The effects of climate change impact the

physical environment A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale ...

, ecosystems and human societies. The environmental effects of climate change are broad and far-reaching. They affect the

water cycle The water cycle, also known as the hydrologic cycle or the hydrological cycle, is a biogeochemical cycle that describes the continuous movement of water on, above and below the surface of the Earth. The mass of water on Earth remains fairly co ...

, oceans,

sea The sea, connected as the world ocean or simply the ocean, is the body of salty water that covers approximately 71% of the Earth's surface. The word sea is also used to denote second-order sections of the sea, such as the Mediterranean Sea, ...

and land ice (

glaciers A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...

sea level Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardis ...

, as well as weather and climate extreme events. The changes in climate are not uniform across the Earth. In particular, most land areas have warmed faster than most ocean areas, and the

Arctic The Arctic ( or ) is a polar regions of Earth, polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada (Yukon, Northwest Territories, Nunavut), Danish Realm (Greenla ...

is warming faster than most other regions. The regional changes vary: at high latitudes it is the average temperature that is increasing, while for the oceans and tropics it is in particular the rainfall and the

where changes are observed. The magnitude of future impacts of

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...

can be reduced by

climate change mitigation Climate change mitigation is action to limit climate change by reducing emissions of greenhouse gases or removing those gases from the atmosphere. The recent rise in global average temperature is mostly caused by emissions from fossil fuels bu ...

and

adaptation In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the po ...

. Climate change has degraded land by raising temperatures, drying soils and increasing

wildfire A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identi ...

risk. Recent warming has strongly affected natural biological systems. Species worldwide are migrating poleward to colder areas. On land, many species move to higher elevations, whereas marine species seek colder water at greater depths. Between 1% and 50% of species on land were assessed to be at substantially higher risk of

extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the Endling, last individual of the species, although the Functional ext ...

due to climate change. Among the

effects of climate change on oceans Among the effects of climate change on oceans are: an increase in sea surface temperature as well as ocean temperatures at greater depths, more frequent marine heatwaves, a reduction in pH value, a rise in sea level from ocean warming and ic ...

are: an increase in

sea surface temperature Sea surface temperature (SST), or ocean surface temperature, is the ocean temperature close to the surface. The exact meaning of ''surface'' varies according to the measurement method used, but it is between and below the sea surface. Air mas ...

as well as ocean temperatures at greater depths, more frequent

marine heatwaves A marine heatwave (MHW) is a period of abnormally high temperatures relative to the average seasonal temperature in a particular region of a sea or ocean. Marine heatwaves are caused by a variety of factors, including shorter term weather phenomen ...

, a reduction in pH value, a rise in sea level from

ocean warming In oceanography and climatology, ocean heat content (OHC) is a term for the energy absorbed by the ocean, where it is stored for indefinite time periods as internal energy or enthalpy. The rise in OHC accounts for over 90% of Earth’s excess the ...

and ice sheet melting, sea ice decline in the Arctic, increased upper ocean stratification, reductions in oxygen levels, increased contrasts in salinity (salty areas becoming saltier and fresher areas becoming less salty), changes to

ocean currents An ocean current is a continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contou ...

including a weakening of the Atlantic meridional overturning circulation, and stronger tropical cyclones and monsoons. The uptake of carbon dioxide from the atmosphere is leading to

ocean acidification Ocean acidification is the reduction in the pH value of the Earth’s ocean. Between 1751 and 2021, the average pH value of the ocean surface has decreased from approximately 8.25 to 8.14. The root cause of ocean acidification is carbon dioxid ...

. All these changes have knock-on effects which disturb marine ecosystems.

Food security Food security speaks to the availability of food in a country (or geography) and the ability of individuals within that country (geography) to access, afford, and source adequate foodstuffs. According to the United Nations' Committee on World ...

and access to fresh water are at risk due to rising temperatures. Climate change has profound impacts on human health, directly via heat stress and indirectly via the spread of infectious diseases. The vulnerability and exposure of humans to climate change varies by

economic sector One classical breakdown of economic activity distinguishes three sectors: * Primary: involves the retrieval and production of raw-material commodities, such as corn, coal, wood or iron. Miners, farmers and fishermen are all workers in the p ...

and by country. Wealthy industrialised countries, which have emitted the most CO₂, have more resources and so are the least vulnerable to global warming. Economic sectors that are likely to be affected include

agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people ...

fisheries Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life; or more commonly, the site where such enterprise takes place ( a.k.a. fishing ground). Commercial fisheries include wild fisheries and fish farms, ...

forestry Forestry is the science and craft of creating, managing, planting, using, conserving and repairing forests, woodlands, and associated resources for human and environmental benefits. Forestry is practiced in plantations and natural stands. ...

energy In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of ...

insurance Insurance is a means of protection from financial loss in which, in exchange for a fee, a party agrees to compensate another party in the event of a certain loss, damage, or injury. It is a form of risk management, primarily used to hedge ...

financial services Financial services are the economic services provided by the finance industry, which encompasses a broad range of businesses that manage money, including credit unions, banks, credit-card companies, insurance companies, accountancy companies, ...

tourism Tourism is travel for pleasure or business; also the theory and practice of touring (disambiguation), touring, the business of attracting, accommodating, and entertaining tourists, and the business of operating tour (disambiguation), tours. Th ...

, and

recreation Recreation is an activity of leisure, leisure being discretionary time. The "need to do something for recreation" is an essential element of human biology and psychology. Recreational activities are often done for enjoyment, amusement, or plea ...

. Some groups may be particularly at risk from climate change, such as the poor,

women A woman is an adult female human. Prior to adulthood, a female human is referred to as a girl (a female child or Adolescence, adolescent). The plural ''women'' is sometimes used in certain phrases such as "women's rights" to denote female hum ...

children A child ( : children) is a human being between the stages of birth and puberty, or between the developmental period of infancy and puberty. The legal definition of ''child'' generally refers to a minor, otherwise known as a person younger ...

and

indigenous peoples Indigenous peoples are culturally distinct ethnic groups whose members are directly descended from the earliest known inhabitants of a particular geographic region and, to some extent, maintain the language and culture of those original people ...

. They also have much lower levels of capacity for coping with the effects of environmental change. Climate change can result in environmental migration, especially in developing countries where people are directly dependent on land for food. Even if global surface temperature is stabilized, sea levels will continue to rise and the ocean will continue to absorb excess heat from the atmosphere for many centuries.

Observed and future changes in temperature

Change in Average Temperature With Fahrenheit

Global warming affects all elements of Earth's climate system. Global surface temperatures have risen by 1 °C and are expected to rise further in the future.IPCC, 2013
Summary for Policymakers.
In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change p.20 Night-time temperatures have increased faster than daytime temperatures. The impact on the environment, wildlife, society and humanity depends on how much more the Earth warms., in . One of the methods scientists use to predict the effects of human-caused climate change is to investigate past natural changes in climate. To assess changes in Earth's past climate scientists have studied

tree rings Dendrochronology (or tree-ring dating) is the scientific method of chronological dating, dating tree rings (also called growth rings) to the exact year they were formed. As well as dating them, this can give data for dendroclimatology, the stud ...

ice core An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier. Since the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper ones, and an ice core contains ...

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and se ...

s, and ocean and lake sediments. These show that recent warming has surpassed anything in the last 2,000 years.The 20th century was the hottest in nearly 2,000 years, studies show
, 25 July 2019 By the end of the 21st century, temperatures may increase to a level not experienced since the mid-

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58 At that time, mean global temperatures were about 2–4 °C warmer than pre-industrial temperatures, and the global mean sea level was up to 25 meters higher than it is today.How much the world warms depends on what humans do or not to limit GHG emissions, and how sensitive the climate is to greenhouse gases. Scientists are pretty sure that with double the amount of GHG in the atmosphere the world would warm by 2.5 °C to 4 °C; but how much more humans will emit is less certain. The projected magnitude of warming by 2100 is closely related to the level of cumulative emissions over the 21st century (total emissions between 2000 and 2100). The higher the cumulative emissions over this time period, the greater the level of warming is projected to occur. , p.28. This publication is also available i
e-book format
If emissions of were to be abruptly stopped and no negative emission technologies deployed, the Earth's climate would not start moving back to its pre-industrial state. Instead, temperatures would stay elevated at the same level for several centuries. After about a thousand years, 20% to 30% of human-emitted will remain in the atmosphere, not taken up by the ocean or the land, committing the climate to a warmer state long after emissions have stopped.

