The Earth Negotiations Bulletin (ENB) is a reporting service providing daily coverage on a variety of global environmental and sustainable development negotiations.
114-670: The team of environmental negotiations specialists document efforts by the United Nations, national governments, civil society organizations, and other actors to respond to pressing global challenges, such as climate change , biodiversity loss , land management, over pollution, widening inequality, chemicals and wastes management, trade in endangered species, deep sea mining , and ocean management. ENB publishes daily reports and summaries in print and online, distributing news through web, email, and social media feeds. Their outputs are also distributed at meeting venues during conferences of
228-574: A 60% surge in lost safe outdoor activity hours, with each person losing 2.2 hours on average each day. The study predicted that by the 2060s, annual heat wave-related mortality is expected to reach 29,000 to 38,000 in China, with a 28% to 37% increase in work hours lost. In July 2019, there were over 50 million people in the United States in jurisdictions with heat advisories. Scientists predicted that many records for highest low temperatures would be broken in
342-549: A broader sense also includes previous long-term changes to Earth's climate. The current rise in global temperatures is driven by human activities , especially fossil fuel 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
456-401: A contributing factor. The heat index in the table above is a measure of how hot it feels when relative humidity is factored with the actual air temperature. Excessive heat causes psychological stress as well as physical stress . This can affect performance. It may also lead to an increase in violent crime. High temperatures are associated with increased conflict between individuals and at
570-587: 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
684-451: A heat wave is five consecutive days at or above 35 °C (95 °F), or three consecutive days at or over 40 °C (104 °F). The Australian Bureau of Meteorology defines a heat wave as three or more days of unusual maximum and minimum temperatures. Before this new Pilot Heatwave Forecast there was no national definition for heat waves or measures of heat wave severity. It is possible to compare heat waves in different regions of
798-511: A heat wave occurs when there are at least three days above 25 °C (77 °F) across much of the country. Greater London has a threshold of 28 °C (82 °F). In the United States, definitions also vary by region. They usually involve a period of at least two or more days of excessively hot weather. In the Northeast , a heat wave is typically when the temperature reaches or exceeds 90 °F (32.2 °C) for three consecutive days. This
912-409: A late rain season scorched tea leaves and reduced yields. Once the body temperature of livestock animals is 3–4 °C (5.4–7.2 °F) above normal, this soon leads to " heat stroke , heat exhaustion, heat syncope , heat cramps , and ultimately organ dysfunction ". Livestock mortality rates are already known to be higher during the hottest months of the year, as well as during heatwaves . During
1026-420: A limited way. Heat waves cause roads and highways to buckle and melt, water lines to burst, and power transformers to detonate, causing fires. A heat wave can also damage railways, by buckling and kinking rails. This can slow down or delay traffic. It can even lead to cancellations of service when rails are too dangerous to traverse by trains. Heat waves often lead to spikes in electricity demand because there
1140-532: 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
1254-412: A marked increase in temperature. Ongoing changes in climate have had no precedent for several thousand years. Multiple independent 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
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#17328910342341368-426: A number of complex feedback mechanisms. These in turn can result in increased surface temperatures. One of the main mechanisms is reduced evaporative cooling of the atmosphere. When water evaporates, it consumes energy. So, it will lower the surrounding temperature. If the soil is very dry, then incoming radiation from the sun will warm the air. But there will be little or no cooling effect from moisture evaporating from
1482-408: 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
1596-457: 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
1710-550: A result of the 2003 European heat wave . Also more than 2,000 people died in Karachi , Pakistan in June 2015 due to a severe heat wave with temperatures as high as 49 °C (120 °F). The number of heat fatalities is probably highly underreported. This is due to a lack of reports and to misreporting. When considering heat-related illnesses as well, actual death tolls from extreme heat may be six times higher than official figures. This
1824-474: 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
1938-701: A severe and long heat wave has impacted India . The heat wave occurred during the Indian dry season , which typically lasts from March to July with peak temperatures in April and May. Rajasthan 's Churu recorded 50.5 °C (122.9 °F), which was the highest temperature in India in eight years. Since April 2024, several Southeast Asian countries have experienced record-breaking temperatures which have left several people dead. Heat indices peaked at 53 °C (127 °F) in Iba in
