132-450: The Paris Agreement (also called the Paris Accords or Paris Climate Accords ) is an international treaty on climate change that was signed in 2016. The treaty covers climate change mitigation , adaptation , and finance . The Paris Agreement was negotiated by 196 parties at the 2015 United Nations Climate Change Conference near Paris , France. As of February 2023, 195 members of
264-609: A bottom-up structure, as its core pledge and review mechanism allows nations to set their own nationally determined contributions (NDCs), rather than having targets imposed top down. Unlike its predecessor, the Kyoto Protocol, which sets commitment targets that have legal force, the Paris Agreement, with its emphasis on consensus building , allows for voluntary and nationally determined targets. The specific climate goals are thus politically encouraged, rather than legally bound. Only
396-549: 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
528-481: A country wants to use more cost-effective cooperative approaches to achieve their NDCs, they will have to monitor carbon units for their economies. So far, as the only country who wants to buy ITMOs, Switzerland has signed deals regarding ITMO tradings with Peru, Ghana, Senegal, Georgia, Dominica, Vanuatu, Thailand and Ukraine. Paragraphs 6.4 –6.7 establish a mechanism "to contribute to the mitigation of greenhouse gases and support sustainable development". Though there
660-587: 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
792-545: A gain of emission units for one party and a reduction of emission units for the other, a so called "corresponding adjustment". Because the NDCs, and domestic carbon trading schemes, are heterogeneous, the ITMOs will provide a format for global linkage under the auspices of the UNFCCC. The provision thus also creates a pressure for countries to adopt emissions management systems – if
924-532: 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
1056-412: 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
1188-408: 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
1320-598: A report released in 2022 the IPCC promotes the need for innovation and technological changes in combination with consumption and production behavioral changes to meet Paris Agreement objectives. To stay below 1.5 °C of global warming, emissions need to be cut by roughly 50% by 2030. This is an aggregate of each country's nationally determined contributions . By mid-century, CO 2 emissions would need to be cut to zero, and total greenhouse gases would need to be net zero just after mid-century. There are barriers to implementing
1452-410: 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
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#17328372463891584-474: 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
1716-417: 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
1848-497: A specific date, nor to meet their targets. There will be only a name and shame system or as János Pásztor , the former U.N. assistant secretary-general on climate change, stated, a "name and encourage" plan. Under the Paris Agreement, countries must increase their ambition every five years. To facilitate this, the agreement established the Global Stocktake , which assesses progress, with the first evaluation in 2023. The outcome
1980-466: A specific division between developed and developing nations. Countries determine themselves what contributions they should make to achieve the aims of the treaty. As such, these plans are called nationally determined contributions (NDCs). Article 3 requires NDCs to be "ambitious efforts" towards "achieving the purpose of this Agreement" and to "represent a progression over time". The contributions should be set every five years and are to be registered by
2112-538: 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
2244-519: 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,
2376-592: Is a binding agreement, but many of its articles do not imply obligations or are there to facilitate international collaboration. It covers most greenhouse gas emissions, but does not apply to international aviation and shipping , which fall under the responsibility of the International Civil Aviation Organization and the International Maritime Organization , respectively. The Paris Agreement has been described as having
2508-557: 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
2640-711: 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
2772-521: Is implemented via national policy. It would involve improvements to energy efficiency to decrease the energy intensity of the global economy. Implementation also requires fossil fuel burning to be cut back and the share of sustainable energy to grow rapidly. Emissions are being reduced rapidly in the electricity sector, but not in the building, transport and heating sector. Some industries are difficult to decarbonize, and for those carbon dioxide removal may be necessary to achieve net zero emissions . In
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#17328372463892904-399: 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
3036-705: Is no official name for the mechanism as yet, it has been referred to as the Sustainable Development Mechanism or SDM. The SDM is considered to be the successor to the Clean Development Mechanism , a mechanism under the Kyoto Protocol by which parties could collaboratively pursue emissions reductions. The SDM is set to largely resemble the Clean Development Mechanism, with the dual goal of contributing to global GHG emissions reductions and supporting sustainable development. Though
3168-465: Is not strict enough. There is debate about the effectiveness of the agreement. While pledges under the Paris Agreement are insufficient for reaching the set temperature goals, there is a mechanism of increased ambition . The Paris Agreement has been successfully used in climate litigation forcing countries and an oil company to strengthen climate action. The aim of the agreement, as described in Article 2,
