Australia. China dominates processing of all of these. +Recycling these metals after the devices they are embedded in are spent is essential to create a circular economy and ensure renewable energy is sustainable. By 2040, recycled copper, lithium, cobalt, and nickel from spent batteries could reduce combined primary supply requirements for these minerals by around 10%. +A controversial approach is deep sea mining. Minerals can be collected from new sources like polymetallic nodules lying on the seabed. This would damage local biodiversity, but proponents point out that biomass on resource-rich seabeds is much scarcer than in the mining regions on land, which are often found in vulnerable habitats like rainforests. +Due to co-occurrence of rare-earth and radioactive elements (thorium, uranium and radium), rare-earth mining results in production of low-level radioactive waste. + + +=== Conservation areas === +Installations used to produce wind, solar and hydropower are an increasing threat to key conservation areas, with facilities built in areas set aside for nature conservation and other environmentally sensitive areas. They are often much larger than fossil fuel power plants, needing areas of land up to 10 times greater than coal or gas to produce equivalent energy amounts. More than 2000 renewable energy facilities are built, and more are under construction, in areas of environmental importance and threaten the habitats of plant and animal species across the globe. The authors' team emphasized that their work should not be interpreted as anti-renewables because renewable energy is crucial for reducing carbon emissions. The key is ensuring that renewable energy facilities are built in places where they do not damage biodiversity. +In 2020 scientists published a world map of areas that contain renewable energy materials as well as estimations of their overlaps with "Key Biodiversity Areas", "Remaining Wilderness" and "Protected Areas". The authors assessed that careful strategic planning is needed. + + +=== Impact of climate change on renewable energy production === +Climate change is making weather patterns less predictable. This can seriously hamper the use of renewable energy. For example, in the year 2023, in Sudan and Namibia, hydropower production dropped by more than half due to drastic reduction in rainfall, in China, India and some regions in Africa unusual weather phenomena reduced the amount of produced wind energy, heatwaves and clouds reduce the effectiveness of solar panels, melting glaciers create problems to hydropower. Nuclear energy is also affected as drought creates water shortage, so nuclear power plants sometimes do not have enough water for cooling. + + +== Society and culture == + + +=== Public support === + +Solar power plants may compete with arable land, while on-shore wind farms often face opposition due to aesthetic concerns and noise. Such opponents are often described as NIMBYs ("not in my back yard"). Some environmentalists are concerned about fatal collisions of birds and bats with wind turbines. Although protests against new wind farms occasionally occur around the world, regional and national surveys generally find broad support for both solar and wind power. +Community-owned wind energy is sometimes proposed as a way to increase local support for wind farms. A 2011 UK Government document stated that "projects are generally more likely to succeed if they have broad public support and the consent of local communities. This means giving communities both a say and a stake." In the 2000s and early 2010s, many renewable projects in Germany, Sweden and Denmark were owned by local communities, particularly through cooperative structures. In the years since, more installations in Germany have been undertaken by large companies, but community ownership remains strong in Denmark. + + +== History == + +Prior to the development of coal in the mid 19th century, nearly all energy used was renewable. The oldest known use of renewable energy, in the form of traditional biomass to fuel fires, dates from more than a million years ago. The use of biomass for fire did not become commonplace until many hundreds of thousands of years later. The second oldest usage of renewable energy was probably harnessing the wind in order to drive ships over water. This practice can be traced back some 7000 years, to ships in the Persian Gulf and on the Nile. Geothermal energy from hot springs has been used for bathing since Paleolithic times and space heating since ancient Roman times. Moving into the time of recorded history, the primary sources of traditional renewable energy were human labor, animal power, water power, wind, in grain crushing windmills, and firewood, a traditional biomass. +In 1885, Werner Siemens, commenting on the discovery of the photovoltaic effect in the solid state, wrote: + +In conclusion, I would say that however great the scientific importance of this discovery may be, its practical value will be no less obvious when we reflect that the supply of solar energy is both without limit and without cost, and that it will continue to pour down upon us for countless ages after all the coal deposits of the earth have been exhausted and forgotten. +Max Weber mentioned the end of fossil fuel in the concluding paragraphs of his Die protestantische Ethik und der Geist des Kapitalismus (The Protestant Ethic and the Spirit of Capitalism), published in 1905. Development of solar engines continued until the outbreak of World War I. The importance of solar energy was recognized in a 1911 Scientific American article: "in the far distant future, natural fuels having been exhausted [solar power] will remain as the only means of existence of the human race". +The theory of peak oil was published in 1956. In the 1970s environmentalists promoted the development of renewable energy both as a replacement for the eventual depletion of oil, as well as for an escape from dependence on oil, and the first electricity-generating wind turbines appeared. Solar had long been used for heating and cooling, but solar panels were too costly to build solar farms until 1980. +New government spending, regulation and policies helped the renewables industry weather the 2008 financial crisis and the Great Recession better than many other sectors. In 2022, renewables accounted for 30% of global electricity generation, up from 21% in 1985. + + +=== Ancient Historical Examples === +Among the most notable historical uses of renewable energy (in the form of ancient and traditional methods), the following examples can be highlighted: + +Windmills in Europe and Asia (such as the windmills of the Netherlands and Nashtifan in Iran). The earliest discovered verified designs of windmills date back to Iran, between 700 and 900 CE. +Water mills (Ancient China and Ancient Persia). +Archimedes' burning lens. +Traditional cooling and ventilation systems based on windcatchers and Solar updraft tower (or Solar chimney). +Traditional architecture aware of natural heat transfer and natural energy transformation processes. +Gravity-based fountains. +Using animal biomass in ancient fuel bricks. +Solar ovens and furnaces in ancient China, India, Egypt, and Persia. +Solar energy applications for traditional agricultural processing (drying), engineering material properties (solar curing of pottery and ceramics), and ancient health practices (natural disinfection by solar radiation). +Long-distance gravitational water flow control in ancient qanat technology for water transport and supply. +Cargo and passenger transportation using sails on rivers, seas, and oceans. +Cargo and passenger transportation based on understanding water currents in rivers, seas, and oceans. +Using renewable vegetation (such as desert shrubs, agricultural waste, and pruned branches) for producing light and heat. +Using renewable oils (vegetable or animal-based) for producing light and heat. +Maximizing use of natural sunlight during the day and moonlight at night in building architecture for purposes such as lighting, decorative applications (e.g., reflective tilework, mirror work, and surface polishing on stone or brick), timekeeping (sundials, noon markers, prayer time indicators, seasonal change markers), etc. + + +== See also == + +Distributed generation – Decentralised electricity generation +Efficient energy use – Methods for higher energy efficiency +Fossil fuel phase-out – Gradual reduction of the use and production of fossil fuels +Thermal energy storage – Technologies to store thermal energy +List of countries by renewable electricity production +List of renewable energy topics by country and territory +Renewable heat – Application of renewable energy + + +== References == + + +=== Sources === + +"Renewable Power Generation Costs in 2019" (PDF). IRENA. 2020. +"Renewable Capacity Statistics 2020". IRENA. 2020. +"Renewable Energy Statistics 2020". IRENA. 2020. + + +=== Further reading === +Sher, Farooq, ed. (2025). Renewable Energy Technologies. Elsevier. ISBN 9780443337710. + + +== External links == + +Energypedia – a wiki platform for collaborative knowledge exchange on renewable energy in developing countries +Renewable Energy Conference – a global platform for industry professionals, academics, and policymakers to exchange knowledge and discuss advancements in renewable energy technologies, with a focus on innovation, sustainability, and future energy solutions. \ No newline at end of file diff --git a/lightrag/evaluation/wiki_documents/finance_cryptocurrency.txt b/lightrag/evaluation/wiki_documents/finance_cryptocurrency.txt new file mode 100644 index 00000000..09b34297 --- /dev/null +++ b/lightrag/evaluation/wiki_documents/finance_cryptocurrency.txt @@ -0,0 +1,432 @@ +A cryptocurrency (colloquially crypto) is a digital currency designed to work through a computer network that is not reliant on any central authority, such as a government or bank, to uphold or maintain it. However, a type of cryptocurrency called a stablecoin may rely upon government action or legislation to require that a stable value be upheld and maintained. + +Individual coin ownership records are stored in a digital ledger or blockchain, which is a computerized database that uses a consensus mechanism to secure transaction records, control the creation of additional coins, and verify the transfer of coin ownership. The two most common consensus mechanisms are proof of work and proof of stake. Despite the name, which has come to describe many of the fungible blockchain tokens that have been created, cryptocurrencies are not considered to be currencies in the traditional sense, and varying legal treatments have been applied to them in various jurisdictions, including classification as commodities, securities, and currencies. Cryptocurrencies are generally viewed as a distinct asset class in practice. +The first cryptocurrency was bitcoin, which was first released as open-source software in 2009. As of June 2023, there were more than 25,000 other cryptocurrencies in the marketplace, of which more than 40 had a market capitalization exceeding $1 billion. As of April 2025, the cryptocurrency market capitalization was already estimated at $2.76 trillion. + + +== History == + +In 1983, American cryptographer David Chaum conceived of a type of cryptographic electronic money called ecash. Later, in 1995, he implemented it through Digicash, an early form of cryptographic electronic payments. Digicash required user software in order to withdraw notes from a bank and designate specific encrypted keys before they could be sent to a recipient. This allowed the digital currency to be untraceable by a third party. +In 1996, the National Security Agency published a paper entitled How to Make a Mint: The Cryptography of Anonymous Electronic Cash, describing a cryptocurrency system. The paper was first published in an MIT mailing list (October 1996) and later (April 1997) in The American Law Review. +In 1998, Wei Dai described "b-money," an anonymous, distributed electronic cash system. Shortly thereafter, Nick Szabo described bit gold. Like bitcoin and other cryptocurrencies that would follow it, bit gold (not to be confused with the later gold-based exchange BitGold) was described as an electronic currency system that required users to complete a proof of work function with solutions being cryptographically put together and published. +In January 2009, bitcoin was created by pseudonymous developer Satoshi Nakamoto. It used SHA-256, a cryptographic hash function, in its proof-of-work scheme. In April 2011, Namecoin was created as an attempt at forming a decentralized DNS. In October 2011, Litecoin was released, which used scrypt as its hash function instead of SHA-256. Peercoin, created in August 2012, used a hybrid of proof-of-work and proof-of-stake. +Cryptocurrency has undergone several periods of growth and retraction, including several bubbles and market crashes, such as in 2011, 2013–2014/15, 2017–2018, and 2021–2023. +In August 2014, the UK announced its Treasury had commissioned a study of cryptocurrencies and what role, if any, they could play in the UK economy. The study was also to report on whether regulation should be considered. Its final report was published in 2018, and it issued a consultation on cryptoassets and stablecoins in January 2021. +In June 2021, El Salvador became the first country to accept bitcoin as legal tender, after the Legislative Assembly had voted 62–22 to pass a bill submitted by President Nayib Bukele classifying the cryptocurrency as such. +In August 2021, Cuba followed with Resolution 215 to recognize and regulate cryptocurrencies such as bitcoin. +In September 2021, the government of China, the single largest market for cryptocurrency, declared all cryptocurrency transactions illegal. This completed a crackdown on cryptocurrency that had previously banned the operation of intermediaries and miners within China. +In September 2022, the world's second largest cryptocurrency at that time, Ethereum, transitioned its consensus mechanism from proof-of-work (PoW) to proof-of-stake (PoS) in an upgrade process known as "the Merge". According to the Ethereum Founder, the upgrade would cut both Ethereum's energy use and carbon-dioxide emissions by 99.9%. +On 11 November 2022, FTX Trading Ltd., a cryptocurrency exchange, which also operated a crypto hedge fund, and had been valued at $18 billion, filed for bankruptcy. The financial impact of the collapse extended beyond the immediate FTX customer base, as reported, while, at a Reuters conference, financial industry executives said that "regulators must step in to protect crypto investors." Technology analyst Avivah Litan commented on the cryptocurrency ecosystem that "everything...needs to improve dramatically in terms of user experience, controls, safety, customer service." +An October 2024 survey from the Pew Research Center found that 63% of adults in the U.S. "have little to no confidence that current ways to invest in, trade or use cryptocurrencies are reliable and safe." The survey also reported that 17% of U.S. adults had directly interacted with cryptocurrency, which was statistically unchanged from 2021. + + +== Formal definition == +According to Jan Lansky, a cryptocurrency is a system that meets six conditions: + +The system does not require a central authority; its state is maintained through distributed consensus. +The system keeps an overview of cryptocurrency units and their ownership. +The system defines whether new cryptocurrency units can be created. If new cryptocurrency units can be created, the system defines the circumstances of their origin and how to determine the ownership of these new units. +Ownership of cryptocurrency units can be proved exclusively cryptographically. +The system allows transactions to be performed in which ownership of the cryptographic units is changed. A transaction statement can only be issued by an entity proving the current ownership of these units. +If two different instructions for changing the ownership of the same cryptographic units are simultaneously entered, the system performs at most one of them. +In March 2018, the word cryptocurrency was added to the Merriam-Webster Dictionary. + + +=== Altcoins === + +After the early innovation of bitcoin in 2008 and the early network effect gained by bitcoin, tokens, cryptocurrencies, and other digital assets that were not bitcoin became collectively known during the 2010s as alternative cryptocurrencies, or "altcoins". +Sometimes the term "alt coins" was used, or disparagingly, "shitcoins". Paul Vigna of The Wall Street Journal described altcoins in 2020 as "alternative versions of Bitcoin" given its role as the model protocol for cryptocurrency designers. A Polytechnic University of Catalonia thesis in 2021 used a broader description, including not only alternative versions of bitcoin but every cryptocurrency other than bitcoin. As of early 2020, there were more than 5,000 cryptocurrencies. + + Altcoins often have underlying differences when compared to bitcoin. For example, Litecoin aims to process a block every 2.5 minutes, rather than bitcoin's 10 minutes which allows Litecoin to confirm transactions faster than bitcoin. Another example is Ethereum, which has smart contract functionality that allows decentralized applications to be run on its blockchain. Ethereum was the most used blockchain in 2020, according to Bloomberg News. In 2016, it had the largest "following" of any altcoin, according to the New York Times. +Significant market price rallies across multiple altcoin markets are often referred to as an "altseason". + + +==== Stablecoins ==== +Stablecoins are cryptocurrencies designed to maintain a stable level of purchasing power. Notably, these designs are not foolproof, as a number of stablecoins have crashed or lost their peg. For example, on 11 May 2022, Terra's stablecoin UST fell from $1 to 26 cents. The subsequent failure of Terraform Labs resulted in the loss of nearly $40B invested in the Terra and Luna coins. In September 2022, South Korean prosecutors requested the issuance of an Interpol Red Notice against the company's founder, Do Kwon. In Hong Kong, the expected regulatory framework for stablecoins in 2023/24 is being shaped and includes a few considerations. + + +==== Memecoins ==== +Memecoins are a category of cryptocurrencies that originated from Internet memes or jokes. The most notable example is Dogecoin, a memecoin featuring the Shiba Inu dog from the Doge meme. Memecoins are known for extreme volatility; for example, the record-high value for a Dogecoin was 73 cents, but that had plunged to 13 cents by mid-2024. Scams are prolific among memecoins. + + +== Physical crypto == +Physical cryptocurrency coins have been made as promotional items and some have become collectibles. Some of these have a private key embedded in them to access crypto worth a few dollars. There have also been attempts to issue bitcoin "bank notes". +The term "physical bitcoin" is used in the finance industry when investment funds that hold crypto purchased from crypto exchanges put their crypto holdings in a specialised bank called a "custodian". +These physical representations of cryptocurrency do not hold any value by themselves; these are only utilized for collectable purposes. For example, the first incarnation of the bitcoin Casascius, coins made of silver, brass or aluminum sometimes with gold plating, or Titan Bitcoin, which in silver or gold versions are sought after by numismatists. + + +== Architecture == + +Cryptocurrency is produced by an entire cryptocurrency system collectively, at a rate that is defined when the system is created and that is publicly stated. In centralized banking and economic systems such as the US Federal Reserve System, corporate boards or governments control the supply of currency. In the case of cryptocurrency, companies or governments cannot produce new units and have not so far provided backing for other firms, banks, or corporate entities that hold asset value measured in it. The underlying technical system upon which cryptocurrencies are based was created by Satoshi Nakamoto. +Within a proof-of-work system such as bitcoin, the safety, integrity, and balance of ledgers are maintained by a community of mutually distrustful parties referred to as miners. Miners use their computers to help validate and timestamp transactions, adding them to the ledger in accordance with a particular timestamping scheme. In a proof-of-stake blockchain, transactions are validated by holders of the associated cryptocurrency, sometimes grouped together in stake pools. +Most cryptocurrencies are designed to gradually decrease the production of that currency, placing a cap on the total amount of that currency that will ever be in circulation. Compared with ordinary currencies held by financial institutions or kept as cash on hand, cryptocurrencies can be more difficult for seizure by law enforcement. + + +=== Blockchain === + +The validity of each cryptocurrency's coins is provided by a blockchain. A blockchain is a continuously growing list of records, called blocks, which are linked and secured using cryptography. Each block typically contains a hash pointer as a link to a previous block, a timestamp, and transaction data. By design, blockchains are inherently resistant to modification of the data. A blockchain is "an open, distributed ledger that can record transactions between two parties efficiently and in a verifiable and permanent way". +For use as a distributed ledger, a blockchain is typically managed by a peer-to-peer network collectively adhering to a protocol for validating new blocks. Once recorded, the data in any given block cannot be altered retroactively without the alteration of all subsequent blocks, which requires collusion of the network majority. +Blockchains are secure by design and are an example of a distributed computing system with high Byzantine fault tolerance. Decentralized consensus has therefore been achieved with a blockchain. + + +=== Nodes === +A node is a computer that connects to a cryptocurrency network. The node supports the cryptocurrency's network through either relaying transactions, validation, or hosting a copy of the blockchain. In terms of relaying transactions, each network computer (node) has a copy of the blockchain of the cryptocurrency it supports. When a transaction is made, the node creating the transaction broadcasts details of the transaction using encryption to other nodes throughout the node network so that the transaction (and every other transaction) is known. +Node owners are either volunteers, those hosted by the organization or body responsible for developing the cryptocurrency blockchain network technology, or those who are enticed to host a node to receive rewards from hosting the node network. + + +==== Timestamping ==== +Cryptocurrencies use various timestamping schemes to "prove" the validity of transactions added to the blockchain ledger without the need for a trusted third party. +The first timestamping scheme invented was the proof-of-work scheme. The most widely used proof-of-work schemes are based on SHA-256 and scrypt. +Some other hashing algorithms that are used for proof-of-work include CryptoNote, Blake, SHA-3, and X11. +Another method is called the proof-of-stake scheme. Proof-of-stake is a method of securing a cryptocurrency network and achieving distributed consensus through requesting users to show ownership of a certain amount of currency. It is different from proof-of-work systems that run difficult hashing algorithms to validate electronic transactions. The scheme is largely dependent on the coin, and there is currently no standard form of it. Some cryptocurrencies use a combined proof-of-work and proof-of-stake scheme. + + +=== Mining === + +On a blockchain, mining is the validation of transactions. For this effort, successful miners obtain new cryptocurrency as a reward. The reward decreases transaction fees by creating a complementary incentive to contribute to the processing power of the network. The rate of generating hashes, which validate any transaction, has been increased by the use of specialized hardware such as FPGAs and ASICs running complex hashing algorithms like SHA-256 and scrypt. This arms race for cheaper-yet-efficient machines has existed since bitcoin was introduced in 2009. Mining is measured by hash rate, typically in TH/s. A 2023 IMF working paper found that crypto mining could generate 450 million tons of CO2 emissions by 2027, accounting for 0.7 percent of global emissions, or 1.2 percent of the world total +With more people entering the world of virtual currency, generating hashes for validation has become more complex over time, forcing miners to invest increasingly large sums of money to improve computing performance. Consequently, the reward for finding a hash has diminished and often does not justify the investment in equipment and cooling facilities (to mitigate the heat the equipment produces) and the electricity required to run them. +Popular regions for mining include those with inexpensive electricity, a cold climate, and jurisdictions with clear and conducive regulations. By July 2019, bitcoin's electricity consumption was estimated to be approximately 7 gigawatts, around 0.2% of the global total, or equivalent to the energy consumed nationally by Switzerland. +Some miners pool resources, sharing their processing power over a network to split the reward equally, according to the amount of work they contributed to the probability of finding a block. A "share" is awarded to members of the mining pool who present a valid partial proof-of-work. +As of February 2018, the Chinese government has halted trading of virtual currency, banned initial coin offerings, and shut down mining. Many Chinese miners have since relocated to Canada and Texas. One company is operating data centers for mining operations at Canadian oil and gas field sites due to low gas prices. In June 2018, Hydro Quebec proposed to the provincial government to allocate 500 megawatts of power to crypto companies for mining. According to a February 2018 report from Fortune, Iceland has become a haven for cryptocurrency miners in part because of its cheap electricity. +In March 2018, the city of Plattsburgh, New York put an 18-month moratorium on all cryptocurrency mining in an effort to preserve natural resources and the "character and direction" of the city. In 2021, Kazakhstan became the second-biggest crypto-currency mining country, producing 18.1% of the global exahash rate. The country built a compound containing 50,000 computers near Ekibastuz. + + +==== GPU price rise ==== +An increase in cryptocurrency mining increased the demand for graphics cards (GPU) in 2017. The computing power of GPUs makes them well-suited to generating hashes. Popular favorites of cryptocurrency miners, such as Nvidia's GTX 1060 and GTX 1070 graphics cards, as well as AMD's RX 570 and RX 580 GPUs, doubled or tripled in price – or were out of stock. +A GTX 1070 Ti, which was released at a price of $450, sold for as much as $1,100. Another popular card, the GTX 1060 (6 GB model), was released at an MSRP of $250 and sold for almost $500. RX 570 and RX 580 cards from AMD were out of stock for almost a year. Miners regularly buy up the entire stock of new GPUs as soon as they are available. +Nvidia has asked retailers to do what they can when it comes to selling GPUs to gamers instead of miners. Boris Böhles, PR manager for Nvidia in the German region, said: "Gamers come first for Nvidia." + + +==== Mining accelerator chips ==== +Numerous companies developed dedicated crypto-mining accelerator chips, capable of price-performance far higher than that of CPU or GPU mining. At one point, Intel marketed its own brand of crypto accelerator chip, named Blockscale. + + +=== Wallets === + +A cryptocurrency wallet is a means of storing the public and private "keys" (address) or seed, which can be used to receive or spend the cryptocurrency. With the private key, it is possible to write in the public ledger, effectively spending the associated cryptocurrency. With the public key, it is possible for others to send currency to the wallet. +There exist multiple methods of storing keys or seed in a wallet. These methods range from using paper wallets (which are public, private, or seed keys written on paper), to using hardware wallets (which are hardware to store your wallet information), to a digital wallet (which is a computer with software hosting your wallet information), to hosting your wallet using an exchange where cryptocurrency is traded, or by storing your wallet information on a digital medium such as plaintext. + + +=== Anonymity === + +Bitcoin is pseudonymous, rather than anonymous; the cryptocurrency in a wallet is not tied to a person but rather to one or more specific keys (or "addresses"). Thereby, bitcoin owners are not immediately identifiable, but all transactions are publicly available in the blockchain. Still, cryptocurrency exchanges are often required by law to collect the personal information of their users. +Some cryptocurrencies, such as Monero, Zerocoin, Zerocash, and CryptoNote, implement additional measures to increase privacy, such as by using zero-knowledge proofs. +A recent 2020 study presented different attacks on privacy in cryptocurrencies. The attacks demonstrated how the anonymity techniques are not sufficient safeguards. In order to improve privacy, researchers suggested several different ideas, including new cryptographic schemes and mechanisms for hiding the IP address of the source. + + +== Economics == + +Cryptocurrencies are used primarily outside banking and governmental institutions and are exchanged over the Internet. + + +=== Block rewards === +Proof-of-work cryptocurrencies, such as bitcoin, offer block rewards incentives for miners. There has been an implicit belief that whether miners are paid by block rewards or transaction fees does not affect the security of the blockchain, but a study suggests that this may not be the case under certain circumstances. +The rewards paid to miners increase the supply of the cryptocurrency. By making sure that verifying transactions is a costly business, the integrity of the network can be preserved as long as benevolent nodes control a majority of computing power. The verification algorithm requires a lot of processing power, and thus electricity, in order to make verification costly enough to accurately validate the public blockchain. Miners have to factor in the costs associated with expensive equipment necessary to stand a chance of solving a hash problem, and consider the significant amount of electrical power in search of the solution. Generally, the block rewards outweigh electricity and equipment costs, but this may not always be the case. +The current value, not the long-term value, of the cryptocurrency supports the reward scheme to incentivize miners to engage in costly mining activities. In 2018, bitcoin's design caused a 1.4% welfare loss compared to an efficient cash system, while a cash system with 2% money growth has a minor 0.003% welfare cost. The main source for this inefficiency is the large mining cost, which is estimated to be US$360 million per year. This translates into users being willing to accept a cash system with an inflation rate of 230% before being better off using bitcoin as a means of payment. However, the efficiency of the bitcoin system can be significantly improved by optimizing the rate of coin creation and minimizing transaction fees. Another potential improvement is to eliminate inefficient mining activities by changing the consensus protocol altogether. + + +=== Transaction fees === +Transaction fees (sometimes also referred to as miner fees or gas fees) for cryptocurrency depend mainly on the supply of network capacity at the time, versus the demand from the currency holder for a faster transaction. The ability for the holder to be allowed to set the fee manually often depends on the wallet software used, and central exchanges for cryptocurrency (CEX) usually do not allow the customer to set a custom transaction fee for the transaction. Their wallet software, such as Coinbase Wallet, however, might support adjusting the fee. +Select cryptocurrency exchanges have offered to let the user choose between different presets of transaction fee values during the currency conversion. One of those exchanges, namely LiteBit, previously headquartered in the Netherlands, was forced to cease all operations in August 2023, "due to market changes and regulatory pressure". +The "recommended fee" suggested by the network will often depend on the time of day (due to depending on network load). +For Ethereum, transaction fees differ by computational complexity, bandwidth use, and storage needs, while bitcoin transaction fees differ by transaction size and whether the transaction uses SegWit. In February 2023, the median transaction fee for Ether corresponded to $2.2845, while for bitcoin it corresponded to $0.659. +Some cryptocurrencies have no transaction fees, the most well-known example being Nano (XNO), and instead rely on client-side proof-of-work as the transaction prioritization and anti-spam mechanism. + + +=== Exchanges === + +Cryptocurrency exchanges allow customers to trade cryptocurrencies for other assets, such as conventional fiat money, or to trade between different digital currencies. +Crypto marketplaces do not guarantee that an investor is completing a purchase or trade at the optimal price. As a result, as of 2020, it was possible to arbitrage to find the difference in price across several markets. + + +=== Atomic swaps === +Atomic swaps are a mechanism where one cryptocurrency can be exchanged directly for another cryptocurrency without the need for a trusted third party, such as an exchange. + + +=== ATMs === + +Jordan Kelley, founder of Robocoin, launched the first bitcoin ATM in the United States in February 2014. The kiosk installed in Austin, Texas, is similar to bank ATMs but has scanners to read government-issued identification such as a driver's license, or a passport to confirm users' identities. + + +=== Initial coin offerings === +An initial coin offering (ICO) is a controversial means of raising funds for a new cryptocurrency venture. An ICO may be used by startups with the intention of avoiding regulation. However, securities regulators in many jurisdictions, including in the U.S. and Canada, have indicated that if a coin or token is an "investment contract" (e.g., under the Howey test, i.e., an investment of money with a reasonable expectation of profit based significantly on the entrepreneurial or managerial efforts of others), it is a security and is subject to securities regulation. In an ICO campaign, a percentage of the cryptocurrency (usually in the form of "tokens") is sold to early backers of the project in exchange for legal tender or other cryptocurrencies, often bitcoin or Ether. +According to PricewaterhouseCoopers, four of the 10 biggest proposed initial coin offerings have used Switzerland as a base, where they are frequently registered as non-profit foundations. The Swiss regulatory agency FINMA stated that it would take a "balanced approach" to ICO projects and would allow "legitimate innovators to navigate the regulatory landscape and so launch their projects in a way consistent with national laws protecting investors and the integrity of the financial system." In response to numerous requests by industry representatives, a legislative ICO working group began to issue legal guidelines in 2018, which are intended to remove