2052-417: 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 2023 the warmest on record at +1.48 °C (2.66 °F) since regular tracking began in 1850. Additional warming will increase these impacts and can trigger tipping points , such as melting all of
2166-898: A spectrum of disorders due to increased body temperature. It can be caused by either environmental conditions or by exertion . It includes minor conditions such as heat cramps, heat syncope, and heat exhaustion as well as the more severe condition known as heat stroke. It can affect any or all anatomical systems. Heat illnesses include: heat stroke , heat exhaustion , heat syncope , heat edema , heat cramps , heat rash , heat tetany . Exposure to extreme heat poses an acute health hazard, especially for people deemed as vulnerable. Vulnerable people with regard to heat illnesses include people with low incomes, minority groups, women (in particular pregnant women), children, older adults (over 65 years old), people with chronic diseases, disabilities and multiple long-term health conditions . Other people at risk include those living in urban environments (due to
2280-538: 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
2394-519: A warming level of 2 °C. Higher atmospheric CO 2 concentrations cause more CO 2 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. 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,
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#17328910342342508-501: Is a period of abnormally hot weather, usually more than 5 days. Definitions vary but are similar. A heat wave is usually measured relative to the usual climate in the area and to normal temperatures for the season. Temperatures that humans from a hotter climate consider normal, can be regarded as a heat wave in a cooler area. This would be the case if the warm temperatures are outside the normal climate pattern for that area. High humidity often occurs during heat waves as well. This
2622-521: Is able to carry more moisture, heatwaves may be followed by extreme rainfall especially in mid-latitude regions. For example, the record-breaking heat wave that afflicted Pakistan beginning in May 2022 led to glacier melt and moisture flow. These were factors in the devastating floods that began in June and claimed over 1,100 lives. Researchers have predicted that roughly 10-40% of all land vertebrate species will be affected by heat waves by 2099, depending on
2736-557: Is an estimated total sea level rise of 2.3 metres per degree Celsius (4.2 ft/°F) after 2000 years. Oceanic CO 2 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
2850-425: Is based on studies of California and Japan. Part of the mortality during a heat wave may be due to short-term forward mortality displacement . In some heat waves there is a decrease in overall mortality in the weeks after a heat wave. These compensatory reductions in mortality suggest that heat affects people who would have died anyway, and brings their deaths forward. Social institutions and structures influence
2964-533: Is common in summer in both the Northern and Southern Hemispheres. This is because the jet stream 'follows the sun'. The high pressure area is on the equator side of the jet stream in the upper layers of the atmosphere. Weather patterns are generally slower to change in summer than in winter. So, this upper level high pressure also moves slowly. Under high pressure, the air sinks toward the surface. It warms and dries adiabatically . This inhibits convection and prevents
3078-711: Is determined by modelling the carbon cycle and climate sensitivity to greenhouse gases. According to UNEP , global warming can be kept below 1.5 °C with a 50% chance if emissions after 2023 do not exceed 200 gigatonnes of CO 2 . This corresponds to around 4 years of current emissions. To stay under 2.0 °C, the carbon budget is 900 gigatonnes of CO 2 , or 16 years of current emissions. 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
3192-414: Is especially the case in oceanic climate countries. Heat waves have become more frequent, and more intense over land, across almost every area on Earth since the 1950s, the increase in frequency and duration being caused by climate change . Heat waves form when a high-pressure area in the upper atmosphere strengthens and remains over a region for several days up to several weeks. This traps heat near
3306-399: 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
3420-457: Is more use of air conditioning. This can create power outages, making the problem worse. During the 2006 North American heat wave , thousands of homes and businesses went without power, especially in California. In Los Angeles, electrical transformers failed, leaving thousands without power for as long as five days. The early 2009 southeastern Australia heat wave caused major power disruptions in
3534-562: Is not always the case. This is because the high temperature ties in with humidity levels to determine a heat index threshold. The same does not apply to drier climates. A heat storm is a Californian term for an extended heat wave. Heat storms occur when the temperature reaches 100 °F (37.8 °C) for three or more consecutive days over a wide area (tens of thousands of square miles). The National Weather Service issues heat advisories and excessive heat warnings when it expects unusual periods of hot weather. In Adelaide, South Australia,