Weather-related changes

The lower and middle atmosphere, where nearly all of the weather occurs, are heating due to the enhanced

greenhouse effect The greenhouse effect is a process that occurs when energy from a planet's host star goes through the planet's atmosphere and heats the planet's surface, but greenhouse gases in the atmosphere prevent some of the heat from returning directly ...

. Increased greenhouse gases cause the higher parts of the atmosphere, the

stratosphere The stratosphere () is the second layer of the atmosphere of the Earth, located above the troposphere and below the mesosphere. The stratosphere is an atmospheric layer composed of stratified temperature layers, with the warm layers of air h ...

, to cool. The heated atmosphere contains more water vapour, which is also a greenhouse gas and acts as a self-reinforcing feedback. As temperatures increase, so does evaporation and atmospheric moisture content that increases heating by trapping outgoing radiation. Excess water vapour gets caught up in storms and makes them more intense, larger, and potentially longer lasting, so that rain and snow events are stronger and increase risk of flooding. Extra drying worsens any natural dry spells and droughts, and increases risk of heat waves and wildfires. Climate change makes many aspects of weather more extreme, especially heat waves, drought, rain intensity, and storm size and intensity.. Global warming leads to an increase in

extreme weather Extreme weather or extreme climate events includes unexpected, unusual, severe, or unseasonal weather; weather at the extremes of the historical distribution—the range that has been seen in the past. Often, extreme events are based on a locat ...

events such as heat waves, droughts, cyclones, blizzards and rainstorms., in . Such events will continue to occur more often and with greater intensity. Extreme event attribution, also known as attribution science, is a field of study in

meteorology Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did no ...

and climate science that tries to measure how ongoing

directly affects recent

events.

Rain and snow

Warming by greenhouse gas forcing has increased contrasts in rainfall amounts between wet and dry seasons, meaning "wet seasons are getting wetter, dry seasons are getting drier". Over oceans, salty areas are getting saltier and other regions are becoming less saline. Warming has also resulted in a detectable increase in the precipitation of northern

high latitudes The polar regions, also called the frigid zones or polar zones, of Earth are the regions of the planet that surround its geographical poles (the North and South Poles), lying within the polar circles. These high latitudes are dominated by floa ...

. Higher temperatures lead to increased evaporation and surface drying. As the air warms, its water-holding capacity also increases, particularly over the oceans. Air can hold 7% more water vapour for every degree Celsius it is warmed. Changes have already been observed in the amount, intensity, frequency, and type of precipitation. Widespread increases in heavy precipitation have occurred even in places where total rain amounts have decreased. In the case of

precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...

, the rising temperatures and extra heat will "intensify" the Earth's

, which means it will increase evaporation. Increased atmospheric water vapour results in more frequent and intense downpours and causes stronger extended droughts in certain regions. As a result, storm-affected areas are likely to experience increases in precipitation and an increased risk of flooding. In contrast, areas far away from storm tracks are likely to experience less precipitation and an increased risk of drought. Overall, there is likely to be longer hot dry spells, broken by more intense heavy rainfalls (along the lines of the English proverb "it never rains but it pours!"). Changes in regional climate are expected to include greater temperature increases over land, with most warming at high northern latitudes, and least warming over the

Southern Ocean The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-smal ...

and parts of the North Atlantic Ocean.IPCC
Synthesis Report Summary for Policymakers

, in . Future changes in precipitation are expected to follow existing trends, with reduced precipitation over

subtropical The subtropical zones or subtropics are geographical and climate zones to the north and south of the tropics. Geographically part of the temperate zones of both hemispheres, they cover the middle latitudes from to approximately 35° north a ...

land areas, and increased precipitation at subpolar latitudes and some

equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can also ...

ial regions.

Heat waves and temperature extremes

20211109 Frequency of extreme weather for different degrees of global warming - bar chart IPCC AR6 WG1 SPM

Global heating boosts the probability of

events such as

heat wave A heat wave, or heatwave, is a period of excessively hot weather, which may be accompanied by high humidity, especially in oceanic climate countries. While definitions vary, a heat wave is usually measured relative to the usual climate in the ...

s where the daily maximum temperature exceeds the average maximum temperature by 5 °C (9 °F) for more than five consecutive days. In the last 30–40 years, heat waves with high humidity have become more frequent and severe. Extremely hot nights have doubled in frequency. The area in which extremely hot summers are observed has increased 50–100 fold. Heat waves with high humidity pose a big risk to human health while heat waves with low humidity lead to dry conditions that increase wildfires. The mortality from extreme heat is larger than the mortality from hurricanes, lightning, tornadoes, floods, and earthquakes together. It was estimated in 2013 that global warming had increased the probability of local record-breaking monthly temperatures worldwide by a factor of 5. This was compared to a baseline climate in which no global warming had occurred. Using a medium global warming scenario, they project that by 2040, the number of monthly heat records globally could be more than 12 times greater than that of a scenario with no long-term warming. Study results indicate that limiting global warming to 1.5 °C would prevent most of the tropics from reaching the wet-bulb temperature of the human physiological limit of 35 °C. Future climate change will include more very hot days and fewer very cold days. IPCC (2013), Table SPM.1, i
Summary for Policymakers, p. 5(archived PDF)
in The frequency, length and intensity of

s will very likely increase over most land areas. Higher growth in anthropogenic GHG emissions would cause more frequent and severe temperature extremes. Globally, cold waves have decreased in frequency. There is some evidence climate change leads to a weakening of the polar vortex, which would make the

jet stream Jet streams are fast flowing, narrow, meandering air currents in the atmospheres of some planets, including Earth. On Earth, the main jet streams are located near the altitude of the tropopause and are westerly winds (flowing west to east) ...

more wavy. This would lead to outbursts of very cold winter weather across parts of Eurasia and North America, as well as very warm air incursions into the

Tropical cyclones and storms

Weather-related impacts

Floods

A warming climate will intensify rainfall events. When floods occur in this warmer future, these floods will be more severe. Some regions will experience an increased in flooding, some a decrease. This depends on several factors, such as changes in snowmelt, soil moisture and rainfall. Flooding can be in the form of urban flooding, river flooding or coastal flooding, Sea level rise further increases risks of coastal flooding: if sea levels rise by a further 0.15 m, 20% more people will be exposed to a 1 in a 100 year coastal flood, assuming no population growth and no further adaptation. With an extra 0.75 m, this rises to a doubling of people exposed. Global warming makes bigger storm events more common due to an intensification of the water cycle. This increase in the frequency of large storm events would alter existing Intensity-Duration-Frequency curves (IDF curves) due to the change in frequency, but also by lifting and steepening the curves in the future.

Droughts

Climate change affects multiple factors associated with

drought A drought is defined as drier than normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, an ...

s, such as how much rain falls and how fast the rain evaporates again. Warming over land drives an increase in atmospheric evaporative demand which will increase the severity and frequency of droughts around much of the world. Scientists predict that in some regions of the world, there will be less rain in future due to global warming. These regions will therefore be more prone to drought in future: subtropical regions like the

Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on ...

southern Africa Southern Africa is the southernmost subregion of the African continent, south of the Congo and Tanzania. The physical location is the large part of Africa to the south of the extensive Congo River basin. Southern Africa is home to a number o ...

, south-western

Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

and south-western

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sou ...

, as well as tropical

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

, western Africa and the

Amazon basin The Amazon basin is the part of South America drained by the Amazon River and its tributaries. The Amazon drainage basin covers an area of about , or about 35.5 percent of the South American continent. It is located in the countries of Boli ...