uncertainty from cryptocurrency offerings and to establish sustainable business practices. + + +=== Price trends === +The market capitalization of a cryptocurrency is calculated by multiplying the price by the number of coins in circulation. The total cryptocurrency market cap has historically been dominated by bitcoin accounting for at least 50% of the market cap value where altcoins have increased and decreased in market cap value in relation to bitcoin. Bitcoin's value is largely determined by speculation among other technological limiting factors known as blockchain rewards coded into the architecture technology of bitcoin itself. +The cryptocurrency market cap follows a trend known as the "halving", which is when the block rewards received from bitcoin are halved due to technological mandated limited factors instilled into bitcoin which in turn limits the supply of bitcoin. As the date reaches near of a halving (twice thus far historically) the cryptocurrency market cap increases, followed by a downtrend. +By June 2021, cryptocurrency had begun to be offered by some wealth managers in the US for 401(k)s. + + +=== Volatility === +Cryptocurrency prices are much more volatile than established financial assets such as stocks. For example, over one week in May 2022, bitcoin lost 20% of its value and Ethereum lost 26%, while Solana and Cardano lost 41% and 35% respectively. The falls were attributed to warnings about inflation. By comparison, in the same week, the Nasdaq tech stock index fell 7.6 per cent and the FTSE 100 was 3.6 per cent down. +In the longer term, of the 10 leading cryptocurrencies identified by the total value of coins in circulation in January 2018, only four (bitcoin, Ethereum, Cardano and Ripple (XRP)) were still in that position in early 2022. The total value of all cryptocurrencies was $2 trillion at the end of 2021, but had halved nine months later. The Wall Street Journal has commented that the crypto sector has become "intertwined" with the rest of the capital markets and "sensitive to the same forces that drive tech stocks and other risk assets," such as inflation forecasts. + + +=== Databases === +There are also centralized databases, outside of blockchains, that store crypto market data. Compared to the blockchain, databases perform fast as there is no verification process. Four of the most popular cryptocurrency market databases are CoinMarketCap, CoinGecko, BraveNewCoin, and Cryptocompare. + + +== Social and political aspects == + +According to Alan Feuer of The New York Times, libertarians and anarcho-capitalists were attracted to the philosophical idea behind bitcoin. Early bitcoin supporter Roger Ver said: "At first, almost everyone who got involved did so for philosophical reasons. We saw bitcoin as a great idea, as a way to separate money from the state." Economist Paul Krugman argues that cryptocurrencies like bitcoin are "something of a cult" based in "paranoid fantasies" of government power. +David Golumbia says that the ideas influencing bitcoin advocates emerge from right-wing extremist movements such as the Liberty Lobby and the John Birch Society and their anti-Central Bank rhetoric, or, more recently, Ron Paul and Tea Party-style libertarianism. Steve Bannon, who owns a "good stake" in bitcoin, sees cryptocurrency as a form of disruptive populism, taking control back from central authorities. +Bitcoin's founder, Satoshi Nakamoto, supported the idea that cryptocurrencies go well with libertarianism. "It's very attractive to the libertarian viewpoint if we can explain it properly," Nakamoto said in 2008. +According to the European Central Bank, the decentralization of money offered by bitcoin has its theoretical roots in the Austrian school of economics, especially with Friedrich von Hayek in his book Denationalisation of Money: The Argument Refined, in which Hayek advocates a complete free market in the production, distribution and management of money to end the monopoly of central banks. + + +== Regulation == + +The rise in the popularity of cryptocurrencies and their adoption by financial institutions has led some governments to assess whether regulation is needed to protect users. The Financial Action Task Force (FATF) has defined cryptocurrency-related services as "virtual asset service providers" (VASPs) and recommended that they be regulated with the same money laundering (AML) and know your customer (KYC) requirements as financial institutions. +In May 2020, the Joint Working Group on interVASP Messaging Standards published "IVMS 101", a universal common language for communication of required originator and beneficiary information between VASPs. The FATF and financial regulators were informed as the data model was developed. +In June 2020, FATF updated its guidance to include the "Travel Rule" for cryptocurrencies, a measure which mandates that VASPs obtain, hold, and exchange information about the originators and beneficiaries of virtual asset transfers. Subsequent standardized protocol specifications recommended using JSON for relaying data between VASPs and identity services. As of December 2020, the IVMS 101 data model has yet to be finalized and ratified by the three global standard setting bodies that created it. +The European Commission published a digital finance strategy in September 2020. This included a draft regulation on Markets in Crypto-Assets (MiCA), which aimed to provide a comprehensive regulatory framework for digital assets in the EU. +In June 2021, the Basel Committee on Banking Supervision proposed that banks that held cryptocurrency assets must set aside capital to cover all potential losses. For instance, if a bank were to hold bitcoin worth $2 billion, it would be required to set aside enough capital to cover the entire $2 billion. This is a more extreme standard than banks are usually held to when it comes to other assets. However, this is a proposal and not a regulation. +The IMF is seeking a coordinated, consistent and comprehensive approach to supervising cryptocurrencies. Tobias Adrian, the IMF's financial counsellor and head of its monetary and capital markets department said in a January 2022 interview that "Agreeing global regulations is never quick. But if we start now, we can achieve the goal of maintaining financial stability while also enjoying the benefits which the underlying technological innovations bring," +In May 2024, 15 years after the advent of the first blockchain, bitcoin, the US Congress advanced a bill to the full House of Representatives to provide regulatory clarity for digital assets. The Financial Innovation and Technology for the 21st Century Act, which defines responsibilities between various US agencies, notably between the Commodity Futures Trading Commission (CFTC) for decentralized blockchains and the Securities and Exchange Commission (SEC) for blockchains that are functional but not decentralized. Stablecoins are excluded from both CFTC and SEC regulation in this bill, "except for fraud and certain activities by registered firms." + + +=== China === +In September 2017, China banned ICOs to cause abnormal return from cryptocurrency decreasing during announcement window. The liquidity changes by banning ICOs in China was temporarily negative while the liquidity effect became positive after news. +On 18 May 2021, China banned financial institutions and payment companies from being able to provide cryptocurrency transaction related services. This led to a sharp fall in the price of the biggest proof of work cryptocurrencies. For instance, bitcoin fell 31%, Ethereum fell 44%, Binance Coin fell 32% and Dogecoin fell 30%. Proof of work mining was the next focus, with regulators in popular mining regions citing the use of electricity generated from highly polluting sources such as coal to create bitcoin and Ethereum. +In September 2021, the Chinese government declared all cryptocurrency transactions of any kind illegal, completing its crackdown on cryptocurrency. + + +=== Cook Islands === +In April 2024, TVNZ's 1News reported that the Cook Islands government was proposing legislation that would allow "recovery agents" to use various means including hacking to investigate or find cryptocurrency that may have been used for illegal means or is the "proceeds of crime." The Tainted Cryptocurrency Recovery Bill was drafted by two lawyers hired by US-based debt collection company Drumcliffe. The proposed legislation was criticised by Cook Islands Crown Law's deputy solicitor general David Greig, who described it as "flawed" and said that some provisions were "clearly unconstitutional". The Cook Islands Financial Services Development Authority described Drumcliffe's involvement as a conflict of interest. +Similar criticism was echoed by Auckland University of Technology cryptocurrency specialist and senior lecturer Jeff Nijsse and University of Otago political scientist Professor Robert Patman, who described it as government overreach and described it as inconsistent with international law. Since the Cook Islands is an associated state that is part of the Realm of New Zealand, Patman said that the law would have "implications for New Zealand's governance arrangements." A spokesperson for New Zealand Foreign Minister Winston Peters confirmed that New Zealand officials were discussing the legislation with their Cook Islands counterparts. Cook Islands Prime Minister Mark Brown defended the legislation as part of the territory's fight against international cybercrime. + + +=== El Salvador === + +On 9 June 2021, El Salvador announced that it will adopt bitcoin as legal tender, becoming the first country to do so. + + +=== EU === + +The EU defines crypto assets as "a digital representation of a value or of a right that is able to be transferred and stored electronically using distributed ledger technology or similar technology." The EU regulation Markets in Crypto-Assets (MiCA) covering asset-referenced tokens (ARTs) and electronic money tokens (EMTs) (also known as stablecoins) came into force on 30 June 2024. As of 17 January 2025, the European Securities and Markets Authority (ESMA) issued guidance to crypto-asset service providers (CASPs) allowing them to maintain crypto-asset services for non-compliant ARTs and EMTs until the end of March 2025. +The rest of MiCA came into force as of 30 December 2024, covering crypto-assets other than ART and EMT and CASPs. MiCA excludes crypto-assets if they qualify as financial instruments according to ESMA guidelines published on 17 December 2024 as well as crypto-assets that are unique and not fungible with other crypto-assets. + + +=== India === +At present, India neither prohibits nor allows investment in the cryptocurrency market. In 2020, the Supreme Court of India had lifted the ban on cryptocurrency, which was imposed by the Reserve Bank of India. Since then, an investment in cryptocurrency is considered legitimate, though there is still ambiguity about the issues regarding the extent and payment of tax on the income accrued thereupon and also its regulatory regime. But it is being contemplated that the Indian Parliament will soon pass a specific law to either ban or regulate the cryptocurrency market in India. +Expressing his public policy opinion on the Indian cryptocurrency market to a well-known online publication, a leading public policy lawyer and Vice President of SAARCLAW (South Asian Association for Regional Co-operation in Law) Hemant Batra has said that the "cryptocurrency market has now become very big with involvement of billions of dollars in the market hence, it is now unattainable and irreconcilable for the government to completely ban all sorts of cryptocurrency and its trading and investment". He mooted regulating the cryptocurrency market rather than completely banning it. He favoured following IMF and FATF guidelines in this regard. + + +=== Singapore === + + +=== South Africa === +South Africa, which has seen a large number of scams related to cryptocurrency, is said to be putting a regulatory timeline in place that will produce a regulatory framework. The largest scam occurred in April 2021, where the two founders of an African-based cryptocurrency exchange called Africrypt, Raees Cajee and Ameer Cajee, disappeared with $3.8 billion worth of bitcoin. Additionally, Mirror Trading International disappeared with $170 million worth of cryptocurrency in January 2021. + + +=== South Korea === +In March 2021, South Korea implemented new legislation to strengthen their oversight of digital assets. This legislation requires all digital asset managers, providers and exchanges to be registered with the Korea Financial Intelligence Unit in order to operate in South Korea. Registering with this unit requires that all exchanges are certified by the Information Security Management System and that they ensure all customers have real name bank accounts. It also requires that the CEO and board members of the exchanges have not been convicted of any crimes and that the exchange holds sufficient levels of deposit insurance to cover losses arising from hacks. + + +=== Switzerland === +Switzerland was one of the first countries to implement the FATF's Travel Rule. FINMA, the Swiss regulator, issued its own guidance to VASPs in 2019. The guidance followed the FATF's Recommendation 16, with stricter requirements. According to FINMA's requirements, VASPs need to verify the identity of the beneficiary of the transfer. + + +=== Turkey === +In April 2021, the Central Bank of the Republic of Turkey banned the use of cryptocurrencies and cryptoassets for making purchases on the grounds that the use of cryptocurrencies for such payments poses significant transaction risks. + + +=== United Arab Emirates === + + +=== United Kingdom === +In the United Kingdom, as of 10 January 2021, all cryptocurrency firms, such as exchanges, advisors and professionals that have either a presence, market product or provide services within the UK market must register with the Financial Conduct Authority. On 27 June 2021, the financial watchdog demanded that Binance cease all regulated activities in the UK. +In November 2024, the incoming Labour government confirmed that it will proceed with the regulation of cryptoassets and new UK requirements are expected to come into force in 2026. + + +=== United States === +In 2021, 17 states in the US passed laws and resolutions concerning cryptocurrency regulation. This led the Securities and Exchange Commission to start considering what steps to take. On 8 July 2021, Senator Elizabeth Warren, part of the Senate Banking Committee, wrote to the chairman of the SEC and demanded answers on cryptocurrency regulation due to the increase in cryptocurrency exchange use and the danger this posed to consumers. On 5 August 2021, the chairman, Gary Gensler, responded to Warren's letter and called for legislation focused on "crypto trading, lending and DeFi platforms," because of how vulnerable investors could be when they traded on crypto trading platforms without a broker. He also argued that many tokens in the crypto market may be unregistered securities without required disclosures or market oversight. Additionally, Gensler did not hold back in his criticism of stablecoins. These tokens, which are pegged to the value of fiat currencies, may allow individuals to bypass important public policy goals related to traditional banking and financial systems, such as anti-money laundering, tax compliance, and sanctions. +On 19 October 2021, the first bitcoin-linked exchange-traded fund (ETF) from ProShares started trading on the NYSE under the ticker "BITO." ProShares CEO Michael L. Sapir said the ETF would expose bitcoin to a wider range of investors without the hassle of setting up accounts with cryptocurrency providers. Ian Balina, the CEO of Token Metrics, stated that SEC approval of the ETF was a significant endorsement for the crypto industry because many regulators globally were not in favor of crypto, and retail investors were hesitant to accept crypto. This event would eventually open more opportunities for new capital and new people in this space. +The Department of the Treasury, on 20 May 2021, announced that it would require any transfer worth $10,000 or more to be reported to the Internal Revenue Service since cryptocurrency already posed a problem where illegal activity like tax evasion was facilitated broadly. This release from the IRS was a part of efforts to promote better compliance and consider more severe penalties for tax evaders. +On 17 February 2022, the Department of Justice named Eun Young Choi as the first director of a National Cryptocurrency Enforcement Team to help identify and deal with misuse of cryptocurrencies and other digital assets. +The Biden administration faced a dilemma as it tried to develop regulations for the cryptocurrency industry. On one hand, officials were hesitant to restrict a growing industry. On the other hand, they were committed to preventing illegal cryptocurrency transactions. To reconcile these conflicting goals, on 9 March 2022, Biden issued an executive order. Followed this, on 16 September 2022, the Comprehensive Framework for Responsible Development of Digital Assets document was released to support development of cryptocurrencies and restrict their illegal use. The executive order included all digital assets, but cryptocurrencies posed both the greatest security risks and potential economic benefits. Though this might not address all of the challenges in crypto industry, it was a significant milestone in the US cryptocurrency regulation history. +In February 2023, the SEC ruled that cryptocurrency exchange Kraken's estimated $42 billion in staked assets globally operated as an illegal securities seller. The company agreed to a $30 million settlement with the SEC and to cease selling its staking service in the US. The case would impact other major crypto exchanges operating staking programs. +On 23 March 2023, the SEC issued an alert to investors stating that firms offering crypto asset securities might not be complying with US laws. The SEC argued that unregistered offerings of crypto asset securities might not include important information. +On 23 January 2025, President Donald Trump signed Executive Order 14178, Strengthening American Leadership in Digital Financial Technology revoking Executive Order 14067 of 9 March 2022, Ensuring Responsible Development of Digital Assets and the Department of the Treasury's Framework for International Engagement on Digital Assets of 7 July 2022. +In addition the order prohibits the establishment, issuance or promotion of Central bank digital currency and establishes a group tasked with proposing a federal regulatory framework for digital assets within 180 days. + + +== Legality == + +The legal status of cryptocurrencies varies substantially from country to country and is still undefined or changing in many of them. At least one study has shown that broad generalizations about the use of bitcoin in illicit finance are significantly overstated and that blockchain analysis is an effective crime fighting and intelligence gathering tool. While some countries have explicitly allowed their use and trade, others have banned or restricted it. +According to the Library of Congress in 2021, +an "absolute ban" on trading or using cryptocurrencies applies in 9 countries: +Algeria, Bangladesh, Bolivia, China, Egypt, Iraq, Morocco, Nepal, and the United Arab Emirates. An "implicit ban" applies in another 39 countries or regions, which include: Bahrain, Benin, Burkina Faso, Burundi, Cameroon, Chad, Cote d’Ivoire, the Dominican Republic, Ecuador, Gabon, Georgia, Guyana, Indonesia, Iran, Jordan, Kazakhstan, Kuwait, Lebanon, Lesotho, Macau, Maldives, Mali, Moldova, Namibia, Niger, Nigeria, Oman, Pakistan, Palau, Republic of Congo, Saudi Arabia, Senegal, Tajikistan, Tanzania, Togo, Turkey, Turkmenistan, Qatar and Vietnam. +In the United States and Canada, state and provincial securities regulators, coordinated through the North American Securities Administrators Association, are investigating "Bitcoin scams" and ICOs in 40 jurisdictions. +Various government agencies, departments, and courts have classified bitcoin differently. China Central Bank banned the handling of bitcoins by financial institutions in China in early 2014. +In Russia, though owning cryptocurrency is legal, its residents are only allowed to purchase goods from other residents using the Russian ruble while nonresidents are allowed to use foreign currency. Regulations and bans that apply to bitcoin probably extend to similar cryptocurrency systems. +In August 2018, the Bank of Thailand announced its plans to create its own cryptocurrency, the Central Bank Digital Currency (CBDC). + + +=== Advertising bans === +Cryptocurrency advertisements have been banned on the following platforms: + +Baidu +Bing—Ended June 2022 +Facebook—Ended December 2021 +Google—Ended August 2021 +Line +LinkedIn +MailChimp +Snapchat +Tencent +Twitter +Weibo +Yandex + + +=== U.S. tax status === +In March 2014, the United States Internal Revenue Service (IRS) ruled that bitcoin will be treated as property for tax purposes. Therefore, virtual currencies are considered commodities subject to capital gains tax. + + +=== Legal concerns relating to an unregulated global economy === +As the popularity and demand for online currencies has increased since the inception of bitcoin in 2009, so have concerns that such an unregulated person to person global economy that cryptocurrencies offer may become a threat to society. Concerns abound that altcoins may become tools for anonymous web criminals. +Cryptocurrency networks display a lack of regulation that has been criticized as enabling criminals who seek to evade taxes and launder money. Money laundering issues are also present in regular bank transfers, however with bank-to-bank wire transfers for instance, the account holder must at least provide a proven identity. +Transactions that occur through the use and exchange of these altcoins are independent from formal banking systems, and therefore can make tax evasion simpler for individuals. Since charting taxable income is based upon what a recipient reports to the revenue service, it becomes extremely difficult to account for transactions made using existing cryptocurrencies, a mode of exchange that is complex and difficult to track. +Systems of anonymity that most cryptocurrencies offer can also serve as a simpler means to launder money. Rather than laundering money through an intricate net of financial actors and offshore bank accounts, laundering money through altcoins can be achieved through anonymous transactions. +Cryptocurrency makes legal enforcement against extremist groups more complicated, which consequently strengthens them. White supremacist Richard Spencer went as far as to declare bitcoin the "currency of the alt-right". + + +=== Loss, theft, and fraud === + +In February 2014, the world's largest bitcoin exchange, Mt. Gox, declared bankruptcy. Likely due to theft, the company claimed that it had lost nearly 750,000 bitcoins belonging to their clients. This added up to approximately 7% of all bitcoins in existence, worth a total of $473 million. Mt. Gox blamed hackers, who had exploited the transaction malleability problems in the network. The price of a bitcoin fell from a high of about $1,160 in December to under $400 in February. +On 21 November 2017, Tether announced that it had been hacked, losing $31 million in USDT from its core treasury wallet. +On 7 December 2017, Slovenian cryptocurrency exchange Nicehash reported that hackers had stolen over $70 million using a hijacked company computer. +On 19 December 2017, Yapian, the owner of South Korean exchange Youbit, filed for bankruptcy after suffering two hacks that year. Customers were still granted access to 75% of their assets. +In May 2018, Bitcoin Gold had its transactions hijacked and abused by unknown hackers. Exchanges lost an estimated $18m and bitcoin Gold was delisted from Bittrex after it refused to pay its share of the damages. +On 13 September 2018, Homero Josh Garza was sentenced to 21 months of imprisonment, followed by three years of supervised release. Garza had founded the cryptocurrency startups GAW Miners and ZenMiner in 2014, acknowledged in a plea agreement that the companies were part of a pyramid scheme, and pleaded guilty to wire fraud in 2015. The SEC separately brought a civil enforcement action in the US against Garza, who was eventually ordered to pay a judgment of $9.1 million plus $700,000 in interest. The SEC's complaint stated that Garza, through his companies, had fraudulently sold "investment contracts representing shares in the profits they claimed would be generated" from mining. +In January 2018, Japanese exchange Coincheck reported that hackers had stolen cryptocurrency worth $530 million. +In June 2018, South Korean exchange Coinrail was hacked, losing over $37 million in crypto. The hack worsened a cryptocurrency selloff by an additional $42 billion. +On 9 July 2018, the exchange Bancor, whose code and fundraising had been subjects of controversy, had $23.5 million in crypto stolen. +A 2020 EU report found that users had lost crypto-assets worth hundreds of millions of US dollars in security breaches at exchanges and storage providers. Between 2011 and 2019, reported breaches ranged from four to twelve a year. In 2019, more than a billion dollars' worth of cryptoassets was reported stolen. Stolen assets "typically find their way to illegal markets and are used to fund further criminal activity". +According to a 2020 report produced by the United States Attorney General's Cyber-Digital Task Force, three categories make up the majority of illicit cryptocurrency uses: "(1) financial transactions associated with the commission of crimes; (2) money laundering and the shielding of legitimate activity from tax, reporting, or other legal requirements; or (3) crimes, such as theft, directly implicating the cryptocurrency marketplace itself." The report concluded that "for cryptocurrency to realize its truly transformative potential, it is imperative that these risks be addressed" and that "the government has legal and regulatory tools available at its disposal to confront the threats posed by cryptocurrency's illicit uses". +According to the UK 2020 national risk assessment—a comprehensive assessment of money laundering and terrorist financing risk in the UK—the risk of using cryptoassets such as bitcoin for money laundering and terrorism financing is assessed as "medium" (from "low" in the previous 2017 report). Legal scholars suggested that the money laundering opportunities may be more perceived than real. Blockchain analysis company Chainalysis concluded that illicit activities like cybercrime, money laundering and terrorism financing made up only 0.15% of all crypto transactions conducted in 2021, representing a total of $14 billion. +In December 2021, Monkey Kingdom, a NFT project based in Hong Kong, lost US$1.3 million worth of cryptocurrencies via a phishing link used by the hacker. +On November 2, 2023, Sam Bankman-Fried was pronounced guilty on seven counts of fraud related to FTX. Federal criminal court sentencing experts speculated on the potential amount of prison time likely to be meted out. On March 28, 2024, the court sentenced Bankman-Fried to 25 years in prison. + + +=== Money laundering === + +According to blockchain data company Chainalysis, criminals laundered US$8,600,000,000 worth of cryptocurrency in 2021, up by 30% from the previous year. The data suggests that rather than managing numerous illicit havens, cybercriminals make use of a small group of purpose built centralized exchanges for sending and receiving illicit cryptocurrency. In 2021, those exchanges received 47% of funds sent by crime linked addresses. Almost $2.2bn worth of cryptocurrencies was embezzled from DeFi protocols in 2021, which represents 72% of all cryptocurrency theft in 2021. +According to Bloomberg and the New York Times, Federation Tower, a two skyscraper complex in the heart of Moscow City, is home to many cryptocurrency businesses under suspicion of facilitating extensive money laundering, including accepting illicit cryptocurrency funds obtained through scams, darknet markets, and ransomware. Notable businesses include Garantex, Eggchange, Cashbank, Buy-Bitcoin, Tetchange, Bitzlato, and Suex, which was sanctioned by the U.S. in 2021. Bitzlato founder and owner Anatoly Legkodymov was arrested following money-laundering charges by the United States Department of Justice. +Dark money has also been flowing into Russia through a dark web marketplace called Hydra, which is powered by cryptocurrency, and enjoyed more than $1 billion in sales in 2020, according to Chainalysis. The platform demands that sellers liquidate cryptocurrency only through certain regional exchanges, which has made it difficult for investigators to trace the money. +Almost 74% of ransomware revenue in 2021 — over $400 million worth of cryptocurrency — went to software strains likely affiliated with Russia, where oversight is notoriously limited. However, Russians are also leaders in the benign adoption of cryptocurrencies, as the ruble is unreliable, and President Putin favours the idea of "overcoming the excessive domination of the limited number of reserve currencies." +In 2022, RenBridge - an unregulated alternative to exchanges for transferring value between blockchains - was found to be responsible for the laundering of at least $540 million since 2020. It is especially popular with people attempting to launder money from theft. This includes a cyberattack on Japanese crypto exchange Liquid that has been linked to North Korea. + + +=== Darknet markets === + +Properties of cryptocurrencies gave them popularity in applications such as a safe haven in banking crises and means of payment, which also led to the cryptocurrency use in controversial settings in the form of online black markets, such as Silk Road. The original Silk Road was shut down in October 2013 and there have been two more versions in use since then. In the year following the initial shutdown of Silk Road, the number of prominent dark markets increased from four to twelve, while the amount of drug listings increased from 18,000 to 32,000. +Darknet markets present challenges in regard to legality. Cryptocurrency used in dark markets are not clearly or legally classified in almost all parts of the world. In the US, bitcoins are regarded as "virtual assets". This type of ambiguous classification puts pressure on law enforcement agencies around the world to adapt to the shifting drug trade of dark markets. + + +=== Wash trades === +Various studies have found that crypto-trading is rife with wash trading. Wash trading is a process, illegal in some jurisdictions, involving buyers and sellers being the same person or group, and may be used to manipulate the price of a cryptocurrency or inflate volume artificially. Exchanges with higher volumes can demand higher premiums from token issuers. A study from 2019 concluded that up to 80% of trades on unregulated cryptocurrency exchanges could be wash trades. A 2019 report by Bitwise Asset Management claimed that 95% of all bitcoin trading volume reported on major website CoinMarketCap had been artificially generated, and of 81 exchanges studied, only 10 provided legitimate volume figures. + + +=== As a tool to evade sanctions === +In 2022, cryptocurrencies attracted attention when Western nations imposed severe economic sanctions on Russia in the aftermath of its invasion of Ukraine in February. However, American sources warned in March that some crypto-transactions could potentially be used to evade economic sanctions against Russia and Belarus. +In April 2022, the computer programmer Virgil Griffith received a five-year prison sentence in the US for attending a Pyongyang cryptocurrency conference, where he gave a presentation on blockchains which might be used for sanctions evasion. + + +== Impacts and analysis == + +The Bank for International Settlements summarized several criticisms of cryptocurrencies in Chapter V of their 2018 annual report. The criticisms include the lack of stability in their price, the high energy consumption, high and variable transactions costs, the poor security and fraud at cryptocurrency exchanges, vulnerability to debasement (from forking), and the influence of miners. + + +=== Speculation, fraud, and adoption === + +Cryptocurrencies have been compared to Ponzi schemes, pyramid schemes and economic bubbles, such as housing market bubbles. Howard Marks of Oaktree Capital Management stated in 2017 that digital currencies were "nothing but an unfounded fad (or perhaps even a pyramid scheme), based on a willingness to ascribe value to something that has little or none beyond what people will pay for it", and compared them to the tulip mania (1637), South Sea Bubble (1720), and dot-com bubble (1999), which all experienced profound price booms and busts. +Regulators in several countries have warned against cryptocurrency and some have taken measures to dissuade users. However, research in 2021 by the UK's financial regulator suggests such warnings either went unheard, or were ignored. Fewer than one in 10 potential cryptocurrency buyers were aware of consumer warnings on the FCA website, and 12% of crypto users were not aware that their holdings were not protected by statutory compensation. Of 1,000 respondents between the ages of eighteen and forty, almost 70% wrongly assumed cryptocurrencies were regulated, 75% of younger crypto investors claimed to be driven by competition with friends and family, 58% said that social media enticed them to make high risk investments. The FCA recommends making use of its warning list, which flags unauthorized financial firms. +Many banks do not offer virtual currency services themselves and can refuse to do business with virtual currency companies. In 2014, Gareth Murphy, a senior banking officer, suggested that the widespread adoption of cryptocurrencies may lead to too much money being obfuscated, blinding economists who would use such information to better steer the economy. While traditional financial products have strong consumer protections in place, there is no intermediary with the power to limit consumer losses if bitcoins are lost or stolen. One of the features cryptocurrency lacks in comparison to credit cards, for example, is consumer protection against fraud, such as chargebacks. +The French regulator Autorité des marchés financiers (AMF) lists 16 websites of companies that solicit investment in cryptocurrency without being authorized to do so in France. +An October 2021 paper by the National Bureau of Economic Research found that bitcoin suffers from systemic risk as the top 10,000 addresses control about one-third of all bitcoin in circulation. It is even worse for miners, with 0.01% controlling 50% of the capacity. According to researcher Flipside Crypto, less than 2% of anonymous accounts control 95% of all available bitcoin supply. This is considered risky as a great deal of the market is in the hands of a few entities. +A paper by John Griffin, a finance professor at the University of Texas, and Amin Shams, a graduate student found that in 2017 the price of bitcoin had been substantially inflated using another cryptocurrency, Tether. +Roger Lowenstein, author of "Bank of America: The Epic Struggle to Create the Federal Reserve," says in a New York Times story that FTX will face over $8 billion in claims. + + +=== Non-fungible tokens === +Non-fungible tokens (NFTs) are digital assets that represent art, collectibles, gaming, etc. Like