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105-585: The 9 laboratories that make up the institute include: This article about a scientific organization is a stub . You can help Misplaced Pages by expanding it . This article about climate change is a stub . You can help Misplaced Pages by expanding it . See guidelines for writing about climate change . Further suggestions might be found on the article's talk page . 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

210-562: 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

315-590: 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

420-433: A disaster: it's only when it affects people or is caused by them that is counts as a disaster. It is argued that natural disasters are always linked to human action or inaction or rooted in anthropogenic processes . Disasters, economic loss, and the underlying vulnerabilities that drive risk are increasing. Global risks like climate change are having major impacts everywhere. Scientists forecast climate change will increase

525-896: A higher share of plant-based foods . This has both mitigation and adaptation benefits. Plant-based options have much lower energy and water requirements. Adaptation options can investigate the dietary patterns that are better suited to the regional, socioeconomic and cultural context. Social-cultural norms strongly affect preferences for foods. Policies such as subsidies, taxes, and marketing can also support dietary choices that help adaptation. Agriculture offers many opportunities for adaptation. These include changing planting times, or changing to crops and livestock that are better adapted to climate conditions and presence of pests. Other examples are breeding more resilient crops and selecting genetically modified crops. All these aim to improve food security and nutrition. Migration counts as behavioural climate adaptation for some, although others refer to it as

630-564: A knowledge loop that includes targeted user communities' access to, interpretation of, communication of, and use of pertinent, accurate, and trustworthy climate information, as well as their feedback on that use. Climate information services involve the timely production, translation and delivery of useful climate data, information and knowledge. Institutional responses include zoning regulations, new building codes , new insurance schemes, and coordination mechanisms. Policies are important tools to integrate issues of climate change adaptation. At

735-542: 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

840-412: 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

945-408: 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

1050-461: 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

1155-474: 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

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1260-417: 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

1365-548: 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

1470-519: 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,

1575-509: A year for the coming decades. In many cases, the cost will be less than the damage that it avoids. The IPCC defines climate change adaptation in this way: Adaptation actions can be incremental and transformative. Incremental actions are actions that aim to maintain the essence and integrity of a system. Transformative actions are actions that change the fundamental attributes of a system in response to climate change and its impacts. Research on climate change adaptation has been ongoing since

1680-430: Is a closely related area of work and research topic that has recently emerged. It describes situations in which adaptation, mitigation and development solutions are pursued together. It is able to benefit from synergies from among the actions and reduce trade-offs. Strategies to limit climate change are complementary to efforts to adapt to it. Limiting warming, by reducing greenhouse gas emissions and removing them from

1785-564: 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

1890-421: Is an important step in understanding current and future adaptation needs and options. As of 2022, the level of warming is 1.2 °C (34.2 °F) above levels before the industrial revolution. It is on track to increase to 2.5 to 2.9 °C (36.5 to 37.2 °F) by the end of the century. This is causing a variety of secondary effects. Many negative effects of climate change involve changes in extremes or

1995-547: Is because evacuation and emergency access becomes easier. Reduced air pollution from public transport improves health. This in turn may lead to improved economic resilience, as healthy workers perform better. There are many adaptation responses. We sometimes call them adaptation measures, strategies or solutions. They help manage impacts and risks to people and nature. Current adaptation focuses on near-term climate risks. It also focuses on particular sectors, such as water and agriculture, and on regions, such as Africa and Asia. It

2100-638: Is because transformational adaptation is connected with implementation at scale and ideally at the system-level. Strengthening resilience is therefore important for maintaining a capacity for transformation. Transformations, and the processes of transition, cover the major systems and sectors at scale. These are energy, land and ecosystems, urban and infrastructure, and industrial and societal. Transformations may fail if they do not integrate social justice, consider power differences and political inclusion, and if they do not deliver improvements in incomes and wellbeing for everyone. Climate resilient development

2205-711: 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

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2310-468: Is important to close gaps between adaptation that is carried out and the needs relative to today's climate in order to reduce risks to a tolerable level. However, future adaptation must also anticipate future climate change risks. Some options may become less effective or entirely unfeasible as global warming increases. Adaptation responses fall into four categories that all directly aim to reduce risks and exploit opportunities: We can also group options

2415-490: Is important to help countries manage climate risks. Plans, policies or strategies are in place in more than 70% of countries. Agreements like the Paris Agreement encourage countries to develop adaptation plans. Other levels of government like cities and provinces also use adaptation planning. So do economic sectors. Donor countries can give money to developing countries to help develop national adaptation plans. This