. Physics dictates that higher temperatures lead to increased evaporation. The effect of this is soil drying and increased plant stress which will have impacts on agriculture. For this reason, even those regions where large changes in precipitation are not expected (such as

central Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known a ...

and northern Europe) will experience soil drying. The latest prediction of scientists in 2022 is that "If emissions of greenhouse gases are not curtailed, about a third of global land areas are projected to suffer from at least moderate drought by 2100". When droughts occur they are likely to be more intense than in the past. Due to limitations on how much data is available about drought in the past, it is often impossible to confidently attribute a specific drought to human-induced climate change. Some areas however, such as the

and

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

, already show the impacts of human activities. Their impacts are made worse because of increased water demand, population growth, urban expansion, and environmental protection efforts in many areas. The frequency and the duration of droughts have both increased: They increased by 29% from the year 2000 to 2022.Daniel Tsegai, Miriam Medel, Patrick Augenstein, Zhuojing Huang (2022
Drought in Numbers 2022 - restoration for readiness and resilience
United Nations Convention to Combat Desertification (UNCCD) The prediction is that by 2050 more than 75% of humanity will live in drought conditions.

Land restoration Land restoration, which may include renaturalisation or rewilding, is the process of ecological restoration of a site to a natural landscape and habitat, safe for humans, wildlife, and plant communities. Ecological destruction, to which land resto ...

, especially by agroforestry, can help reduce the impact of droughts. In 2019 the Intergovernmental Panel on Climate Change issued a

Special Report on Climate Change and Land The United Nations' Intergovernmental Panel on Climate Change's (IPCC) Special Report on Climate Change and Land (SRCCL), also known as the "Special Report on climate change, desertification, land degradation, sustainable land management, food s ...

. The main statements of the report include: Between 1960 and 2013 the area of drylands in drought increased by 1% per year. In 2015, around 500 million people lived in areas impacted by

desertification Desertification is a type of land degradation in drylands in which biological productivity is lost due to natural processes or induced by human activities whereby fertile areas become increasingly arid. It is the spread of arid areas caused ...

between the 1980s and 2000s. People who live in areas affected by land degradation and desertification are "increasingly negatively affected by climate change". In the past, there were some apparently conflicting results in the scientific literature about how drought is changing due to climate change. This was found to be mostly due to problems with collection and analysis of data, for example in the formulation of the Palmer Drought Severity Index (PDSI) and the data sets used to determine the evapotranspiration component. The accurate attribution of the causes of drought also requires accounting for natural variability, especially

El Niño Southern Oscillation EL, El or el may refer to: Religion * El (deity), a Semitic word for "God" People * EL (rapper) (born 1983), stage name of Elorm Adablah, a Ghanaian rapper and sound engineer * El DeBarge, music artist * El Franco Lee (1949–2016), American po ...

(ENSO) effects and better analysis of precipitation data.

Wildfires

Wildfire acres burned in the United States, OWID

Globally, climate change promotes the type of weather that makes wildfires more likely. In some areas, an increase of wildfires has been attributed directly to climate change. That warmer climate conditions pose more risks of wildfire is consistent with evidence from Earth's past: there was more fire in warmer periods, and less in colder climatic periods. Climate change increases evaporation, which can cause vegetation to dry out. When a fire starts in an area with very dry vegetation, it can spread rapidly. Higher temperatures can also make the fire season longer, the time period in which severe wildfires are most likely. In regions where snow is disappearing, the fire season may get particularly more extended. Even though weather conditions are raising the risks of wildfires, the total area burnt by wildfires has decreased globally. This is mostly the result of the conversion of

savanna A savanna or savannah is a mixed woodland- grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground ...

into croplands, after which there is less forest area that can burn. Prescribed burning, an indigenous practice in the US and Australia, can reduce the area burnt too, and may form an adaptation to increased risk. The carbon released from wildfires can further increase greenhouse gas concentrations. This feedback is not yet fully integrated into climate models.

Oceans

From 1850 until 2022, the ocean has absorbed 26 % of total anthropogenic emissions. CC-BY_icon

Text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License Emissions during the period 1850–2021 amounted to 670 ± 65 gigatons of carbon and were partitioned among the atmosphere (41 %), ocean (26 %), and land (31 %). Bleached coral (24577819729)

Ice and snow

The cryosphere, the area of the Earth covered by snow or ice, is extremely sensitive to changes in global climate. Northern Hemisphere average annual snow cover has declined in recent decades. This pattern is consistent with warmer global temperatures. Some of the largest declines have been observed in the

spring Spring(s) may refer to: Common uses * Spring (season), a season of the year * Spring (device), a mechanical device that stores energy * Spring (hydrology), a natural source of water * Spring (mathematics), a geometric surface in the shape of a h ...

and summer months. During the 21st century, snow cover is projected to continue its retreat in almost all regions.

Glaciers and ice sheets decline

Since the beginning of the twentieth century, there has been a widespread retreat of glaciers. The melting of the

Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland ...

and West Antarctic ice sheets will continue to contribute to sea level rise over long time-scales. The Greenland ice sheet loss is mainly driven by melt from the top, whereas Antarctic ice loss is driven by warm ocean water melting the

outlet glacier Glacier morphology, or the form a glacier takes, is influenced by temperature, precipitation, topography, and other factors. The goal of glacial morphology is to gain a better understanding of glaciated landscapes and the way they are shaped. Ty ...

s. Research on Antarctica published in 2022, including the first map of iceberg calving, doubles the previous estimates of loss from ice shelves. Future melt of the West Antarctic ice sheet is potentially abrupt under a high emission scenario, as a consequence of a partial collapse. Part of the ice sheet is grounded on

bedrock In geology, bedrock is solid rock that lies under loose material ( regolith) within the crust of Earth or another terrestrial planet. Definition Bedrock is the solid rock that underlies looser surface material. An exposed portion of be ...

below sea level, making it possibly vulnerable to the self-enhancing process of marine ice sheet instability. A further hypothesis is that ''marine ice cliff instability'' would also contribute to a partial collapse, but limited evidence is available for its importance. A partial collapse of the ice sheet would lead to rapid sea level rise and a local decrease in ocean salinity. It would be irreversible on a timescale between decades and millennia. In contrast to the West Antarctic ice sheet, melt of the

Greenland ice sheet The Greenland ice sheet ( da, Grønlands indlandsis, kl, Sermersuaq) is a vast body of ice covering , roughly near 80% of the surface of Greenland. It is sometimes referred to as an ice cap, or under the term ''inland ice'', or its Danish equi ...

is projected to be taking place more gradually over millennia. Sustained warming between 1 °C (low confidence) and 4 °C (medium confidence) would lead to a complete loss of the ice sheet, contributing 7 m to sea levels globally. The ice loss could become irreversible due to a further self-enhancing feedback: the elevation-surface mass balance feedback. When ice melts on top of the ice sheet, the elevation drops. As air temperature is higher at lower

altitude Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context ...

, this promotes further melt.

Sea ice changes

Sea ice reflects 50% to 70% of the incoming solar radiation, while 6% of the incoming solar energy is reflected by the ocean. With less solar energy, the sea ice absorbs and holds the surface colder, which can be a positive feedback toward climate change. As the climate warms, snow cover and sea ice extent decrease. Large-scale measurements of

sea-ice Sea ice arises as seawater freezes. Because ice is less dense than water, it floats on the ocean's surface (as does fresh water ice, which has an even lower density). Sea ice covers about 7% of the Earth's surface and about 12% of the world's oce ...

have only been possible since the satellite era. The age of the sea ice is an important feature of the state of the sea ice cover.

Arctic sea ice decline

Arctic sea ice began to decline at the beginning of the twentieth century but the rate is accelerating. Since 1979, satellite records indicate the decline in summer sea ice coverage has been about 13% per decade. The thickness of sea ice has also decreased by 66% or 2.0 m over the last six decades with a shift from permanent ice to largely seasonal ice cover. While ice-free summers are expected to be rare at 1.5 °C degrees of warming, they are set to occur at least once every decade at a warming level of 2.0 °C. The Arctic will likely become ice-free at the end of some summers before 2050.Fox-Kemper, B., H.T. Hewitt, C. Xiao, G. Aðalgeirsdóttir, S.S. Drijfhout, T.L. Edwards, N.R. Golledge, M. Hemer, R.E. Kopp, G. Krinner, A. Mix, D. Notz, S. Nowicki, I.S. Nurhati, L. Ruiz, J.-B. Sallée, A.B.A. Slangen, and Y. Yu, 2021
Chapter 9: Ocean, Cryosphere and Sea Level Change
I
Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change
[Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1211–1362, doi:10.1017/9781009157896.011.