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3648-497: Is not suitable for extreme heat. In 2016, a marine heatwave in Chile and its subsequent harmful algal bloom caused $ 800 million (USD) in export losses for the aquaculture industry as salmon and shellfish died off. Heat waves are a big threat to agricultural production. In 2019 heat waves in the Mulanje region of Malawi involved temperatures as high as 40 °C (104 °F). This and
3762-450: 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
3876-444: 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. Different regions of the world warm at different rates . The pattern
3990-516: 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 effect of clouds. 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
4104-407: Is the major reason why different climate models project different magnitudes of warming for a given amount of emissions. 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
4218-607: Is to set up air-conditioned public cooling centres. Adding air conditioning in schools provides a cooler work place. But it can result in additional greenhouse gas emissions unless solar energy is used. Policymakers, funders and researchers have created the Extreme Heat Resilience Alliance coalition under the Atlantic Council . This advocates for naming heat waves, measuring them, and ranking them to build better awareness of their impacts. Since May 2024,
4332-417: 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
4446-497: The 2003 European heat wave , for instance, thousands of pigs, poultry, and rabbits died in the French regions of Brittany and Pays-de-la-Loire alone. Livestock can also suffer multiple sublethal impacts from heat stress, such as reduced milk production. Once the temperatures exceed 30 °C (86 °F), cattle, sheep, goats, pigs and chickens all begin to consume 3–5% less feed for each subsequent degree of temperature increase. At
4560-507: 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 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 CO 2 's long atmospheric lifetime. The result
4674-657: 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
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4788-568: 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
4902-835: 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. Limiting warming to 1.5 °C would require halving emissions by 2030 and achieving net-zero emissions by 2050. Fossil fuel use can be phased out by 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
5016-514: The Hellenic National Meteorological Service defines a heat wave as occurring over three consecutive days with temperatures at 39 °C (102 °F) or higher. In the same period the minimum temperature is 26 °C (79 °F) or more. During this period, there are either no winds or only weak winds. These conditions occur in a broad area. The Netherlands defines a heat wave as a period of at least five consecutive days in which
5130-626: 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 CO 2 and methane had increased by about 50% and 164%, respectively, since 1750. These CO 2 levels are higher than they have been at any time during
5244-501: The International Hydropower Association World Congress on Sustainable Hydropower, and special-interest days within larger conferences, such as "Business Day" during UN Climate Change conferences. Climate change Present-day climate change includes both global warming —the ongoing increase in global average temperature —and its wider effects on Earth's climate . Climate change in
5358-459: The Philippines on 28 April 2024. The heat wave has been attributed to a combination of causes, including climate change and El Niño . A study found the average resident in China was exposed to 16 days of heat waves in 2023, with more than 37,000 heat wave-related deaths. Besides, the number of work hours lost due to heat stress in China was 36.9 billion in 2023, and China’s citizens experienced
5472-509: 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
5586-414: The carbon cycle . While plants on land and in the ocean absorb most excess emissions of CO 2 every year, that CO 2 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 CO 2 emissions. The ocean has absorbed 20 to 30% of emitted CO 2 over
5700-402: 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
5814-971: 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. The effects of climate change are impacting humans everywhere in
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#17328910342345928-432: The socioeconomic scenario and the mitigation scenario, models produce atmospheric CO 2 concentrations that range widely between 380 and 1400 ppm. 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
6042-427: The urban heat island effect ), outdoor workers and people who take certain prescription drugs . Health experts warn that "exposure to extreme heat increases the risk of death from cardiovascular , cerebrovascular , and respiratory conditions and all-cause mortality. Heat-related deaths in people older than 65 years reached a record high of an estimated 345 000 deaths in 2019". More than 70,000 Europeans died as
6156-405: 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
6270-551: 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. Frequency of tropical cyclones has not increased as
6384-500: The 1980s, the terms global warming and climate change became more common, often being used interchangeably. Scientifically, global warming refers only to increased surface warming, 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
6498-440: 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
