of 2.3 metres per degree celsius (4.2 ft/°f) after 2000 years. nature and wildlife further information: effects of climate change on oceans and effects of climate change on ecosystems recent warming has driven many terrestrial and freshwater species poleward and towards higher altitudes. higher atmospheric co2 levels and an extended growing season have resulted in global greening. however, heatwaves and drought have reduced ecosystem productivity in some regions. the future balance of these opposing effects is unclear. climate change has contributed to the expansion of drier climate zones, such as the expansion of deserts in the subtropics. the size and speed of global warming is making abrupt changes in ecosystems more likely. overall, it is expected that climate change will result in the extinction of many species. the oceans have heated more slowly than the land, but plants and animals in the ocean have migrated towards the colder poles faster than species on land. just as on land, heat waves in the ocean occur more frequently due to climate change, harming a wide range of organisms such as corals, kelp, and seabirds. ocean acidification makes it harder for marine calcifying organisms such as mussels, barnacles and corals to produce shells and skeletons; and heatwaves have bleached coral reefs. harmful algal blooms enhanced by climate change and eutrophication lower oxygen levels, disrupt food webs and cause great loss of marine life. coastal ecosystems are under particular stress. almost half of global wetlands have disappeared due to climate change and other human impacts. climate change impacts on the environment ecological collapse. coral bleaching from thermal stress has damaged the great barrier reef and threatens coral reefs worldwide. extreme weather. drought and high temperatures worsened the 2020 bushfires in australia. arctic warming. permafrost thaws undermine infrastructure and release methane, a greenhouse gas. habitat destruction. many arctic animals rely on sea ice, which has been disappearing in a warming arctic. pest propagation. mild winters allow more pine beetles to survive to kill large swaths of forest. humans main article: effects of climate change further information: effects of climate change on human health, climate security, economics of climate change, and effects of climate change on agriculture extreme weather will be progressively more common as the earth warms. the effects of climate change are impacting humans everywhere in the world. impacts can now be observed on all continents and ocean regions, with low-latitude, less developed areas facing the greatest risk. continued warming has potentially “severe, pervasive and irreversible impacts” for people and ecosystems. the risks are unevenly distributed, but are generally greater for disadvantaged people in developing and developed countries. food and health the who has classified climate change as the greatest threat to global health in the 21st century. extreme weather leads to injury and loss of life, and crop failures to malnutrition. various infectious diseases are more easily transmitted in a warmer climate, such as dengue fever and malaria. young children are the most vulnerable to food shortages. both children and older people are vulnerable to extreme heat. the world health organization (who) has estimated that between 2030 and 2050, climate change would cause around 250,000 additional deaths per year. they assessed deaths from heat exposure in elderly people, increases in diarrhea, malaria, dengue, coastal flooding, and childhood malnutrition. over 500,000 more adult deaths are projected yearly by 2050 due to reductions in food availability and quality. by 2100, 50% to 75% of the global population may face climate conditions that are life-threatening due to combined effects of extreme heat and humidity. climate change is affecting food security. it has caused reduction in global yields of maize, wheat, and soybeans between 1981 and 2010. future warming could further reduce global yields of major crops. crop production will probably be negatively affected in low-latitude countries, while effects at northern latitudes may be positive or negative. up to an additional 183 million people worldwide, particularly those with lower incomes, are at risk of hunger as a consequence of these impacts. climate change also impacts fish populations. globally, less will be available to be fished. regions dependent on glacier water, regions that are already dry, and small islands have a higher risk of water stress due to climate change. livelihoods economic damages due to climate change may be severe and there is a chance of disastrous consequences. climate change has likely already increased global economic inequality, and this trend is projected to continue. most of the severe impacts are expected in sub-saharan africa, where most of the local inhabitants are dependent upon natural and agricultural resources and south-east asia. the world bank estimates that climate change could drive over 120 million people into poverty by 2030. current inequalities based on wealth and social status have worsened due to climate change. major difficulties in mitigating, adapting, and recovering to climate shocks are faced by marginalized people who have less control over resources. indigenous people, who are subsistent on their land and ecosystems, will face endangerment to their wellness and lifestyles due to climate change. an expert elicitation concluded that the role of climate change in armed conflict has been small compared to factors such as socio-economic inequality and state capabilities. low-lying islands and coastal communities are threatened by sea level rise, which makes flooding more common. sometimes, land is permanently lost to the sea. this could lead to statelessness for people in island nations, such as the maldives and tuvalu. in some regions, the rise in temperature and humidity may be too severe for humans to adapt to. with worst-case climate change, models project that almost one-third of humanity might live in extremely hot and uninhabitable climates, similar to the current climate found in the sahara. these factors can drive environmental migration, both within and between countries. more people are expected to be displaced because of sea level rise, extreme weather and conflict from increased competition over natural resources. climate change may also increase vulnerability, leading to "trapped populations" who are not able to move due to a lack of resources. climate change impacts on people environmental migration. sparser rainfall