Sea ice changes in Antarctica

The annual mean Antarctic sea ice area is not showing a clear downwards or upwards trend over the period of reliable satellite data starting in 1979. There are remaining uncertainties on how to interpret this data due to the limited observational records and discrepancies between modelled and observed results for the sea ice cover.

Permafrost thawing

The southern part of the

region (home to 4 million people) has experienced a temperature rise of 1 °C to 3 °C (1.8 °F to 5.4 °F) over the last 50 years. Canada,

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U ...

and Russia are experiencing initial melting of

permafrost Permafrost is ground that continuously remains below 0 °C (32 °F) for two or more years, located on land or under the ocean. Most common in the Northern Hemisphere, around 15% of the Northern Hemisphere or 11% of the global surface ...

. This may disrupt ecosystems and by increasing bacterial activity in the soil lead to these areas becoming carbon sources instead of carbon sinks. Eastern

Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part ...

's permafrost is gradually disappearing in the southern regions, leading to the loss of nearly 11% of Siberia's nearly 11,000 lakes since 1971. At the same time, western Siberia is at the initial stage where melting permafrost is creating new lakes, which will eventually start disappearing as in the east. Furthermore, permafrost melting will eventually cause methane release from melting permafrost peat bogs.

Wildlife and nature

Recent warming has strongly affected natural biological systems. Species worldwide are moving poleward to colder areas. On land, species may move to higher elevations, whereas marine species find colder water at greater depths. Of the drivers with the biggest global impact on

nature Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are ...

, climate change ranks third over the five decades before 2020, with only change in land use and sea use, and direct exploitation of organisms having a greater impact. The impacts of climate change in nature and nature's contributions to humans are projected to become more pronounced in the next few decades. Examples of climatic disruptions include fire, drought, pest infestation, invasion of species, storms, and

coral bleaching Coral bleaching is the process when corals become white due to various stressors, such as changes in temperature, light, or nutrients. Bleaching occurs when coral polyps expel the zooxanthellae ( dinoflagellates that are commonly referred to as ...

events. The stresses caused by climate change, added to other stresses on ecological systems (e.g. land conversion, land degradation,

harvest Harvesting is the process of gathering a ripe crop from the fields. Reaping is the cutting of grain or pulse for harvest, typically using a scythe, sickle, or reaper. On smaller farms with minimal mechanization, harvesting is the most l ...

ing, and

pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, th ...

), threaten substantial damage to or complete loss of some unique ecosystems, and

of some critically endangered species. Key interactions between species within ecosystems are often disrupted because species from one location do not move to colder habitats at the same rate, giving rise to rapid changes in the functioning of the ecosystem. Impacts include changes in regional rainfall patterns, earlier leafing of

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...

s and

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae excl ...

s over many regions; movements of species to higher latitudes and altitudes in the Northern Hemisphere; changes in

bird migration Bird migration is the regular seasonal movement, often north and south along a flyway, between breeding and wintering grounds. Many species of bird migrate. Migration carries high costs in predation and mortality, including from hunting b ...

s in Europe, North America and Australia; and shifting of the oceans'

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a cruc ...

and

fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the living hagfish, lampreys, and Chondrichthyes, cartilaginous and bony fish as we ...

from cold- to warm-adapted communities.

Ecosystems on land

Climate change has been estimated to be a major driver of biodiversity loss in cool

conifer Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All ext ...

forests,

s, mediterranean-climate systems,

tropical forest Tropical forests (a.k.a. jungle) are forested landscapes in tropical regions: ''i.e.'' land areas approximately bounded by the tropic of Cancer and Capricorn, but possibly affected by other factors such as prevailing winds. Some tropical fore ...

s, and the Arctic tundra., in . In other ecosystems,

land-use Land use involves the management and modification of natural environment or wilderness into built environment such as settlements and semi-natural habitats such as arable fields, pastures, and managed woods. Land use by humans has a long his ...

change may be a stronger driver of biodiversity loss, at least in the near-term. Beyond the year 2050, climate change may be the major driver for biodiversity loss globally. Climate change interacts with other pressures such as habitat modification, pollution and invasive species. Interacting with these pressures, climate change increases extinction risk for a large fraction of terrestrial and freshwater species. Between 1% and 50% of species in different groups were assessed to be at substantially higher risk of extinction due to climate change.

Amazon rainforest

20210331 Global tree cover loss - World Resources Institute

Rainfall that falls on the

Amazon rainforest The Amazon rainforest, Amazon jungle or ; es, Selva amazónica, , or usually ; french: Forêt amazonienne; nl, Amazoneregenwoud. In English, the names are sometimes capitalized further, as Amazon Rainforest, Amazon Forest, or Amazon Jungle. ...

is recycled when it evaporates back into the atmosphere instead of running off away from the rainforest. This water is essential for sustaining the rainforest. Due to deforestation the rainforest is losing this ability, exacerbated by climate change which brings more frequent droughts to the area. The higher frequency of droughts seen in the first two decades of the 21st century, as well as other data, signal that a tipping point from rainforest to

might be close. One study concluded that this ecosystem could enter a mode of a 50-years-long collapse to a savanna around 2021, after which it would become increasingly and disproportionally more difficult to prevent or reverse this shift.

Marine ecosystems

Marine heatwaves have seen an increased frequency and have widespread impacts on life in the oceans, such as mass dying events and

. Harmful algae blooms have increased in response to warming waters, loss of oxygen and

eutrophication Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phyt ...

. Between one-quarter and one-third of our fossil fuel emissions are consumed by the earth's oceans, which are now 30 percent more acidic than they were in pre-industrial times. This acidification poses a serious threat to aquatic life, particularly creatures such as oysters, clams, and coral with calcified shells or skeletons. Melting sea ice destroys habitat, including for

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular micr ...

that grows on its underside. It is likely that the oceans warmed faster between 1993 and 2017 compared to the period starting in 1969. Warm water coral reefs are very sensitive to global warming and

. Coral reefs provide a

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

for thousands of species and

ecosystem services Ecosystem services are the many and varied benefits to humans provided by the natural environment and healthy ecosystems. Such ecosystems include, for example, agroecosystems, forest ecosystem, grassland ecosystems, and aquatic ecosystems. ...

such as coastal protection and food. The resilience of reefs can be improved by curbing local pollution and overfishing, but 70–90% of today's warm water coral reefs will disappear even if warming is kept to 1.5 °C. Coral reefs are not the only framework organisms, organisms that build physical structures that form habitats for other sea creatures, affected by climate change:

mangroves A mangrove is a shrub or tree that grows in coastal saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evolution in sever ...

and

seagrass Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families ( Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae), all in the ...

are considered to be at moderate risk for lower levels of global warming according to the Special Report on the Ocean and Cryosphere in a Changing Climate.

Tipping points and irreversible impacts

Self-reinforcing feedbacks amplify climate change. The climate system exhibits "threshold behaviour" or tipping points when these feedbacks lead parts of the Earth system into a new state, such as the runaway loss of ice sheets or the destruction of forests. Tipping points are studied using data from Earth's distant past and by physical modelling. There is already moderate risk of global tipping points at 1 °C above pre-industrial temperatures, and that risk becomes high at 2.5 °C. Tipping points are "perhaps the most 'dangerous' aspect of future climate changes", leading to irreversible impacts on society. Many tipping points are interlinked, so that triggering one may lead to a cascade of effects, even well below 2 °C of warming. A 2018 study states that 45% of environmental problems, including those caused by climate change are interconnected and make the risk of a domino effect bigger. There are a number of climate change impacts on the environment that may be irreversible, at least over the timescale of many human generations. These include the large-scale singularities such as the melting of the Greenland and West Antarctic ice sheets, and changes to the Atlantic Meridional Overturning Circulation. In biological systems, the extinction of species would be an irreversible impact. In social systems, unique

culture Culture () is an umbrella term which encompasses the social behavior, institutions, and norms found in human societies, as well as the knowledge, beliefs, arts, laws, customs, capabilities, and habits of the individuals in these groups ...

s may be lost or the survival of endangered languages may be exacerbated due to climate change. For example, humans living on

atoll An atoll () is a ring-shaped island, including a coral rim that encircles a lagoon partially or completely. There may be coral islands or cays on the rim. Atolls are located in warm tropical or subtropical oceans and seas where corals can gro ...

islands face risks due to sea level rise, sea surface warming, and increased frequency and intensity of extreme weather events.