6612-435: 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 CO 2 into the atmosphere. Around half of human-caused CO 2 emissions have been absorbed by land plants and by the oceans. This fraction is not static and if future CO 2 emissions decrease,
6726-542: The CO 2 released by the chemical reactions for making cement , steel , aluminum , 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, CO 2 lasts much longer. The Earth's surface absorbs CO 2 as part of
6840-547: The Canadian Participatory Committee for UNCED, Pamela Chasek , a doctoral student at Johns Hopkins University's Paul H. Nitze School of Advanced International Studies , and Langston James Goree VI "Kimo", a former UNDP programme officer and NGO activist from the Western Amazon. The International Institute for Sustainable Development (IISD) approached the three founders with an offer to continue publishing
6954-632: The Earth Summit Bulletin at follow-up negotiations to the Earth Summit. In November 1992, the Earth Summit Bulletin was renamed the Earth Negotiations Bulletin. Since 1993, the Earth Negotiations Bulletin has covered over 30 negotiating processes within the United Nations system. Many writers join the team while in graduate school and eventually move on to careers in international organizations. Conversely, retired career diplomats from
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#17328910342347068-604: 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,
7182-616: The Karoo interior. The temperature will rise about 10 Celsius from the interior to the coast. Humidity is usually very low. The temperature can be over 40 Celsius in summer. The highest temperature recorded in South Africa (51.5 Celsius) occurred one summer during a berg wind along the Eastern Cape coastline. The level of soil moisture can intensify heat waves in Europe. Low soil moisture leads to
7296-464: The United States, Russia, and China have also brought their experience to the team. The ENB covers a range of topics in sustainability. Core coverage areas include: Reporting teams are also sent to a variety of conferences on sustainability that fall outside the confines of the list above, under agreements with conference organizers. These conferences include regional negotiations, conferences dealing with sustainability in specific industries such as
7410-441: 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. As the Sun is the Earth's primary energy source, changes in incoming sunlight directly affect
7524-550: The amount of future greenhouse gas emissions. Heatwaves present an additional form of stress and evolutionary pressure for species that already deal with habitat loss and climate change. Species have a thermal range of tolerance that describes the temperatures where they perform best. Temperature conditions that are outside of this range may experience decreased fitness and the inability to reproduce. The species with sufficient genetic variation will be able to ensure some individuals can survive frequent days of high temperatures in
7638-411: The atmosphere , for instance by increasing forest cover and farming with methods that capture carbon in soil . 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
7752-452: The atmosphere. volcanic CO 2 emissions are more persistent, but they are equivalent to less than 1% of current human-caused CO 2 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. The climate system's response to an initial forcing
7866-409: The average maximum temperature across more than half the country exceeds 28 °C (82.4 °F). The Danish Meteorological Institute also has a definition for a "warmth wave" ( varmebølge ). It defines this using the same criteria for a 25 °C (77.0 °F) temperature. Sweden defines a heat wave as at least five days in a row with a daily high exceeding 25 °C (77.0 °F). In Greece,
7980-469: The back side of the high continue to pump hot, humid Gulf air northeastwards. This results in a spell of hot and humid weather for much of the eastern United States and into southeastern Canada. In the Western Cape Province of South Africa, a heat wave can occur when the low-pressure area offshore and the high-pressure area inland combine to form a bergwind . The air warms as it descends from
8094-454: 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
8208-540: The carbon cycle, such as the fertilizing effect of CO 2 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
8322-719: The city of Melbourne. They left over half a million people without power as the heat wave blew transformers and overloaded a power grid. A heat wave occurring during a drought can contribute to bushfires and wildfires. This is because a drought dries out vegetation, so it is more likely to catch fire. During the disastrous heat wave that struck Europe in 2003 , fires raged through Portugal. They destroyed over 3,010 square kilometres (1,160 sq mi) of forest and 440 square kilometres (170 sq mi) of agricultural land. They caused about €1 billion worth of damage. High end farmlands have irrigation systems to back up crops . Heat waves can also contribute to flooding. Because hot air
8436-543: 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
8550-668: 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 . Around 1850 thermometer records began to provide global coverage. Between
8664-403: 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
8778-427: The destroyed trees release CO 2 , 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