crypto, their data is stored on the blockchain. NFTs are bought and traded using cryptocurrency. The Ethereum blockchain was the first place where NFTs were implemented, but now many other blockchains have created their own versions of NFTs. + + +=== Banks === + +According to Vanessa Grellet, renowned panelist in blockchain conferences, there was an increasing interest from traditional stock exchanges in crypto-assets at the end of the 2010s, while crypto-exchanges such as Coinbase were gradually entering the traditional financial markets. This convergence marked a significant trend where conventional financial actors were adopting blockchain technology to enhance operational efficiency, while the crypto world introduced innovations like Security Token Offering (STO), enabling new ways of fundraising. Tokenization, turning assets such as real estate, investment funds, and private equity into blockchain-based tokens, had the potential to make traditionally illiquid assets more accessible to investors. Despite the regulatory risks associated with such developments, major financial institutions, including JPMorgan Chase, were actively working on blockchain initiatives, exemplified by the creation of Quorum, a private blockchain platform. +As the first big Wall Street bank to embrace cryptocurrencies, Morgan Stanley announced on 17 March 2021 that they will be offering access to bitcoin funds for their wealthy clients through three funds which enable bitcoin ownership for investors with an aggressive risk tolerance. BNY Mellon on 11 February 2021 announced that it would begin offering cryptocurrency services to its clients. +On 20 April 2021, Venmo added support to its platform to enable customers to buy, hold and sell cryptocurrencies. +In October 2021, financial services company Mastercard announced it is working with digital asset manager Bakkt on a platform that would allow any bank or merchant on the Mastercard network to offer cryptocurrency services. + + +=== Environmental effects === + +Mining for proof-of-work cryptocurrencies requires enormous amounts of electricity and consequently comes with a large carbon footprint due to causing greenhouse gas emissions. Proof-of-work blockchains such as bitcoin, Ethereum, Litecoin, and Monero were estimated to have added between 3 million and 15 million tons of carbon dioxide (CO2) to the atmosphere in the period from 1 January 2016 to 30 June 2017. By November 2018, bitcoin was estimated to have an annual energy consumption of 45.8TWh, generating 22.0 to 22.9 million tons of CO2, rivalling nations like Jordan and Sri Lanka. By the end of 2021, bitcoin was estimated to produce 65.4 million tons of CO2, as much as Greece, and consume between 91 and 177 terawatt-hours annually. +Critics have also identified a large electronic waste problem in disposing of mining rigs. Mining hardware is improving at a fast rate, quickly resulting in older generations of hardware. +Bitcoin is the least energy-efficient cryptocurrency, using 707.6 kilowatt-hours of electricity per transaction. +Before June 2021, China was the primary location for bitcoin mining. However, due to concerns over power usage and other factors, China forced out bitcoin operations, at least temporarily. As a result, the United States promptly emerged as the top global leader in the industry. An example of a gross amount of electronic waste associated with bitcoin mining operations in the US is a facility that located in Dalton, Georgia which is consuming nearly the same amount of electricity as the combined power usage of 97,000 households in its vicinity. Another example is that Riot Platforms operates a bitcoin mining facility in Rockdale, Texas, which consumes approximately as much electricity as the nearby 300,000 households. This makes it the most energy-intensive bitcoin mining operation in the United States. +The world's second-largest cryptocurrency, Ethereum, uses 62.56 kilowatt-hours of electricity per transaction. XRP is the world's most energy efficient cryptocurrency, using 0.0079 kilowatt-hours of electricity per transaction. +Although the biggest PoW blockchains consume energy on the scale of medium-sized countries, the annual power demand from proof-of-stake (PoS) blockchains is on a scale equivalent to a housing estate. The Times identified six "environmentally friendly" cryptocurrencies: Chia, IOTA, Cardano, Nano, Solarcoin and Bitgreen. Academics and researchers have used various methods for estimating the energy use and energy efficiency of blockchains. A study of the six largest proof-of-stake networks in May 2021 concluded: + +Cardano has the lowest electricity use per node; +Polkadot has the lowest electricity use overall; and +Solana has the lowest electricity use per transaction. +In terms of annual consumption (kWh/yr), the figures were: Polkadot (70,237), Tezos (113,249), Avalanche (489,311), Algorand (512,671), Cardano (598,755) and Solana (1,967,930). This equates to Polkadot consuming 7 times the electricity of an average U.S. home, Cardano 57 homes and Solana 200 times as much. The research concluded that PoS networks consumed 0.001% the electricity of the bitcoin network. University College London researchers reached a similar conclusion. +Variable renewable energy power stations could invest in bitcoin mining to reduce curtailment, hedge electricity price risk, stabilize the grid, increase the profitability of renewable energy power stations and therefore accelerate transition to sustainable energy. + + +=== Technological limitations === +There are also purely technical elements to consider. For example, technological advancement in cryptocurrencies such as bitcoin result in high up-front costs to miners in the form of specialized hardware and software. Cryptocurrency transactions are normally irreversible after a number of blocks confirm the transaction. Additionally, cryptocurrency private keys can be permanently lost from local storage due to malware, data loss or the destruction of the physical media. This precludes the cryptocurrency from being spent, resulting in its effective removal from the markets. + + +=== Academic studies === + +In September 2015, the establishment of the peer-reviewed academic journal Ledger (ISSN 2379-5980) was announced. It covers studies of cryptocurrencies and related technologies, and is published by the University of Pittsburgh. +The journal encourages authors to digitally sign a file hash of submitted papers, which will then be timestamped into the bitcoin blockchain. Authors are also asked to include a personal bitcoin address in the first page of their papers. + + +=== Aid agencies === +A number of aid agencies have started accepting donations in cryptocurrencies, including UNICEF. Christopher Fabian, principal adviser at UNICEF Innovation, said the children's fund would uphold donor protocols, meaning that people making donations online would have to pass checks before they were allowed to deposit funds. +However, in 2021, there was a backlash against donations in bitcoin because of the environmental emissions it caused. Some agencies stopped accepting bitcoin and others turned to "greener" cryptocurrencies. The U.S. arm of Greenpeace stopped accepting bitcoin donations after seven years. It said: "As the amount of energy needed to run bitcoin became clearer, this policy became no longer tenable." +In 2022, the Ukrainian government raised over US$10,000,000 worth of aid through cryptocurrency following the 2022 Russian invasion of Ukraine. + + +=== Criticism === +Bitcoin has been characterized as a speculative bubble by eight winners of the Nobel Memorial Prize in Economic Sciences: Paul Krugman, Robert J. Shiller, Joseph Stiglitz, Richard Thaler, James Heckman, Thomas Sargent, Angus Deaton, and Oliver Hart; and by central bank officials including Alan Greenspan, Agustín Carstens, Vítor Constâncio, and Nout Wellink. +Investors Warren Buffett and George Soros have respectively characterized it as a "mirage" and a "bubble"; while business executives Jack Ma and JP Morgan Chase CEO Jamie Dimon have called it a "bubble" and a "fraud", respectively, although Jamie Dimon later said he regretted dubbing bitcoin a fraud. BlackRock CEO Laurence D. Fink called bitcoin an "index of money laundering". +In June 2022, business magnate Bill Gates said that cryptocurrencies are "100% based on greater fool theory". +Legal scholars criticize the lack of regulation, which hinders conflict resolution when crypto assets are at the center of a legal dispute, for example a divorce or an inheritance. In Switzerland, jurists generally deny that cryptocurrencies are objects that fall under property law, as cryptocurrencies do not belong to any class of legally defined objects (Typenzwang, the legal numerus clausus). Therefore, it is debated whether anybody could even be sued for embezzlement of cryptocurrency if they had access to someone's wallet. However, in the law of obligations and contract law, any kind of object would be legally valid, but the object would have to be tied to an identified counterparty. However, as the more popular cryptocurrencies can be freely and quickly exchanged into legal tender, they are financial assets and have to be taxed and accounted for as such. +Losses associated with crytocurrency investments have been linked to suicides. In 2018, an increase in crypto-related suicides was noticed after the cryptocurrency market crashed in August. The situation was particularly critical in Korea as crypto traders were on "suicide watch". The May 2022 collapse of the Luna currency operated by Terra also led to reports of suicidal investors in crypto-related subreddits. + + +== See also == + +2018 crypto crash – Speculative bubble involving cryptocurrency pricesPages displaying short descriptions of redirect targets +Blockchain-based remittances company – Money transfer by a foreign worker to their home countryPages displaying short descriptions of redirect targets +Cryptocurrency bubble – Speculative bubble involving cryptocurrency prices +Cryptocurrency exchange – Trading exchange for crypto- and digital currencies +Cryptographic protocol – Aspect of cryptography +Cryptojacking – Hijacking computers to mine currency +Ponzi scheme – Type of financial fraud +List of cryptocurrencies +Virtual currency law in the United States – Federal financial regulations + + +== References == + + +== Further reading == +Chayka, Kyle (2 July 2013). "What Comes After Bitcoin?". Pacific Standard. Retrieved 18 January 2014. +Guadamuz, Andres; Marsden, Chris (2015). "Blockchains and Bitcoin: Regulatory Responses to Cryptocurrencies" (PDF). First Monday. 20 (12). doi:10.5210/fm.v20i12.6198. S2CID 811921. +Haynie, Dana L.; Duxbury, Scott W. (2024). "Online Illegal Cryptomarkets". Annual Review of Sociology. + + +== External links == + Media related to Cryptocurrency at Wikimedia Commons + Quotations related to Cryptocurrency at Wikiquote + Learning materials related to Should cryptocurrencies be banned? at Wikiversity \ No newline at end of file diff --git a/lightrag/evaluation/wiki_documents/finance_stock_market.txt b/lightrag/evaluation/wiki_documents/finance_stock_market.txt new file mode 100644 index 00000000..315f2890 --- /dev/null +++ b/lightrag/evaluation/wiki_documents/finance_stock_market.txt @@ -0,0 +1,235 @@ +A stock market, equity market, or share market is the aggregation of buyers and sellers of stocks (also called shares), which represent ownership claims on businesses; these may include securities listed on a public stock exchange as well as stock that is only traded privately, such as shares of private companies that are sold to investors through equity crowdfunding platforms. Investments are usually made with an investment strategy in mind. + + +== Size of the market == +The total market capitalization of all publicly traded stocks worldwide rose from US$2.5 trillion in 1980 to US$111 trillion by the end of 2023. +As of 2016, there are 60 stock exchanges in the world. Of these, there are 16 exchanges with a market capitalization of $1 trillion or more, and they account for 87% of global market capitalization. Apart from the Australian Securities Exchange, these 16 exchanges are all in North America, Europe, or Asia. +By country, the largest stock markets as of January 2022 are in the United States of America (about 59.9%), followed by Japan (about 6.2%) and United Kingdom (about 3.9%). + + +== Stock exchange == + +A stock exchange is an exchange (or bourse) where stockbrokers and traders can buy and sell shares (equity stock), bonds, and other securities. Many large companies have their stocks listed on a stock exchange. This makes the stock more liquid and thus more attractive to many investors. The exchange may also act as a guarantor of settlement. These and other stocks may also be traded "over the counter" (OTC), that is, through a dealer. Some large companies will have their stock listed on more than one exchange in different countries, so as to attract international investors. +Stock exchanges may also cover other types of securities, such as fixed-interest securities (bonds) or (less frequently) derivatives, which are more likely to be traded OTC. +Trade in stock markets means the transfer (in exchange for money) of a stock or security from a seller to a buyer. This requires these two parties to agree on a price. Equities (stocks or shares) confer an ownership interest in a particular company. +Participants in the stock market range from small individual stock investors to larger investors, who can be based anywhere in the world, and may include banks, insurance companies, pension funds and hedge funds. Their buy or sell orders may be executed on their behalf by a stock exchange trader. +Some exchanges are physical locations where transactions are carried out on a trading floor, by a method known as open outcry. This method is used in some stock exchanges and commodities exchanges, and involves traders shouting bid and offer prices. The other type of stock exchange has a network of computers where trades are made electronically. An example of such an exchange is the NASDAQ. +A potential buyer bids a specific price for a stock, and a potential seller asks a specific price for the same stock. Buying or selling at the Market means you will accept any ask price or bid price for the stock. When the bid and ask prices match, a sale takes place, on a first-come, first-served basis if there are multiple bidders at a given price. +The purpose of a stock exchange is to facilitate the exchange of securities between buyers and sellers, thus providing a marketplace. The exchanges provide real-time trading information on the listed securities, facilitating price discovery. +The New York Stock Exchange (NYSE) is a physical exchange, with a hybrid market for placing orders electronically from any location as well as on the trading floor. Orders executed on the trading floor enter by way of exchange members and flow down to a floor broker, who submits the order electronically to the floor trading post for the Designated market maker ("DMM") for that stock to trade the order. The DMM's job is to maintain a two-sided market, making orders to buy and sell the security when there are no other buyers or sellers. If a bid–ask spread exists, no trade immediately takes place – in this case, the DMM may use their own resources (money or stock) to close the difference. Once a trade has been made, the details are reported on the "tape" and sent back to the brokerage firm, which then notifies the investor who placed the order. Computers play an important role, especially for program trading. +The NASDAQ is an electronic exchange, where all of the trading is done over a computer network. The process is similar to the New York Stock Exchange. One or more NASDAQ market makers will always provide a bid and ask the price at which they will always purchase or sell 'their' stock. +The Paris Bourse, now part of Euronext, is an order-driven, electronic stock exchange. It was automated in the late 1980s. Prior to the 1980s, it consisted of an open outcry exchange. Stockbrokers met on the trading floor of the Palais Brongniart. In 1986, the CATS trading system was introduced, and the order matching system was fully automated. +People trading stock will prefer to trade on the most popular exchange since this gives the largest number of potential counter parties (buyers for a seller, sellers for a buyer) and probably the best price. However, there have always been alternatives such as brokers trying to bring parties together to trade outside the exchange. Some third markets that were popular are Instinet, and later Island and Archipelago (the latter two have since been acquired by Nasdaq and NYSE, respectively). One advantage is that this avoids the commissions of the exchange. However, it also has problems such as adverse selection. Financial regulators have probed dark pools. + + +== Market participant == + +Market participants include individual retail investors, institutional investors (e.g., pension funds, insurance companies, mutual funds, index funds, exchange-traded funds, hedge funds, investor groups, banks and various other financial institutions), and also publicly traded corporations trading in their own shares. Robo-advisors, which automate investment for individuals, are also major participants. + + +=== Stock market participation post-2020 pandemic === +In 2021, the value of world stock markets experienced an increase of 26.5%, amounting to US$22.3 trillion. Developing countries contributed US$9.9 trillion and developed countries US$12.4 trillion. Asia and Oceania accounted for 45%, Europe had 37%, and America had 16%, while Africa had 2% of the global market. + + +=== Stock market participation factors === +Factors such as high trading prices, market ratings, information about stock exchange dynamics, and financial institutions can influence individual and corporate participation in stock markets. Additionally, the appeal of stock ownership, driven by the potential for higher returns compared to other financial instruments, plays a crucial role in attracting individuals to invest in the stock market. +Regional and country-specific factors can also impact stock market participation rates. For example, in the United States, stock market participation rates vary widely across states, with regional factors potentially influencing these disparities. It is noted that individual participation costs alone cannot explain such large differences in participation rates from state to state, indicating the presence of other regional factors at play. +Behavioral factors are recognized as significant influences on stock market participation, as evidenced by the low participation rates observed in the Ghanaian stock market. +Factors such as factor endowments, geography, political stability, liberal trade policies, foreign direct investment inflows, and domestic industrial capacity are also identified as important in determining participation. + + +=== Demographics of market participation === + + +==== Indirect versus direct investment ==== +Indirect investment involves owning shares indirectly, such as via a mutual fund or an exchange traded fund. Direct investment involves direct ownership of shares. +Direct ownership of stock by individuals rose slightly from 17.8% in 1992 to 17.9% in 2007, with the median value of these holdings rising from $14,778 to $17,000. Indirect participation in the form of retirement accounts rose from 39.3% in 1992 to 52.6% in 2007, with the median value of these accounts more than doubling from $22,000 to $45,000 in that time. Rydqvist, Spizman, and Strebulaev attribute the differential growth in direct and indirect holdings to differences in the way each are taxed in the United States. Investments in pension funds and 401ks, the two most common vehicles of indirect participation, are taxed only when funds are withdrawn from the accounts. Conversely, the money used to directly purchase stock is subject to taxation as are any dividends or capital gains they generate for the holder. In this way, the current tax code incentivizes individuals to invest indirectly. + + +==== Participation by income and wealth strata ==== +Rates of participation and the value of holdings differ significantly across strata of income. In the bottom quintile of income, 5.5% of households directly own stock and 10.7% hold stocks indirectly in the form of retirement accounts. The top decile of income has a direct participation rate of 47.5% and an indirect participation rate in the form of retirement accounts of 89.6%. The median value of directly owned stock in the bottom quintile of income is $4,000 and is $78,600 in the top decile of income as of 2007. The median value of indirectly held stock in the form of retirement accounts for the same two groups in the same year is $6,300 and $214,800 respectively. Since the Great Recession of 2008 households in the bottom half of the income distribution have lessened their participation rate both directly and indirectly from 53.2% in 2007 to 48.8% in 2013, while over the same period households in the top decile of the income distribution slightly increased participation 91.7% to 92.1%. The mean value of direct and indirect holdings at the bottom half of the income distribution moved slightly downward from $53,800 in 2007 to $53,600 in 2013. In the top decile, mean value of all holdings fell from $982,000 to $969,300 in the same time. The mean value of all stock holdings across the entire income distribution is valued at $269,900 as of 2013. + + +==== Participation by race and gender ==== +The racial composition of stock market ownership shows households headed by whites are nearly four and six times as likely to directly own stocks than households headed by blacks and Hispanics respectively. As of 2011 the national rate of direct participation was 19.6%, for white households the participation rate was 24.5%, for black households it was 6.4% and for Hispanic households it was 4.3%. Indirect participation in the form of 401k ownership shows a similar pattern with a national participation rate of 42.1%, a rate of 46.4% for white households, 31.7% for black households, and 25.8% for Hispanic households. Households headed by married couples participated at rates above the national averages with 25.6% participating directly and 53.4% participating indirectly through a retirement account. 14.7% of households headed by men participated in the market directly and 33.4% owned stock through a retirement account. 12.6% of female-headed households directly owned stock and 28.7% owned stock indirectly. + + +==== Determinants and possible explanations of stock market participation ==== +A 2003 paper by Annette Vissing-Jørgensen attempts to explain disproportionate rates of participation along wealth and income groups as a function of fixed costs associated with investing. Her research concludes that a fixed cost of $200 per year is sufficient to explain why nearly half of all U.S. households do not participate in the market. Participation rates have been shown to strongly correlate with education levels, promoting the hypothesis that information and transaction costs of market participation are better absorbed by more educated households. Behavioral economists Harrison Hong, Jeffrey Kubik and Jeremy Stein suggest that sociability and participation rates of communities have a statistically significant impact on an individual's decision to participate in the market. Their research indicates that social individuals living in states with higher than average participation rates are 5% more likely to participate than individuals that do not share those characteristics. This phenomenon also explained in cost terms. Knowledge of market functioning diffuses through communities and consequently lowers transaction costs associated with investing. + + +== History == +In 12th-century France, the courtiers de change were concerned with managing and regulating the debts of agricultural communities on behalf of the banks. Because these men also traded with debts, they could be called the first brokers. The Italian historian Lodovico Guicciardini described how, in late 13th-century Bruges, commodity traders gathered outdoors at a market square containing an inn owned by a family called Van der Beurze, and in 1409 they became the "Brugse Beurse", institutionalizing what had been, until then, an informal meeting. The idea quickly spread around Flanders and neighboring countries and "Beurzen" soon opened in Ghent and Rotterdam. International traders, and specially the Italian bankers, present in Bruges since the early 13th-century, took back the word in their countries to define the place of a stock market exchange: first the Italians (borsa), but soon also the French (bourse), the Germans (börse), Russians (birža), Czechs (burza), Swedes (börs), Danes and Norwegians (børs). In most languages, the word coincides with that for money bag, dating back to the Latin "bursa", from which also derives the name of the Van der Beurse family. +In the middle of the 13th century, Venetian bankers began to trade in government securities. In 1351 the Venetian government outlawed spreading rumors intended to lower the price of government funds. Bankers in Pisa, Verona, Genoa and Florence also began trading in government securities during the 14th century. This was only possible because these were independent city-states not ruled by a duke but a council of influential citizens. Italian companies were also the first to issue shares. Companies in England and the Low Countries followed in the 16th century. Around this time, a joint stock company—one whose stock is owned jointly by the shareholders—emerged and became important for the colonization of what Europeans called the "New World". + +There are now stock markets in virtually every developed and most developing countries, with the world's largest markets being in the United States, United Kingdom, Japan, India, China, Canada, Germany, France, South Korea and the Netherlands. + + +== Importance == +Even in the days before perestroika, socialism was never a monolith. Within the Communist countries, the spectrum of socialism ranged from the quasi-market, quasi-syndicalist system of Yugoslavia to the centralized totalitarianism of neighboring Albania. One time I asked Professor von Mises, the great expert on the economics of socialism, at what point on this spectrum of statism would he designate a country as "socialist" or not. At that time, I wasn't sure that any definite criterion existed to make that sort of clear-cut judgment. And so I was pleasantly surprised at the clarity and decisiveness of Mises's answer. "A stock market," he answered promptly. "A stock market is crucial to the existence of capitalism and private property. For it means that there is a functioning market in the exchange of private titles to the means of production. There can be no genuine private ownership of capital without a stock market: there can be no true socialism if such a market is allowed to exist." + + +=== Function and purpose === +The stock market is one of the most important ways for companies to raise money, along with debt markets which are generally more imposing but do not trade publicly. This allows businesses to be publicly traded, and raise additional financial capital for expansion by selling shares of ownership of the company in a public market. The liquidity that an exchange affords the investors enables their holders to quickly and easily sell securities. This is an attractive feature of investing in stocks, compared to other less liquid investments such as property and other immoveable assets. +History has shown that the price of stocks and other assets is an important part of the dynamics of economic activity, and can influence or be an indicator of social mood. An country where the stock market is on the rise is considered to be an up-and-coming economy. The stock market is considered one of the economic indicators of a country's economic strength and development. +Rising share prices, for instance, tend to be associated with increased business investment and vice versa. Share prices also affect the wealth of households and their consumption. Therefore, central banks tend to keep an eye on the control and behavior of the stock market and, in general, on the smooth operation of financial system functions. Economic stability is one of the central bank mandates. +Exchanges also act as the clearinghouse for each transaction, meaning that they collect and deliver the shares, and guarantee payment to the seller of a security. This eliminates the risk to an individual buyer or seller that the counterparty could default on the transaction. +The smooth functioning of all these activities facilitates economic growth in that lower costs and enterprise risks promote the production of goods and services as well as possibly employment. In this way the financial system is assumed to contribute to increased prosperity, although some controversy exists as to whether the optimal financial system is bank-based or market-based. +Events such as the 2008 financial crisis have prompted a heightened degree of scrutiny of the impact of the structure of stock markets (called market microstructure), in particular to the stability of the financial system and the transmission of systemic risk. + + +=== Relation to the modern financial system === +A transformation is the move to electronic trading to replace human trading of listed securities. + + +=== Behavior of stock prices === + +Changes in stock prices are mostly caused by external factors such as socioeconomic conditions, inflation, exchange rates. Intellectual capital does not affect a company stock's current earnings. Intellectual capital contributes to a stock's return growth. +The efficient-market hypothesis (EMH) is a hypothesis in financial economics that states that asset prices reflect all available information at the current time. +The 'hard' efficient-market hypothesis does not explain the cause of events such as the crash in 1987, when the Dow Jones Industrial Average plummeted 22.6 percent—the largest-ever one-day fall in the United States. +This event demonstrated that share prices can fall dramatically even though no generally agreed upon definite cause has been found: a thorough search failed to detect any 'reasonable' development that might have accounted for the crash. (Such events are predicted to occur strictly by randomness, although very rarely.) It seems also to be true more generally that many price movements (beyond those which are predicted to occur 'randomly') are not occasioned by new information; a study of the fifty largest one-day share price movements in the United States in the post-war period seems to confirm this. +A 'soft' EMH has emerged which does not require that prices remain at or near equilibrium, but only that market participants cannot systematically profit from any momentary 'market anomaly'. Moreover, while EMH predicts that all price movement (in the absence of change in fundamental information) is random (i.e. non-trending), many studies have shown a marked tendency for the stock market to trend over time periods of weeks or longer. Various explanations for such large and apparently non-random price movements have been promulgated. For instance, some research has shown that changes in estimated risk, and the use of certain strategies, such as stop-loss limits and value at risk limits, theoretically could cause financial markets to overreact. But the best explanation seems to be that the distribution of stock market prices is non-Gaussian (in which case EMH, in any of its current forms, would not be strictly applicable). +Other research has shown that psychological factors may result in exaggerated (statistically anomalous) stock price movements (contrary to EMH which assumes such behaviors 'cancel out'). Psychological research has demonstrated that people are predisposed to 'seeing' patterns, and often will perceive a pattern in what is, in fact, just noise, e.g. seeing familiar shapes in clouds or ink blots. In the present context, this means that a succession of good news items about a company may lead investors to overreact positively, driving the price up. A period of good returns also boosts the investors' self-confidence, reducing their (psychological) risk threshold. +Another phenomenon—also from psychology—that works against an objective assessment is group thinking. As social animals, it is not easy to stick to an opinion that differs markedly from that of a majority of the group. An example with which one may be familiar is the reluctance to enter a restaurant that is empty; people generally prefer to have their opinion validated by those of others in the group. +In one paper the authors draw an analogy with gambling. In normal times the market behaves like a game of roulette; the probabilities are known and largely independent of the investment decisions of the different players. In times of market stress, however, the game becomes more like poker (herding behavior takes over). The players now must give heavy weight to the psychology of other investors and how they are likely to react psychologically. +Stock markets play an essential role in growing industries that ultimately affect the economy through transferring available funds from units that have excess funds (savings) to those who are suffering from funds deficit (borrowings) (Padhi and Naik, 2012). In other words, capital markets facilitate funds movement between the above-mentioned units. This process leads to the enhancement of available financial resources which in turn affects the economic growth positively. +Economic and financial theories argue that stock prices are affected by macroeconomic trends. Macroeconomic trends include such as changes in GDP, unemployment rates, national income, price indices, output, consumption, unemployment, inflation, saving, investment, energy, international trade, immigration, productivity, aging populations, innovations, international finance. increasing corporate profit, increasing profit margins, higher concentration of business, lower company income, less vigorous activity, less progress, lower investment rates, lower productivity growth, less employee share of corporate revenues, decreasing worker to beneficiary ratio (year 1960 5:1, year 2009 3:1, year 2030 2.2:1), and the increasing female to male ratio of college graduates. + + +=== Irrational behavior === +Sometimes, the market seems to react irrationally to economic or financial news, even if that news is likely to have no real effect on the fundamental value of securities itself. However, this market behaviour may be more apparent than real, since often such news was anticipated, and a counter reaction may occur if the news is better (or worse) than expected. Therefore, the stock market may be swayed in either direction by press releases, rumors, euphoria and mass panic. +Over the short term, stocks and other securities can be battered or bought by any number of fast market-changing events, making the stock market behavior difficult to predict. Emotions can drive prices up and down, people are generally not as rational as they think, and the reasons for buying and selling are generally accepted. +Behaviorists argue that investors often behave irrationally when making investment decisions thereby incorrectly pricing securities, which causes market inefficiencies, which, in turn, are opportunities to make money. However, the whole notion of EMH is that these non-rational reactions to information