2520-458: Is important to help them implement more adaptation. Monitoring and evaluation activities are key parts of adaptation efforts. They ensure strategies work well and allow for necessary changes along the way. The adaptation carried out so far is not enough to manage risks at current levels of climate change. And adaptation must also anticipate future risks of climate change. The costs of climate change adaptation are likely to cost billions of dollars

2625-799: Is in three categories: 1. Structural and physical adaptation (including engineering and built environment, technological, ecosystem-based, services); 2. Social adaptation (educational, informational, behavioural); 3. Institutional adaptation (economic organizations, laws and regulation, government policies and programmes). Other ways to distinguish types of adaptation are anticipatory versus reactive, autonomous versus planned and incremental versus transformational. Built environment options include installing or upgrading infrastructure to protect against flooding, sea level rise, heatwaves and extreme heat. They also include infrastructure to respond to changed rainfall patterns in agriculture. This could be infrastructure for irrigation. These are explained further in

2730-399: 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

2835-443: Is not possible to directly reduce hazards. This is because hazards are affected by current and future changes in climate. Instead, adaptation addresses the risks of climate impacts that arise from the way climate-related hazards interact with the exposure and vulnerability of human and ecological systems. Exposure refers to the presence of people, livelihoods, ecosystems and other assets in places that could suffer negative effects. It

2940-470: Is one way to reduce vulnerability to climate hazards. For instance, mangroves can dampen storm energy. So they can help prevent flooding. In this way, protection of the mangrove ecosystem can be a form of adaptation. Insurance and livelihood diversification increase resilience and decrease vulnerability. Other ways to decrease vulnerability include strengthening social protection and building infrastructure more resistant to hazards. Adaptive capacity in

3045-412: Is part of the broader consideration of sustainable development . Climate change adaptation and disaster risk reduction have similar goals (to reduce potential impacts of hazards and increase the resilience of people at risk). They use similar concepts and are informed by similar sources and studies. Disasters are often triggered by natural hazards. A natural event such as a fire or flood is not of itself

3150-447: Is possible to reduce exposure by retreating from areas with high climate risks, such as floodplains. Improving systems for early warnings and evacuations are other ways to reduce exposure. The IPCC defines climate change vulnerability as "the propensity or predisposition to be adversely affected" by climate change. It can apply to humans but also to natural systems . Human and ecosystem vulnerability are interdependent. According to

3255-450: 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

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3360-444: 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

3465-516: 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

3570-504: Is strong variation within countries. The determinants of adaptive capacity include: The IPCC considers climate resilience to be “the capacity of social, economic and ecosystems to cope with a hazardous event or trend or disturbance”. It includes the abilities to reorganise and learn. This definition is similar to that of climate change adaptation. However, resilience involves a more systematic approach to absorbing change. It involves using those changes to become more efficient. The idea

3675-423: Is that people can intervene to reorganise the system when disturbance creates an opportunity to do so. Implemented adaptation most often builds upon resilience as a way of bouncing back to recover after a disturbance. Experts consider it to be incremental rather than transformational. On the other hand, climate resilience-focused projects can be activities to promote and support transformational adaptation. This

3780-407: 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

3885-484: Is the process of adjusting to the effects of climate change . These can be both current or expected impacts. Adaptation aims to moderate or avoid harm for people, and is usually done alongside climate change mitigation . It also aims to exploit opportunities. Humans may also intervene to help adjust for natural systems. There are many adaptation strategies or options. For instance, building hospitals that can withstand natural disasters, roads that don't get washed away in

3990-417: 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

4095-511: 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

4200-661: 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

4305-573: 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

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4410-840: 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

4515-635: 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

4620-518: 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

4725-414: 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

4830-402: 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

4935-628: The codes or regulations that buildings must conform to is important for keeping people healthy and comfortable during extremes of hot and cold and protecting them from floods. There are many ways to do this. They include increasing the insulation values, adding solar shading, increasing natural ventilation or passive cooling , codes for green roofs to reduce urban heat island effects or requiring waterfront properties to have higher foundations. Land use zoning controls are central to investment in urban development . They can reduce risks to areas threatened by floods and landslides. Insurance spreads

5040-971: 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

5145-432: 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

5250-405: 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

5355-612: 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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5460-500: 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