8892-401: The distribution of heat and precipitation around the globe. The World Meteorological Organization estimates there is an 80% chance that global temperatures will exceed 1.5 °C warming for at least one year between 2024 and 2028. The chance of the 5-year average being above 1.5 °C is almost half. The IPCC expects the 20-year average global temperature to exceed +1.5 °C in
9006-444: The dominant direct influence on temperature from land use change. Thus, land use change to date is estimated to have a slight cooling effect. 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
9120-610: 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
9234-406: The earth's surface. It is usually possible to forecast heat waves, thus allowing the authorities to issue a warning in advance. Heat waves have an impact on the economy. They can reduce labour productivity, disrupt agricultural and industrial processes and damage infrastructure. Severe heat waves have caused catastrophic crop failures and thousands of deaths from hyperthermia . They have increased
9348-418: The effect of population growth (increasing the urban heat island effect) during those years is excluded, the exposure increased a further 50%. The researchers compiled a comprehensive list of past urban extreme heat events. Heat waves form when a high pressure area at an altitude of 10,000–25,000 feet (3,000–7,600 metres) strengthens and remains over a region for several days and up to several weeks. This
9462-508: The effects of ozone pollution in urban areas worse. This raises heat-related mortality during heat waves. During heat waves in urban areas, ground level ozone pollution can be 20 percent higher than usual. One study looked at fine particle concentrations and ozone concentrations from 1860 to 2000. It found that the global population-weighted fine particle concentrations increased by 5 percent due to climate change. Near-surface ozone concentrations rose by 2 percent. An investigation to assess
9576-414: The effects of risks. This factor can also help explain the underreporting of heat waves as a health risk. The deadly French heat wave in 2003 showed that heat wave dangers result from a combination of natural and social factors. Social invisibility is one such factor. Heat-related deaths can occur indoors, for instance among elderly people living alone. In these cases it can be challenging to assign heat as
9690-862: The emissions continue to increase for the rest of century, then over 9 million climate-related deaths would occur annually by 2100. 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. Heat wave A heat wave or heatwave , sometimes described as extreme heat ,
9804-430: 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 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
9918-436: The formation of clouds. A reduction of clouds increases the shortwave radiation reaching the surface. A low pressure area at the surface leads to surface wind from lower latitudes that brings warm air, enhancing the warming. The surface winds could also blow from the hot continental interior towards the coastal zone. This would lead to heat waves on the coast. They could also blow from high towards low elevations. This enhances
10032-557: The future. Marine heatwaves may cause mass mortality in fish populations, especially for species that are better adapted to cooler temperatures. Species that have adapted to warmer temperatures may expand their range during a heatwave. These invasive species may outcompete the native species that experience higher mortality during a heatwave, which disrupts ecosystem functioning. Marine heatwaves have also been correlated with negative impacts on foundation species such as coral and kelp. A possible public health measure during heat waves
10146-592: 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
10260-539: The joint mortality effects of ozone and heat during the European heat waves in 2003 concluded that these appear to be reinforce each other and increase mortality when combined. Calculations from 2022 suggest that heat waves will shrink the global economy by about 1 percent decrease by the middle of the 21st century. Heat waves often have complex effects on economies. They reduce labour productivity, disrupt agricultural and industrial processes and damage infrastructure that
10374-572: 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 CO 2 . Of these emissions, 75% was CO 2 , 18% was methane , 4% was nitrous oxide, and 2% was fluorinated gases . CO 2 emissions primarily come from burning fossil fuels to provide energy for transport , manufacturing, heating , and electricity. Additional CO 2 emissions come from deforestation and industrial processes , which include
10488-436: The last two decades. CO 2 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. 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
10602-441: 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 years like 2023 exhibiting temperatures well above even
10716-608: The lower atmosphere. Carbon dioxide , the primary greenhouse gas driving global warming, has grown by about 50% and is at 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
10830-419: The maximum daytime temperature and minimum nighttime temperature rise above the threshold for a particular region. The length of time above that threshold determines the level. Level 1 represents normal summer conditions. Level 2 occurs when there is a 60% or higher risk that the temperature will be above the threshold levels for two days and the intervening night. Level 3 arises when the temperature has been above