cancel out, leaving the prices of stocks rationally determined. + + +=== Crashes === + +A stock market crash is often defined as a sharp dip in share prices of stocks listed on the stock exchanges. In parallel with various economic factors, a reason for stock market crashes is also due to panic and investing public's loss of confidence. Often, stock market crashes end speculative economic bubbles. +There have been famous stock market crashes that have ended in the loss of billions of dollars and wealth destruction on a massive scale. An increasing number of people are involved in the stock market, especially since the social security and retirement plans are being increasingly privatized and linked to stocks and bonds and other elements of the market. There have been a number of famous stock market crashes like the Wall Street Crash of 1929, the stock market crash of 1973–4, Black Monday of 1987, the dot-com bubble of 2000, and the 2008 financial crisis. + + +=== 1929 === +One of the most famous stock market crashes started October 24, 1929, on Black Thursday. The Dow Jones Industrial Average lost 50% during this stock market crash. It was the beginning of the Great Depression. + + +=== 1987 === +Another famous crash took place on October 19, 1987 – Black Monday. The crash began in Hong Kong and quickly spread around the world. +By the end of October, stock markets in Hong Kong had fallen 45.5%, Australia 41.8%, Spain 31%, the United Kingdom 26.4%, the United States 22.68%, and Canada 22.5%. Black Monday itself was the largest one-day percentage decline in stock market history – the Dow Jones fell by 22.6% in a day. The names "Black Monday" and "Black Tuesday" are also used for October 28–29, 1929, which followed Terrible Thursday—the starting day of the stock market crash in 1929. +The crash in 1987 raised some puzzles – main news and events did not predict the catastrophe and visible reasons for the collapse were not identified. This event raised questions about many important assumptions of modern economics, namely, the theory of rational human conduct, the theory of market equilibrium and the efficient-market hypothesis. For some time after the crash, trading in stock exchanges worldwide was halted, since the exchange computers did not perform well owing to enormous quantity of trades being received at one time. This halt in trading allowed the Federal Reserve System and central banks of other countries to take measures to control the spreading of a financial crisis. In the United States the SEC introduced several new measures of control into the stock market in an attempt to prevent a re-occurrence of the events of Black Monday. + + +=== 2007–2009 === +This marked the beginning of the Great Recession. Starting in 2007 and lasting through 2009, financial markets experienced one of the sharpest declines in decades. It was more widespread than just the stock market as well. The housing market, lending market, and even global trade experienced unimaginable decline. Sub-prime lending led to the housing bubble bursting and was made famous by movies like The Big Short where those holding large mortgages were unwittingly falling prey to lenders. This saw banks and major financial institutions completely fail in many cases and took major government intervention to remedy during the period. From October 2007 to March 2009, the S&P 500 fell 57% and wouldn't recover to its 2007 levels until April 2013. + + +=== 2020 === +The 2020 stock market crash was a major and sudden global stock market crash that began on February 20, 2020, and ended on April 7. This market crash was due to the sudden outbreak of the global pandemic, COVID-19. The crash ended with a new deal that had a positive impact on the market. + + +=== Circuit breakers === +Since the early 1990s, many of the largest exchanges have adopted electronic 'matching engines' to bring together buyers and sellers, replacing the open outcry system. Electronic trading now accounts for the majority of trading in many developed countries. Computer systems were upgraded in the stock exchanges to handle larger trading volumes in a more accurate and controlled manner. The SEC modified the margin requirements in an attempt to lower the volatility of common stocks, stock options and the futures market. The New York Stock Exchange and the Chicago Mercantile Exchange introduced the concept of a circuit breaker. The circuit breaker halts trading if the Dow declines a prescribed number of points for a prescribed amount of time. In February 2012, the Investment Industry Regulatory Organization of Canada (IIROC) introduced single-stock circuit breakers. + +New York Stock Exchange (NYSE) circuit breakers + + +== Stock market index == + +The movements of the prices in global, regional or local markets are captured in price indices called stock market indices, of which there are many, e.g. the S&P, the FTSE, the Euronext indices and the NIFTY & SENSEX of India. Such indices are usually market capitalization weighted, with the weights reflecting the contribution of the stock to the index. The constituents of the index are reviewed frequently to include/exclude stocks in order to reflect the changing business environment. + + +== Derivative instruments == + +Financial innovation has brought many new financial instruments whose pay-offs or values depend on the prices of stocks. Some examples are exchange-traded funds (ETFs), stock index and stock options, equity swaps, single-stock futures, and stock index futures. These last two may be traded on futures exchanges (which are distinct from stock exchanges—their history traces back to commodity futures exchanges), or traded over-the-counter. As all of these products are only derived from stocks, they are sometimes considered to be traded in a (hypothetical) derivatives market, rather than the (hypothetical) stock market. + + +== Leveraged strategies == +Stock that a trader does not actually own may be traded using short selling; margin buying may be used to purchase stock with borrowed funds; or, derivatives may be used to control large blocks of stocks for a much smaller amount of money than would be required by outright purchase or sales. + + +=== Short selling === + +In short selling, the trader borrows stock (usually from his brokerage which holds its clients shares or its own shares on account to lend to short sellers) then sells it on the market, betting that the price will fall. The trader eventually buys back the stock, making money if the price fell in the meantime and losing money if it rose. Exiting a short position by buying back the stock is called "covering". This strategy may also be used by unscrupulous traders in illiquid or thinly traded markets to artificially lower the price of a stock. Hence most markets either prevent short selling or place restrictions on when and how a short sale can occur. The practice of naked shorting is illegal in most (but not all) stock markets. + + +=== Margin buying === + +In margin buying, the trader borrows money (at interest) to buy a stock and hopes for it to rise. Most industrialized countries have regulations that require that if the borrowing is based on collateral from other stocks the trader owns outright, it can be a maximum of a certain percentage of those other stocks' value. In the United States, the margin requirements have been 50% for many years (that is, if you want to make a $1000 investment, you need to put up $500, and there is often a maintenance margin below the $500). +A margin call is made if the total value of the investor's account cannot support the loss of the trade. (Upon a decline in the value of the margined securities additional funds may be required to maintain the account's equity, and with or without notice the margined security or any others within the account may be sold by the brokerage to protect its loan position. The investor is responsible for any shortfall following such forced sales.) +Regulation of margin requirements (by the Federal Reserve) was implemented after the Crash of 1929. Before that, speculators typically only needed to put up as little as 10 percent (or even less) of the total investment represented by the stocks purchased. Other rules may include the prohibition of free-riding: putting in an order to buy stocks without paying initially (there is normally a three-day grace period for delivery of the stock), but then selling them (before the three-days are up) and using part of the proceeds to make the original payment (assuming that the value of the stocks has not declined in the interim). + + +== Types of financial markets == +Financial markets can be divided into different subtypes: + + +=== For the assets transferred === +Money market : It is traded with money or financial assets with short-term maturity and high liquidity, generally assets with a term of less than one year. +Capital market : Financial assets with medium and long-term maturity are traded, which are basic for carrying out certain investment processes. + + +=== Depending on its structure === +Organized market +Non-organized markets denominated in English (Over The Counter or OTC). + + +=== According to the negotiation phase of financial assets === +Primary market : Financial assets are created. In this market, assets are transmitted directly by their issuer. +Secondary market : Only existing financial assets are exchanged, which were issued at a previous time. This market allows holders of financial assets to sell instruments that were already issued in the primary market (or that had already been transmitted in the secondary market) and that are in their possession, or to buy other financial assets. + + +=== According to the geographical perspective === +National markets. The currency in which the financial assets are denominated and the residence of those involved is national. +International markets. The markets situated outside a country's geographical area. + + +=== According to the type of asset traded === +Traditional market. In which financial assets such as demand deposits, stocks or bonds are traded. +Alternative market. In which alternative financial assets are traded such as portfolio investments, promissory notes, factoring, real estate (e.g. through fiduciary rights), in private equity funds, venture capital funds, hedge funds, investment projects (e.g. infrastructure, cinema, etc.) among many others. + + +=== Other markets === +Commodity markets, which allow the trading of commodities. +Derivatives markets, which provide instruments for managing financial risk. +Forward markets, which provide standardized forward contracts to trade products at a future date. +Insurance markets, which allows the redistribution of varied risks. +Foreign exchange market, which allows the exchange of foreign currencies. + + +=== Stock market and foreign exchange market === +While the stock market is the marketplace for buying and selling company stocks, the foreign exchange market, also known as forex or FX, is the global marketplace for the purchase and sale of national currencies. It serves several functions, including facilitating currency conversions, managing foreign exchange risk through futures and forwards, and providing a platform for speculative investors to earn a profit on FX trading. The market includes various types of products, such as the spot market, futures market, forward market, swap market, and options market. For example, the spot market involves the immediate buying and selling of currencies, while the forward market allows for the buying and selling of currencies at an agreed exchange rate, with the actual exchange taking place at a future delivery date. The foreign exchange market is needed for facilitating global trade, including investments, the exchange of goods and services, and financial transactions, and it is considered one of the largest markets in the global economy. + + +=== Electronic trading market === +The electronic trading market refers to the digital marketplace where financial instruments such as stocks, bonds, currencies, commodities, and derivatives are bought and sold through online platforms. This market operates via electronic trading platforms, also known as online trading platforms, which are software applications that enable the trading of financial products over a network, typically through a financial intermediary. Platforms, such as eToro, Plus500, Robinhood, and AvaTrade serve as a digital medium for trading financial instruments and make financial markets more accessible, allowing individual investors to participate in trading without the need for traditional brokers or substantial capital. They also provide features such as real-time market data, stock price analysis, research reports, and news updates, which support decision-making in trading activities. +These platforms often incorporate systems, such as the Martingale Trading System, used in forex trading. Additionally, online trading has evolved to include mobile trading apps, enabling transactions to be conducted remotely via smartphones. + + +== Investment strategies == + +Many strategies can be classified as either fundamental analysis or technical analysis. Fundamental analysis refers to analyzing companies by their financial statements found in SEC filings, business trends, and general economic conditions. Technical analysis studies price actions in markets through the use of charts and quantitative techniques to attempt to forecast price trends based on historical performance, regardless of the company's financial prospects. One example of a technical strategy is the Trend following method, used by John W. Henry and Ed Seykota, which uses price patterns and is also rooted in risk management and diversification. +Additionally, many choose to invest via passive index funds. In this method, one holds a portfolio of the entire stock market or some segment of the stock market (such as the S&P 500 Index or Wilshire 5000). The principal aim of this strategy is to maximize diversification, minimize taxes from realizing gains, and ride the general trend of the stock market to rise. +Responsible investment emphasizes and requires a long-term horizon on the basis of fundamental analysis only, avoiding hazards in the expected return of the investment. Socially responsible investing is another investment preference. + + +== Annual stock market growth == +The average annual growth rate of the stock market, as measured by the S&P 500 index, has historically been around 10%. This figure represents the long-term average return and is often cited as a benchmark for assessing the performance of the stock market as a whole. +The market's results from one year to the next may vary substantially from the long-term average. For instance, in 2012–2021, the S&P 500 index had an average annual return of 14.8%. However, individual annual returns can fluctuate widely, with some years experiencing negative growth and others seeing substantial gains. +While the average stock market return is around 10% per year, there is also the impact of inflation, resulting in investors' losing purchasing power of 2% to 3% every year due to it, which reduces the real rate of return on investments. + + +== Taxation == +Taxation is a consideration of all investment strategies; profit from owning stocks, including dividends received, is subject to different tax rates depending on the type of security and the holding period. Most profit from stock investing is taxed via a capital gains tax. In many countries, the corporations pay taxes to the government and the shareholders once again pay taxes when they profit from owning the stock, known as "double taxation". + + +== Stock market scams == + +The Indian stock exchanges, Bombay Stock Exchange and National Stock Exchange of India, have been rocked by several high-profile corruption scandals. At times, the Securities and Exchange Board of India (SEBI) has barred various individuals and entities from trading on the exchanges for stock manipulation, especially in illiquid small-cap and penny stocks. + + +== See also == + + +== References == + + +== Further reading == \ No newline at end of file diff --git a/lightrag/evaluation/wiki_documents/medical_covid-19.txt b/lightrag/evaluation/wiki_documents/medical_covid-19.txt new file mode 100644 index 00000000..a3587389 --- /dev/null +++ b/lightrag/evaluation/wiki_documents/medical_covid-19.txt @@ -0,0 +1,424 @@ +Coronavirus disease 2019 (COVID-19) is a contagious disease caused by the coronavirus SARS-CoV-2. In January 2020, the disease spread worldwide, resulting in the COVID-19 pandemic. +The symptoms of COVID‑19 can vary but often include fever, fatigue, cough, breathing difficulties, loss of smell, and loss of taste. Symptoms may begin one to 14 days after exposure to the virus. At least a third of people who are infected do not develop noticeable symptoms. Of those who develop symptoms noticeable enough to be classified as patients, most (81%) develop mild to moderate symptoms (up to mild pneumonia), while 14% develop severe symptoms (dyspnea, hypoxia, or more than 50% lung involvement on imaging), and 5% develop critical symptoms (respiratory failure, shock, or multiorgan dysfunction). Older people have a higher risk of developing severe symptoms. Some complications result in death. Some people continue to experience a range of effects (long COVID) for months or years after infection, and damage to organs has been observed. Multi-year studies on the long-term effects are ongoing. +COVID‑19 transmission occurs when infectious particles are breathed in or come into contact with the eyes, nose, or mouth. The risk is highest when people are in close proximity, but small airborne particles containing the virus can remain suspended in the air and travel over longer distances, particularly indoors. Transmission can also occur when people touch their eyes, nose, or mouth after touching surfaces or objects that have been contaminated by the virus. People remain contagious for up to 20 days and can spread the virus even if they do not develop symptoms. +Testing methods for COVID-19 to detect the virus's nucleic acid include real-time reverse transcription polymerase chain reaction (RT‑PCR), transcription-mediated amplification, and reverse transcription loop-mediated isothermal amplification (RT‑LAMP) from a nasopharyngeal swab. +Several COVID-19 vaccines have been approved and distributed in various countries, many of which have initiated mass vaccination campaigns. Other preventive measures include physical or social distancing, quarantining, ventilation of indoor spaces, use of face masks or coverings in public, covering coughs and sneezes, hand washing, and keeping unwashed hands away from the face. While drugs have been developed to inhibit the virus, the primary treatment is still symptomatic, managing the disease through supportive care, isolation, and experimental measures. +The first known case was identified in Wuhan, China, in December 2019. Most scientists believe that the SARS-CoV-2 virus entered into human populations through natural zoonosis, similar to the SARS-CoV-1 and MERS-CoV outbreaks, and consistent with other pandemics in human history. Social and environmental factors including climate change, natural ecosystem destruction and wildlife trade increased the likelihood of such zoonotic spillover. + + +== Nomenclature == + +During the initial outbreak in Wuhan, the virus was commonly called "coronavirus" and "Wuhan coronavirus", and the disease was referred to by the same terms and sometimes as "Wuhan pneumonia". In the past, many diseases have been named after geographical locations, such as the Spanish flu, Middle East respiratory syndrome, and Zika virus. In January 2020, the World Health Organization (WHO) recommended 2019-nCoV and 2019-nCoV acute respiratory disease as interim names for the virus and disease per 2015 guidance and international guidelines against using geographical locations or groups of people in disease and virus names to prevent social stigma. The official names COVID‑19 and SARS-CoV-2 were issued by the WHO on 11 February 2020 with COVID-19 being shorthand for "coronavirus disease 2019". The WHO additionally uses "the COVID‑19 virus" and "the virus responsible for COVID‑19" in public communications. + + +== Signs and symptoms == + + +=== Complications === + +Complications may include pneumonia, acute respiratory distress syndrome (ARDS), multi-organ failure, septic shock, and death. Cardiovascular complications may include heart failure, arrhythmias (including atrial fibrillation), heart inflammation, thrombosis, particularly venous thromboembolism, and endothelial cell injury and dysfunction. Approximately 20–30% of people who present with COVID‑19 have elevated liver enzymes, reflecting liver injury. +Neurologic manifestations include seizure, stroke, encephalitis, and Guillain–Barré syndrome (which includes loss of motor functions). Following the infection, children may develop paediatric multisystem inflammatory syndrome, which has symptoms similar to Kawasaki disease, which can be fatal. In very rare cases, acute encephalopathy can occur, and it can be considered in those who have been diagnosed with COVID‑19 and have an altered mental status. +According to the US Centers for Disease Control and Prevention, pregnant women are at increased risk of becoming seriously ill from COVID‑19. This is because pregnant women with COVID‑19 appear to be more likely to develop respiratory and obstetric complications that can lead to miscarriage, premature delivery and intrauterine growth restriction. +Fungal infections such as aspergillosis, candidiasis, cryptococcosis and mucormycosis have been recorded in people recovering from COVID‑19. + + +== Cause == +COVID‑19 is caused by infection with a strain of coronavirus known as "severe acute respiratory syndrome coronavirus 2" (SARS-CoV-2). + + +=== Transmission === + + +=== Virology === + +Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel severe acute respiratory syndrome coronavirus. It was first isolated from three people with pneumonia connected to the cluster of acute respiratory illness cases in Wuhan. All structural features of the novel SARS-CoV-2 virus particle occur in related coronaviruses in nature, particularly in Rhinolophus sinicus (Chinese horseshoe bats). +Outside the human body, the virus is destroyed by household soap which bursts its protective bubble. Hospital disinfectants, alcohols, heat, povidone-iodine, and ultraviolet-C (UV-C) irradiation are also effective disinfection methods for surfaces. +SARS-CoV-2 is closely related to the original SARS-CoV. It is thought to have an animal (zoonotic) origin. Genetic analysis has revealed that the coronavirus genetically clusters with the genus Betacoronavirus, in subgenus Sarbecovirus (lineage B) together with two bat-derived strains. It is 96% identical at the whole genome level to other bat coronavirus samples (BatCov RaTG13). The structural proteins of SARS-CoV-2 include membrane glycoprotein (M), envelope protein (E), nucleocapsid protein (N), and the spike protein (S). The M protein of SARS-CoV-2 is about 98% similar to the M protein of bat SARS-CoV, maintains around 98% homology with pangolin SARS-CoV, and has 90% homology with the M protein of SARS-CoV; whereas, the similarity is only around 38% with the M protein of MERS-CoV. + + +=== SARS-CoV-2 variants === + +The many thousands of SARS-CoV-2 variants are grouped into either clades or lineages. The WHO, in collaboration with partners, expert networks, national authorities, institutions and researchers, have established nomenclature systems for naming and tracking SARS-CoV-2 genetic lineages by GISAID, Nextstrain and Pango. The expert group convened by the WHO recommended the labelling of variants using letters of the Greek alphabet, for example, Alpha, Beta, Delta, and Gamma, giving the justification that they "will be easier and more practical to discussed by non-scientific audiences". Nextstrain divides the variants into five clades (19A, 19B, 20A, 20B, and 20C), while GISAID divides them into seven (L, O, V, S, G, GH, and GR). The Pango tool groups variants into lineages, with many circulating lineages being classed under the B.1 lineage. +Several notable variants of SARS-CoV-2 emerged throughout 2020. Cluster 5 emerged among minks and mink farmers in Denmark. After strict quarantines and the slaughter of all the country's mink, the cluster was assessed to no longer be circulating among humans in Denmark as of 1 February 2021. +As of December 2021, there are five dominant variants of SARS-CoV-2 spreading among global populations: the Alpha variant (B.1.1.7, formerly called the UK variant), first found in London and Kent, the Beta variant (B.1.351, formerly called the South Africa variant), the Gamma variant (P.1, formerly called the Brazil variant), the Delta variant (B.1.617.2, formerly called the India variant), and the Omicron variant (B.1.1.529), which had spread to 57 countries as of 7 December. +On 19 December 2023, the WHO declared that another distinctive variant, JN.1, had emerged as a "variant of interest". Though the WHO expected an increase in cases globally, particularly for countries entering winter, the overall global health risk was considered low. + + +== Pathophysiology == + +The SARS-CoV-2 virus can infect a wide range of cells and systems of the body. COVID‑19 is most known for affecting the upper respiratory tract (sinuses, nose, and throat) and the lower respiratory tract (windpipe and lungs). The lungs are the organs most affected by COVID‑19 because the virus accesses host cells via the receptor for the enzyme angiotensin-converting enzyme 2 (ACE2), which is most abundant on the surface of type II alveolar cells of the lungs. The virus uses a special surface glycoprotein called a "spike" to connect to the ACE2 receptor and enter the host cell. + + +=== Respiratory tract === +Following viral entry, COVID‑19 infects the ciliated epithelium of the nasopharynx and upper airways. Autopsies of people who died of COVID‑19 have found diffuse alveolar damage, and lymphocyte-containing inflammatory infiltrates within the lung. +From the CT scans of COVID-19 infected lungs, white patches were observed containing fluid known as ground-glass opacity (GGO) or simply ground glass. This tended to correlate with the clear jelly liquid found in lung autopsies of people who died of COVID-19. One possibility addressed in medical research is that hyuralonic acid (HA) could be the leading factor for this observation of the clear jelly liquid found in the lungs, in what could be hyuralonic storm, in conjunction with cytokine storm. + + +=== Nervous system === + +One common symptom, loss of smell, results from infection of the support cells of the olfactory epithelium, with subsequent damage to the olfactory neurons. The involvement of both the central and peripheral nervous system in COVID‑19 has been reported in many medical publications. It is clear that many people with COVID-19 exhibit neurological or mental health issues. The virus is not detected in the central nervous system (CNS) of the majority of people with COVID-19 who also have neurological issues. However, SARS-CoV-2 has been detected at low levels in the brains of those who have died from COVID‑19, but these results need to be confirmed. While virus has been detected in cerebrospinal fluid of autopsies, the exact mechanism by which it invades the CNS remains unclear and may first involve invasion of peripheral nerves given the low levels of ACE2 in the brain. The virus may also enter the bloodstream from the lungs and cross the blood–brain barrier to gain access to the CNS, possibly within an infected white blood cell. + + Research conducted when Alpha was the dominant variant has suggested COVID-19 may cause brain damage. Later research showed that all variants studied (including Omicron) killed brain cells, but the exact cells killed varied by variant. It is unknown if such damage is temporary or permanent. Observed individuals infected with COVID-19 (most with mild cases) experienced an additional 0.2% to 2% of brain tissue lost in regions of the brain connected to the sense of smell compared with uninfected individuals, and the overall effect on the brain was equivalent on average to at least one extra year of normal ageing; infected individuals also scored lower on several cognitive tests. All effects were more pronounced among older ages. + + +=== Gastrointestinal tract === +The virus also affects gastrointestinal organs as ACE2 is abundantly expressed in the glandular cells of gastric, duodenal and rectal epithelium as well as endothelial cells and enterocytes of the small intestine. + + +=== Cardiovascular system === +The virus can cause acute myocardial injury and chronic damage to the cardiovascular system. An acute cardiac injury was found in 12% of infected people admitted to the hospital in Wuhan, China, and is more frequent in severe disease. Rates of cardiovascular symptoms are high, owing to the systemic inflammatory response and immune system disorders during disease progression, but acute myocardial injuries may also be related to ACE2 receptors in the heart. ACE2 receptors are highly expressed in the heart and are involved in heart function. +A high incidence of thrombosis and venous thromboembolism occurs in people transferred to intensive care units with COVID‑19 infections, and may be related to poor prognosis. Blood vessel dysfunction and clot formation (as suggested by high D-dimer levels caused by blood clots) may have a significant role in mortality, incidents of clots leading to pulmonary embolisms, and ischaemic events (strokes) within the brain found as complications leading to death in people infected with COVID‑19. Infection may initiate a chain of vasoconstrictive responses within the body, including pulmonary vasoconstriction – a possible mechanism in which oxygenation decreases during pneumonia. Furthermore, damage of arterioles and capillaries was found in brain tissue samples of people who died from COVID‑19. +COVID‑19 may also cause substantial structural changes to blood cells, sometimes persisting for months after hospital discharge. A low level of blood lymphocytess may result from the virus acting through ACE2-related entry into lymphocytes. + + +=== Kidneys === +Another common cause of death is complications related to the kidneys. Early reports show that up to 30% of people hospitalised with COVID-19 both in China and in New York have experienced some injury to their kidneys, including some persons with no previous kidney problems. + + +=== Immunopathology === + +Although SARS-CoV-2 has a tropism for ACE2-expressing epithelial cells of the respiratory tract, people with severe COVID‑19 have symptoms of systemic hyperinflammation. Clinical laboratory findings of elevated IL‑2, IL‑6, IL‑7, as well as the following suggest an underlying immunopathology: + +Granulocyte-macrophage colony-stimulating factor (GM‑CSF) +Interferon gamma-induced protein 10 (IP‑10) +Monocyte chemoattractant protein 1 (MCP1) +Macrophage inflammatory protein 1‑alpha (MIP‑1‑alpha) +Tumour necrosis factor (TNF‑α) indicative of cytokine release syndrome (CRS) +Interferon alpha plays a complex, Janus-faced role in the pathogenesis of COVID-19. Although it promotes the elimination of virus-infected cells, it also upregulates the expression of ACE-2, thereby facilitating the SARS-Cov2 virus to enter cells and to replicate. A competition of negative feedback loops (via protective effects of interferon alpha) and positive feedback loops (via upregulation of ACE-2) is assumed to determine the fate of people with COVID-19. +Additionally, people with COVID‑19 and acute respiratory distress syndrome (ARDS) have classical serum biomarkers of CRS, including elevated C-reactive protein (CRP), lactate dehydrogenase (LDH), D-dimer, and ferritin. +Systemic inflammation results in vasodilation, allowing inflammatory lymphocytic and monocytic infiltration of the lung and the heart. In particular, pathogenic GM-CSF-secreting T cells were shown to correlate with the recruitment of inflammatory IL-6-secreting monocytes and severe lung pathology in people with COVID‑19. Lymphocytic infiltrates have also been reported at autopsy. + + +=== Viral and host factors === + + +==== Virus proteins ==== + +Multiple viral and host factors affect the pathogenesis of the virus. The S-protein, otherwise known as the spike protein, is the viral component that attaches to the host receptor via the ACE2 receptors. It includes two subunits: S1 and S2. + +S1 determines the virus-host range and cellular tropism via the receptor-binding domain. +S2 mediates the membrane fusion of the virus to its potential cell host via the H1 and HR2, which are heptad repeat regions. +Studies have shown that S1 domain induced IgG and IgA antibody levels at a much higher capacity. It is the focus spike proteins expression that are involved in many effective COVID‑19 vaccines. +The M protein is the viral protein responsible for the transmembrane transport of nutrients. It is the cause of the bud release and the formation of the viral envelope. The N and E protein are accessory proteins that interfere with the host's immune response. + + +==== Host factors ==== +Human angiotensin converting enzyme 2 (hACE2) is the host factor that SARS-CoV-2 virus targets causing COVID‑19. Theoretically, the usage of angiotensin receptor blockers (ARB) and ACE inhibitors upregulating ACE2 expression might increase morbidity with COVID‑19, though animal data suggest some potential protective effect of ARB; however no clinical studies have proven susceptibility or outcomes. Until further data is available, guidelines and recommendations for people with hypertension remain. +The effect of the virus on ACE2 cell surfaces leads to leukocytic infiltration, increased blood vessel permeability, alveolar wall permeability, as well as decreased secretion of lung surfactants. These effects cause the majority of the respiratory symptoms. However, the aggravation of local inflammation causes a cytokine storm eventually leading to a systemic inflammatory response syndrome. +Among healthy adults not exposed to SARS-CoV-2, about 35% have CD4+ T cells that recognise the SARS-CoV-2 S protein (particularly the S2 subunit) and about 50% react to other proteins of the virus, suggesting cross-reactivity from previous common colds caused by other coronaviruses. +It is unknown whether different persons use similar antibody genes in response to COVID‑19. + + +=== Host cytokine response === + +The severity of the inflammation can be attributed to the severity of what is known as the cytokine storm. Levels of interleukin 1B, interferon-gamma, interferon-inducible protein 10, and monocyte chemoattractant protein 1 were all associated with COVID‑19 disease severity. Treatment has been proposed to combat the cytokine storm as it remains to be one of the leading causes of morbidity and mortality in COVID‑19 disease. +A cytokine storm is due to an acute hyperinflammatory response that is responsible for clinical illness in an array of diseases but in COVID‑19, it is related to worse prognosis and increased fatality. The storm causes acute respiratory distress syndrome, blood clotting events such as strokes, myocardial infarction, encephalitis, acute kidney injury, and vasculitis. The production of IL-1, IL-2, IL-6, TNF-alpha, and interferon-gamma, all crucial components of normal immune responses, inadvertently become the causes of a cytokine storm. The cells of the central nervous system, the microglia, neurons, and astrocytes, are also