Health, food security and water security

Health

Food security

Climate change will impact agriculture and food production around the world due to the effects of elevated CO₂ in the atmosphere; higher temperatures; altered precipitation and

transpiration Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. Water is necessary for plants but only a small amount of water taken up by the roots is used for growth ...

regimes; increased frequency of extreme events; and modified weed, pest, and

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a g ...

pressure. Droughts result in crop failures and the loss of pasture for livestock. Loss and poor growth of livestock cause milk yield and meat production to decrease. The rate of

soil erosion Soil erosion is the denudation or wearing away of the upper layer of soil. It is a form of soil degradation. This natural process is caused by the dynamic activity of erosive agents, that is, water, ice (glaciers), snow, air (wind), plants, a ...

is 10–20 times higher than the rate of soil accumulation in agricultural areas that use no-till farming. In areas with tilling it is 100 times higher. Climate change makes this type of land degradation and desertification worse. Climate change is projected to negatively affect all four pillars of food security: not only how much food is available, but also how easy food is to access (prices), food quality and how stable the

food system The term food system describes the interconnected systems and processes that influence nutrition, food, health, community development, and agriculture. A food system includes all processes and infrastructure involved in feeding a population: growi ...

is. For example, climate change is already affecting the productivity of

wheat Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...

and other key staples. The availability, quality and stability of wines are impacted by shifts in temperature affecting the traditional range and practices of viniculture, and by

smoke taint Smoke taint is a broad term for a set of smoke imparted compounds found in affected wines, constituting a wine fault. Increasing incidences of smoke tainted wines are an important issue, given the recent occurrences of wildfires or bushfires in wine ...

from extreme fire events. In many areas,

have already seen their catch decrease because of global warming and changes in biochemical cycles. In combination with

overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing fish stock), resulting in t ...

, warming waters decrease the maximum catch potential. Global catch potential is projected to reduce further in 2050 by less than 4% if emissions are reduced strongly, and by about 8% for very high future emissions, with growth in the

Arctic Ocean The Arctic Ocean is the smallest and shallowest of the world's five major oceans. It spans an area of approximately and is known as the coldest of all the oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, a ...

Water security

Between 1.5 and 2.5 billion people live in areas with regular water security issues. If global warming would reach , water insecurity would affect about twice as many people. Water resources are projected to decrease in most dry subtropical regions and mid-latitudes, but increase in high latitudes. However, as streamflow becomes more variable, even regions with increased water resources can experience additional short-term

shortages In economics, a shortage or excess demand is a situation in which the demand for a product or service exceeds its supply in a market. It is the opposite of an excess supply ( surplus). Definitions In a perfect market (one that matches a ...

. The arid regions of India, China, the US and Africa are already seeing dry spells and drought impact water availability. Water resources can be affected by climate change in various ways. The total amount of

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does incl ...

available can change, for instance due to dry spells or droughts. Heavy rainfall and flooding can have an impact on water quality: pollutants can be transported into water bodies by the increased

surface runoff Surface runoff (also known as overland flow) is the flow of water occurring on the ground surface when excess rainwater, stormwater, meltwater, or other sources, can no longer sufficiently rapidly infiltrate in the soil. This can occur when t ...

. In coastal regions, more salt may find its way into water resources due to higher sea levels and more intense storms. Higher temperatures also directly degrade water quality: warm water contains less oxygen.

Economic impacts

20220712 Global economic damage due to greenhouse gas emissions - by country

Economic forecasts of the impact of global warming vary considerably. Researchers have warned that current economic modelling may seriously underestimate the impact of potentially catastrophic climate change, and point to the need for new models that give a more accurate picture of potential damages. Nevertheless, one 2018 study found that potential global economic gains if countries implement mitigation strategies to comply with the 2 °C target set at the Paris Agreement are in the vicinity of US$17 trillion per year up to 2100 compared to a very high emission scenario. Global losses reveal rapidly rising costs due to extreme weather events since the 1970s., in .

Socio-economic Socioeconomics (also known as social economics) is the social science that studies how economic activity affects and is shaped by social processes. In general it analyzes how modern societies progress, stagnate, or regress because of their loc ...

factors have contributed to the observed trend of global losses, such as population growth and increased

wealth Wealth is the abundance of valuable financial assets or physical possessions which can be converted into a form that can be used for transactions. This includes the core meaning as held in the originating Old English word , which is from an I ...

. Part of the growth is also related to regional climatic factors, e.g., changes in precipitation and flooding events. It is difficult to quantify the relative impact of socio-economic factors and climate change on the observed trend., p. 55, . The trend does, however, suggest increasing vulnerability of social systems to climate change.

Economic inequality

The_share_of_firms_whose_business_activities_have_been_affected_by_climate_change

Climate change has contributed towards global economic inequality. Wealthy countries in colder regions have either felt little overall economic impact from climate change, or possibly benefited, whereas poor hotter countries very likely grew less than if global warming had not occurred. The total economic impacts from climate change are difficult to estimate, but increase for higher temperature changes. For instance, total damages are estimated to be 90% less if global warming is limited to 1.5 °C compared to 3.66 °C, a warming level chosen to represent no mitigation. One study found a 3.5% reduction in global GDP by the end of the century if warming is limited to 3 °C, excluding the potential effect of tipping points. Another study noted that global economic impact is underestimated by a factor of two to eight when tipping points are excluded from consideration. In the Oxford Economics high emission scenario, a temperature rise of 2 degrees by 2050 would reduce global GDP by 2.5% – 7.5%. By the year 2100 in this case, the temperature would rise by 4 degrees, which could reduce the global GDP by 30% in the worst case.

Most affected sectors apart from agriculture and fisheries

Thermal power station A thermal power station is a type of power station in which heat energy is converted to electrical energy. In a steam-generating cycle heat is used to boil water in a large pressure vessel to produce high-pressure steam, which drives a stea ...

s (fossil fuel plants and nuclear power plants) depend on water to cool them. Not only is there increased demand for fresh water, but climate change can increase the likelihood of

and fresh water shortages. Another impact for thermal power plants, is that increasing the temperatures in which they operate reduces their efficiency and hence their output.Dr. Frauke Urban and Dr. Tom Mitchell 2011
Climate change, disasters and electricity generation
. London: Overseas Development Institute and

Institute of Development Studies The Institute of Development Studies (IDS) is a think tank affiliated with the University of Sussex in Brighton, England, and based on its campus in Falmer, East Sussex. It delivers research and teaching in the area of development studies, ...

Changes in the amount of river flow correlate with the amount of energy produced by a dam. The result of diminished river flow can be a power shortage in areas that depend heavily on hydroelectric power.

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

in particular, is vulnerable due to its having reliance on hydroelectricity as increasing temperatures, lower water flow, and alterations in the rainfall regime, could reduce total energy production by 7% annually by the end of the century. Oil and natural gas infrastructure is affected by the effects of climate change and the increased risk of disasters such as storm,

cyclone In meteorology, a cyclone () is a large air mass that rotates around a strong center of low atmospheric pressure, counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere as viewed from above (opposite to an an ...

s, flooding and

rising sea levels Rising may refer to: * Rising, a stage in baking - see Proofing (baking technique) *Elevation * Short for Uprising, a rebellion Film and TV * "Rising" (''Stargate Atlantis''), the series premiere of the science fiction television program ''Starg ...