10944-672: The maximum temperature in De Bilt exceeds 25 °C (77 °F). During this period the maximum temperature in De Bilt must exceed 30 °C (86 °F) for at least three days. Belgium also uses this definition of a heat wave with Ukkel as a reference point. So does Luxembourg. In the United Kingdom, the Met Office operates a Heat Health Watch system. This places each Local Authority region into one of four levels. Heat wave conditions occur when
11058-413: The more popular term after NASA climate scientist James Hansen used it in his 1988 testimony in the U.S. Senate . Since the 2000s, climate change has increased usage. 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 . Over the last few million years
11172-723: The parties to multilateral environmental agreements. ENB is a division of the International Institute for Sustainable Development . The Earth Negotiations Bulletin (originally titled the Earth Summit Bulletin) began as the joint initiative of three individuals from the NGO community, who were publishing a daily bulletin at the United Nations Conference on Environment and Development (UNCED) in 1992. Namely, Johannah Bernstein, an environmental lawyer and Director of
11286-619: 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 CO 2 (≈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
11400-522: 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
11514-613: 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
11628-405: The recent average. 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
11742-411: 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
11856-476: 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
11970-431: The risk of wildfires in areas with drought . They can lead to widespread electricity outages because more air conditioning is used. A heat wave counts as extreme weather . It poses danger to human health, because heat and sunlight overwhelm the thermoregulation in humans . There are several definitions of heat waves: Denmark defines a national heat wave ( hedebølge ) as a period of at least 3 consecutive days in which
12084-646: The same time, they increase respiratory and sweating rates, and the combination of these responses can lead to metabolic disorders . One examples is ketosis , or the rapid accumulation of ketone bodies, caused by the animal's body rapidly catabolizing its fat stores to sustain itself. Heat stress also causes an increase in antioxidant enzyme activities, which can result in an imbalance of oxidant and antioxidant molecules, otherwise known as oxidative stress . Feed supplementation with antioxidants like chromium can help address oxidative stress and prevent it from leading to other pathological conditions, but only in
12198-583: The sea levels by at least 3.3 m (10 ft 10 in) over approximately 2000 years. 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 CO 2 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
12312-541: The social level. In every society, crime rates go up when temperatures go up. This is particularly the case with violent crimes such as assault, murder and rape. In politically unstable countries, high temperatures can exacerbate factors that lead to civil war. High temperatures also have a significant effect on income. A study of countries in the United States found that the economic productivity of individual days declines by about 1.7 percent for each degree Celsius above 15 °C (59 °F). High temperatures also make
12426-400: The soil. Heatwaves over land have become more frequent and more intense in almost all world regions since the 1950s, due to climate change . Heat waves are more likely to occur simultaneously with droughts. Marine heatwaves are twice as likely as they were in 1980. Climate change will lead to more very hot days and fewer very cold days. There are fewer cold waves . Heat illness is
12540-605: The subsidence or sinking of the air and therefore the adiabatic warming. In the eastern regions of the United States a heat wave can occur when a high pressure system originating in the Gulf of Mexico becomes stationary just off the Atlantic Seaboard. Hot humid air masses form over the Gulf of Mexico and the Caribbean Sea. At the same time hot dry air masses form over the desert Southwest and northern Mexico. The southwest winds on
12654-424: The threshold for the preceding day and night, and there is a 90% or higher chance that it will stay above the threshold in the following day. Level 4 is triggered if conditions are more severe than those of the preceding three levels. Each of the first three levels gives rise to a particular state of readiness and response by the social and health services. Level 4 involves a more widespread response. The threshold for
12768-453: The world with different climates thanks to a general indicator that appeared in 2015. With these indicators, experts estimated heat waves at the global scale from 1901 to 2010. They found a substantial and sharp increase in the number of affected areas in the last two decades. One study in 2021 investigated 13,115 cities. It found that extreme heat exposure of a wet bulb globe temperature above 30 Celsius tripled between 1983 and 2016, and if
12882-438: 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. The World Health Organization calls climate change one of
12996-524: 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
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