involved in the release of pro-inflammatory cytokines affecting the nervous system, and effects of cytokine storms toward the CNS are not uncommon. + + +=== Pregnancy response === +There are many unknowns for pregnant women during the COVID-19 pandemic. Given that they are prone to have complications and severe disease infection with other types of coronaviruses, they have been identified as a vulnerable group and advised to take supplementary preventive measures. +Physiological responses to pregnancy can include: + +Immunological: The immunological response to COVID-19, like other viruses, depends on a working immune system. It adapts during pregnancy to allow the development of the foetus whose genetic load is only partially shared with their mother, leading to a different immunological reaction to infections during the course of pregnancy. +Respiratory: Many factors can make pregnant women more vulnerable to hard respiratory infections. One of them is the total reduction of the lungs' capacity and inability to clear secretions. +Coagulation: During pregnancy, there are higher levels of circulating coagulation factors, and the pathogenesis of SARS-CoV-2 infection can be implicated. The thromboembolic events with associated mortality are a risk for pregnant women. +However, from the evidence base, it is difficult to conclude whether pregnant women are at increased risk of grave consequences of this virus. +In addition to the above, other clinical studies have proved that SARS-CoV-2 can affect the period of pregnancy in different ways. On the one hand, there is little evidence of its impact up to 12 weeks gestation. On the other hand, COVID-19 infection may cause increased rates of unfavourable outcomes in the course of the pregnancy. Some examples of these could be foetal growth restriction, preterm birth, and perinatal mortality, which refers to the foetal death past 22 or 28 completed weeks of pregnancy as well as the death among live-born children up to seven completed days of life. For preterm birth, a 2023 review indicates that there appears to be a correlation with COVID-19. +Unvaccinated women in later stages of pregnancy with COVID-19 are more likely than other people to need very intensive care. Babies born to mothers with COVID-19 are more likely to have breathing problems. Pregnant women are strongly encouraged to get vaccinated. + + +== Diagnosis == + +COVID‑19 can provisionally be diagnosed on the basis of symptoms and confirmed using reverse transcription polymerase chain reaction (RT-PCR) or other nucleic acid testing of infected secretions. Along with laboratory testing, chest CT scans may be helpful to diagnose COVID‑19 in individuals with a high clinical suspicion of infection. Detection of a past infection is possible with serological tests, which detect antibodies produced by the body in response to the infection. + + +=== Viral testing === + +The standard methods of testing for presence of SARS-CoV-2 are nucleic acid tests, which detects the presence of viral RNA fragments. As these tests detect RNA but not infectious virus, its "ability to determine duration of infectivity of patients is limited". The test is typically done on respiratory samples obtained by a nasopharyngeal swab; however, a nasal swab or sputum sample may also be used. Results are generally available within hours. The WHO has published several testing protocols for the disease. +Several laboratories and companies have developed serological tests, which detect antibodies produced by the body in response to infection. Some have been evaluated by Public Health England and approved for use in the UK. +The University of Oxford's CEBM has pointed to mounting evidence that "a good proportion of 'new' mild cases and people re-testing positives after quarantine or discharge from hospital are not infectious, but are simply clearing harmless virus particles which their immune system has efficiently dealt with" and have called for "an international effort to standardize and periodically calibrate testing" In September 2020, the UK government issued "guidance for procedures to be implemented in laboratories to provide assurance of positive SARS-CoV-2 RNA results during periods of low prevalence, when there is a reduction in the predictive value of positive test results". + + +=== Imaging === + +Chest CT scans may be helpful to diagnose COVID‑19 in individuals with a high clinical suspicion of infection but are not recommended for routine screening. Bilateral multilobar ground-glass opacities with a peripheral, asymmetric, and posterior distribution are common in early infection. Subpleural dominance, crazy paving (lobular septal thickening with variable alveolar filling), and consolidation may appear as the disease progresses. Characteristic imaging features on chest radiographs and computed tomography (CT) of people who are symptomatic include asymmetric peripheral ground-glass opacities without pleural effusions. +Many groups have created COVID‑19 datasets that include imagery such as the Italian Radiological Society which has compiled an international online database of imaging findings for confirmed cases. Due to overlap with other infections such as adenovirus, imaging without confirmation by rRT-PCR is of limited specificity in identifying COVID‑19. A large study in China compared chest CT results to PCR and demonstrated that though imaging is less specific for the infection, it is faster and more sensitive. + + +=== Coding === +In late 2019, the WHO assigned emergency ICD-10 disease codes U07.1 for deaths from lab-confirmed SARS-CoV-2 infection and U07.2 for deaths from clinically or epidemiologically diagnosed COVID‑19 without lab-confirmed SARS-CoV-2 infection. + + +=== Pathology === +The main pathological findings at autopsy are: + +Macroscopy: pericarditis, lung consolidation and pulmonary oedema +Lung findings: +Minor serous exudation, minor fibrin exudation +Pulmonary oedema, pneumocyte hyperplasia, large atypical pneumocytes, interstitial inflammation with lymphocytic infiltration and multinucleated giant cell formation +Diffuse alveolar damage (DAD) with diffuse alveolar exudates. DAD is the cause of acute respiratory distress syndrome (ARDS) and severe hypoxaemia. +Organisation of exudates in alveolar cavities and pulmonary interstitial fibrosis +Plasmocytosis in bronchoalveolar lavage (BAL) +Blood and vessels: disseminated intravascular coagulation (DIC); leukoerythroblastic reaction, endotheliitis, hemophagocytosis +Heart: cardiac muscle cell necrosis +Liver: microvesicular steatosis +Nose: shedding of olfactory epithelium +Brain: infarction +Kidneys: acute tubular damage. +Spleen: white pulp depletion. + + +== Prevention == + +Preventive measures to reduce the chances of infection include getting vaccinated, staying at home, wearing a mask in public, avoiding crowded places, keeping distance from others, ventilating indoor spaces, managing potential exposure durations, washing hands with soap and water often and for at least 20 seconds, practising good respiratory hygiene, and avoiding touching the eyes, nose, or mouth with unwashed hands. +Those diagnosed with COVID‑19 or who believe they may be infected are advised by the CDC to stay home except to get medical care, call ahead before visiting a healthcare provider, wear a face mask before entering the healthcare provider's office and when in any room or vehicle with another person, cover coughs and sneezes with a tissue, regularly wash hands with soap and water and avoid sharing personal household items. +The first COVID‑19 vaccine was granted regulatory approval on 2 December 2020 by the UK medicines regulator MHRA. It was evaluated for emergency use authorisation (EUA) status by the US FDA, and in several other countries. Initially, the US National Institutes of Health guidelines do not recommend any medication for prevention of COVID‑19, before or after exposure to the SARS-CoV-2 virus, outside the setting of a clinical trial. Without a vaccine, other prophylactic measures, or effective treatments, a key part of managing COVID‑19 is trying to decrease and delay the epidemic peak, known as "flattening the curve". This is done by slowing the infection rate to decrease the risk of health services being overwhelmed, allowing for better treatment of active cases, and delaying additional cases until effective treatments or a vaccine become available. + + +=== Vaccine === + + +=== Face masks and respiratory hygiene === + + +=== Indoor ventilation and avoiding crowded indoor spaces === +The CDC states that avoiding crowded indoor spaces reduces the risk of COVID-19 infection. When indoors, increasing the rate of air change, decreasing recirculation of air and increasing the use of outdoor air can reduce transmission. The WHO recommends ventilation and air filtration in public spaces to help clear out infectious aerosols. +Exhaled respiratory particles can build-up within enclosed spaces with inadequate ventilation. The risk of COVID‑19 infection increases especially in spaces where people engage in physical exertion or raise their voice (e.g., exercising, shouting, singing) as this increases exhalation of respiratory droplets. Prolonged exposure to these conditions, typically more than 15 minutes, leads to higher risk of infection. +Displacement ventilation with large natural inlets can move stale air directly to the exhaust in laminar flow while significantly reducing the concentration of droplets and particles. Passive ventilation reduces energy consumption and maintenance costs but may lack controllability and heat recovery. Displacement ventilation can also be achieved mechanically with higher energy and maintenance costs. The use of large ducts and openings helps to prevent mixing in closed environments. Recirculation and mixing should be avoided because recirculation prevents dilution of harmful particles and redistributes possibly contaminated air, and mixing increases the concentration and range of infectious particles and keeps larger particles in the air. + + +=== Hand-washing and hygiene === + +Thorough hand hygiene after any cough or sneeze is required. The WHO also recommends that individuals wash hands often with soap and water for at least 20 seconds, especially after going to the toilet or when hands are visibly dirty, before eating and after blowing one's nose. When soap and water are not available, the CDC recommends using an alcohol-based hand sanitiser with at least 60% alcohol. For areas where commercial hand sanitisers are not readily available, the WHO provides two formulations for local production. In these formulations, the antimicrobial activity arises from ethanol or isopropanol. Hydrogen peroxide is used to help eliminate bacterial spores in the alcohol; it is "not an active substance for hand antisepsis". Glycerol is added as a humectant. + + +=== Social distancing === + +Social distancing (also known as physical distancing) includes infection control actions intended to slow the spread of the disease by minimising close contact between individuals. Methods include quarantines; travel restrictions; and the closing of schools, workplaces, stadiums, theatres, or shopping centres. Individuals may apply social distancing methods by staying at home, limiting travel, avoiding crowded areas, using no-contact greetings, and physically distancing themselves from others. +In 2020, outbreaks occurred in prisons due to crowding and an inability to enforce adequate social distancing. In the United States, the prisoner population is ageing and many of them are at high risk for poor outcomes from COVID‑19 due to high rates of coexisting heart and lung disease, and poor access to high-quality healthcare. + + +=== Surface cleaning === +After being expelled from the body, coronaviruses can survive on surfaces for hours to days. If a person touches the dirty surface, they may deposit the virus at the eyes, nose, or mouth where it can enter the body and cause infection. Evidence indicates that contact with infected surfaces is not the main driver of COVID‑19, leading to recommendations for optimised disinfection procedures to avoid issues such as the increase of antimicrobial resistance through the use of inappropriate cleaning products and processes. Deep cleaning and other surface sanitation has been criticised as hygiene theatre, giving a false sense of security against something primarily spread through the air. +The amount of time that the virus can survive depends significantly on the type of surface, the temperature, and the humidity. Coronaviruses die very quickly when exposed to the UV light in sunlight. Like other enveloped viruses, SARS-CoV-2 survives longest when the temperature is at room temperature or lower, and when the relative humidity is low (<50%). +On many surfaces, including glass, some types of plastic, stainless steel, and skin, the virus can remain infective for several days indoors at room temperature, or even about a week under ideal conditions. On some surfaces, including cotton fabric and copper, the virus usually dies after a few hours. The virus dies faster on porous surfaces than on non-porous surfaces due to capillary action within pores and faster aerosol droplet evaporation. However, of the many surfaces tested, two with the longest survival times are N95 respirator masks and surgical masks, both of which are considered porous surfaces. +The CDC says that in most situations, cleaning surfaces with soap or detergent, not disinfecting, is enough to reduce risk of transmission. The CDC recommends that if a COVID‑19 case is suspected or confirmed at a facility such as an office or day care, all areas such as offices, bathrooms, common areas, shared electronic equipment like tablets, touch screens, keyboards, remote controls, and ATMs used by the ill persons should be disinfected. Surfaces may be decontaminated with the following: + +62–71% ethanol +50–100% isopropanol +0.1% sodium hypochlorite +0.5% hydrogen peroxide +0.2–7.5% povidone-iodine +50–200 ppm hypochlorous acid +Other solutions, such as benzalkonium chloride and chlorhexidine gluconate, are less effective. Ultraviolet germicidal irradiation may also be used, although popular devices require 5–10 min exposure and may deteriorate some materials over time. A datasheet listing the authorised substances to disinfection in the food industry (including suspension or surface tested, kind of surface, use dilution, disinfectant and inoculum volumes) can be seen in the supplementary material of a 2021 Foods article. + + +=== Self-isolation === +Self-isolation at home has been recommended for those diagnosed with COVID‑19 and those who suspect they have been infected. Health agencies have issued detailed instructions for proper self-isolation. Many governments have mandated or recommended self-quarantine for entire populations. The strongest self-quarantine instructions have been issued to those in high-risk groups. Those who may have been exposed to someone with COVID‑19 and those who have recently travelled to a country or region with the widespread transmission have been advised to self-quarantine for 14 days from the time of last possible exposure. + + +=== International travel-related control measures === +A 2021 Cochrane rapid review found that based upon low-certainty evidence, international travel-related control measures such as restricting cross-border travel may help to contain the spread of COVID‑19. Additionally, symptom/exposure-based screening measures at borders may miss many positive cases. While test-based border screening measures may be more effective, it could also miss many positive cases if only conducted upon arrival without follow-up. The review concluded that a minimum 10-day quarantine may be beneficial in preventing the spread of COVID‑19 and may be more effective if combined with an additional control measure like border screening. + + +== Treatment == + + +== Prognosis and risk factors == + +The severity of COVID‑19 varies. The disease may take a mild course with few or no symptoms, resembling other common upper respiratory diseases such as the common cold. In 3–4% of cases (7.4% for those over age 65) symptoms are severe enough to cause hospitalisation. Mild cases typically recover within two weeks, while those with severe or critical diseases may take three to six weeks to recover. Among those who have died, the time from symptom onset to death has ranged from two to eight weeks. The Italian Istituto Superiore di Sanità reported that the median time between the onset of symptoms and death was twelve days, with seven being hospitalised. However, people transferred to an ICU had a median time of ten days between hospitalisation and death. Abnormal sodium levels during hospitalisation with COVID-19 are associated with poor prognoses: high sodium with a greater risk of death, and low sodium with an increased chance of needing ventilator support. Prolonged prothrombin time and elevated C-reactive protein levels on admission to the hospital are associated with severe course of COVID‑19 and with a transfer to ICU. +Some early studies suggest 10% to 20% of people with COVID‑19 will experience symptoms lasting longer than a month. A majority of those who were admitted to hospital with severe disease report long-term problems including fatigue and shortness of breath. On 30 October 2020, WHO chief Tedros Adhanom warned that "to a significant number of people, the COVID virus poses a range of serious long-term effects". He has described the vast spectrum of COVID‑19 symptoms that fluctuate over time as "really concerning". They range from fatigue, a cough and shortness of breath, to inflammation and injury of major organs – including the lungs and heart, and also neurological and psychologic effects. Symptoms often overlap and can affect any system in the body. Infected people have reported cyclical bouts of fatigue, headaches, months of complete exhaustion, mood swings, and other symptoms. Tedros therefore concluded that a strategy of achieving herd immunity by infection, rather than vaccination, is "morally unconscionable and unfeasible". +In terms of hospital readmissions about 9% of 106,000 individuals had to return for hospital treatment within two months of discharge. The average to readmit was eight days since first hospital visit. There are several risk factors that have been identified as being a cause of multiple admissions to a hospital facility. Among these are advanced age (above 65 years of age) and presence of a chronic condition such as diabetes, COPD, heart failure or chronic kidney disease. +According to scientific reviews smokers are more likely to require intensive care or die compared to non-smokers. Acting on the same ACE2 pulmonary receptors affected by smoking, air pollution has been correlated with the disease. Short-term and chronic exposure to air pollution seems to enhance morbidity and mortality from COVID‑19. Pre-existing heart and lung diseases and also obesity, especially in conjunction with fatty liver disease, contributes to an increased health risk of COVID‑19. +It is also assumed that those that are immunocompromised are at higher risk of getting severely sick from SARS-CoV-2. One research study that looked into the COVID‑19 infections in hospitalised kidney transplant recipients found a mortality rate of 11%. +Men with untreated hypogonadism were 2.4 times more likely than men with eugonadism to be hospitalised if they contracted COVID-19; Hypogonad men treated with testosterone were less likely to be hospitalised for COVID-19 than men who were not treated for hypogonadism. + + +=== Genetic risk factors === +Genetics plays an important role in the ability to fight off Covid. For instance, those that do not produce detectable type I interferons or produce auto-antibodies against these may get much sicker from COVID‑19. Genetic screening is able to detect interferon effector genes. Some genetic variants are risk factors in specific populations. For instance, an allele of the DOCK2 gene (dedicator of cytokinesis 2 gene) is a common risk factor in Asian populations but much less common in Europe. The mutation leads to lower expression of DOCK2 especially in younger people with severe COVID-19 infections. In fact, many other genes and genetic variants have been found that determine the outcome of SARS-CoV-2 infections. + + +==== Blood group ==== + + +=== Children === + +While very young children have experienced lower rates of infection, older children have a rate of infection that is similar to the population as a whole. Children are likely to have milder symptoms and are at lower risk of severe disease than adults. The CDC reports that in the US roughly a third of hospitalised children were admitted to the ICU, while a European multinational study of hospitalised children from June 2020, found that about 8% of children admitted to a hospital needed intensive care. Four of the 582 children (0.7%) in the European study died, but the actual mortality rate may be "substantially lower" since milder cases that did not seek medical help were not included in the study. + + +=== Long-term effects === + +Around 10% to 30% of non-hospitalised people with COVID-19 go on to develop long COVID. For those that do need hospitalisation, the incidence of long-term effects is over 50%. Long COVID is an often severe multisystem disease with a large set of symptoms. There are likely various, possibly coinciding, causes. Organ damage from the acute infection can explain a part of the symptoms, but long COVID is also observed in people where organ damage seems to be absent. +By a variety of mechanisms, the lungs are the organs most affected in COVID‑19. In people requiring hospital admission, up to 98% of CT scans performed show lung abnormalities after 28 days of illness even if they had clinically improved. People with advanced age, severe disease, prolonged ICU stays, or who smoke are more likely to have long-lasting effects, including pulmonary fibrosis. Overall, approximately one-third of those investigated after four weeks will have findings of pulmonary fibrosis or reduced lung function as measured by DLCO, even in asymptomatic people, but with the suggestion of continuing improvement with the passing of more time. After severe disease, lung function can take anywhere from three months to a year or more to return to previous levels. +The risks of cognitive deficit, dementia, psychotic disorders, and epilepsy or seizures persists at an increased level two years after infection. + + +=== Immunity === + +The immune response by humans to SARS-CoV-2 virus occurs as a combination of the cell-mediated immunity and antibody production, just as with most other infections. B cells interact with T cells and begin dividing before selection into the plasma cell, partly on the basis of their affinity for antigen. Since SARS-CoV-2 has been in the human population only since December 2019, it remains unknown if the immunity is long-lasting in people who recover from the disease. The presence of neutralising antibodies in blood strongly correlates with protection from infection, but the level of neutralising antibody declines with time. Those with asymptomatic or mild disease had undetectable levels of neutralising antibody two months after infection. In another study, the level of neutralising antibodies fell four-fold one to four months after the onset of symptoms. However, the lack of antibodies in the blood does not mean antibodies will not be rapidly produced upon reexposure to SARS-CoV-2. Memory B cells specific for the spike and nucleocapsid proteins of SARS-CoV-2 last for at least six months after the appearance of symptoms. +As of August 2021, reinfection with COVID‑19 was possible but uncommon. The first case of reinfection was documented in August 2020. A systematic review found 17 cases of confirmed reinfection in medical literature as of May 2021. With the Omicron variant, as of 2022, reinfections have become common, albeit it is unclear how common. COVID-19 reinfections are thought to likely be less severe than primary infections, especially if one was previously infected by the same variant. + + +== Mortality == + +Several measures are commonly used to quantify mortality. These numbers vary by region and over time and are influenced by the volume of testing, healthcare system quality, treatment options, time since the initial outbreak, and population characteristics such as age, sex, and overall health. +The mortality rate reflects the number of deaths within a specific demographic group divided by the population of that demographic group. Consequently, the mortality rate reflects the prevalence as well as the severity of the disease within a given population. Mortality rates are highly correlated to age, with relatively low rates for young people and relatively high rates among the elderly. In fact, one relevant factor of mortality rates is the age structure of the countries' populations. For example, the case fatality rate for COVID‑19 is lower in India than in the US since India's younger population represents a larger percentage than in the US. + + +=== Case fatality rate === +The case fatality rate (CFR) reflects the number of deaths divided by the number of diagnosed cases within a given time interval. Based on Johns Hopkins University statistics, the global death-to-case ratio is 1.02% (6,881,955/676,609,955) as of 10 March 2023. The number varies by region. + + +=== Infection fatality rate === +A key metric in gauging the severity of COVID‑19 is the infection fatality rate (IFR), also referred to as the infection fatality ratio or infection fatality risk. This metric is calculated by dividing the total number of deaths from the disease by the total number of infected individuals; hence, in contrast to the CFR, the IFR incorporates asymptomatic and undiagnosed infections as well as reported cases. + + +==== Estimates ==== + +A December 2020 systematic review and meta-analysis estimated that population IFR during the first wave of the pandemic was about 0.5% to 1% in many locations (including France, Netherlands, New Zealand, and Portugal), 1% to 2% in other locations (Australia, England, Lithuania, and Spain), and exceeded 2% in Italy. That study also found that most of these differences in IFR reflected corresponding differences in the age composition of the population and age-specific infection rates; in particular, the metaregression estimate of IFR is very low for children and younger adults (e.g., 0.002% at age 10 and 0.01% at age 25) but increases progressively to 0.4% at age 55, 1.4% at age 65, 4.6% at age 75, and 15% at age 85. These results were also highlighted in a December 2020 report issued by the WHO. + +An analysis of those IFR rates indicates that COVID‑19 is hazardous not only for the elderly but also for middle-aged adults, for whom the infection fatality rate of COVID-19 is two orders of magnitude greater than the annualised risk of a fatal automobile accident and far more dangerous than seasonal influenza. + + +==== Earlier estimates of IFR ==== +At an early stage of the pandemic, the World Health Organization reported estimates of IFR between 0.3% and 1%. On 2 July, The WHO's chief scientist reported that the average IFR estimate presented at a two-day WHO expert forum was about 0.6%. In August, the WHO found that studies incorporating data from broad serology testing in Europe showed IFR estimates converging at approximately 0.5–1%. Firm lower limits of IFRs have been established in a number of locations such as New York City and Bergamo in Italy since the IFR cannot be less than the population fatality rate. (After sufficient time however, people can get reinfected). As of 10 July, in New York City, with a population of 8.4 million, 23,377 individuals (18,758 confirmed and 4,619 probable) have died with COVID‑19 (0.3% of the population). Antibody testing in New York City suggested an IFR of ≈0.9%, and ≈1.4%. In Bergamo province, 0.6% of the population has died. In September 2020, the U.S. Centers for Disease Control and Prevention (CDC) reported preliminary estimates of age-specific IFRs for public health planning purposes. + + +=== Sex differences === + +COVID‑19 case fatality rates are higher among men than women in most countries. However, in a few countries like India, Nepal, Vietnam, and Slovenia the fatality cases are higher in women than men. Globally, men are more likely to be admitted to the ICU and more likely to die. One meta-analysis found that globally, men were more likely to get COVID‑19 than women; there were approximately 55 men and 45 women per 100 infections (CI: 51.43–56.58). +The Chinese Center for Disease Control and Prevention reported the death rate was 2.8% for men and 1.7% for women. Later reviews in June 2020 indicated that there is no significant difference in susceptibility or in CFR between genders. One review acknowledges the different mortality rates in Chinese men, suggesting that it may be attributable to lifestyle choices such as smoking and drinking alcohol rather than genetic factors. Smoking, which in some countries like China is mainly a male activity, is a habit that contributes to increasing significantly the case fatality rates among men. Sex-based immunological differences, lesser prevalence of smoking in women and men developing co-morbid conditions such as hypertension at a younger age than women could have contributed to the higher mortality in men. In Europe as of February 2020, 57% of the infected people were men and 72% of those died with COVID‑19 were men. As of April 2020, the US government is not tracking sex-related data of COVID‑19 infections. Research has shown that viral illnesses like Ebola, HIV, influenza and SARS affect men and women differently. + + +=== Ethnic differences === +In the US, a greater proportion of deaths due to COVID‑19 have occurred among African Americans and other minority groups. Structural factors that prevent them from practising social distancing include their concentration in crowded substandard housing and in "essential" occupations such as retail grocery workers, public transit employees, health-care workers and custodial staff. Greater prevalence of lacking health insurance and care of underlying conditions such as diabetes, hypertension, and heart disease also increase their risk of death. Similar issues affect Native American and Latino communities. On the one hand, in the Dominican Republic there is a clear example of both gender and ethnic inequality. In this Latin American territory, there is great inequality and precariousness that especially affects Dominican women, with greater emphasis on those of Haitian descent. According to a US health policy non-profit, 34% of American Indian and Alaska Native People (AIAN) non-elderly adults are at risk of serious illness compared to 21% of white non-elderly adults. The source attributes it to disproportionately high rates of many health conditions that may put them at higher risk as well as living conditions like lack of access to clean water. +Leaders have called for efforts to research and address the disparities. In the UK, a greater proportion of deaths due to COVID‑19 have occurred in those of a Black, Asian, and other ethnic minority background. More severe impacts upon patients including the relative incidence of the necessity of hospitalisation requirements, and vulnerability to the disease has been associated via DNA analysis to be expressed in genetic variants at chromosomal region 3, features that are associated with European Neanderthal heritage. That structure imposes greater risks that those affected will develop a more severe form of the disease. The findings are from Professor Svante Pääbo and researchers he leads at the Max Planck Institute for Evolutionary Anthropology and the Karolinska Institutet. This admixture of modern human and Neanderthal genes is estimated to have occurred roughly between 50,000 and 60,000 years ago in Southern Europe. + + +=== Comorbidities === +Biological factors (immune response) and the general behaviour (habits) can strongly determine the consequences of COVID‑19. Most of those who die of COVID‑19 have pre-existing (underlying) conditions, including hypertension, diabetes mellitus, and cardiovascular disease. According to March data from the United States, 89% of those hospitalised had preexisting conditions. The Italian Istituto Superiore di Sanità reported that out of 8.8% of deaths where medical charts were available, 96.1% of people had at least one comorbidity with the average person having 3.4 diseases. According to this report the most common comorbidities are hypertension (66% of deaths), type 2 diabetes (29.8% of deaths), ischaemic heart disease (27.6% of deaths), atrial fibrillation (23.1% of deaths) and chronic renal failure (20.2% of deaths). +Most critical respiratory comorbidities according to the US Centers for Disease Control and Prevention (CDC), are: moderate or severe asthma, pre-existing COPD, pulmonary fibrosis, and cystic fibrosis. Evidence stemming from meta-analysis of several smaller research papers also suggests that smoking can be associated with worse outcomes. When someone with existing respiratory problems is infected with COVID‑19, they might be at greater risk for severe symptoms. COVID‑19 also poses a greater risk to people who misuse opioids and amphetamines, insofar as their drug use may have caused lung damage. +In August 2020, the CDC issued a caution that tuberculosis (TB) infections could increase the risk of severe illness or death. The WHO recommended that people with respiratory symptoms be screened for both diseases, as testing positive for COVID‑19 could not rule out co-infections. Some projections have estimated that reduced TB detection due to the pandemic could result in 6.3 million additional TB cases and 1.4 million TB-related deaths by 2025. + + +== History == + +The virus is thought to be of natural animal origin, most likely through spillover infection. A joint-study conducted in early 2021 by the People's Republic of China and the World Health Organization indicated that the virus descended from a coronavirus that infects wild bats, and likely spread to humans through an intermediary wildlife host. There are several theories about where the index case originated and investigations into the origin of the pandemic are ongoing. According to articles published in July 2022 in Science, virus transmission into humans occurred through two spillover events in November 2019 and was likely due to live wildlife trade on the Huanan wet market in the city of Wuhan (Hubei, China). Doubts about the conclusions have mostly centered on the precise site of spillover. Earlier phylogenetics estimated that SARS-CoV-2 arose in October or November 2019. A phylogenetic algorithm analysis suggested that the virus may have been circulating in Guangdong before Wuhan. +Most scientists believe the virus spilled into human populations through natural zoonosis, similar to the SARS-CoV-1 and MERS-CoV outbreaks, and consistent with other pandemics in human history. According to the Intergovernmental Panel on Climate Change several social and environmental factors including climate change, natural ecosystem destruction and wildlife trade increased the likelihood of such zoonotic spillover. One study made with the support of the European Union found climate change increased the likelihood of the pandemic by influencing distribution of bat species. +Available evidence suggests that the SARS-CoV-2 virus was originally harboured by bats, and spread to humans multiple times from infected wild animals at the Huanan Seafood