3300-557: Is possible that the SDM will see difficulties. Climate change adaptation received more focus in Paris negotiations than in previous climate treaties. Collective, long-term adaptation goals are included in the agreement, and countries must report on their adaptation actions, making it a parallel component with mitigation. The adaptation goals focus on enhancing adaptive capacity , increasing resilience , and limiting vulnerability. The Paris Agreement
3432-450: 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
3564-444: 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
3696-516: 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
3828-407: 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
3960-452: Is to be used as input for new nationally determined contributions of parties. The Talanoa Dialogue in 2018 was seen as an example for the global stocktake. After a year of discussion, a report was published and there was a call for action, but countries did not increase ambition afterwards. The stocktake works as part of the Paris Agreement's effort to create a "ratcheting up" of ambition in emissions cuts. Because analysts agreed in 2014 that
4092-512: Is to have a stronger response to the danger of climate change; it seeks to enhance the implementation of the United Nations Framework Convention on Climate Change through: (a) Holding the increase in the global average temperature to well below 2 °C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5 °C above pre-industrial levels, recognizing that this would significantly reduce
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4224-417: 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
4356-507: 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
4488-657: 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
4620-568: 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
4752-835: 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
4884-626: 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
5016-664: The Nationally Determined Contributions , and may bring down temperatures by a further 0.5°C. With initial pledges by countries inadequate, faster and more expensive future mitigation would be needed to still reach the targets. Furthermore, there is a gap between pledges by countries in their NDCs and implementation of these pledges; one third of the emission gap between the lowest-costs and actual reductions in emissions would be closed by implementing existing pledges. A pair of studies in Nature found that as of 2017 none of
5148-583: The Rio de Janeiro Conference or the Earth Summit (Portuguese: ECO92, Cúpula da Terra), was a major United Nations conference held in Rio de Janeiro from 3 to 14 June 1992. Earth Summit was created as a means for member states to cooperate together internationally on development issues after the Cold War . Due to issues relating to sustainability being too big for individual member states to handle, Earth Summit
5280-609: The Trump administration delivered an official notice to the United Nations that the United States, the second largest emitter of greenhouse gases after China, intended to withdraw from the Paris Agreement as soon as it was eligible to do so. The notice of withdrawal could not be submitted until the agreement was in force for three years for the US, on 4 November 2019. The U.S. government deposited
5412-511: The UNFCCC Secretariat . Each further ambition should be more ambitious than the previous one, known as the principle of progression . Countries can cooperate and pool their nationally determined contributions. The Intended Nationally Determined Contributions pledged during the 2015 Climate Change Conference are converted to NDCs when a country ratifies the Paris Agreement, unless they submit an update. The Paris Agreement does not prescribe
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5544-584: The United Nations Framework Convention on Climate Change (UNFCCC) are parties to the agreement. Of the three UNFCCC member states which have not ratified the agreement, the only major emitter is Iran . The United States withdrew from the agreement in 2020, but rejoined in 2021. The Paris Agreement has a long-term temperature goal which is to keep the rise in global surface temperature to well below 2 °C (3.6 °F) above pre-industrial levels. The treaty also states that preferably
5676-509: 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
5808-414: 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
5940-402: 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
6072-580: The environment . Malaysia was successful at blocking the US-proposed convention on forests and its prime-minister Mahathir Mohamad accused later the global North of exercising eco-imperialism at this summit. According to Vandana Shiva , Earth Summit create a "moral base for green imperialism" . Green Cross International was founded to build upon the work of the Summit. The first edition of Water Quality Assessments, published by WHO/ Chapman & Hall ,
6204-971: 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
6336-439: The international transfer of mitigation outcomes (ITMOs). The agreement recognizes the rights of parties to use emissions reductions outside of their own borders toward their NDC, in a system of carbon accounting and trading. This provision requires the "linkage" of carbon emissions trading systems – because measured emissions reductions must avoid "double counting", transferred mitigation outcomes must be recorded as
6468-432: 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
6600-405: 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
6732-599: 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
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#17328372463896864-500: 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