Insurance Insurance is a means of protection from financial loss in which, in exchange for a fee, a party agrees to compensate another party in the event of a certain loss, damage, or injury. It is a form of risk management, primarily used to hedge ...

is an important tool to manage risks, but often unavailable to poorer households. Due to climate change, premiums are going up for certain types of insurance, such as flood insurance. Poor adaptation to climate change further widens the gap between what people can afford and the costs of insurance, as risks increase. In 2019, Munich Re noted that climate change could cause

home insurance Home insurance, also commonly called homeowner's insurance (often abbreviated in the US real estate industry as HOI), is a type of property insurance that covers a private residence. It is an insurance policy that combines various personal insu ...

to become unaffordable for households at or below average incomes. Roads, airport runways, railway lines and pipelines, (including

oil pipeline Pipeline transport is the long-distance transportation of a liquid or gas through a system of pipes—a pipeline—typically to a market area for consumption. The latest data from 2014 gives a total of slightly less than of pipeline in 120 count ...

s, sewers, water mains etc.) may require increased maintenance and renewal as they become subject to greater temperature variation. Regions already adversely affected include areas of

, which are subject to high levels of

subsidence Subsidence is a general term for downward vertical movement of the Earth's surface, which can be caused by both natural processes and human activities. Subsidence involves little or no horizontal movement, which distinguishes it from slope mov ...

, resulting in buckling roads, sunken foundations, and severely cracked runways.

Impacts on societies

Climate change impacts

health Health, according to the World Health Organization, is "a state of complete physical, mental and social well-being and not merely the absence of disease and infirmity".World Health Organization. (2006)''Constitution of the World Health Organ ...

, the availability of drinking water and food, inequality and economic growth. The effects of climate change are often interlinked and can exacerbate each other as well as existing vulnerabilities. The impacts are often exacerbated by related environmental disruptions and pressures such as

and biodiversity loss. Some areas may become too hot for humans to live in. People in some areas may experience internal or long-distance displacement (and thus become climate refugees) triggered by climate change related changes or disasters. The effects of climate change, in combination with the sustained increases in greenhouse gas emissions, have led scientists to characterize it as a "climate emergency" or " climate crisis". Some climate researchers and activists have called it an "existential threat to civilization".

Displacement and migration

Overlap between future population distribution and extreme heat

Climate change affects displacement of people in several ways. Firstly, involuntary displacement may increase through the increased number and severity of weather-related disasters which destroy homes and habitats. Effects of climate change such as

and

gradually erode livelihood and force communities to abandon traditional homelands for more accommodating environments. On the other hand, some households may fall (further) into poverty due to climate change, limiting their ability to move to areas less affected. According to the Internal Displacement Monitoring Centre in 2020 approximately 30 million people were displaced by extreme weather events while approximately 10 million by violence and wars and climate change significantly contributed to this. The United Nations says there are already 64 million migrants in the world fleeing wars, hunger, persecution and the effects of global warming. In 2018, the World Bank estimated that climate change will cause internal migration of between 31 and 143 million people as they escape crop failures, water scarcity, and sea level rise. The study only included Sub-Saharan Africa, South Asia, and Latin America. Majuro_-_Main_Atoll_of_the_RMI

Asia and the Pacific is the global area most prone to natural disasters, both in terms of the absolute number of disasters and of populations affected. It is highly exposed to climate impacts, and is home to highly vulnerable population groups, who are disproportionately poor and marginalized. A 2015 Asian Development Bank report highlights "environmental hot spots" that are particular risk of flooding, cyclones, typhoons, and water stress. Gradual but pervasive environmental change and sudden natural disasters both influence the nature and extent of human migration but in different ways.

United Nations High Commissioner for Refugees The United Nations High Commissioner for Refugees (UNHCR) is a United Nations agency mandated to aid and protect refugees, forcibly displaced communities, and stateless people, and to assist in their voluntary repatriation, local integrati ...

stated that climate change increases mass displacement, in many regions, including

Sahel The Sahel (; ar, ساحل ' , "coast, shore") is a region in North Africa. It is defined as the ecoclimatic and biogeographic realm of transition between the Sahara to the north and the Sudanian savanna to the south. Having a hot semi-arid cli ...

, East Africa, South Asia, the "drought corridor" in Latin America. 90% of refugees comes from "climate vulnerable hotspots". Some Pacific Ocean island nations, such as

Tuvalu Tuvalu ( or ; formerly known as the Ellice Islands) is an island country and microstate in the Polynesian subregion of Oceania in the Pacific Ocean. Its islands are situated about midway between Hawaii and Australia. They lie east-northea ...

Kiribati Kiribati (), officially the Republic of Kiribati ( gil, ibaberikiKiribati),Kiribati
''The Wor ...

, and the

Maldives Maldives (, ; dv, ދިވެހިރާއްޖެ, translit=Dhivehi Raajje, ), officially the Republic of Maldives ( dv, ދިވެހިރާއްޖޭގެ ޖުމްހޫރިއްޔާ, translit=Dhivehi Raajjeyge Jumhooriyyaa, label=none, ), is an archipelag ...

, are considering the eventual possibility of evacuation, as flood defense may become economically unrealistic. Governments have considered various approaches to reduce migration compelled by environmental conditions in at-risk communities, including programs of social protection, livelihoods development, basic urban infrastructure development, and disaster risk management. Some experts support migration as an appropriate way for people to cope with environmental changes. However, this is controversial because migrants – particularly low-skilled ones – are among the most vulnerable people in society and are often denied basic protections and access to services. Slow-onset disasters and gradual environmental erosion such as desertification, reduction of soil fertility, coastal erosion and sea-level rise are likely to induce long-term migration. Migration related to desertification and reduced soil fertility is likely to be predominantly from

rural area In general, a rural area or a countryside is a geographic area that is located outside towns and cities. Typical rural areas have a low population density and small settlements. Agricultural areas and areas with forestry typically are descr ...

s in

developing countries A developing country is a sovereign state with a lesser developed industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is also no clear agreem ...

to towns and cities., p. 109, .

Conflict

Climate change can worsen conflicts by exacerbating tensions over limited resources like

drinking water Drinking water is water that is used in drink or food preparation; potable water is water that is safe to be used as drinking water. The amount of drinking water required to maintain good health varies, and depends on physical activity level, ...

(in the case of water conflicts). Climate change also has the potential to cause large population dislocations and migration, which can also lead to increased tensions. However, factors other than climate change are judged to be substantially more important in affecting conflict. These factors include intergroup inequality and low socio-economic development. In some cases, climate change can even lead to more peaceful relationships between groups, as environmental problems requires common policy to be developed. Global warming has been described as a "threat multiplier". Certain conditions make it more likely that climate change impacts conflict: ethnic exclusion, an economy dependent on agriculture, insufficient infrastructure, poor local governance, and low levels of development. A spike in wheat prices following crop losses from a period of drought may have contributed to the onset of the "

Arab Spring The Arab Spring ( ar, الربيع العربي) was a series of anti-government protests, uprisings and armed rebellions that spread across much of the Arab world in the early 2010s. It began in Tunisia in response to corruption and econo ...

" protests and revolutions in 2010.

Social impacts on vulnerable groups

The impacts of climate change on humans are not distributed uniformly within communities. Individual and social factors such as gender, age, education, ethnicity, geography and language lead to differential vulnerability and capacity to adapt to the effects of climate change. The following more vulnerable groups have been identified: * People living in poverty: Climate change disproportionally affects poor people in low-income communities and

around the world. Those in poverty have a higher chance of experiencing the ill-effects of climate change due to the increased exposure and vulnerability. A 2020 World Bank paper estimated that between 32 million to 132 million additional people will be pushed into

extreme poverty Extreme poverty, deep poverty, abject poverty, absolute poverty, destitution, or penury, is the most severe type of poverty, defined by the United Nations (UN) as "a condition characterized by severe deprivation of basic human needs, includi ...

by 2030 due to climate change. *

Women A woman is an adult female human. Prior to adulthood, a female human is referred to as a girl (a female child or Adolescence, adolescent). The plural ''women'' is sometimes used in certain phrases such as "women's rights" to denote female hum ...