Market in Wuhan in December 2019. A minority of scientists and some members of the U.S intelligence community believe the virus may have been unintentionally leaked from a laboratory such as the Wuhan Institute of Virology. The US intelligence community has mixed views on the issue, but overall agrees with the scientific consensus that the virus was not developed as a biological weapon and is unlikely to have been genetically engineered. There is no evidence SARS-CoV-2 existed in any laboratory prior to the pandemic. +The first confirmed human infections were in Wuhan. A study of the first 41 cases of confirmed COVID‑19, published in January 2020 in The Lancet, reported the earliest date of onset of symptoms as 1 December 2019. Official publications from the WHO reported the earliest onset of symptoms as 8 December 2019. Human-to-human transmission was confirmed by the WHO and Chinese authorities by 20 January 2020. According to official Chinese sources, these were mostly linked to the Huanan Seafood Wholesale Market, which also sold live animals. In May 2020, George Gao, the director of the CDC, said animal samples collected from the seafood market had tested negative for the virus, indicating that the market was the site of an early superspreading event, but that it was not the site of the initial outbreak. Traces of the virus have been found in wastewater samples that were collected in Milan and Turin, Italy, on 18 December 2019. +By December 2019, the spread of infection was almost entirely driven by human-to-human transmission. The number of COVID-19 cases in Hubei gradually increased, reaching 60 by 20 December, and at least 266 by 31 December. On 24 December, Wuhan Central Hospital sent a bronchoalveolar lavage fluid (BAL) sample from an unresolved clinical case to sequencing company Vision Medicals. On 27 and 28 December, Vision Medicals informed the Wuhan Central Hospital and the Chinese CDC of the results of the test, showing a new coronavirus. A pneumonia cluster of unknown cause was observed on 26 December and treated by the doctor Zhang Jixian in Hubei Provincial Hospital, who informed the Wuhan Jianghan CDC on 27 December. On 30 December, a test report addressed to Wuhan Central Hospital, from company CapitalBio Medlab, stated an erroneous positive result for SARS, causing a group of doctors at Wuhan Central Hospital to alert their colleagues and relevant hospital authorities of the result. The Wuhan Municipal Health Commission issued a notice to various medical institutions on "the treatment of pneumonia of unknown cause" that same evening. Eight of these doctors, including Li Wenliang (punished on 3 January), were later admonished by the police for spreading false rumours and another, Ai Fen, was reprimanded by her superiors for raising the alarm. +The Wuhan Municipal Health Commission made the first public announcement of a pneumonia outbreak of unknown cause on 31 December, confirming 27 cases – enough to trigger an investigation. +During the early stages of the outbreak, the number of cases doubled approximately every seven and a half days. In early and mid-January 2020, the virus spread to other Chinese provinces, helped by the Chinese New Year migration and Wuhan being a transport hub and major rail interchange. On 20 January, China reported nearly 140 new cases in one day, including two people in Beijing and one in Shenzhen. Later official data shows 6,174 people had already developed symptoms by then, and more may have been infected. A report in The Lancet on 24 January indicated human transmission, strongly recommended personal protective equipment for health workers, and said testing for the virus was essential due to its "pandemic potential". On 30 January, the WHO declared COVID-19 a Public Health Emergency of International Concern. By this time, the outbreak spread by a factor of 100 to 200 times. +Italy had its first confirmed cases on 31 January 2020, two tourists from China. Italy overtook China as the country with the most deaths on 19 March 2020. By 26 March the United States had overtaken China and Italy with the highest number of confirmed cases in the world. Research on coronavirus genomes indicates the majority of COVID-19 cases in New York came from European travellers, rather than directly from China or any other Asian country. Retesting of prior samples found a person in France who had the virus on 27 December 2019, and a person in the United States who died from the disease on 6 February 2020. +RT-PCR testing of untreated wastewater samples from Brazil and Italy have suggested detection of SARS-CoV-2 as early as November and December 2019, respectively, but the methods of such sewage studies have not been optimised, many have not been peer-reviewed, details are often missing, and there is a risk of false positives due to contamination or if only one gene target is detected. A September 2020 review journal article said, "The possibility that the COVID‑19 infection had already spread to Europe at the end of last year is now indicated by abundant, even if partially circumstantial, evidence", including pneumonia case numbers and radiology in France and Italy in November and December. +As of 1 October 2021, Reuters reported that it had estimated the worldwide total number of deaths due to COVID‑19 to have exceeded five million. +The Public Health Emergency of International Concern for COVID-19 ended on 5 May 2023. By this time, everyday life in most countries had returned to how it was before the pandemic. + + +== Misinformation == + +After the initial outbreak of COVID‑19, misinformation and disinformation regarding the origin, scale, prevention, treatment, and other aspects of the disease rapidly spread online. +In September 2020, the US Centers for Disease Control and Prevention (CDC) published preliminary estimates of the risk of death by age groups in the United States, but those estimates were widely misreported and misunderstood. + + +== Other species == + +Humans appear to be capable of spreading the virus to some other animals, a type of disease transmission referred to as zooanthroponosis. +Some pets, especially cats and ferrets, can catch this virus from infected humans. Symptoms in cats include respiratory (such as a cough) and digestive symptoms. Cats can spread the virus to other cats, and may be able to spread the virus to humans, but cat-to-human transmission of SARS-CoV-2 has not been proven. Compared to cats, dogs are less susceptible to this infection. Behaviours which increase the risk of transmission include kissing, licking, and petting the animal. +The virus does not appear to be able to infect pigs, ducks, or chickens at all. Mice, rats, and rabbits, if they can be infected at all, are unlikely to be involved in spreading the virus. +Tigers and lions in zoos have become infected as a result of contact with infected humans. As expected, monkeys and great ape species such as orangutans can also be infected with the COVID‑19 virus. +Minks, which are in the same family as ferrets, have been infected. Minks may be asymptomatic, and can also spread the virus to humans. Multiple countries have identified infected animals in mink farms. Denmark, a major producer of mink pelts, ordered the slaughter of all minks over fears of viral mutations, following an outbreak referred to as Cluster 5. A vaccine for mink and other animals is being researched. + + +== Research == + +International research on vaccines and medicines in COVID‑19 is underway by government organisations, academic groups, and industry researchers. The CDC has classified it to require a BSL3 grade laboratory. There has been a great deal of COVID‑19 research, involving accelerated research processes and publishing shortcuts to meet the global demand. +As of December 2020, hundreds of clinical trials have been undertaken, with research happening on every continent except Antarctica. As of November 2020, more than 200 possible treatments have been studied in humans. + + +=== Transmission and prevention research === + +Modelling research has been conducted with several objectives, including predictions of the dynamics of transmission, diagnosis and prognosis of infection, estimation of the impact of interventions, or allocation of resources. Modelling studies are mostly based on compartmental models in epidemiology, estimating the number of infected people over time under given conditions. Several other types of models have been developed and used during the COVID‑19 pandemic including computational fluid dynamics models to study the flow physics of COVID‑19, retrofits of crowd movement models to study occupant exposure, mobility-data based models to investigate transmission, or the use of macroeconomic models to assess the economic impact of the pandemic. + + +=== Treatment-related research === + +Repurposed antiviral drugs make up most of the research into COVID‑19 treatments. Other candidates in trials include vasodilators, corticosteroids, immune therapies, lipoic acid, bevacizumab, and recombinant angiotensin-converting enzyme 2. +In March 2020, the World Health Organization (WHO) initiated the Solidarity trial to assess the treatment effects of some promising drugs: + +An experimental drug called remdesivir +Anti-malarial drugs chloroquine and hydroxychloroquine +Two anti-HIV drugs, lopinavir/ritonavir and interferon-beta +More than 300 active clinical trials are underway as of April 2020. +Research on the antimalarial drugs hydroxychloroquine and chloroquine showed that they were ineffective at best, and that they may reduce the antiviral activity of remdesivir. By May 2020, France, Italy, and Belgium had banned the use of hydroxychloroquine as a COVID‑19 treatment. +In June, initial results from the randomised RECOVERY Trial in the United Kingdom showed that dexamethasone reduced mortality by one third for people who are critically ill on ventilators and one fifth for those receiving supplemental oxygen. Because this is a well-tested and widely available treatment, it was welcomed by the WHO, which is in the process of updating treatment guidelines to include dexamethasone and other steroids. Based on those preliminary results, dexamethasone treatment has been recommended by the NIH for peoples with COVID‑19 who are mechanically ventilated or who require supplemental oxygen but not in people with COVID‑19 who do not require supplemental oxygen. +In September 2020, the WHO released updated guidance on using corticosteroids for COVID‑19. The WHO recommends systemic corticosteroids rather than no systemic corticosteroids for the treatment of people with severe and critical COVID‑19 (strong recommendation, based on moderate certainty evidence). The WHO suggests not to use corticosteroids in the treatment of people with non-severe COVID‑19 (conditional recommendation, based on low certainty evidence). The updated guidance was based on a meta-analysis of clinical trials of people critically ill with COVID‑19. +In September 2020, the European Medicines Agency (EMA) endorsed the use of dexamethasone in adults and adolescents from 12 years of age and weighing at least 40 kilograms (88 lb) who require supplemental oxygen therapy. Dexamethasone can be taken by mouth or given as an injection or infusion (drip) into a vein. +In November 2020, the US Food and Drug Administration (FDA) issued an emergency use authorisation for the investigational monoclonal antibody therapy bamlanivimab for the treatment of mild-to-moderate COVID‑19. Bamlanivimab is authorised for people with positive results of direct SARS-CoV-2 viral testing who are twelve years of age and older weighing at least 40 kilograms (88 lb), and who are at high risk for progressing to severe COVID‑19 or hospitalisation. This includes those who are 65 years of age or older, or who have chronic medical conditions. +In February 2021, the FDA issued an emergency use authorisation (EUA) for bamlanivimab and etesevimab administered together for the treatment of mild to moderate COVID‑19 in people twelve years of age or older weighing at least 40 kilograms (88 lb) who test positive for SARS‑CoV‑2 and who are at high risk for progressing to severe COVID‑19. The authorised use includes treatment for those who are 65 years of age or older or who have certain chronic medical conditions. +In April 2021, the FDA revoked the emergency use authorisation (EUA) that allowed for the investigational monoclonal antibody therapy bamlanivimab, when administered alone, to be used for the treatment of mild-to-moderate COVID‑19 in adults and certain paediatric patients. + + +==== Cytokine storm ==== + +A cytokine storm can be a complication in the later stages of severe COVID‑19. A cytokine storm is a potentially deadly immune reaction where a large amount of pro-inflammatory cytokines and chemokines are released too quickly. A cytokine storm can lead to ARDS and multiple organ failure. Data collected from Jin Yin-tan Hospital in Wuhan, China indicates that people who had more severe responses to COVID‑19 had greater amounts of pro-inflammatory cytokines and chemokines in their system than people who had milder responses. These high levels of pro-inflammatory cytokines and chemokines indicate presence of a cytokine storm. +Tocilizumab has been included in treatment guidelines by China's National Health Commission after a small study was completed. It is undergoing a Phase II non-randomised trial at the national level in Italy after showing positive results in people with severe disease. Combined with a serum ferritin blood test to identify a cytokine storm (also called cytokine storm syndrome, not to be confused with cytokine release syndrome), it is meant to counter such developments, which are thought to be the cause of death in some affected people. The interleukin-6 receptor (IL-6R) antagonist was approved by the FDA to undergo a Phase III clinical trial assessing its effectiveness on COVID‑19 based on retrospective case studies for the treatment of steroid-refractory cytokine release syndrome induced by a different cause, CAR T cell therapy, in 2017. There is no randomised, controlled evidence that tocilizumab is an efficacious treatment for CRS. Prophylactic tocilizumab has been shown to increase serum IL-6 levels by saturating the IL-6R, driving IL-6 across the blood–brain barrier, and exacerbating neurotoxicity while having no effect on the incidence of CRS. +Lenzilumab, an anti-GM-CSF monoclonal antibody, is protective in murine models for CAR T cell-induced CRS and neurotoxicity and is a viable therapeutic option due to the observed increase of pathogenic GM-CSF secreting T cells in hospitalised patients with COVID‑19. + + +==== Passive antibodies ==== + +Transferring purified and concentrated antibodies produced by the immune systems of those who have recovered from COVID‑19 to people who need them is being investigated as a non-vaccine method of passive immunisation. Viral neutralisation is the anticipated mechanism of action by which passive antibody therapy can mediate defence against SARS-CoV-2. The spike protein of SARS-CoV-2 is the primary target for neutralising antibodies. As of 8 August 2020, eight neutralising antibodies targeting the spike protein of SARS-CoV-2 have entered clinical studies. It has been proposed that selection of broad-neutralising antibodies against SARS-CoV-2 and SARS-CoV might be useful for treating not only COVID‑19 but also future SARS-related CoV infections. Other mechanisms, however, such as antibody-dependant cellular cytotoxicity or phagocytosis, may be possible. Other forms of passive antibody therapy, for example, using manufactured monoclonal antibodies, are in development. +The use of passive antibodies to treat people with active COVID‑19 is also being studied. This involves the production of convalescent serum, which consists of the liquid portion of the blood from people who recovered from the infection and contains antibodies specific to this virus, which is then administered to active patients. This strategy was tried for SARS with inconclusive results. An updated Cochrane review in May 2023 found high certainty evidence that, for the treatment of people with moderate to severe COVID‑19, convalescent plasma did not reduce mortality or bring about symptom improvement. There continues to be uncertainty about the safety of convalescent plasma administration to people with COVID‑19 and differing outcomes measured in different studies limits their use in determining efficacy. + + +=== Bioethics === +Since the outbreak of the COVID‑19 pandemic, scholars have explored the bioethics, normative economics, and political theories of healthcare policies related to the public health crisis. Academics have pointed to the moral distress of healthcare workers, ethics of distributing scarce healthcare resources such as ventilators, and the global justice of vaccine diplomacies. The socio-economic inequalities between genders, races, groups with disabilities, communities, regions, countries, and continents have also drawn attention in academia and the general public. + + +== See also == +Coronavirus diseases, a group of closely related syndromes +Disease X, a WHO term +Law of declining virulence – Disproved hypothesis of epidemiologist Theobald Smith +Theory of virulence – Theory by biologist Paul W. Ewald + + +== References == + + +== Further reading == + + +== External links == + + +=== Health agencies === +Coronavirus disease (COVID‑19) Facts by the World Health Organization (WHO) +Coronavirus (COVID‑19) by the UK National Health Service (NHS) +Coronavirus 2019 (COVID-19) by the US Centers for Disease Control and Prevention (CDC) + + +=== Directories === +Coronavirus Resource Center at the Center for Inquiry +COVID‑19 Information on FireMountain.net Archived 13 January 2022 at the Wayback Machine +COVID‑19 Resource Directory on OpenMD + + +=== Medical journals === +BMJ's Coronavirus (covid‑19) Hub by the BMJ +Coronavirus (Covid‑19) by The New England Journal of Medicine +Coronavirus (COVID‑19) Research Highlights by Springer Nature +Coronavirus Disease 2019 (COVID‑19) by JAMA +COVID‑19 Resource Centre by The Lancet +Covid‑19: Novel Coronavirus Archived 24 September 2020 at the Wayback Machine by Wiley Publishing +Novel Coronavirus Information Center by Elsevier + + +=== Treatment guidelines === +"Bouncing Back From COVID-19: Your Guide to Restoring Movement" (PDF). Johns Hopkins Medicine. +"Coronavirus Disease 2019 (COVID-19) Treatment Guidelines" (PDF). National Institutes of Health. +"Guidelines on the Treatment and Management of Patients with COVID-19". Infectious Diseases Society of America. +"JHMI Clinical Recommendations for Available Pharmacologic Therapies for COVID-19" (PDF). Johns Hopkins Medicine. +NHS England and NHS Improvement (28 July 2022). National Guidance for post-COVID syndrome assessment clinics (Report). +World Health Organization (2022). Therapeutics and COVID-19: living guideline, 14 January 2022 (Report). hdl:10665/351006. WHO/2019-nCoV/therapeutics/2022.1. \ No newline at end of file diff --git a/lightrag/evaluation/wiki_documents/medical_diabetes.txt b/lightrag/evaluation/wiki_documents/medical_diabetes.txt new file mode 100644 index 00000000..a9d6ac4c --- /dev/null +++ b/lightrag/evaluation/wiki_documents/medical_diabetes.txt @@ -0,0 +1,239 @@ +Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin or the cells of the body becoming unresponsive to insulin's effects. Classic symptoms include the three Ps: polydipsia (excessive thirst), polyuria (excessive urination), polyphagia (excessive hunger), weight loss, and blurred vision. If left untreated, the disease can lead to various health complications, including disorders of the cardiovascular system, eye, kidney, and nerves. Diabetes accounts for approximately 4.2 million deaths every year, with an estimated 1.5 million caused by either untreated or poorly treated diabetes. +The major types of diabetes are type 1 and type 2. The most common treatment for type 1 is insulin replacement therapy (insulin injections), while anti-diabetic medications (such as metformin and semaglutide or tirzepatide) and lifestyle modifications can be used to manage type 2. Gestational diabetes, a form that sometimes arises during pregnancy, normally resolves shortly after delivery. Type 1 diabetes is an autoimmune condition where the body's immune system attacks the beta cells (β-cell) in the pancreas, preventing the production of insulin. This condition is typically present from birth or develops early in life. Type 2 diabetes occurs when the body becomes resistant to insulin, meaning the cells do not respond effectively to it, and thus, glucose remains in the bloodstream instead of being absorbed by the cells. Additionally, diabetes can also result from other specific causes, such as genetic conditions (monogenic diabetes syndromes like neonatal diabetes and maturity-onset diabetes of the young), diseases affecting the pancreas (such as pancreatitis), or the use of certain medications and chemicals (such as glucocorticoids, other specific drugs and after organ transplantation). +The number of people diagnosed as living with diabetes has increased sharply in recent decades, from 200 million in 1990 to 830 million by 2022. It affects one in seven of the adult population, with type 2 diabetes accounting for more than 95% of cases. These numbers have already risen beyond earlier projections of 783 million adults by 2045. The prevalence of the disease continues to increase, most dramatically in low- and middle-income nations. Rates are similar in women and men, with diabetes being the seventh leading cause of death globally. The global expenditure on diabetes-related healthcare is an estimated US$760 billion a year. + + +== Signs and symptoms == + Common symptoms of diabetes include increased thirst, frequent urination, extreme hunger, and unintended weight loss. Several other non-specific signs and symptoms may also occur, including fatigue, blurred vision, sweet smelling urine/semen and genital itchiness due to Candida infection. About half of affected individuals may also be asymptomatic. Type 1 presents abruptly following a pre-clinical phase, while type 2 has a more insidious onset; patients may remain asymptomatic for many years. +Diabetic ketoacidosis is a medical emergency that occurs most commonly in type 1, but may also occur in type 2 if it has been longstanding or if the individual has significant β-cell dysfunction. Excessive production of ketone bodies leads to signs and symptoms including nausea, vomiting, abdominal pain, the smell of acetone in the breath, deep breathing known as Kussmaul breathing, and in severe cases decreased level of consciousness. Hyperosmolar hyperglycemic state is another emergency characterized by dehydration secondary to severe hyperglycemia, with resultant hypernatremia leading to an altered mental state and possibly coma. +Hypoglycemia is a recognized complication of insulin treatment used in diabetes. An acute presentation can include mild symptoms such as sweating, trembling, and palpitations, to more serious effects including impaired cognition, confusion, seizures, coma, and rarely death. Recurrent hypoglycemic episodes may lower the glycemic threshold at which symptoms occur, meaning mild symptoms may not appear before cognitive deterioration begins to occur. + + +=== Long-term complications === + +The major long-term complications of diabetes relate to damage to blood vessels at both macrovascular and microvascular levels. Diabetes doubles the risk of cardiovascular disease, and about 75% of deaths in people with diabetes are due to coronary artery disease. Other macrovascular morbidities include stroke and peripheral artery disease. +Microvascular disease affects the eyes, kidneys, and nerves. Damage to the retina, known as diabetic retinopathy, is the most common cause of blindness in people of working age. The eyes can also be affected in other ways, including development of cataract and glaucoma. It is recommended that people with diabetes visit an optometrist or ophthalmologist once a year. +Diabetic nephropathy is a major cause of chronic kidney disease, accounting for over 50% of patients on dialysis in the United States. Diabetic neuropathy, damage to nerves, manifests in various ways, including sensory loss, neuropathic pain, and autonomic dysfunction (such as postural hypotension, diarrhea, and erectile dysfunction). Loss of pain sensation predisposes to trauma that can lead to diabetic foot problems (such as ulceration), the most common cause of non-traumatic lower-limb amputation. +Hearing loss is another long-term complication associated with diabetes. +Based on extensive data and numerous cases of gallstone disease, it appears that a causal link might exist between type 2 diabetes and gallstones. People with diabetes are at a higher risk of developing gallstones compared to those without diabetes. +There is a link between cognitive deficit and diabetes; studies have shown that diabetic individuals are at a greater risk of cognitive decline, and have a greater rate of decline compared to those without the disease. Diabetes increases the risk of dementia, and the earlier that one is diagnosed with diabetes, the higher the risk becomes. The condition also predisposes to falls in the elderly, especially those treated with insulin. + + +== Types == + +Diabetes is classified by the World Health Organization into six categories: + +Type 1 diabetes +Type 2 diabetes +Hybrid forms of diabetes(including slowly evolving, immune-mediated diabetes of adults and ketosis-prone type 2 diabetes) +Hyperglycemia first detected during pregnancy +Other specific types +Unclassified diabetes +Diabetes is a more variable disease than once thought, and individuals may have a combination of forms. + + +=== Type 1 === + +Type 1 accounts for 5 to 10% of diabetes cases and is the most common type of diabetes diagnosed in patients under 20 years; however, the older term "juvenile-onset diabetes" is no longer used as onset in adulthood is possible. The disease is characterized by loss of the insulin-producing beta cells of the pancreatic islets, leading to severe insulin deficiency, and can be further classified as immune-mediated or idiopathic (without known cause). The majority of cases are immune-mediated, in which a T cell-mediated autoimmune attack causes loss of beta cells and thus insulin deficiency. Patients often have irregular and unpredictable blood sugar levels due to very low insulin and an impaired counter-response to hypoglycemia. +Type 1 diabetes is partly inherited, with multiple genes, including certain HLA genotypes, known to influence the risk of diabetes. In genetically susceptible people, the onset of diabetes can be triggered by one or more environmental factors, such as a viral infection or diet. Several viruses have been implicated, but to date there is no stringent evidence to support this hypothesis in humans. +Type 1 diabetes can occur at any age, and a significant proportion is diagnosed during adulthood. Latent autoimmune diabetes of adults (LADA) is the diagnostic term applied when type 1 diabetes develops in adults; it has a slower onset than the same condition in children. Given this difference, some use the unofficial term "type 1.5 diabetes" for this condition. Adults with LADA are frequently initially misdiagnosed as having type 2 diabetes, based on age rather than a cause. LADA leaves adults with higher levels of insulin production than type 1 diabetes, but not enough insulin production for healthy blood sugar levels. + + +=== Type 2 === + +Type 2 diabetes is characterized by insulin resistance, which may be combined with relatively reduced insulin secretion. The defective responsiveness of body tissues to insulin is believed to involve the insulin receptor. However, the specific defects are not known. Diabetes mellitus cases due to a known defect are classified separately. Type 2 diabetes is the most common type of diabetes mellitus accounting for 95% of diabetes. Many people with type 2 diabetes have evidence of prediabetes (impaired fasting glucose and/or impaired glucose tolerance) before meeting the criteria for type 2 diabetes. The progression of prediabetes to overt type 2 diabetes can be slowed or reversed by lifestyle changes or medications that improve insulin sensitivity or reduce the liver's glucose production. +Type 2 diabetes is primarily due to lifestyle factors and genetics. A number of lifestyle factors are known to be important to the development of type 2 diabetes, including obesity (defined by a body mass index of greater than 30), lack of physical activity, poor diet such as Western Pattern Diet, and stress. Excess body fat is associated with 30% of cases in people of Chinese and Japanese descent, 60–80% of cases in those of European and African descent, and 100% of Pima Indians and Pacific Islanders. Even those who are not obese may have a high waist–hip ratio. +Dietary factors such as sugar-sweetened drinks are associated with an increased risk. The type of fats in the diet is also important, with saturated fat and trans fats increasing the risk and polyunsaturated and monounsaturated fat decreasing the risk. Eating white rice excessively may increase the risk of diabetes, especially in Chinese and Japanese people. +Adverse childhood experiences, including abuse, neglect, and household difficulties, increase the likelihood of type 2 diabetes later in life by 32%, with neglect having the strongest effect. +Antipsychotic medication, SSRI, and SNRI side effects (specifically metabolic abnormalities, dyslipidemia and weight gain) are also potential risk factors. + + +=== Gestational diabetes === + +Gestational diabetes resembles type 2 diabetes in several respects, involving a combination of relatively inadequate insulin secretion and responsiveness. It occurs in about 2–10% of all pregnancies and may improve or disappear after delivery. It is recommended that all pregnant women get tested starting around 24–28 weeks gestation. It is most often diagnosed in the second or third trimester because of the increase in insulin-antagonist hormone levels that occurs at this time. However, after pregnancy approximately 5–10% of women with gestational diabetes are found to have another form of diabetes, most commonly type 2. Gestational diabetes is fully treatable, but requires careful medical supervision throughout the pregnancy. Management may include dietary changes, blood glucose monitoring, and in some cases, insulin may be required. +Though it may be transient, untreated gestational diabetes can damage the health of the fetus or mother. Risks to the baby include macrosomia (high birth weight), congenital heart and central nervous system abnormalities, and skeletal muscle malformations. Increased levels of insulin in a fetus's blood may inhibit fetal surfactant production and cause infant respiratory distress syndrome. A high blood bilirubin level may result from red blood cell destruction. In severe cases, perinatal death may occur, most commonly as a result of poor placental perfusion due to vascular impairment. Labor induction may be indicated with decreased placental function. A caesarean section may be performed if there is marked fetal distress or an increased risk of injury associated with macrosomia, such as shoulder dystocia. +As the risk of developing type 2 diabetes is about 10 times higher in women with a history of gestational diabetes, postpartum screening may involve dietary, lifestyle, and drug interventions to prevent or delay its progression. + + +=== Maturity-onset diabetes of the young === + +Maturity-onset diabetes of the young (MODY) is a rare autosomal dominant inherited form of diabetes, due to one of several single-gene mutations causing defects in insulin production. It is significantly less common than the three main types, constituting 1–2% of all cases. The name of this disease refers to early hypotheses as to its nature. Being due to a defective gene, this disease varies in age at presentation and in severity according to the specific gene defect; thus, there are at least 14 subtypes of MODY. People with MODY often can control it without using insulin. + + +=== Type 5 (malnutrition-related) === +Malnutrition-related diabetes, also termed Type 5 diabetes, involves decreased insulin production, similar to Type 1 diabetes, but is primarily related to malnutrition rather than autoimmune damage of pancreas beta cells. Unlike in Type 1 diabetes, patients with Type 5 diabetes do not develop ketonuria or ketosis. The ICD-10 (1992) diagnostic entity, malnutrition-related diabetes mellitus (ICD-10 code E12), was previously deprecated by the World Health Organization (WHO) when the current taxonomy was introduced in 1999. + + +=== Other types === +Some cases of diabetes are caused by the body's tissue receptors not responding to insulin (even when insulin levels are normal, which is what separates it from type 2 diabetes); this form is very uncommon. Genetic mutations (autosomal or mitochondrial) can lead to defects in beta cell function. Abnormal insulin action may also have been genetically determined in some cases. Any disease that causes extensive damage to the pancreas may lead to diabetes (for example, chronic pancreatitis and cystic fibrosis). Diseases associated with excessive secretion of insulin-antagonistic hormones can cause diabetes (which is typically resolved once the hormone excess is removed). Many drugs impair insulin secretion and some toxins damage pancreatic beta cells, whereas others increase insulin resistance (especially glucocorticoids which can provoke "steroid diabetes"). Yet another form of diabetes that people may develop is double diabetes. This is when a type 1 diabetic becomes insulin resistant, the hallmark for type 2 diabetes or has a family history for type 2 diabetes. It was first discovered in 1990 or 1991. +The following is a list of disorders that may increase the risk of diabetes: + + +=== Unofficial === +Insulin resistance in the brain caused by Alzheimer's disease has been termed by some researchers as Type 3 diabetes, though this label is also rejected by some to avoid confusion with other types classified as Type 3. "Type 4 diabetes" has been used to describe age-related insulin resistance in lean mice. Neither of these terms are commonly used in human health care. + + +== Pathophysiology == + +Insulin is the principal hormone that regulates the uptake of glucose from the blood into most cells of the body, especially liver, adipose tissue and muscle, except smooth muscle, in which insulin acts via the IGF-1. Therefore, deficiency of insulin or the insensitivity of its receptors play a central role in all forms of diabetes mellitus. +The body obtains glucose from three main sources: the intestinal absorption of food; the breakdown of glycogen (glycogenolysis), the storage form of glucose found in the liver; and gluconeogenesis, the generation of glucose from non-carbohydrate substrates in the body. Insulin plays a critical role in regulating glucose levels in the body. Insulin can inhibit the breakdown of glycogen or the process of gluconeogenesis, it can stimulate the transport of glucose into fat and muscle cells, and it can stimulate the storage of glucose in the form of glycogen. +Insulin is released into the blood by beta cells (β-cells), found in the islets of Langerhans in the pancreas, in response to rising levels of blood glucose, typically after eating. Insulin is used by about two-thirds of the body's cells to absorb glucose from the blood for use as fuel, for conversion to other needed molecules, or for storage. Lower glucose