effects of climate change effects of climate change climate change affects the physical environment, ecosystems and human societies. changes in the climate system include an overall warming trend, more extreme weather and rising sea levels. these in turn impact nature and wildlife, as well as human settlements and societies. the effects of human-caused climate change are broad and far-reaching, especially if significant climate action is not taken. the projected and observed negative impacts of climate change are sometimes referred to as the climate crisis. some climate change effects, clockwise from top left: wildfire caused by heat and dryness, bleached coral caused by ocean acidification and heating, coastal flooding caused by storms and sea level rise, and environmental migration caused by desertification the primary causes and the wide-ranging impacts: 3–36 of climate change. some effects act as feedbacks that intensify climate change. 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 is warming faster than most other regions. among the effects of climate change on oceans are an increase of ocean temperatures, a rise in sea level from ocean warming and ice sheet melting, increased ocean stratification, and changes to ocean currents including a weakening of the atlantic meridional overturning circulation.: 10 carbon dioxide from the atmosphere is acidifiying the ocean. recent warming has strongly affected natural biological systems. it has degraded land by raising temperatures, drying soils and increasing wildfire risk.: 9 species worldwide are migrating poleward to colder areas. on land, many species move to higher ground, whereas marine species seek colder water at greater depths. at 2 °c (3.6 °f) of warming, around 10% of species on land would become critically endangered.: 259 food security 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 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 affected include agriculture, fisheries, forestry, energy, insurance, and tourism. some groups may be particularly at risk from climate change, such as the poor, women, children and indigenous peoples. climate change can lead to displacement and changes in migration flows. changes in temperature average surface air temperatures from 2011 to 2021 compared to the 1956–1976 average. source: nasa global warming affects all elements of earth's climate system. global surface temperatures have risen by 1.1 °c (2.0 °f) and are expected to rise further in the future. 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 is warming faster than most other regions. in addition, 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. 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, ice cores, corals, and ocean and lake sediments. these show that recent temperatures have surpassed anything in the last 2,000 years. by the end of the 21st century, temperatures may increase to a level not experienced since the mid-pliocene, around 3 million years ago. at that time, mean global temperatures were about 2–4 °c (3.6–7.2 °f) warmer than pre-industrial temperatures, and the global mean sea level was up to 25 meters higher than it is today. the modern observed rise in temperature and co2 concentrations has been so rapid that even abrupt geophysical events in earth's history do not approach current rates.projected temperature and sea-level rise relative to the 2000–2019 mean for rcp climate change scenarios up to 2500.how much the world warms depends on human greenhouse gas emissions and how sensitive the climate is to greenhouse gases. the more carbon dioxide (co2) emitted in the 21st century the hotter the world will be by 2100. for a doubling of greenhouse gas concentrations, the global mean temperature would rise by about 2.5–4 °c (4.5–7.2 °f). if emissions of co2 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 co2 would 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. mitigation policies currently in place will result in about 2.7 °c (2.0–3.6 °c) warming above pre-industrial levels by 2100. if all unconditional pledges and targets made by governments are achieved, the temperature will rise by around 2.4 °c (4.3 °f). if additionally all the countries that have set or are considering setting net-zero targets achieve them, the temperature will rise by around 1.8 °c (3.2 °f). there is a substantial gap between national plans and commitments and actions so far taken by governments around the world. weather the lower and middle atmosphere, where nearly all of the weather occurs, are heating due to the enhanced greenhouse effect. as temperatures increase, so does evaporation and atmospheric moisture content. as water vapour is also a greenhouse gas, this process acts as a self-reinforcing feedback. the excess water vapour also gets caught up in storms and makes them more intense, larger, and potentially longer-lasting. this in turn causes rain and snow events to become stronger and leads to increased risk of flooding. extra drying worsens natural dry spells and droughts, and increases risk of heat waves and wildfires. with recent climate trends clearly identified as caused by human activities, extreme event attribution estimates the impact of climate change on extreme weather events. for instance, such research can demonstrate that a specific heatwave was more intense due to climate change based on historical data for that region. heat waves and temperature extremes large increases in both the frequency and intensity of extreme weather events (for increasing degrees of global warming) are expected.: 18 map of increasing heatwave trends (frequency and cumulative intensity) over the midlatitudes and europe, july–august 1979–2020. heatwaves over land have become more frequent and more intense in almost all world regions