6996-472: The 1992 Earth Summit is one of the first international treaties on the topic. It stipulates that parties should meet regularly to address climate change, at the Conference of Parties or COP. It forms the foundation to future climate agreements. The Kyoto Protocol , adopted in 1997, regulated greenhouse gas reductions for a limited set of countries from 2008 to 2012. The protocol was extended until 2020 with
7128-495: The 2°C upper target of the Paris Agreement, that the probabilities of major emitters meeting their NDCs without such an increase is very low. It estimated that with current trends the probability of staying below 2 °C of warming is 5% – and 26% if NDCs were met and continued post-2030 by all signatories. As of 2020, there is little scientific literature on the topics of the effectiveness of the Paris Agreement on capacity building and adaptation, even though they feature prominently in
7260-440: 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
7392-435: 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,
7524-542: 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
7656-572: The COP 21, Laurent Fabius , argued that the implementation of the Paris Agreement could be bolstered by the adoption of a Global Pact for the Environment . The latter would define the environmental rights and duties of states, individuals and businesses. The effectiveness of the Paris Agreement to reach its climate goals is under debate, with most experts saying it is insufficient for its more ambitious goal of keeping global temperature rise under 1.5°C. Many of
7788-563: The Doha Amendment in 2012. The United States decided not to ratify the Protocol, mainly because of its legally-binding nature. This, and distributional conflict, led to failures of subsequent international climate negotiations. The 2009 negotiations were intended to produce a successor treaty of Kyoto, but the negotiations collapsed and the resulting Copenhagen Accord was not legally binding and did not get adopted universally. The Accord did lay
7920-512: The EU deposited its instruments of ratification on 5 October 2016, along with seven EU member states. The EU and 194 states, totalling over 98% of greenhouse gas emissions , have ratified or acceded to the agreement. The only countries which have not ratified are some greenhouse gas emitters in the Middle East : Iran with 2% of the world total being the largest. Libya and Yemen have also not ratified
8052-821: The Earth Summit established the Commission on Sustainable Development (CSD). In 2013, the CSD was replaced by the High-level Political Forum on Sustainable Development that meets every year as part of the ECOSOC meetings, and every fourth year as part of the General Assembly meetings. Critics point out that many of the agreements made in Rio have not been realized regarding such fundamental issues as fighting poverty and cleaning up
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#17328372463898184-505: The Earth Summit. Youth concerns were consolidated at a World Youth Environmental Meeting, Juventud (Youth) 92, held in Costa Rica, before the Earth Summit. "The involvement of today's youth in environment and development decision-making...is critical to the long term success of Agenda 21" (UNCED 1992). Parallel to UNCED, youth organized the Youth '92 conference with participation from around
8316-604: 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,
8448-516: The European Union) on the first day it was opened for signature. As of March 2021, 194 states and the European Union have signed the agreement. The agreement would enter into force (and thus become fully effective) if 55 countries that produce at least 55% of the world's greenhouse gas emissions (according to a list produced in 2015) ratify or otherwise join the treaty. Alternative ways to join
8580-517: The Fifth Assessment Report of the IPCC and the work of the subsidiary bodies of the UNFCCC. The resulting agreement was to be adopted in 2015. Negotiations in Paris took place over a two-week span, and continued throughout the three final nights. Various drafts and proposals had been debated and streamlined in the preceding year. According to one commentator two ways in which the French increased
8712-510: The French solved the problem by changing it as a "typographical error". At the conclusion of COP21 (the 21st meeting of the Conference of the Parties), on 12 December 2015, the final wording of the Paris Agreement was adopted by consensus by the 195 UNFCCC participating member states and the European Union. Nicaragua indicated they had wanted to object to the adoption as they denounced the weakness of
8844-484: The NDCs would not limit rising temperatures below 2 °C, the global stocktake reconvenes parties to assess how their new NDCs must evolve so that they continually reflect a country's "highest possible ambition". While ratcheting up the ambition of NDCs is a major aim of the global stocktake, it assesses efforts beyond mitigation. The five-year reviews will also evaluate adaptation, climate finance provisions, and technology development and transfer. On November 30, 2023,
8976-606: The Paris Agreement and the Kyoto Protocol is their scope. The Kyoto Protocol differentiated between Annex-I , richer countries with a historical responsibility for climate change, and non-Annex-I countries, but this division is blurred in the Paris Agreement as all parties are required to submit emissions reduction plans. The Paris Agreement still emphasizes the principle of Common but Differentiated Responsibility and Respective Capabilities – the acknowledgement that different nations have different capacities and duties to climate action – but it does not provide
9108-460: The Paris Agreement as a framework for a global carbon market. Article 6 is the only important part of the agreement yet to be resolved; negotiations in 2019 did not produce a result. The topic was settled during the 2021 COP26 in Glasgow . A mechanism, the "corresponding adjustment", was established to avoid double counting for emission offsets. Paragraphs 6.2 and 6.3 establish a framework to govern