levels result in decreased insulin release from the beta cells and in the breakdown of glycogen to glucose. This process is mainly controlled by the hormone glucagon, which acts in the opposite manner to insulin. +If the amount of insulin available is insufficient, or if cells respond poorly to the effects of insulin (insulin resistance), or if the insulin itself is defective, then glucose is not absorbed properly by the body cells that require it, and is not stored appropriately in the liver and muscles. The net effect is persistently high levels of blood glucose, poor protein synthesis, and other metabolic derangements, such as metabolic acidosis in cases of complete insulin deficiency. +When there is too much glucose in the blood for a long time, the kidneys cannot absorb it all (reach a threshold of reabsorption) and the extra glucose gets passed out of the body through urine (glycosuria). This increases the osmotic pressure of the urine and inhibits reabsorption of water by the kidney, resulting in increased urine production (polyuria) and increased fluid loss. Lost blood volume is replaced osmotically from water in body cells and other body compartments, causing dehydration and increased thirst (polydipsia). In addition, intracellular glucose deficiency stimulates appetite leading to excessive food intake (polyphagia). + + +== Diagnosis == + +Diabetes mellitus is diagnosed with a test for the glucose content in the blood, and is diagnosed by demonstrating any one of the following: + +Fasting plasma glucose level ≥ 7.0 mmol/L (126 mg/dL). For this test, blood is taken after a period of fasting, i.e. in the morning before breakfast, after the patient had sufficient time to fast overnight or at least 8 hours before the test. +Plasma glucose ≥ 11.1 mmol/L (200 mg/dL) two hours after a 75 gram oral glucose load as in a glucose tolerance test (OGTT) +Symptoms of high blood sugar and plasma glucose ≥ 11.1 mmol/L (200 mg/dL) either while fasting or not fasting +Glycated hemoglobin (HbA1C) ≥ 48 mmol/mol (≥ 6.5 DCCT %). + +A positive result, in the absence of unequivocal high blood sugar, should be confirmed by a repeat of any of the above methods on a different day. It is preferable to measure a fasting glucose level because of the ease of measurement and the considerable time commitment of formal glucose tolerance testing, which takes two hours to complete and offers no prognostic advantage over the fasting test. According to the current definition, two fasting glucose measurements at or above 7.0 mmol/L (126 mg/dL) is considered diagnostic for diabetes mellitus. +Per the WHO, people with fasting glucose levels from 6.1 to 6.9 mmol/L (110 to 125 mg/dL) are considered to have impaired fasting glucose. People with plasma glucose at or above 7.8 mmol/L (140 mg/dL), but not over 11.1 mmol/L (200 mg/dL), two hours after a 75 gram oral glucose load are considered to have impaired glucose tolerance. Of these two prediabetic states, the latter in particular is a major risk factor for progression to full-blown diabetes mellitus, as well as cardiovascular disease. The American Diabetes Association (ADA) since 2003 uses a slightly different range for impaired fasting glucose of 5.6 to 6.9 mmol/L (100 to 125 mg/dL). +Glycated hemoglobin is better than fasting glucose for determining risks of cardiovascular disease and death from any cause. + + +== Prevention == + +There is no known preventive measure for type 1 diabetes. However, islet autoimmunity and multiple antibodies can be a strong predictor of the onset of type 1 diabetes. Type 2 diabetes—which accounts for 85–90% of all cases worldwide—can often be prevented or delayed by maintaining a normal body weight, engaging in physical activity, and eating a healthy diet. Higher levels of physical activity (more than 90 minutes per day) reduce the risk of diabetes by 28%. Dietary changes known to be effective in helping to prevent diabetes include maintaining a diet rich in whole grains and fiber, and choosing good fats, such as the polyunsaturated fats found in nuts, vegetable oils, and fish. Limiting sugary beverages and eating less red meat and other sources of saturated fat can also help prevent diabetes. Tobacco smoking is also associated with an increased risk of diabetes and its complications, so smoking cessation can be an important preventive measure as well. +The relationship between type 2 diabetes and the main modifiable risk factors (excess weight, unhealthy diet, physical inactivity and tobacco use) is similar in all regions of the world. There is growing evidence that the underlying determinants of diabetes are a reflection of the major forces driving social, economic and cultural change: globalization, urbanization, population aging, and the general health policy environment. + + +== Comorbidity == +Diabetes patients' comorbidities have a significant impact on medical expenses and related costs. It has been demonstrated that patients with diabetes are more likely to experience respiratory, urinary tract, and skin infections, develop atherosclerosis, hypertension, and chronic kidney disease, putting them at increased risk of infection and complications that require medical attention. Patients with diabetes mellitus are more likely to experience certain infections, such as COVID-19, with prevalence rates ranging from 5.3 to 35.5%. Maintaining adequate glycemic control is the primary goal of diabetes management since it is critical to managing diabetes and preventing or postponing such complications. +People with type 1 diabetes have higher rates of autoimmune disorders than the general population. An analysis of a type 1 diabetes registry found that 27% of the 25,000 participants had other autoimmune disorders. Between 2% and 16% of people with type 1 diabetes also have celiac disease. + + +== Management == + +Diabetes management concentrates on keeping blood sugar levels close to normal, without causing low blood sugar. This can usually be accomplished with dietary changes, exercise, weight loss, and use of appropriate medications (insulin, oral medications). +Learning about the disease and actively participating in the treatment is important, since complications are far less common and less severe in people who have well-managed blood sugar levels. The goal of treatment is an HbA1C level below 7%. Attention is also paid to other health problems that may accelerate the negative effects of diabetes. These include smoking, high blood pressure, metabolic syndrome, obesity, and lack of regular exercise. Specialized footwear is widely used to reduce the risk of diabetic foot ulcers by relieving the pressure on the foot. Foot examination for patients living with diabetes should be done annually which includes sensation testing, foot biomechanics, vascular integrity and foot structure. +Concerning those with severe mental illness, the efficacy of type 2 diabetes self-management interventions is still poorly explored, with insufficient scientific evidence to show whether these interventions have similar results to those observed in the general population. + + +=== Lifestyle === + +People with diabetes can benefit from education about the disease and treatment, dietary changes, and exercise, with the goal of keeping both short-term and long-term blood glucose levels within acceptable bounds. In addition, given the associated higher risks of cardiovascular disease, lifestyle modifications are recommended to control blood pressure. +Weight loss can prevent progression from prediabetes to diabetes type 2, decrease the risk of cardiovascular disease, or result in a partial remission in people with diabetes. No single dietary pattern is best for all people with diabetes. Healthy dietary patterns, such as the Mediterranean diet, low-carbohydrate diet, or DASH diet, are often recommended, although evidence does not support one over the others. According to the ADA, "reducing overall carbohydrate intake for individuals with diabetes has demonstrated the most evidence for improving glycemia", and for individuals with type 2 diabetes who cannot meet the glycemic targets or where reducing anti-glycemic medications is a priority, low or very-low carbohydrate diets are a viable approach. For overweight people with type 2 diabetes, any diet that achieves weight loss is effective. +A 2020 Cochrane systematic review compared several non-nutritive sweeteners to sugar, placebo and a nutritive low-calorie sweetener (tagatose), but the results were unclear for effects on HbA1C, body weight and adverse events. The studies included were mainly of very low-certainty and did not report on health-related quality of life, diabetes complications, all-cause mortality or socioeconomic effects. + + +=== In children === +While type 1 diabetes is more prevalent in pediatric diabetes, type 2 diabetes has increasing prevalence, accounting for some 33% of new diagnoses. Risk factors for type 2 diabetes include ethnicity, family history, sedentary lifestyle, unhealthy diet, a mother with gestational diabetes, female gender, and obesity. Children with type 2 diabetes have increased risk of developing complications, which include insulin resistance, hyperglycemia, polyuria, ketosis, and dehydration. Early recognition, screening, treatment, and education of diabetic children are needed to prevent long-term disease complications. +Screening for type 2 diabetes typically starts at 10 years old for obese children and those who have at least two risk factors. Diagnostic criteria include plasma blood glucose of more than 200 mg per deciliter (dl) or a fasting blood glucose above 126 mg per dl in children with overt symptoms. Differentiating type 1 from type 2 diabetes may include assessment of fasting blood insulin or C-peptide, or determination of autoantibodies for type 1 diabetes. + + +==== Treatment and management ==== +Adoption of healthy lifestyle practices and metformin medication are recommended as initial treatments. Lifestyle changes include daily exercise for at least 60 minutes, reduced screen time, and dietary education. +Metformin at 500 mg per day is used upon diagnosis. Insulin is used for children with a blood glucose of more than 250 mg per dl and a HbA1C greater than 8.5%. + + +==== Education ==== +Diabetes management for children requires the integration of the family and health care team to be committed and continuous for promotion of self-management. A health care team may include a pediatric endocrinologist or physician trained in pediatric diabetes, a diabetes specialist nurse, a registered dietitian, a psychologist, a social worker, and child life specialist. +The goal of the health care team and child's family is to empower the child to make informed decisions for health‐promoting lifestyle choices. + + +=== Medications === + + +==== Glucose control ==== + +Most medications used to treat diabetes act by lowering blood sugar levels through different mechanisms. There is broad consensus that when people with diabetes maintain tight glucose control – keeping the glucose levels in their blood within normal ranges – they experience fewer complications, such as kidney problems or eye problems. There is, however, debate as to whether this is appropriate and cost effective for people later in life in whom the risk of hypoglycemia may be more significant. +There are a number of different classes of anti-diabetic medications. Type 1 diabetes requires treatment with insulin, ideally using a "basal bolus" regimen that most closely matches normal insulin release: long-acting insulin for the basal rate and short-acting insulin with meals. Type 2 diabetes is generally treated with medication that is taken by mouth (e.g. metformin) although some eventually require injectable treatment with insulin or GLP-1 agonists. +Metformin is generally recommended as a first-line treatment for type 2 diabetes, as there is good evidence that it decreases mortality. It works by decreasing the liver's production of glucose, and increasing the amount of glucose stored in peripheral tissue. Several other groups of drugs, mainly oral medication, may also decrease blood sugar in type 2 diabetes. These include agents that increase insulin release (sulfonylureas), agents that decrease absorption of sugar from the intestines (acarbose), agents that inhibit the enzyme dipeptidyl peptidase-4 (DPP-4) that inactivates incretins such as GLP-1 and GIP (sitagliptin), agents that make the body more sensitive to insulin (thiazolidinedione) and agents that increase the excretion of glucose in the urine (SGLT2 inhibitors). When insulin is used in type 2 diabetes, a long-acting formulation is usually added initially, while continuing oral medications. +Some severe cases of type 2 diabetes may also be treated with insulin, which is increased gradually until glucose targets are reached. + + +==== Blood pressure lowering ==== +Cardiovascular disease is a serious complication associated with diabetes, and many international guidelines recommend blood pressure treatment targets that are lower than 140/90 mmHg for people with diabetes. However, there is only limited evidence regarding what the lower targets should be. A 2016 systematic review found potential harm to treating to targets lower than 140 mmHg, and a subsequent systematic review in 2019 found no evidence of additional benefit from blood pressure lowering to between 130 – 140mmHg, although there was an increased risk of adverse events. +2015 American Diabetes Association recommendations are that people with diabetes and albuminuria should receive an inhibitor of the renin-angiotensin system to reduce the risks of progression to end-stage renal disease, cardiovascular events, and death. There is some evidence that angiotensin converting enzyme inhibitors (ACEIs) are superior to other inhibitors of the renin-angiotensin system such as angiotensin receptor blockers (ARBs), or aliskiren in preventing cardiovascular disease. Although a more recent review found similar effects of ACEIs and ARBs on major cardiovascular and renal outcomes. There is no evidence that combining ACEIs and ARBs provides additional benefits. + + +==== Aspirin ==== +The use of aspirin to prevent cardiovascular disease in diabetes is controversial. Aspirin is recommended by some in people at high risk of cardiovascular disease; however, routine use of aspirin has not been found to improve outcomes in uncomplicated diabetes. 2015 American Diabetes Association recommendations for aspirin use (based on expert consensus or clinical experience) are that low-dose aspirin use is reasonable in adults with diabetes who are at intermediate risk of cardiovascular disease (10-year cardiovascular disease risk, 5–10%). National guidelines for England and Wales by the National Institute for Health and Care Excellence (NICE) recommend against the use of aspirin in people with type 1 or type 2 diabetes who do not have confirmed cardiovascular disease. + + +=== Surgery === +Weight loss surgery in those with obesity and type 2 diabetes is often an effective measure. Many are able to maintain normal blood sugar levels with little or no medications following surgery and long-term mortality is decreased. There is, however, a short-term mortality risk of less than 1% from the surgery. The body mass index cutoffs for when surgery is appropriate are not yet clear. It is recommended that this option be considered in those who are unable to get both their weight and blood sugar under control. +A pancreas transplant is occasionally considered for people with type 1 diabetes who have severe complications of their disease, including end stage kidney disease requiring kidney transplantation. +Diabetic peripheral neuropathy (DPN) affects 30% of all diabetes patients. When DPN is superimposed with nerve compression, DPN may be treatable with multiple nerve decompressions. The theory is that DPN predisposes peripheral nerves to compression at anatomical sites of narrowing, and that the majority of DPN symptoms are actually attributable to nerve compression, a treatable condition, rather than DPN itself. The surgery is associated with lower pain scores, higher two-point discrimination (a measure of sensory improvement), lower rate of ulcerations, fewer falls (in the case of lower extremity decompression), and fewer amputations. + + +=== Self-management and support === +In countries using a general practitioner system, such as the United Kingdom, care may take place mainly outside hospitals, with hospital-based specialist care used only in case of complications, difficult blood sugar control, or research projects. In other circumstances, general practitioners and specialists share care in a team approach. Evidence has shown that social prescribing led to slight improvements in blood sugar control for people with type 2 diabetes. Home telehealth support can be an effective management technique. +The use of technology to deliver educational programs for adults with type 2 diabetes includes computer-based self-management interventions to collect for tailored responses to facilitate self-management. There is no adequate evidence to support effects on cholesterol, blood pressure, behavioral change (such as physical activity levels and dietary), depression, weight and health-related quality of life, nor in other biological, cognitive or emotional outcomes. + + +== Epidemiology == + +An estimated 382 million people worldwide had diabetes in 2013 up from 108 million in 1980. Accounting for the shifting age structure of the global population, the prevalence of diabetes is 8.8% among adults, nearly double the rate of 4.7% in 1980. Type 2 makes up about 90% of the cases. Some data indicate rates are roughly equal in women and men, but male excess in diabetes has been found in many populations with higher type 2 incidence, possibly due to sex-related differences in insulin sensitivity, consequences of obesity and regional body fat deposition, and other contributing factors such as high blood pressure, tobacco smoking, and alcohol intake. +The WHO estimates that diabetes resulted in 1.5 million deaths in 2012, making it the 8th leading cause of death. However, another 2.2 million deaths worldwide were attributable to high blood glucose and the increased risks of cardiovascular disease and other associated complications (e.g. kidney failure), which often lead to premature death and are often listed as the underlying cause on death certificates rather than diabetes. For example, in 2017, the International Diabetes Federation (IDF) estimated that diabetes resulted in 4.0 million deaths worldwide, using modeling to estimate the total number of deaths that could be directly or indirectly attributed to diabetes. +Diabetes occurs throughout the world but is more common (especially type 2) in more developed countries. The greatest increase in rates has, however, been seen in low- and middle-income countries, where more than 80% of diabetic deaths occur. The fastest prevalence increase is expected to occur in Asia and Africa, where most people with diabetes will probably live in 2030. The increase in rates in developing countries follows the trend of urbanization and lifestyle changes, including increasingly sedentary lifestyles, less physically demanding work and the global nutrition transition, marked by increased intake of foods that are high energy-dense but nutrient-poor (often high in sugar and saturated fats, sometimes referred to as the "Western-style" diet). The global number of diabetes cases might increase by 48% between 2017 and 2045. +As of 2020, 38% of all US adults had prediabetes. Prediabetes is an early stage of diabetes. + + +== History == + +Diabetes was one of the first diseases described, with an Egyptian manuscript from c. 1500 BCE mentioning "too great emptying of the urine." The Ebers papyrus includes a recommendation for a drink to take in such cases. The first described cases are believed to have been type 1 diabetes. +The term "diabetes" or "to pass through" was first used in 230 BCE by the Greek Apollonius of Memphis. The disease was considered rare during the time of the Roman empire, with Galen commenting he had only seen two cases during his career. This is possibly due to the diet and lifestyle of the ancients, or because the clinical symptoms were observed during the advanced stage of the disease. Galen named the disease "diarrhea of the urine" (diarrhea urinosa). Indian physicians around the sixth century CE identified the disease and classified it as madhumeha or "honey urine", noting the urine would attract ants. +The earliest surviving work with a detailed reference to diabetes is that of Aretaeus of Cappadocia (2nd or early 3rd century CE). He described the symptoms and the course of the disease, which he attributed to the moisture and coldness, reflecting the beliefs of the "Pneumatic School". He hypothesized a correlation between diabetes and other diseases, and he discussed differential diagnosis from the snakebite, which also provokes excessive thirst. His work remained unknown in the West until 1552, when the first Latin edition was published in Venice. +Two types of diabetes were identified as separate conditions for the first time by the Indian physicians Sushruta and Charaka in 400–500 CE with one type being associated with youth and another type with being overweight. Effective treatment was not developed until the early part of the 20th century when Canadians Frederick Banting and Charles Best isolated and purified insulin in 1921 and 1922. This was followed by the development of the long-acting insulin NPH in the 1940s. + + +=== Etymology === +The word diabetes ( or ) comes from Latin diabētēs, which in turn comes from Ancient Greek διαβήτης (diabētēs), which literally means "a passer through; a siphon". Ancient Greek physician Aretaeus of Cappadocia (fl. 2nd century CE) used that word, with the intended meaning "excessive discharge of urine", as the name for the disease. Ultimately, the word comes from Greek διαβαίνειν (diabainein), meaning "to pass through", which is composed of δια- (dia-), meaning "through" and βαίνειν (bainein), meaning "to go". The word "diabetes" is first recorded in English, in the form diabete, in a medical text written around 1425. +The word mellitus ( or ) comes from the classical Latin word mellītus, meaning "mellite" (i.e. sweetened with honey; honey-sweet). The Latin word comes from mell-, which comes from mel, meaning "honey"; sweetness; pleasant thing, and the suffix -ītus, whose meaning is the same as that of the English suffix "-ite". It was Thomas Willis who in 1675 added "mellitus" to the word "diabetes" as a designation for the disease, when he noticed the urine of a person with diabetes had a sweet taste (glycosuria). This sweet taste had been noticed in urine by the ancient Greeks, Chinese, Egyptians, and Indians. + + +== Society and culture == + +The 1989 "St. Vincent Declaration" was the result of international efforts to improve the care accorded to those with diabetes. Doing so is important not only in terms of quality of life and life expectancy but also economically – expenses due to diabetes have been shown to be a major drain on health – and productivity-related resources for healthcare systems and governments. +Several countries established more and less successful national diabetes programmes to improve treatment of the disease. + + +=== Diabetes stigma === +Diabetes stigma describes the negative attitudes, judgment, discrimination, or prejudice against people with diabetes. Often, the stigma stems from the idea that diabetes (particularly Type 2 diabetes) resulted from poor lifestyle and unhealthy food choices rather than other causal factors such as genetics and social determinants of health. Manifestation of stigma can be seen throughout different cultures and contexts. Scenarios include diabetes statuses affecting marriage proposals, workplace-employment, and social standing in communities. +Stigma is also seen internally, as people with diabetes can also have negative beliefs about themselves. Often these cases of self-stigma are associated with higher diabetes-specific distress, lower self-efficacy, higher rates of depression, and poorer provider-patient interactions during diabetes care. + + +=== Inequalities in Diabetes === + +Racial and ethnic minorities are disproportionately affected with higher prevalence of diabetes compared to non-minority individuals. While US adults overall have a 40% chance of developing type 2 diabetes, Hispanic/Latino adults chance is more than 50%. African Americans also are much more likely to be diagnosed with diabetes compared to White Americans. Asians have increased risk of diabetes as diabetes can develop at lower BMI due to differences in visceral fat compared to other races. For Asians, diabetes can develop at a younger age and lower body fat compared to other groups. Additionally, diabetes is highly underreported in Asian American people, as 1 in 3 cases are undiagnosed compared to the average 1 in 5 for the nation. +People with diabetes who have neuropathic symptoms such as numbness or tingling in feet or hands are twice as likely to be unemployed as those without the symptoms. +In 2010, diabetes-related emergency room (ER) visit rates in the United States were higher among people from the lowest income communities (526 per 10,000 population) than from the highest income communities (236 per 10,000 population). Approximately 9.4% of diabetes-related ER visits were for the uninsured. +Women also have worse experiences with diabetes and care for Diabetes than men do. Women experience more mental health issues, like eating disorders, spanning from diabetes. Women are also three times more likely to be housebound because of societal pressures put on people with diabetes. Overall, women seek out more medical help, while at the same time receiving less help than men who are the same race and economic class. Transgender people also struggle with diabetes care reporting less preferential treatment than people who are not trans. + + +=== Naming === +The term "type 1 diabetes" has replaced several former terms, including childhood-onset diabetes, juvenile diabetes, and insulin-dependent diabetes mellitus. Likewise, the term "type 2 diabetes" has replaced several former terms, including adult-onset diabetes, obesity-related diabetes, and noninsulin-dependent diabetes mellitus. Beyond these two types, there is no agreed-upon standard nomenclature. +Diabetes mellitus is also occasionally known as "sugar diabetes" to differentiate it from diabetes insipidus. Diabetes insipidus is an unrelated disease with symptoms that can mimic diabetes mellitus. + + +== Diabetes in other animals == + +Diabetes can occur in mammals or reptiles. Birds do not develop diabetes because of their unusually high tolerance for elevated blood glucose levels. There is some indication that amphibians have the ability to develop diabetes. +In animals, diabetes is most commonly encountered in dogs and cats. Middle-aged animals are most commonly affected. Female dogs are twice as likely to be affected as males, while according to some sources, male cats are more prone than females. In both species, all breeds may be affected, but some small dog breeds are particularly likely to develop diabetes, such as Miniature Poodles. +Feline diabetes is strikingly similar to human type 2 diabetes. The Burmese, Russian Blue, Abyssinian, and Norwegian Forest cat breeds are at higher risk than other breeds. Overweight cats are also at higher risk. +The symptoms may relate to fluid loss and polyuria, but the course may also be insidious. Diabetic animals are more prone to infections. The long-term complications recognized in humans are much rarer in animals. The principles of treatment (weight loss, oral antidiabetics, subcutaneous insulin) and management of emergencies (e.g. ketoacidosis) are similar to those in humans. + + +== See also == +Blood glucose monitoring +Diabetic foot +Outline of diabetes + + +== References == + + +== External links == + +American Diabetes Association +IDF Diabetes Atlas +National Diabetes Education Program +ADA's Standards of Medical Care in Diabetes 2019 +Polonsky KS (October 2012). "The past 200 years in diabetes". The New England Journal of Medicine. 367 (14): 1332–1340. doi:10.1056/NEJMra1110560. PMID 23034021. S2CID 9456681. +"Diabetes". MedlinePlus. U.S. National Library of Medicine. \ No newline at end of file diff --git a/lightrag/evaluation/wiki_documents/sports_fifa_world_cup.txt b/lightrag/evaluation/wiki_documents/sports_fifa_world_cup.txt new file mode 100644 index 00000000..f5327fe2 --- /dev/null +++ b/lightrag/evaluation/wiki_documents/sports_fifa_world_cup.txt @@ -0,0 +1,228 @@ +The FIFA World Cup, often called the World Cup, is an international association football competition among the senior men's national teams of the members of the Fédération Internationale de Football Association (FIFA), the sport's global governing body. The tournament has been held every four years since the inaugural tournament in 1930, with the exception of 1942 and 1946 due to the Second World War. The reigning champions are Argentina, who won their third title at the 2022 World Cup by defeating France. +The contest starts with the qualification phase, which takes place over the preceding three years to determine which teams qualify for the tournament phase. In the tournament phase, 32 teams compete for the title at venues within the host nation(s) over the course of about a month. The host nation(s) automatically qualify for the group stage of the tournament. The competition is scheduled to expand to 48 teams, starting with the 2026 World Cup. +As of the 2022 World Cup, 22 final tournaments have been held since the event's inception in 1930, and a total of 80 national teams have competed. The trophy has been won by eight national teams. With five wins, Brazil is the only team to have played in every tournament. The other World Cup winners are Germany and Italy, with four titles each; Argentina, with three titles; France and inaugural winner Uruguay, each with two titles; and England and Spain, with one title each. +The World Cup is globally regarded as the most prestigious association football competition, as well as the most widely viewed and followed sporting event in the world. The viewership of the 2018 World Cup was estimated to be 3.57 billion, close to half of the global population, while the engagement with the 2022 World Cup was estimated to be 5 billion, with about 1.5 billion people watching the final match. +Eighteen countries have hosted the World Cup, most recently Qatar, who hosted the 2022 event. The 2026 tournament will be jointly hosted by Canada, Mexico, and the United States, which will give Mexico the distinction of being the first country to host games in three World Cups. + + +== History == + + +=== Previous international competitions === +The world's first international football match was a challenge match played in Glasgow in 1872 between Scotland and England. The first international tournament for nations, the inaugural British Home Championship, took place in 1884 and included games between England, Scotland, Wales, and Ireland. As football grew in popularity in other parts of the world at the start of the 20th century, it was held as a demonstration sport with no medals awarded at the 1900 and 1904 Summer Olympics; however, the International Olympic Committee has retroactively upgraded their status to official events, as well as the 1906 Intercalated Games. +After FIFA was founded in 1904, it tried to arrange an international football tournament between nations outside the Olympic framework in Switzerland in 1906. These were very early days for international football, and the official history of FIFA describes the competition as having been unsuccessful. + +At the 1908 Summer Olympics in London, football became an official Olympic sport. Planned by the Football Association (the FA), England's football governing body, the event was for amateur players only and was regarded suspiciously as a show rather than a competition. Great Britain (represented by the England national amateur football team) won the gold medals. They repeated the feat at the 1912 Summer Olympics in Stockholm. +With the Olympic event continuing to be a contest between amateur teams only, Sir Thomas Lipton organised the Sir Thomas Lipton Trophy tournament in Turin in 1909. The Lipton tournament was a championship between individual clubs (not national teams) from different nations, each of which represented an entire nation. The competition is sometimes described as The First World Cup, and featured the most prestigious professional club sides from Italy, Germany and Switzerland, but the FA of England refused to be associated with the competition and declined the offer to send a professional team. Lipton invited West Auckland, an amateur side from County Durham, to represent England instead. West Auckland won the tournament and returned in 1911 to successfully defend their title. Prior to the Lipton competition, from 1876 to 1904, games that were considered to be the "football world championship" were meetings between leading English and Scottish clubs, such as the 1895 game between Sunderland A.F.C. and the Heart of Midlothian F.C., which Sunderland won. +In 1914, FIFA agreed to recognise the Olympic tournament as a "world football championship for amateurs", and took responsibility for managing the event. This paved the way for the world's first intercontinental football competition for nations, at the 1920 Summer Olympics, contested by Egypt and 13 European teams, and won by Belgium. Uruguay won the next two Olympic football tournaments in 1924 and 1928. Those were also the first two open world championships, as 1924 was the start of FIFA's professional era, and is the reason why Uruguay is allowed to wear 4 stars. + + +=== World Cups before World War II === + +Due to the success of the Olympic football tournaments, FIFA, with President Jules Rimet as the driving force, again started looking at staging its own international tournament outside of the Olympics. On 28 May 1928, the FIFA Congress in Amsterdam decided to stage a world championship. With Uruguay now two-time official football world champions and to celebrate their centenary of independence in 1930, FIFA named Uruguay as the host country of the inaugural World Cup tournament. +The national associations of selected nations were invited to send a team, but the choice of Uruguay as a venue for the competition meant a long and costly trip across the Atlantic Ocean for European sides, especially in the midst of the Great Depression. As such, no European country pledged to send a team until two months before the start of the competition. Rimet eventually persuaded teams from Belgium, France, Romania, and Yugoslavia to make the trip. In total, 13 nations took part: seven from South America, four from Europe, and two from North America. + +The first two World Cup matches took place simultaneously on 13 July 1930, and were won by France and the United States, who defeated Mexico 4–1 and Belgium 3–0 respectively. The first goal in World Cup history was scored by Lucien Laurent of France. In the final, Uruguay defeated Argentina 4–2 in front of 93,000 spectators in Montevideo, and became the first nation to win the World Cup. After the creation of the World Cup, FIFA and the IOC disagreed over the status of amateur players; football was dropped from the 1932 Summer Olympics. After the IOC and FIFA worked out their differences, Olympic football returned at the 1936 Summer Olympics, but was now overshadowed by the more prestigious World Cup. +The issues facing the early World Cup tournaments were the difficulties of intercontinental travel and war. Few South American teams were willing to travel to Europe for the 1934 World Cup and all North and South American nations except Brazil and Cuba boycotted the 1938 tournament. Brazil was the only South American team to compete in both. The 1942 and 1946 competitions, which Germany and Brazil sought to host, were cancelled due to World War II. + + +=== World Cups after World War II === + +The 1950 World Cup, held in Brazil, was the first to include British football associations. Scotland, England, Wales, and Northern Ireland had withdrawn from FIFA in 1920, partly out of unwillingness to play against the countries they had been at war with, and partly as a protest against foreign influence on football. The teams rejoined in 1946 following FIFA's invitation. The tournament also saw the return of 1930 champions Uruguay, who had boycotted the previous two World Cups. Uruguay won the tournament again after defeating the host nation Brazil, in the match called "Maracanazo" (Portuguese: Maracanaço). +In the tournaments between 1934 and 1978, 16 teams competed in each tournament, except in 1938, when Austria was absorbed into Germany after qualifying, leaving the tournament with 15 teams, and in 1950, when India, Scotland, and Turkey withdrew, leaving the tournament with 13 teams. Most of the participating nations were from Europe and South America, with a small minority from North America, Africa, Asia, and Oceania. These teams were usually defeated easily by the European and South American teams. Until 1982, the only teams from outside Europe and South America to advance out of the first round were: United States, semi-finalists in 1930; Cuba, quarter-finalists in 1938; North Korea, quarter-finalists in 1966; and Mexico, quarter-finalists in 1970. + + +=== Expansion to 24 and 32 teams === + +The tournament was expanded to 24 teams in 1982, and then to 32 in 1998, allowing more teams from Africa, Asia and North America to take part. Since then, teams from these regions have enjoyed more success, with several having reached the quarter-finals: Mexico, quarter-finalists in 1986; Cameroon, quarter-finalists in 1990; South Korea, finishing in fourth place in 2002; Senegal, along with USA, both quarter-finalists in 2002; Ghana, quarter-finalists in 2010; Costa Rica, quarter-finalists in 2014; and Morocco, finishing in fourth place in 2022. European and South American teams continue to dominate, e.g., the quarter-finalists in 1994, 1998, 2006 and 2018 were all from Europe or South America and so were the finalists of all tournaments so far. +Two hundred teams entered the 2002 FIFA World Cup qualification rounds. 