since the 1950s, due to climate change. furthermore, heat waves are more likely to occur simultaneously with droughts. and marine heatwaves are twice as likely as they were in 1980. climate change will lead to more very hot days and fewer very cold days.: 7 there are fewer cold waves.: 8 the intensity of individual heat waves can often be attributed to global warming. some extreme events would have been nearly impossible without human influence on the climate system. a heatwave that would occur once every ten years before global warming started, now occurs 2.8 times as often. under further warming, heatwaves are set to become more frequent. an event that would occur each ten year, would occur every other year if global warming reaches 2 °c (3.6 °f). heat stress is not only related to temperature, but also increases if humidity is higher. the wet-bulb temperature measures both temperature and humidity. above a wet-bulb temperature of 35 °c (95 °f), this heat stress is beyond human adaptation, and can kill people. if global warming is kept below 1.5 or 2 °c (2.7 or 3.6 °f), this deadly heat and humidity can likely be avoided in most of the tropics, but there may still be negative health impacts. there is some evidence climate change leads to a weakening of the polar vortex, which would make the jet stream 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 arctic. rain warming increases global average precipitation (such as rain and snow).: 1057 higher temperatures lead to increased evaporation and surface drying. as the air warms it can hold more water - 7% more water vapour for every degree celsius.: 1057 changes have already been observed in the amount, intensity, frequency, and type of precipitation. overall, climate change is causing longer hot dry spells, broken by more intense heavy rainfall.: 151, 154 widespread increases in heavy precipitation have occurred even in places where total rain amounts have decreased. climate change has increased contrasts in rainfall amounts between wet and dry seasons: wet seasons are getting wetter and dry seasons are getting drier. in the northern high latitutes, warming has also caused an increase in the amount of snow and rain.: 1057 in the southern hemisphere, the rain associated with the storm tracks has shifted south. changes in monsoons vary a lot: more monsoon systems are becoming wetter than drier. in asia summer monsoons are getting wetter, whereas the west african monsoon is getting wetter over the central sahel, and drier in the far western sahel.: 1058 extreme storms new orleans submerged after hurricane katrina, september 2005 storms, including tropical cyclones and extratropical cyclones, become wetter under climate change. both the maximum and mean rainfall rates increase. this more extreme rainfall is also true for thunderstorms in some regions. furthermore, tropical cyclones and the storm tracks are moving poleward, so that some regions will see large changes in maximum wind speeds. there will likely be fewer tropical cyclones, but their strength is expected to increase. there has also been an increase in the number of tropical cyclones undergoing rapid intensification. impacts on land floods high tide flooding is increasing due to sea level rise, land subsidence, and the loss of natural barriers.long-term sea level rise occurs in addition to intermittent tidal flooding. noaa predicts different levels of sea level rise for coastlines within a single country. due to an increase in heavy rainfall events, floods are expected to become more severe when they do occur.: 1155 however, the interactions between rainfall and flooding are complex. there are some regions in which flooding is expected to become rarer. this depends on several factors, such as changes in rain and snowmelt, but also soil moisture.: 1156 for instance, climate change leaves soils drier in some areas, so they may absorb rainfall more quickly, leading to less flooding. however, dry soils can also become harder, causing heavy rainfall to runoff into rivers and lakes, which increases risks of flooding.: 1155 droughts a dry lakebed in california. in 2022, the state was experiencing its most serious drought in 1,200 years, worsened by climate change.climate change affects multiple factors associated with droughts, such as how much rain falls and how fast the rain evaporates again. warming over land increases the severity and frequency of droughts around much of the world.: 1057 in some tropical and subtropical regions of the world, there will likely be less rain due to global warming, making them more prone to drought. these regions where droughts are set to worsen are central america, the amazon and south-western south america, west and southern africa, as well as the mediterranean and south-western australia.: 1157 higher temperatures lead to increased evaporation, thus drying the soil and increasing plant stress, which will have impacts on agriculture. for this reason, even regions where overall rainfall is expected to remain relatively stable, such as central and northern europe, will experience these impacts.: 1157 without climate change mitigation, it is expected that around a third of land areas will experience moderate or more severe drought by 2100.: 1157 due to global warming droughts are more frequent and intense than in the past. their impacts are made worse because of increased water demand, population growth and urban expansion in many areas. land restoration, especially by agroforestry, can help reduce the impact of droughts. wildfires average u.s. acreage burned annually by wildfires has almost tripled in three decades.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. evidence from earth's past also shows more fire in warmer periods. climate change increases evaporation, which can