: Climate change increases gender inequality, reduces women's ability to be financially independent, and has an overall negative impact on the social and political rights of women, especially in economies that are heavily based on agriculture. *

Indigenous peoples Indigenous peoples are culturally distinct ethnic groups whose members are directly descended from the earliest known inhabitants of a particular geographic region and, to some extent, maintain the language and culture of those original people ...

: Indigenous communities geographically tend to be located in regions more vulnerable to climate change such as native

rainforest Rainforests are characterized by a closed and continuous tree canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforest can be classified as tropical rainforest or temperate rainfores ...

s, the

, and coastal areas. Indigenous communities across the globe generally have economic disadvantages that are not as prevalent in non-indigenous communities due to the ongoing oppression they have experienced. These disadvantages include lower education levels and higher rates of poverty and unemployment, which add to their vulnerability to climate change. *

Children A child ( : children) is a human being between the stages of birth and puberty, or between the developmental period of infancy and puberty. The legal definition of ''child'' generally refers to a minor, otherwise known as a person younger ...

: The Lancet review on health and climate change lists children as the worst-affected category by climate change. Children are also 14–44 percent more likely to die from environmental factors, again leaving them the most vulnerable. Those in urban areas will be affected by lower air quality and overcrowding, and will struggle the most to better their situation. *

Racial minorities The term 'minority group' has different usages depending on the context. According to its common usage, a minority group can simply be understood in terms of demographic sizes within a population: i.e. a group in society with the least number o ...

: The

environmental justice Environmental justice is a social movement to address the unfair exposure of poor and marginalized communities to harms from hazardous waste, resource extraction, and other land uses.Schlosberg, David. (2007) ''Defining Environmental Justi ...

(EJ) movement and

climate justice Climate justice is a concept that addresses the just division, fair sharing, and equitable distribution of the burdens of climate change and its mitigation and responsibilities to deal with climate change. "Justice", "fairness", and "equity" ar ...

(CJ) movement address environmental racism in bringing attention and enacting change so that marginalized populations are not disproportionately vulnerable to climate change and

Human settlements

A major challenge for human settlements is

sea level rise Globally, sea levels are rising due to human-caused climate change. Between 1901 and 2018, the globally averaged sea level rose by , or 1–2 mm per year on average.IPCC, 2019Summary for Policymakers InIPCC Special Report on the Ocean and Cr ...

, indicated by ongoing observation and research of rapid declines in ice-mass balance from both Greenland and Antarctica. Estimates for 2100 are at least twice as large as previously estimated by IPCC AR4, with an upper limit of about two meters. Depending on regional changes, increased precipitation patterns can cause more flooding or extended drought stresses water resources. A 2020 study projects that regions inhabited by a third of the human population could become as hot as the hottest parts of the

Sahara , photo = Sahara real color.jpg , photo_caption = The Sahara taken by Apollo 17 astronauts, 1972 , map = , map_image = , location = , country = , country1 = , ...

within 50 years without a change in patterns of population growth and without migration, unless greenhouse gas emissions are reduced. The projected annual average temperature of above 29 °C for these regions would be outside the "human temperature niche" – a suggested range for climate biologically suitable for humans based on historical data of mean annual temperatures (MAT) – and the most affected regions have little adaptive capacity as of 2020. In small islands and megadeltas, inundation as a result of

is expected to threaten vital infrastructure and human settlements. This could lead to issues of

statelessness In international law, a stateless person is someone who is "not considered as a national by any state under the operation of its law". Some stateless people are also refugees. However, not all refugees are stateless, and many people who are s ...

for populations in countries such as the

and

homelessness Homelessness or houselessness – also known as a state of being unhoused or unsheltered – is the condition of lacking stable, safe, and adequate housing. People can be categorized as homeless if they are: * living on the streets, also kn ...

in countries with low-lying areas such as

Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mo ...

. In 1991, 140,000 people died and the 10 million became homeless when the floods hit Bangladesh. In Myanmar, the storm killed 146,000 people which was hit in 2007. Climate change threatens the health and survival of urban trees and the various benefits they deliver to urban inhabitants.

Projections for cities in 2050

In 2019 the Crowther Lab from ETH

Zürich , neighboring_municipalities = Adliswil, Dübendorf, Fällanden, Kilchberg, Maur, Oberengstringen, Opfikon, Regensdorf, Rümlang, Schlieren, Stallikon, Uitikon, Urdorf, Wallisellen, Zollikon , twintowns = Kunming, San Francisco Z ...

paired the climatic conditions of 520 major cities worldwide with the predicted climatic conditions of cities in 2050. 22% of the major cities are predicted to have climatic conditions that do not exist in any city today. 2050

London London is the capital and List of urban areas in the United Kingdom, largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary dow ...

will have a climate similar to 2019

Melbourne Melbourne ( ; Boonwurrung/ Woiwurrung: ''Narrm'' or ''Naarm'') is the capital and most populous city of the Australian state of Victoria, and the second-most populous city in both Australia and Oceania. Its name generally refers to a metro ...

Athens Athens ( ; el, Αθήνα, Athína ; grc, Ἀθῆναι, Athênai (pl.) ) is both the capital and largest city of Greece. With a population close to four million, it is also the seventh largest city in the European Union. Athens dominates a ...

and

Madrid Madrid ( , ) is the capital and most populous city of Spain. The city has almost 3.4 million inhabitants and a metropolitan area population of approximately 6.7 million. It is the second-largest city in the European Union (EU), and ...

Fez, Morocco Fez or Fes (; ar, فاس, fās; zgh, ⴼⵉⵣⴰⵣ, fizaz; french: Fès) is a city in northern inland Morocco and the capital of the Fès-Meknès administrative region. It is the second largest city in Morocco, with a population of 1.11 m ...

Nairobi Nairobi ( ) is the capital and largest city of Kenya. The name is derived from the Maasai phrase ''Enkare Nairobi'', which translates to "place of cool waters", a reference to the Nairobi River which flows through the city. The city proper ...

Maputo Maputo (), formerly named Lourenço Marques until 1976, is the capital, and largest city of Mozambique. Located near the southern end of the country, it is within of the borders with Eswatini and South Africa. The city has a population of 1,0 ...

. The Indian city

Pune Pune (; ; also known as Poona, ( the official name from 1818 until 1978) is one of the most important industrial and educational hubs of India, with an estimated population of 7.4 million As of 2021, Pune Metropolitan Region is the largest i ...

will be like

Bamako Bamako ( bm, ߓߡߊ߬ߞߐ߬ ''Bàmakɔ̌'', ff, 𞤄𞤢𞤥𞤢𞤳𞤮 ''Bamako'') is the capital and largest city of Mali, with a 2009 population of 1,810,366 and an estimated 2022 population of 2.81 million. It is located on the Niger Rive ...

Mali Mali (; ), officially the Republic of Mali,, , ff, 𞤈𞤫𞤲𞥆𞤣𞤢𞥄𞤲𞤣𞤭 𞤃𞤢𞥄𞤤𞤭, Renndaandi Maali, italics=no, ar, جمهورية مالي, Jumhūriyyāt Mālī is a landlocked country in West Africa. Ma ...

, Bamako will be like Niamey in

Niger ) , official_languages = , languages_type = National languagesBrasilia will be like Goiania. Increased extreme heat exposure from both climate change and the urban heat island effect threatens urban settlements.

Especially affected regions

The

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

, small islands,

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

n megadeltas and the Middle East are regions that are likely to be especially affected by climate change., in . Low-latitude, less-developed regions are at most risk of experiencing negative impacts due to climate change. The ten countries of the

Association of Southeast Asian Nations ASEAN ( , ), officially the Association of Southeast Asian Nations, is a political and economic union of 10 member states in Southeast Asia, which promotes intergovernmental cooperation and facilitates economic, political, security, mi ...