9240-428: The Paris Agreement pledges, the average temperature would rise by 2.4°C, and with every zero emission target reached, the average temperature would rise by 2.0°C. The Production Gap 2021 report states that world governments still plan to produce 110% more fossil fuels in 2030 (including 240% more coal, 57% more oil and 71% more gas) than the 1.5 degree limit. In September 2023 the first global stocktake report about
9372-405: The Paris Agreement that are yet to be set. Most NDCs have a conditional component. While the NDCs themselves are not binding, the procedures surrounding them are. These procedures include the obligation to prepare, communicate and maintain successive NDCs, set a new one every five years, and provide information about the implementation. There is no mechanism to force a country to set a NDC target by
9504-467: The Paris Agreement. A strong preference was reported that the EU and its 28 member states ratify at the same time to ensure that they do not engage themselves to fulfilling obligations that strictly belong to the other, and there were fears by observers that disagreement over each member state's share of the EU-wide reduction target, as well as Britain's vote to leave the EU might delay the Paris pact. However,
9636-422: The Paris Agreement. The literature available is mostly mixed in its conclusions about loss and damage, and adaptation. According to the stocktake report, the agreement has a significant effect: while in 2010 the expected temperature rise by 2100 was 3.7–4.8 °C, at COP 27 it was 2.4–2.6°C and if all countries will fulfill their long-term pledges even 1.7–2.1 °C. Despite it, the world is still very far from reaching
9768-615: The UN Headquarters in New York. Signing of the agreement is the first step towards ratification , but it is possible to accede to the agreement without signing. It binds parties to not act in contravention of the goal of the treaty. On 1 April 2016, the United States and China, which represent almost 40% of global emissions confirmed they would sign the Paris Climate Agreement. The agreement was signed by 175 parties (174 states and
9900-500: The US would "earn its way back" into legitimacy in the Paris process. United Nations Secretary-General António Guterres welcomed the return of the United States as restoring the "missing link that weakened the whole". The Paris Agreement is a short agreement with 16 introductory paragraphs and 29 articles. It contains procedural articles (covering, for example, the criteria for its entry into force) and operational articles (covering, for example, mitigation, adaptation and finance). It
10032-535: The United Nations Climate Change Conference (COP28) commenced in Dubai with renewed calls for amplified efforts towards climate action. Article 6 has been flagged as containing some of the key provisions of the Paris Agreement. Broadly, it outlines the cooperative approaches that parties can take in achieving their nationally determined carbon emissions reductions. In doing so, it helps establish
10164-895: The United Nations Conference on Environment and Development (UNCED). By 2022, the UNFCCC had 198 parties. Its supreme decision-making body, the Conference of the Parties (COP) meets annually to assess progress in dealing with climate change. Since the creation of the UNFCC many related environmental conferences, climate-related forums, and ongoing scientific research initiatives in the fields of sustainability, climate, and environmental security have continued to develop these intersecting issues. Non-governmental organizations (NGOs) and educational institutions have been prominent participants. The Earth Summit played an influential role in diffusing several key principles of environmental treaties , such as
10296-441: 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
10428-401: The agreement . Eritrea is the latest country to ratify the agreement, on 7 February 2023. Article 28 enables parties to withdraw from the agreement after sending a withdrawal notification to the depositary . Notice can be given no earlier than three years after the agreement goes into force for the country. Withdrawal is effective one year after the depositary is notified. On 4 August 2017,
10560-414: The agreement, but were not given a chance. In the agreement the members promised to reduce their carbon output "as soon as possible" and to do their best to keep global warming " to well below 2 degrees C " (3.6 °F). The Paris Agreement was open for signature by states and regional economic integration organizations that are parties to the UNFCCC (the convention) from 22 April 2016 to 21 April 2017 at
10692-417: The agreement, each country must determine, plan, and regularly report on its contributions. No mechanism forces a country to set specific emissions targets , but each target should go beyond previous targets. In contrast to the 1997 Kyoto Protocol , the distinction between developed and developing countries is blurred, so that the latter also have to submit plans for emission reductions. The Paris Agreement
10824-407: The agreement. Some countries struggle to attract the finance necessary for investments in decarbonization. Climate finance is fragmented, further complicating investments. Another issue is the lack of capabilities in government and other institutions to implement policy. Clean technology and knowledge is often not transferred to countries or places that need it. In December 2020, the former chair of
10956-467: The aim of the agreement: limiting temperature rise to 1.5 degrees. For doing this, emissions must peak by 2025. In September 2021, the Climate Action Tracker estimated that, with current policies, global emissions will double above the 2030 target level. The gap is 20-23 Gt CO2e. Countries such as Iran, Russia, Saudi Arabia, Singapore, and Thailand have been criticised of not doing enough to meet
11088-411: 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