5565-747: The 1990s. The number and variety of subtopics has greatly increased since then. Adaptation has become an established policy area in the 2010s and since the Paris Agreement, and an important topic for policy research. Scientific research into climate change adaptation generally starts with analyses of the likely effects of climate change on people, ecosystems, and the environment. These impacts cover its effects on lives, livelihoods, health and well-being, ecosystems and species, economic, social and cultural assets, and infrastructure. Impacts may include changed agricultural yields, increased floods, and droughts or coral reef bleaching. Analysis of such impacts

5670-440: 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

5775-435: 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,

5880-545: 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

5985-604: 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,

6090-619: The Global Goal are in development as of 2023. It will support the long-term adaptation goals of the governments that are parties to the agreement. It also aims to fund support for the most vulnerable countries’ adaptation needs in the context of the 1.5/2 °C goal. It has three core components. These are reducing vulnerability to climate change, enhancing adaptive capacity, and strengthening resilience. Adaptation can help decrease climate risk by addressing three interacting risk factors. These are hazards , vulnerability , and exposure. It

6195-555: The IPCC, climate change vulnerability encompasses a variety of concepts and elements, including sensitivity or susceptibility to harm and lack of capacity to cope and adapt. Sensitivity to climate change could be reduced by for example increasing the storage capacity of a reservoir, or planting crops that are more resistant to climate variability. It is also possible to reduce vulnerability in towns and cities with green garden spaces. These can reduce heat stress and food insecurity for low-income neighbourhoods. Ecosystem-based adaptation

6300-497: The UN is running a partnership titled "Climate Risk and Early Warning Systems" to aid high risk countries with neglected warning systems in developing them. Climate Information Services (CIS) (or climate services) entail the dissemination of climate data in a way that aids people and organizations in making decisions. CIS helps its users foresee and control the hazards associated with a changing and unpredictable climate. It encompasses

6405-578: The ability to design and implement effective adaptation strategies, or to react to evolving hazards and stresses. Societies that can respond to change quickly and successfully have a high adaptive capacity. Conversely, high adaptive capacity does not necessarily lead to successful adaptation action. It does not necessarily succeed in goals of equity and enhancing well-being. In general, adaptation capacity differs between high and low-income countries. By some indices such as ND-GAIN , high-income countries tend to have higher adaptive capacity. However, there

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6510-441: 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

6615-418: The adoption of resilient building codes to mitigate potential damages. Coordination helps achieve goals shared by a range of people or organizations. Examples are information-sharing or joint implementation of adaptation options. Coordination helps use resources effectively. It avoids duplication, promotes consistency across government, and makes it easier for all people and organizations involved to understand

6720-411: 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

6825-400: The atmosphere, is also known as climate change mitigation . There are some synergies or co-benefits between adaptation and mitigation. Synergies include the benefits of public transport for both mitigation and adaptation. Public transport has lower greenhouse gas emissions per kilometer travelled than cars. A good public transport network also increases resilience in case of disasters. This

6930-452: 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

7035-454: 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

7140-540: 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

7245-500: The climate changes or is expected to change, which is different from place to place. Adaptation is particularly important in developing countries because they are most vulnerable to climate change. Adaptation needs are high for food, water and other sectors important for economic output, jobs and incomes. One of the challenges is to prioritize the needs of communities, including the poorest, to help ensure they are not disproportionately affected by climate change. Adaptation planning

7350-551: 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

7455-433: The context of climate change covers human, natural, or managed systems. It looks at how they respond to both climate variability and extremes. It covers the ability of a system to adjust to climate change to moderate potential damages, to take advantage of opportunities, or to cope with consequences. Adaptive capacity is the ability to reduce the likelihood of negative impacts of climate-related hazards. It does this through

7560-684: 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

7665-403: 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

7770-427: 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

7875-401: 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

7980-444: 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

8085-610: 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

8190-842: 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. Climate change adaptation Climate change adaptation

8295-430: 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

8400-939: The face of rains and floods. They can help manage impacts and risks to people and nature. The four types of adaptation actions are infrastructural , institutional, behavioural and nature-based options. Some examples of these are building seawalls or inland flood defenses, providing new insurance schemes, changing crop planting times or varieties, and installing green roofs or green spaces. Adaptation can be reactive (responding to climate impacts as they happen) or proactive (taking steps in anticipation of future climate change). The need for adaptation varies from place to place. Different regions must adapt differently because they each face particular sets of climate risks . For instance, coastal regions might prioritize sea-level rise defenses and mangrove restoration. Arid areas could focus on water scarcity solutions, land restoration and heat management. The needs for adaptation will also depend on how much