198 nations attempted to qualify for the 2006 FIFA World Cup. A record 204 countries entered qualification for the 2010 FIFA World Cup. + + +=== Expansion to 48 teams === +In October 2013, Sepp Blatter spoke of guaranteeing the Caribbean Football Union's region a position in the World Cup. In the edition of 25 October 2013 of the FIFA Weekly Blatter wrote that: "From a purely sporting perspective, I would like to see globalisation finally taken seriously, and the African and Asian national associations accorded the status they deserve at the FIFA World Cup. It cannot be that the European and South American confederations lay claim to the majority of the berths at the World Cup." Those two remarks suggested to commentators that Blatter could be putting himself forward for re-election to the FIFA Presidency. +Following the magazine's publication, Blatter's would-be opponent for the FIFA Presidency, UEFA President Michel Platini, responded that he intended to extend the World Cup to 40 national associations, increasing the number of participants by eight. Platini said that he would allocate an additional berth to UEFA, two each to the Asian Football Confederation and the Confederation of African Football, two shared between CONCACAF and CONMEBOL, and a guaranteed place for the Oceania Football Confederation. Platini was clear about why he wanted to expand the World Cup. He said: "[The World Cup is] not based on the quality of the teams because you don't have the best 32 at the World Cup ... but it's a good compromise. ... It's a political matter so why not have more Africans? The competition is to bring all the people of all the world. If you don't give the possibility to participate, they don't improve." +In October 2016, FIFA president Gianni Infantino stated his support for a 48-team World Cup in 2026. On 10 January 2017, FIFA confirmed the 2026 World Cup will have 48 finalist teams. + + +=== 2015 FIFA corruption case === + +By May 2015, the games were under a particularly dark cloud because of the 2015 FIFA corruption case, allegations and criminal charges of bribery, fraud and money laundering to corrupt the issuing of media and marketing rights (rigged bids) for FIFA games, with FIFA officials accused of taking bribes totaling more than $150 million over 24 years. In late May, the U.S. Department of Justice announced a 47-count indictment with charges of racketeering, wire fraud and money laundering conspiracy against 14 people. Arrests of over a dozen FIFA officials were made since that time, particularly on 29 May and 3 December. By the end of May 2015, a total of nine FIFA officials and five executives of sports and broadcasting markets had already been charged on corruption. At the time, FIFA president Sepp Blatter announced he would relinquish his position in February 2016. +On 4 June 2015, Chuck Blazer while co-operating with the FBI and the Swiss authorities admitted that he and the other members of FIFA's then-executive committee were bribed in order to promote the 1998 and 2010 World Cups. On 10 June 2015, Swiss authorities seized computer data from the offices of Sepp Blatter. The same day, FIFA postponed the bidding process for the 2026 FIFA World Cup in light of the allegations surrounding bribery in the awarding of the 2018 and 2022 tournaments. Then-secretary general Jérôme Valcke stated, "Due to the situation, I think it's nonsense to start any bidding process for the time being." On 28 October 2015, Blatter and FIFA VP Michel Platini, a potential candidate for presidency, were suspended for 90 days; both maintained their innocence in statements made to the news media. +On 3 December 2015 two FIFA vice-presidents were arrested on suspicion of bribery in the same Zurich hotel where seven FIFA officials had been arrested in May. An additional 16 indictments by the US Department of Justice were announced on the same day. + + +=== Biennial World Cup proposition === +A biennial World Cup plan was first proposed by the Saudi Arabian Football Federation at the 71st FIFA Congress on 21 May 2021 and prominently backed by former Arsenal manager Arsène Wenger and national federations in Africa and Asia. +Continental confederations such as UEFA and CONMEBOL are not on board with the plan but, in total, the idea is supported by 166 of the 210 member associations of FIFA. + + +=== Other FIFA tournaments === + +An equivalent tournament for women's football, the FIFA Women's World Cup, was first held in 1991 in China. The women's tournament is smaller in scale and profile than the men's, but is growing; the number of entrants for the 2007 tournament was 120, more than double that of 1991. +Men's football has been included in every Summer Olympic Games except 1896 and 1932. Unlike many other sports, the men's football tournament at the Olympics is not a top-level tournament, and since 1992, an under-23 tournament with each team allowed three over-age players. Women's football made its Olympic debut in 1996. +The FIFA Confederations Cup was a tournament held one year before the World Cup at the World Cup host nation(s) as a dress rehearsal for the upcoming World Cup. It is contested by the winners of each of the six FIFA confederation championships, along with the FIFA World Cup champion and the host country. The first edition took place in 1992 and the last edition was played in 2017. In March 2019, FIFA confirmed that the tournament would no longer be active owing to an expansion of the FIFA Club World Cup in 2021. +FIFA also organises international tournaments for youth football (FIFA U-20 World Cup, FIFA U-17 World Cup, FIFA U-20 Women's World Cup, FIFA U-17 Women's World Cup), club football (FIFA Club World Cup), and football variants such as futsal (FIFA Futsal World Cup) and beach soccer (FIFA Beach Soccer World Cup). The latter three do not have a women's version, although a FIFA Women's Club World Cup has been proposed. +The FIFA U-20 Women's World Cup is held biannually, including the year before each Women's World Cup. Both tournaments were awarded in a single bidding process on three occasions, with the U-20 tournament serving as a dress rehearsal for the larger competition each time (2010, 2014 and 2018). + + +== Trophy == + +From 1930 to 1970, the Jules Rimet Trophy was awarded to the World Cup winning team. It was originally simply known as the World Cup or Coupe du Monde, but in 1946 it was renamed after the FIFA president Jules Rimet who set up the first tournament. In 1970, Brazil's third victory in the tournament entitled them to keep the trophy permanently. However, the trophy was stolen in 1983 and has never been recovered, apparently melted down by the thieves. +After 1970, a new trophy, known as the FIFA World Cup Trophy, was designed. The experts of FIFA, coming from seven countries, evaluated the 53 presented models, finally opting for the work of the Italian designer Silvio Gazzaniga. The new trophy is 36 cm (14.2 in) high, made of solid 18 carat (75%) gold and weighs 6.175 kg (13.6 lb). +The base contains two layers of semi-precious malachite while the bottom side of the trophy bears the engraved year and name of each FIFA World Cup winner since 1974. The description of the trophy by Gazzaniga was: "The lines spring out from the base, rising in spirals, stretching out to receive the world. From the remarkable dynamic tensions of the compact body of the sculpture rise the figures of two athletes at the stirring moment of victory." +This new trophy is not awarded to the winning nation permanently. World Cup winners retain the trophy only until the post-match celebration is finished. They are awarded a gold-plated replica rather than the solid gold original immediately afterwards. +All members (players, coaches, and managers) of the top three teams receive medals with an insignia of the World Cup Trophy; winners' (gold), runners-up' (silver), and third-place (bronze). In the 2002 edition, fourth-place medals were awarded to hosts South Korea. Before the 1978 tournament, medals were only awarded to the eleven players on the pitch at the end of the final and the third-place match. In November 2007, FIFA announced that all members of World Cup-winning squads between 1930 and 1974 were to be retroactively awarded winners' medals. +Since 2006, winners of the competition are also awarded the right to wear the FIFA Champions Badge, up until the time at which the winner of the next competition is decided. + + +== Format == + + +=== Qualification === + +Since the second World Cup in 1934, qualifying tournaments have been held to thin the field for the final tournament. They are held within the six FIFA continental zones (Africa, Asia, North and Central America and Caribbean, South America, Oceania, and Europe), overseen by their respective confederations. For each tournament, FIFA decides the number of places awarded to each of the continental zones beforehand, generally based on the relative strength of the confederations' teams. +The qualification process can start as early as almost three years before the final tournament and last over a two-year period. The formats of the qualification tournaments differ between confederations. Usually, one or two places are awarded to winners of intercontinental play-offs. For example, the winner of the Oceanian zone and the fifth-placed team from the Asian zone entered a play-off for a spot in the 2010 World Cup. From the 1938 World Cup onwards, host nations receive automatic qualification to the final tournament. This right was also granted to the defending champions between 1938 and 2002, but was withdrawn from the 2006 FIFA World Cup onward, requiring the champions to qualify, as previous defending champions had uncompetitive performances at subsequent editions of the FIFA World Cup. Brazil, winners in 2002, were the first defending champions to play qualifying matches. + + +=== Final tournament === + +The final tournament format since 1998 has had 32 national teams competing over the course of a month in the host nations. There are two stages: the group stage, followed by the knockout stage. +In the group stage, teams compete within eight groups of four teams each. Eight teams are seeded, including the hosts, with the other seeded teams selected using a formula based on the FIFA World Rankings or performances in recent World Cups, and drawn to separate groups. The other teams are assigned to different "pots", usually based on geographical criteria, and teams in each pot are drawn at random to the eight groups. Since 1998, constraints have been applied to the draw to ensure that no group contains more than two European teams or more than one team from any other confederation. +Each group plays a round-robin tournament in which each team is scheduled for three matches against other teams in the same group. This means that a total of six matches are played within a group. The last round of matches of each group is scheduled at the same time to preserve fairness among all four teams. The top two teams from each group advance to the knockout stage. Points are used to rank the teams within a group. Since 1994, three points have been awarded for a win, one for a draw and none for a loss (before, winners received two points). +Considering six matches in a group each with three possible outcomes (win, draw, loss), there are 729 (= 36) possible final table outcomes for the 40 possible combinations of the four teams' points. However, 14 of the 40 points combinations (or 207 of the 729 possible outcomes) lead to ties between the second and third places. In such case, the ranking among these teams is determined by: + +Greatest combined goal difference in all group matches +Greatest combined number of goals scored in all group matches +If more than one team remain level after applying the above criteria, their ranking will be determined as follows: +Greatest number of points in head-to-head matches among those teams +Greatest goal difference in head-to-head matches among those teams +Greatest number of goals scored in head-to-head matches among those teams +Fair play points, defined by the number of yellow and red cards received in the group stage: +Yellow card: minus 1 point +Indirect red card (as a result of a second yellow card): minus 3 points +Direct red card: minus 4 points +Yellow card and direct red card: minus 5 points +If any of the teams above remain level after applying the above criteria, their ranking will be determined by the drawing of lots +The knockout stage is a single-elimination tournament in which teams play each other in one-off matches, with extra time and penalty shootouts used to decide the winner if necessary. It begins with the round of 16 (or the second round) in which the winner of each group plays against the runner-up of another group. This is followed by the quarter-finals, the semi-finals, the third-place match (contested by the losing semi-finalists), and the final. +On 10 January 2017, FIFA approved a new format, the 48-team World Cup (to accommodate more teams), which was to consist of 16 groups of three teams each, with two teams qualifying from each group, to form a round of 32 knockout stage, to be implemented by 2026. On 14 March 2023, FIFA approved a revised format of the 2026 tournament, which features 12 groups of four teams each, with the top 8 third-placed teams joining the group winners and runners-up in a new round of 32. +In March 2025, it was reported that FIFA was considering an one-off expansion to 64 teams for the 2030 FIFA World Cup, the centennial anniversary of the FIFA World Cup. + + +== Hosts == + + +=== Selection process === + +Early World Cups were given to countries at meetings of FIFA's congress. The locations were controversial because South America and Europe were by far the two centres of strength in football and travel between them required three weeks by boat. The decision to hold the first World Cup in Uruguay, for example, led to only four European nations competing. The next two World Cups were both held in Europe. The decision to hold the second of these in France was disputed, as the South American countries understood that the location would alternate between the two continents. Both Argentina and Uruguay thus boycotted the 1938 FIFA World Cup. +Since the 1958 FIFA World Cup, to avoid future boycotts or controversy, FIFA began a pattern of alternating the hosts between the Americas and Europe, which continued until the 1998 FIFA World Cup. The 2002 FIFA World Cup, hosted jointly by South Korea and Japan, was the first one held in Asia, and the first tournament with multiple hosts. South Africa became the first African nation to host the World Cup in 2010. The 2014 FIFA World Cup was hosted by Brazil, the first held in South America since Argentina 1978, and was the first occasion where consecutive World Cups were held outside Europe. + +The host country is now chosen in a vote by FIFA's Council. This is done under an exhaustive ballot system. The national football association of a country desiring to host the event receives a "Hosting Agreement" from FIFA, which explains the steps and requirements that are expected from a strong bid. The bidding association also receives a form, the submission of which represents the official confirmation of the candidacy. After this, a FIFA designated group of inspectors visit the country to identify that the country meets the requirements needed to host the event and a report on the country is produced. The decision on who will host the World Cup is usually made six or seven years in advance of the tournament. There have been occasions where the hosts of multiple future tournaments were announced at the same time, as was the case for the 2018 and 2022 World Cups, which were awarded to Russia and Qatar, with Qatar becoming the first Middle Eastern country to host the tournament. +For the 2010 and 2014 World Cups, the final tournament was rotated between confederations, allowing only countries from the chosen confederation (Africa in 2010, South America in 2014) to bid to host the tournament. The rotation policy was introduced after the controversy surrounding Germany's victory over South Africa in the vote to host the 2006 tournament. However, the policy of continental rotation did not continue beyond 2014, so any country, except those belonging to confederations that hosted the two preceding tournaments, can apply as hosts for World Cups starting from 2018. This is partly to avoid a similar scenario to the bidding process for the 2014 tournament, where Brazil was the only official bidder. +The 2026 FIFA World Cup was chosen to be held in the United States, Canada and Mexico, marking the first time a World Cup has been shared by three host nations. The 2026 tournament will be the biggest World Cup ever held, with 48 teams playing 104 matches. Sixty matches will take place in the US, including all matches from the quarter-finals onward, while Canada and Mexico will host 10 games each. + + +=== Summary by confederation === + + +=== Performances === + +Six of the eight champions have won one of their titles while playing in their own homeland, the exceptions being Brazil, who finished as runners-up after losing the deciding match on home soil in 1950 and lost their semi-final against Germany in 2014, and Spain, which reached the second round on home soil in 1982. England (1966) won its only title while playing as a host nation. Uruguay (1930), Italy (1934), Argentina (1978), and France (1998) won their first titles as host nations but have gone on to win again, while Germany (1974) won their second title on home soil. +Other nations have also been successful when hosting the tournament. Switzerland (quarter-finals 1954), Sweden (runners-up in 1958), Chile (third place in 1962), South Korea (fourth place in 2002), Russia (quarter-finals 2018), and Mexico (quarter-finals in 1970 and 1986) all have their best results when serving as hosts. So far, South Africa (2010) and Qatar (2022) failed to advance beyond the first round. + + +== Broadcasting and promotion == + +The World Cup was first televised in 1954 and as of 2006 is the most widely viewed and followed sporting event in the world. The cumulative viewership of all matches of the 2006 World Cup was estimated to be 26.29 billion. 715.1 million individuals watched the final match of the tournament, almost a ninth of the entire population of the planet. The 2006 World Cup draw, which decided the distribution of teams into groups, was watched by 300 million viewers. The World Cup attracts major sponsors such as Coca-Cola, McDonald's and Adidas. For these companies and many more, being a sponsor strongly impacts their global brands. Host countries typically experience a multimillion-dollar revenue increase from the month-long event. +The governing body of the sport, FIFA, generated $4.8 billion in revenue from the 2014 tournament, and $6.1 billion from the 2018 tournament. + +Each FIFA World Cup since 1966 has its own mascot or logo. World Cup Willie, the mascot for the 1966 competition, was the first World Cup mascot. World Cups feature official match balls specially designed for each tournament. After Slazenger produced the ball for the 1966 World Cup, Adidas became the official supplier to FIFA. Each World Cup also has an official song, which have been performed by artists ranging from Shakira to Will Smith. Other songs, such as "Nessun dorma", performed by The Three Tenors at four World Cup concerts, have also become identified with the tournament. + +Forming a partnership with FIFA in 1970, Panini published its first sticker album for the 1970 World Cup. Since then, collecting and trading stickers and cards has become part of the World Cup experience, especially for the younger generation. FIFA has licensed World Cup video games since 1986, sponsored by Electronic Arts. + + +== Results == + +Key +a.e.t.: result/match won after extra time +p: match won after penalty shoot-out + +Notes + +In all, 80 nations have played in at least one World Cup. Of these, eight national teams have won the World Cup, and they have added stars to their badges, with each star representing a World Cup victory. Uruguay, however, chose to display four stars on their badge, representing their two gold medals at the 1924 and 1928 Summer Olympics, which are recognized by FIFA as World Championships, and their two World Cup titles in 1930 and 1950. +With five titles, Brazil are the most successful World Cup team and also the only nation to have played in every World Cup (22) to date. Brazil were also the first team to win the World Cup for the third (1970), fourth (1994) and fifth (2002) time. Italy (1934 and 1938) and Brazil (1958 and 1962) are the only nations to have won consecutive titles. West Germany (1982–1990) and Brazil (1994–2002) are the only nations to appear in three consecutive World Cup finals. Germany has made the most top-four finishes (13), medals (12), as well as the most finals (8). + + +=== Teams reaching the top four === + + +=== Best performances by confederations === + +To date, the final of the World Cup has only been contested by teams from the UEFA (Europe) and CONMEBOL (South America) confederations. European nations have won twelve titles, while South American nations have won ten. Only three teams from outside these two continents have ever reached the semi-finals of the competition: United States (North, Central America and Caribbean) in 1930; South Korea (Asia) in 2002; and Morocco (Africa) in 2022. Only one Oceanian qualifier, Australia in 2006, has advanced to the second round, a feat they later reaccomplished in 2022. +Brazil, Argentina, Spain and Germany are the only teams to win a World Cup hosted outside their continental confederation; Brazil came out victorious in Europe (1958), North America (1970 and 1994) and Asia (2002). Argentina won a World Cup in North America in 1986 and in Asia in 2022. Spain won in Africa in 2010. In 2014, Germany became the first and so far the only European team to win in the Americas. Only on five occasions have consecutive World Cups been won by teams from the same continent; the longest streak of tournaments won by a single confederation is four, with the 2006, 2010, 2014, and 2018 tournaments all won by UEFA teams (Italy, Spain, Germany, and France, respectively). + + +== Records and statistics == + +Six players share the record for playing in the most World Cups; Mexico's Antonio Carbajal (1950–1966). Rafael Márquez (2002–2018), and Andrés Guardado (2006–2022); Germany's Lothar Matthäus (1982–1998); Argentina's Lionel Messi (2006–2022); and Portugal's Cristiano Ronaldo (2006–2022) all played in five tournaments, with Ronaldo also being the first and only player to score in five tournaments. Messi has played the most World Cup matches overall, with 26 appearances. Brazil's Djalma Santos (1954–1962), West Germany's Franz Beckenbauer (1966–1974), and Germany's Philipp Lahm (2006–2014) are the only players to be named to three World Cup All-Star Teams. +Miroslav Klose of Germany (2002–2014) is the all-time top scorer at the World Cup with 16 goals. He broke Ronaldo of Brazil's record of 15 goals (1998–2006) during the 2014 semi-final match against Brazil. West Germany's Gerd Müller (1970–1974) is third, with 14 goals. The fourth-placed goalscorer, France's Just Fontaine, holds the record for the most goals scored in a single World Cup; all his 13 goals were scored in the 1958 tournament. + +In November 2007, FIFA announced that all members of World Cup-winning squads between 1930 and 1974 were to be retroactively awarded winners' medals. This made Brazil's Pelé the only player to have won three World Cup winners' medals (1958, 1962, and 1970, although he did not play in the 1962 final due to injury), with 20 other players who have won two winners' medals. Seven players have collected all three types of World Cup medals (winners', runner- ups', and third-place); five players were from West Germany's squad of 1966–1974: Franz Beckenbauer, Jürgen Grabowski, Horst-Dieter Höttges, Sepp Maier, and Wolfgang Overath (1966–1974), Italy's Franco Baresi (1982, 1990, 1994) and the most recent has been Miroslav Klose of Germany (2002–2014) with four consecutive medals. +Brazil's Mário Zagallo, West Germany's Franz Beckenbauer and France's Didier Deschamps are the only people to date to win the World Cup as both player and head coach. Zagallo won in 1958 and 1962 as a player and in 1970 as head coach. Beckenbauer won in 1974 as captain and in 1990 as head coach, and Deschamps repeated the feat in 2018, after having won in 1998 as captain. Italy's Vittorio Pozzo is the only head coach to ever win two World Cups (1934 and 1938). All World Cup-winning head coaches were natives of the country they coached to victory. +Among the national teams, Brazil has played the most World Cup matches (114), Germany appeared in the most finals (8), semi-finals (13), and quarter-finals (16), while Brazil has appeared in the most World Cups (22), has the most wins (76) and has scored the most goals (237). The two teams have played each other twice in the World Cup, in the 2002 final and in the 2014 semi-final. + + +=== Top goalscorers === + +Individual +Players in bold are still active. + +Country + + +== Awards == + +At the end of each World Cup, awards are presented to the players and teams for accomplishments other than their final team positions in the tournament. + +There are five post-tournament awards from the FIFA Technical Study Group: + +the Golden Ball (named for its sponsor "Adidas Golden Ball") for best player, first awarded in 1982; +the Golden Boot (named for its sponsor "Adidas Golden Boot", formerly known as the "adidas Golden Shoe" from 1982 to 2006) for top goalscorer, first awarded in 1982; +the Golden Glove (named for its sponsor "Adidas Golden Glove", formerly known as the "Lev Yashin Award" from 1994 to 2006) for best goalkeeper, first awarded in 1994; +the FIFA Young Player Award (formerly known as the "Best Young Player Award" from 2006 to 2010) for best player under 21 years of age at the start of the calendar year, first awarded in 2006; +the FIFA Fair Play Trophy for the team that advanced to the second round with the best record of fair play, first awarded in 1970. +There is currently one award voted on by fans during the tournament.: +the Player of the Match (currently commercially termed "Budweiser Player of the Match", formerly known as the "Man of the Match" from 2002 to 2018) for outstanding performance during each match of the tournament, first awarded in 2002. +There are two awards voted on by fans after the conclusion of the tournament: +the Goal of the Tournament, (currently commercially termed "Hyundai Goal of the Tournament") for the fans' best goal scored during the tournament, first awarded in 2006; +the Most Entertaining Team during the World Cup final tournament, as determined by a poll of the general public. +One other award was given between 1994 and 2006: +an All-Star Team comprising the best players of the tournament chosen by the FIFA Technical Study Group. From 2010 onwards, all Dream Teams or Statistical Teams are unofficial, as reported by FIFA itself. + + +== See also == + +List of FIFA World Cup finals +FIFA World Cup records and statistics +FIFA World Cup awards +FIFA U-20 World Cup +FIFA U-17 World Cup +FIFA Club World Cup +FIFA Beach Soccer World Cup +FIFA Futsal World Cup +FIFA Confederations Cup +List of association football competitions + + +== Notes == + + +== References == + + +== Bibliography == + + +== External links == + +Official website +World Cup overview at the RSSSF \ No newline at end of file diff --git a/lightrag/evaluation/wiki_test_dataset.json b/lightrag/evaluation/wiki_test_dataset.json new file mode 100644 index 00000000..a2b30eef --- /dev/null +++ b/lightrag/evaluation/wiki_test_dataset.json @@ -0,0 +1,49 @@ +{ + "test_cases": [ + { + "question": "What are the main causes of climate change?", + "ground_truth": "Climate change is primarily caused by human activities that release greenhouse gases into the atmosphere, including burning fossil fuels like coal, oil, and natural gas for energy, deforestation, industrial processes, and agriculture. These activities increase concentrations of carbon dioxide, methane, and other greenhouse gases that trap heat in Earth's atmosphere.", + "project": "wiki_evaluation" + }, + { + "question": "What are the different types of renewable energy sources?", + "ground_truth": "Renewable energy sources include solar energy from photovoltaic panels and solar thermal systems, wind energy from turbines, hydroelectric power from dams and flowing water, geothermal energy from Earth's internal heat, biomass energy from organic materials, and tidal/wave energy from ocean movements. These sources are sustainable because they naturally replenish and produce minimal greenhouse gas emissions.", + "project": "wiki_evaluation" + }, + { + "question": "How does Bitcoin and cryptocurrency work?", + "ground_truth": "Bitcoin and cryptocurrencies work using blockchain technology, a decentralized digital ledger that records all transactions across a network of computers. Transactions are verified through cryptographic protocols and consensus mechanisms like proof-of-work mining. Users have digital wallets with public and private keys to send and receive cryptocurrency. The decentralized nature means no central authority controls the currency.", + "project": "wiki_evaluation" + }, + { + "question": "What factors influence stock market prices?", + "ground_truth": "Stock market prices are influenced by multiple factors including company earnings and financial performance, economic indicators like GDP growth and unemployment rates, interest rates set by central banks, investor sentiment and market psychology, geopolitical events and global trade policies, industry trends and competition, and supply and demand dynamics. Technical analysis of trading patterns also affects short-term price movements.", + "project": "wiki_evaluation" + }, + { + "question": "What were the main symptoms and transmission methods of COVID-19?", + "ground_truth": "COVID-19 symptoms include fever, cough, fatigue, loss of taste or smell, shortness of breath, body aches, and in severe cases, pneumonia and respiratory failure. The virus primarily spreads through respiratory droplets and aerosols when infected people cough, sneeze, talk, or breathe. It can also spread through contaminated surfaces, though less commonly. Close contact in poorly ventilated spaces increases transmission risk.", + "project": "wiki_evaluation" + }, + { + "question": "What are the types and risk factors for diabetes?", + "ground_truth": "There are three main types of diabetes: Type 1 diabetes is an autoimmune condition where the body attacks insulin-producing cells, Type 2 diabetes occurs when the body becomes resistant to insulin or doesn't produce enough, and gestational diabetes develops during pregnancy. Risk factors include genetics, obesity, sedentary lifestyle, poor diet, age, and certain ethnicities. Management involves blood sugar monitoring, medication or insulin, diet, and exercise.", + "project": "wiki_evaluation" + }, + { + "question": "Which country has won the most FIFA World Cups?", + "ground_truth": "Brazil has won the most FIFA World Cup titles with 5 championships in 1958, 1962, 1970, 1994, and 2002. Germany and Italy have each won 4 titles. Argentina has won 3 World Cups including the most recent in 2022. France has won 2 titles. The FIFA World Cup is held every four years and is the most prestigious tournament in international football.", + "project": "wiki_evaluation" + }, + { + "question": "What is the history and significance of the Olympic Games?", + "ground_truth": "The Olympic Games originated in ancient Greece around 776 BC at Olympia and were held every four years as athletic competitions honoring Zeus. The modern Olympics were revived in 1896 by Pierre de Coubertin in Athens. Today, the Olympics include Summer and Winter Games alternating every two years, featuring thousands of athletes from over 200 nations competing in hundreds of events. The Games promote international cooperation, athletic excellence, and peaceful competition among nations.", + "project": "wiki_evaluation" + }, + { + "question": "What are the main applications and concerns about artificial intelligence?", + "ground_truth": "Artificial intelligence applications include machine learning for data analysis and predictions, natural language processing for chatbots and translation, computer vision for image recognition, autonomous vehicles, healthcare diagnostics, recommendation systems, and robotics. Key concerns include job displacement through automation, algorithmic bias and fairness, privacy and surveillance, AI safety and control, potential misuse in autonomous weapons, and ensuring AI systems align with human values.", + "project": "wiki_evaluation" + } + ] +}