11220-452: 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
11352-454: 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
11484-540: 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
11616-543: 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
11748-523: The conference were difficult to negotiate and the agency's international results were mixed, including the U.S. failure to sign the proposed Convention on Biological Diversity. Twelve cities were also honored with the Local Government Honours Award for innovative local environmental programs. These included Sudbury in Canada for its ambitious program to rehabilitate environmental damage from
11880-668: 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
12012-403: 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
12144-427: 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
12276-401: 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
12408-444: 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
12540-610: 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
12672-880: 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. Earth Summit The United Nations Conference on Environment and Development ( UNCED ), also known as
12804-430: 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
12936-408: The exact nature of the NDCs. At a minimum, they should contain mitigation provisions, but they may also contain pledges on adaptation, finance, technology transfer , capacity building and transparency. Some of the pledges in the NDCs are unconditional, but others are conditional on outside factors such as getting finance and technical support, the ambition from other parties or the details of rules of
13068-399: The exact provisions of the Paris Agreement have yet to be straightened out, so that it may be too early to judge effectiveness. According to the 2020 United Nations Environment Programme ( UNEP ), with the current climate commitments of the Paris Agreement, global mean temperatures will likely rise by more than 3°C by the end of the 21st century. Newer net zero commitments were not included in
13200-482: The framework for bottom-up approach of the Paris Agreement. Under the leadership of UNFCCC executive secretary Christiana Figueres , negotiation regained momentum after Copenhagen's failure. During the 2011 United Nations Climate Change Conference , the Durban Platform was established to negotiate a legal instrument governing climate change mitigation measures from 2020. The platform had a mandate to be informed by
13332-592: 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
13464-729: The implementation of the agreement was released. According to the report contrarily to expectations, the agreement has a significant effect: while in 2010 the expected temperature rise by 2100 was 3.7–4.8 °C, at COP 27 it was 2.4–2.6°C and if all countries will fulfill their long-term pledges 1.7–2.1 °C. However, the world remains very far from limiting warming to 1.5 degrees. To meet this benchmark, global emissions must peak by 2025, and although emissions have peaked in some countries, global emissions have not. 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
13596-572: 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
13728-436: 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
13860-441: 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
13992-481: The likelihood of success were: firstly to ensure that Intended Nationally Determined Contributions (INDCs) were completed before the start of the negotiations, and secondly to invite leaders just for the beginning of the conference. The negotiations almost failed because of a single word when the US legal team realized at the last minute that "shall" had been approved, rather than "should", meaning that developed countries would have been legally obliged to cut emissions:
14124-621: The limit of the increase should only be 1.5 °C (2.7 °F). The lower the temperature increase, the smaller the effects of climate change can be expected. To achieve this temperature goal, greenhouse gas emissions should be reduced as soon as, and by as much as, possible. They should even reach net zero by the middle of the 21st century. To stay below 1.5 °C of global warming, emissions need to be cut by roughly 50% by 2030. This figure takes into account each country's documented pledges . The treaty aims to help countries adapt to climate change effects, and mobilize enough finance. Under
14256-505: The local mining industry, Austin in the United States for its green building strategy, and Kitakyūshū in Japan for incorporating an international education and training component into its municipal pollution control program. The Earth Summit resulted in the following documents: Moreover, important legally binding agreements ( Rio Convention ) were opened for signature: At Rio it
14388-608: 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
14520-415: The major industrialized nations were implementing the policies they had pledged, and none met their pledged emission reduction targets, and even if they had, the sum of all member pledges (as of 2016) would not keep global temperature rise "well below 2°C". In 2021, a study using a probabilistic model concluded that the rates of emissions reductions would have to increase by 80% beyond NDCs to likely meet
14652-413: 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
14784-565: The notification with the Secretary General of the United Nations and officially withdrew one year later on 4 November 2020. President Joe Biden signed an executive order on his first day in office, 20 January 2021, to re-admit the United States into the Paris Agreement. Following the 30-day period set by Article 21.3, the U.S. was readmitted to the agreement. United States Climate Envoy John Kerry took part in virtual events, saying that