(ASEAN) are among the most vulnerable in the world to the negative effects of climate change, however, ASEAN's climate mitigation efforts are not commensurate with the climate change threats the region faces.

is one of the most vulnerable continents to climate variability and change because of multiple existing stresses and low adaptive capacity. Climate change is projected to decrease

availability in central, south, east and southeast Asia, particularly in large

river basin A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, ...

s. With

population growth Population growth is the increase in the number of people in a population or dispersed group. Actual global human population growth amounts to around 83 million annually, or 1.1% per year. The global population has grown from 1 billion in 1800 to ...

and increasing demand from higher standards of living, this decrease could adversely affect more than a billion people by the 2050s. Small islands, whether located in the tropics or higher latitudes, are already exposed to extreme weather events and changes in sea level. This existing exposure will likely make these areas sensitive to the effects of climate change.

Developed countries A developed country (or industrialized country, high-income country, more economically developed country (MEDC), advanced country) is a sovereign state that has a high quality of life, developed economy and advanced technological infrastruct ...

are also vulnerable to climate change, and have already been negatively affected by increases in the severity and frequency of some

events, such as heat waves, floods, wildfires, and tropical cyclones.

Low-lying coastal regions

Cyclone Nargis flooding before-and-after

For historical reasons to do with

trade Trade involves the transfer of goods and services from one person or entity to another, often in exchange for money. Economists refer to a system or network that allows trade as a market. An early form of trade, barter, saw the direct exc ...

, many of the world's largest and most prosperous cities are on the

coast The coast, also known as the coastline or seashore, is defined as the area where land meets the ocean, or as a line that forms the boundary between the land and the coastline. The Earth has around of coastline. Coasts are important zones in n ...

. In developing countries, the poorest often live on

floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...

s, because it is the only available space, or fertile agricultural land. These settlements often lack infrastructure such as dykes and early warning systems. Poorer communities also tend to lack the insurance, savings, or access to credit needed to recover from disasters. Socioeconomic impacts of climate change in coastal and low-lying areas will be overwhelmingly adverse. The following impacts were projected in 2007 with very high confidence: *Coastal and low-lying areas would be exposed to increasing risks including coastal erosion due to climate change and sea level rise. *By the 2080s, millions of people would experience floods every year due to sea level rise. The numbers affected were projected to be largest in the densely populated and low-lying mega-deltas of Asia and Africa; and smaller islands were judged to be especially vulnerable. Given high coastal

population density Population density (in agriculture: standing stock or plant density) is a measurement of population per unit land area. It is mostly applied to humans, but sometimes to other living organisms too. It is a key geographical term.Matt RosenberPopu ...

, estimates of the number of people at risk of coastal flooding from climate-driven sea-level rise varies from 190 million, to 300 million or even 640 million in a worst-case scenario related to the instability of the Antarctic ice sheet. The most people affected are in the densely-populated and low-lying megadeltas of Asia and Africa. The Greenland ice sheet is estimated to have reached a point of no return, continuing to melt even if warming stopped. Over time that would submerge many of the world's coastal cities including low-lying islands, especially combined with

storm surges A storm surge, storm flood, tidal surge, or storm tide is a coastal flood or tsunami-like phenomenon of rising water commonly associated with low-pressure weather systems, such as cyclones. It is measured as the rise in water level above the no ...

and high tides.

Small islands

Small islands developing states are especially vulnerable to the effects of climate change, especially sea level rise. They are expected to experience more intense storm surges, salt water intrusion, and coastal destruction. Low-lying small islands in the Pacific, Indian, and Caribbean regions are at risk of permanent inundation and population displacement. On the islands of

Fiji Fiji ( , ,; fj, Viti, ; Fiji Hindi: फ़िजी, ''Fijī''), officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consis ...

Tonga Tonga (, ; ), officially the Kingdom of Tonga ( to, Puleʻanga Fakatuʻi ʻo Tonga), is a Polynesian country and archipelago. The country has 171 islands – of which 45 are inhabited. Its total surface area is about , scattered over in ...

and western

Samoa Samoa, officially the Independent State of Samoa; sm, Sāmoa, and until 1997 known as Western Samoa, is a Polynesian island country consisting of two main islands ( Savai'i and Upolu); two smaller, inhabited islands ( Manono and Apolima); ...

, concentrations of migrants from outer islands inhabit low and unsafe areas along the coasts.

Atoll An atoll () is a ring-shaped island, including a coral rim that encircles a lagoon partially or completely. There may be coral islands or cays on the rim. Atolls are located in warm tropical or subtropical oceans and seas where corals can gro ...

nations, which include countries that are composed entirely of the smallest form of islands, called motus, are at risk of entire population displacement. These nations include

Kiribati Kiribati (), officially the Republic of Kiribati ( gil, ibaberikiKiribati),Kiribati
''The Wor ...

, the

Marshall Islands The Marshall Islands ( mh, Ṃajeḷ), officially the Republic of the Marshall Islands ( mh, Aolepān Aorōkin Ṃajeḷ),'' () is an independent island country and microstate near the Equator in the Pacific Ocean, slightly west of the Inte ...

, Tokelau, and

. Vulnerability is increased by small size, isolation from other land, low financial resources, and lack of protective infrastructure. A study that engaged the experiences of residents in atoll communities found that the cultural identities of these populations are strongly tied to these lands. Human rights activists argue that the potential loss of entire atoll countries, and consequently the loss of national sovereignty, self-determination, cultures, and indigenous lifestyles cannot be compensated for financially. Some researchers suggest that the focus of international dialogues on these issues should shift from ways to relocate entire communities to strategies that instead allow for these communities to remain on their lands.

Possibility of societal collapse

Several researchers have suggested that collapse of the current societal organization – the contemporary global, interconnected

civilization A civilization (or civilisation) is any complex society characterized by the development of a state, social stratification, urbanization, and symbolic systems of communication beyond natural spoken language (namely, a writing system). ...

– could occur at 3 degrees of warming, especially when considering that climate change is not the only environmental pressure and challenge humanity faces.

Possible responses

The magnitude of future impacts of

can be reduced by

and

. Mitigation policies currently in place will result in about 2.7 °C (2.0–3.6 °C, depending on how sensitive the climate is to greenhouse gas emissions) warming above pre-industrial levels. If all unconditional pledges and targets made by governments are achieved the temperature will rise by around 2.4 °C. If additionally all the countries that adopted or are considering to adopt net-zero targets will achieve it the temperature will rise by a median of 1.8 °C. There is a substantial gap between national plans and commitments and actions so far taken by governments around the world.

References

Sources

* (pb: ). * (pb: ). * . * . Summary for Policymaker
available
in Arabic, Chinese, French, Russian, and Spanish. *
Climate Change 2013 Working Group 1 website.
* . Archived * * * * * *

External links

IPCC Working Group I (WG I)

Intergovernmental Panel on Climate Change The Intergovernmental Panel on Climate Change (IPCC) is an intergovernmental body of the United Nations. Its job is to advance scientific knowledge about climate change caused by human activities. The World Meteorological Organization (WMO) ...

group which assesses the physical scientific aspects of the climate system and climate change.
Climate
from the

World Meteorological Organization The World Meteorological Organization (WMO) is a specialized agency of the United Nations responsible for promoting international cooperation on atmospheric science, climatology, hydrology and geophysics. The WMO originated from the Inter ...

Climate change
UN Department of Economic and Social Affairs Sustainable Development
Effects of climate change
from the

Met Office The Meteorological Office, abbreviated as the Met Office, is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy and is led by CEO Penelop ...

United Nations Environment Programme and climate change
Climate change and society Glob Articles containing video clips {{Authority control

Observed and future changes in temperature

Weather-related changes

Rain and snow

Heat waves and temperature extremes

Tropical cyclones and storms

Weather-related impacts

Floods

Droughts

Wildfires

Oceans

Ice and snow

Glaciers and ice sheets decline

Sea ice changes

Arctic sea ice decline

Sea ice changes in Antarctica

Permafrost thawing

Wildlife and nature

Ecosystems on land

Amazon rainforest

Marine ecosystems

Tipping points and irreversible impacts

Health, food security and water security

Health

Food security

Water security

Economic impacts

Economic inequality

Most affected sectors apart from agriculture and fisheries

Impacts on societies

Displacement and migration

Conflict

Social impacts on vulnerable groups

Human settlements

Projections for cities in 2050

Especially affected regions

Low-lying coastal regions

Small islands

Possibility of societal collapse

Possible responses

See also

References

Sources

External links