8505-432: The financial impact of flooding and other extreme weather events. There is an increasing availability of such options. For example, index-based insurance is a new product which triggers payment when weather indices such as precipitation or temperature cross a threshold. It aims to help customers such as farmers deal with production risks. Access to reinsurance may make cities more resilient. Where there are failures in

8610-624: The food supply chain. Thus it can be a risk to food security and nutrition. Adaptation measures can review the production, processing and other handling practices of suppliers. Examples include further sorting to separate damaged products, drying the product for better storage or improved packaging. Other behaviour change options for retailers and consumers include accepting fruit and vegetables that appear less than perfect, redistributing food surpluses, and lowering prices on nearly expired food. Dietary change options in regions with excess consumption of calories include replacing meat and dairy foods with

8715-506: The frequency and severity of extreme weather events and disasters. So adaptation may include measures to increase preparedness and relevant disaster response capacities. For humans, adaptation aims to moderate or avoid harm, and to exploit opportunities. For natural systems, humans may intervene to help adjustment. The Paris Agreement of 2015 requires countries to keep global temperature rise this century to less than 2 °C above pre-industrial levels, and to pursue efforts to limit

8820-604: 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

8925-508: The global south. Behavioural adaptation is a change in the strategies, practices and actions that help to reduce risk. These can include protecting homes from flooding, protecting crops from drought, and adopting different income-earning activities. Behavioural change is the most common form of adaptation. Food waste spoilage increases with exposure to higher temperatures and humidity. It also increases with extreme events such as flooding and contamination. This can happen at different points in

9030-572: 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

9135-436: 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

9240-441: 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

9345-608: 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

9450-413: 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

9555-805: The national level, adaptation strategies appear in National Adaptation Plans (NAPS) and National Adaptation Programmes of Action ( NAPA ). They also occur in national climate change policies and strategies. These are at different levels of development in different countries and in cities. This is discussed further in the section below on "implementation". Cities, states, and provinces often have considerable responsibility in land use planning, public health, and disaster management. Institutional adaptation actions occur more frequently in cities than in other sectors. Some have begun to adapt to threats intensified by climate change, such as flooding, bushfires, heatwaves, and rising sea levels. Managing

9660-648: The private insurance market, the public sector can subsidize premiums. One study identified key equity issues for policy considerations: Government-subsidized insurance, such as the U.S. National Flood Insurance Program, comes under criticism for providing a perverse incentive to develop properties in hazardous areas. This increases overall risk. Insurance can also undermine other efforts such as property level protection and resilience to increase adaptation. Appropriate land-use policies can counter this behavioural effect. These policies limit new construction where there are current or future climate risks. They also encourage

9765-619: 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

9870-522: 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

9975-622: 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

10080-405: 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

10185-411: 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

10290-476: 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

10395-583: 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

10500-455: The section below "by type of climate change impact". Because of changes in extreme weather and sea level rise , due to climate change, the UN has recommended early warning systems as key elements of climate change adaptation and climate risk management . Flooding, cyclones and other rapidly changing weather events can make communities in coastal areas, along floodzones and reliant on agriculture very vulnerable to extreme events. To this end

10605-402: The temperature increase to 1.5 °C. Even if greenhouse gas emissions are stopped relatively soon, global warming and its effects will last many years. This is due to the inertia of the climate system . So both carbon neutrality ("net zero") and adaptation are necessary. The Global Goal on Adaptation was also established under the Paris Agreement. The specific targets and indicators for

10710-562: The way conditions vary rather than changes in average conditions. For example, the average sea level in a port might not be as important as the height of water during a storm surge. That is because a storm surge can cause flooding. The average rainfall in an area might not be as important as how frequent and severe droughts and extreme precipitation events become. Climate change contributes to disaster risk. So experts sometimes see climate change adaptation as one of many processes within disaster risk reduction . In turn, disaster risk reduction

10815-454: The work. In the food production sector, adaptation projects financed through the UNFCCC often include coordination between national governments and administrations at the state, provincial or city level. There are fewer examples of coordination between community-level and national government. Individuals and households play a central role in adaptation. There are many examples particularly in

10920-438: 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

11025-524: 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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