14916-711: The precautionary principle, common but differentiated responsibilities , and the polluter pays principle . The issues addressed include: An important achievement of the summit was an agreement on the Climate Change Convention which in turn led to the Kyoto Protocol and the Paris Agreement . Another agreement was to "not to carry out any activities on the lands of indigenous peoples that would cause environmental degradation or that would be culturally inappropriate". The Convention on Biological Diversity
15048-574: The processes governing the reporting and review of these goals are mandated under international law . This structure is especially notable for the United States—because there are no legal mitigation or finance targets, the agreement is considered an "executive agreement rather than a treaty". Because the UNFCCC treaty of 1992 received the consent of the US Senate, this new agreement does not require further legislation. Another key difference between
15180-619: 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
15312-522: 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
15444-613: 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
15576-405: 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
15708-411: 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
15840-476: 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
15972-456: The requirements of the agreement, and are on track to achieve a 4°C warming of the planet if current policies are implemented more widely. Of the world's countries, only the Gambia's emissions are at the level required by the Paris Agreement. Models predicted that if the necessary measures were not implemented by autumn 2021, the global average temperature would rise by 2.9°C. With the implementation of
16104-548: The risks and impacts of climate change; (b) Increasing the ability to adapt to the adverse impacts of climate change and foster climate resilience and low greenhouse gas emissions development, in a manner that does not threaten food production; (c) Making finance flows consistent with a pathway towards low greenhouse gas emissions and climate-resilient development. Countries furthermore aim to reach "global peaking of greenhouse gas emissions as soon as possible." The UN Framework Convention on Climate Change (UNFCCC), adopted at
16236-583: 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
16368-584: The structure and processes governing the SDM are not yet determined, certain similarities and differences from the Clean Development Mechanisms have become clear. A key difference is that the SDM will be available to all parties as opposed to only Annex-I parties , making it much wider in scope. The Clean Development Mechanism of the Kyoto Protocol was criticized for failing to produce either meaningful emissions reductions or sustainable development benefits in most instances. and for its complexity. It
16500-436: The treaty are acceptance, approval or accession. The first two are typically used when a head of state is not necessary to bind a country to a treaty, whereas the latter typically happens when a country joins a treaty already in force. After ratification by the European Union, the agreement obtained enough parties to enter into effect on 4 November 2016. Both the EU and its member states are individually responsible for ratifying
16632-438: 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
16764-577: Was agreed that an International Negotiating Committee for a third convention the United Nations Convention to Combat Desertification would be set up. This convention was negotiated within two years of Rio and then open for signature. It became effective in 1996 after receiving 50 ratifications. In order to ensure compliance to the agreements at Rio (particularly the Rio Declaration on Environment and Development and Agenda 21 ), delegates to
16896-422: Was held as a platform for other member states to collaborate. A key achievement of the 1992 conference was the establishment of the United Nations Framework Convention on Climate Change (UNFCCC) established in part as an international environmental treaty to combat "dangerous human interference with the climate system" and to stabilize greenhouse gas concentrations in the atmosphere. It was signed by 154 states at
17028-899: Was launched at the Rio Global Forum. At this stage, youth were not officially recognised within climate governance. Although youth were not given specific recognition, there was a significant youth turnout at UNCED. Youth were involved in negotiating Chapter 25 of Agenda 21 on Children & Youth in Sustainable Development. "25.2 It is imperative that youth from all parts of the world participate actively in all relevant levels of decision-making processes because it affects their lives today and has implications for their futures. In addition to their intellectual contribution and their ability to mobilize support, they bring unique perspectives that need to be taken into account." Two years prior to UNCED youth organized internationally to prepare for
17160-467: Was opened for signature at the Earth Summit and made a start towards a redefinition of measures that did not inherently encourage the destruction of natural ecoregions and so-called uneconomic growth . World Oceans Day was initially proposed at this conference and has been recognized since then. Although President George H. W. Bush signed the Earth Summit's Convention on Climate, his EPA Administrator William K. Reilly acknowledges that U.S. goals at
17292-608: Was opened for signature on 22 April 2016 ( Earth Day ) at a ceremony inside the UN Headquarters in New York . After the European Union ratified the agreement, sufficient countries had ratified the agreement responsible for enough of the world's greenhouse gases for the agreement to enter into force on 4 November 2016. World leaders have lauded the agreement. However, some environmentalists and analysts have criticized it, saying it
17424-524: 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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