leads to desertification that harms agriculture and can displace populations. shown: telly, mali (2008). agricultural changes. droughts, rising temperatures, and extreme weather negatively impact agriculture. shown: texas, us (2013). tidal flooding. sea-level rise increases flooding in low-lying coastal regions. shown: venice, italy (2004). storm intensification. bangladesh after cyclone sidr (2007) is an example of catastrophic flooding from increased rainfall. heat wave intensification. events like the 2022 southern cone heat wave are becoming more common. reducing and recapturing emissions global greenhouse gas emission scenarios, based on policies and pledges as of 11/21 climate change can be mitigated by reducing the rate at which greenhouse gases are emitted into the atmosphere, and by increasing the rate at which carbon dioxide is removed from the atmosphere. in order to limit global warming to less than 1.5 °c global greenhouse gas emissions needs to be net-zero by 2050, or by 2070 with a 2 °c target. this requires far-reaching, systemic changes on an unprecedented scale in energy, land, cities, transport, buildings, and industry. the united nations environment programme estimates that countries need to triple their pledges under the paris agreement within the next decade to limit global warming to 2 °c. an even greater level of reduction is required to meet the 1.5 °c goal. with pledges made under the paris agreement as of october 2021, global warming would still have a 66% chance of reaching about 2.7 °c (range: 2.2–3.2 °c) by the end of the century. globally, limiting warming to 2 °c may result in higher economic benefits than economic costs. although there is no single pathway to limit global warming to 1.5 or 2 °c, most scenarios and strategies see a major increase in the use of renewable energy in combination with increased energy efficiency measures to generate the needed greenhouse gas reductions. to reduce pressures on ecosystems and enhance their carbon sequestration capabilities, changes would also be necessary in agriculture and forestry, such as preventing deforestation and restoring natural ecosystems by reforestation. other approaches to mitigating climate change have a higher level of risk. scenarios that limit global warming to 1.5 °c typically project the large-scale use of carbon dioxide removal methods over the 21st century. there are concerns, though, about over-reliance on these technologies, and environmental impacts. solar radiation modification (srm) is also a possible supplement to deep reductions in emissions. however, srm would raise significant ethical and legal issues, and the risks are poorly understood. clean energy coal, oil, and natural gas remain the primary global energy sources even as renewables have begun rapidly increasing. wind and solar power, germany renewable energy is key to limiting climate change. fossil fuels accounted for 80% of the world's energy in 2018. the remaining share was split between nuclear power and renewables (including hydropower, bioenergy, wind and solar power and geothermal energy). that mix is projected to change significantly over the next 30 years. solar panels and onshore wind are now among the cheapest forms of adding new power generation capacity in many locations. renewables represented 75% of all new electricity generation installed in 2019, nearly all solar and wind. other forms of clean energy, such as nuclear and hydropower, currently have a larger share of the energy supply. however, their future growth forecasts appear limited in comparison. to achieve carbon neutrality by 2050, renewable energy would become the dominant form of electricity generation, rising to 85% or more by 2050 in some scenarios. investment in coal would be eliminated and coal use nearly phased out by 2050. electricity generated from renewable sources would also need to become the main energy source for heating and transport. transport can switch away from internal combustion engine vehicles and towards electric vehicles, public transit, and active transport (cycling and walking). for shipping and flying, low-carbon fuels would reduce emissions. heating could be increasingly decarbonised with technologies like heat pumps. there are obstacles to the continued rapid growth of clean energy, including renewables. for wind and solar, there are environmental and land use concerns for new projects. wind and solar also produce energy intermittently and with seasonal variability. traditionally, hydro dams with reservoirs and conventional power plants have been used when variable energy production is low. going forward, battery storage can be expanded, energy demand and supply can be matched, and long-distance transmission can smooth variability of renewable outputs. bioenergy is often not carbon-neutral and may have negative consequences for food security. the growth of nuclear power is constrained by controversy around radioactive waste, nuclear weapon proliferation, and accidents. hydropower growth is limited by the fact that the best sites have been developed, and new projects are confronting increased social and environmental concerns. low-carbon energy improves human health by minimising climate change. it also has the near-term benefit of reducing air pollution deaths, which were estimated at 7 million annually in 2016. meeting the paris agreement goals that limit warming to a 2 °c increase could save about a million of those lives per year by 2050, whereas limiting global warming to 1.5 °c could save millions and simultaneously increase energy security and reduce poverty. improving air quality also has economic benefits which may be larger than mitigation costs. energy conservation reducing energy demand is another major aspect of reducing emissions. if less energy is needed, there is more flexibility for clean energy development. it also makes it easier to manage the electricity grid, and minimises carbon-intensive infrastructure development. major increases in energy efficiency investment will be required to achieve climate goals, comparable to the level of investment in renewable energy. several covid-19 related changes in energy use patterns, energy efficiency investments, and funding have made forecasts for this decade more difficult and uncertain. strategies to reduce energy demand vary by sector. in transport, passengers and freight can switch to more efficient travel modes, such as buses and trains, or use electric vehicles. industrial strategies to reduce energy demand include improving heating systems and motors, designing less energy-intensive products, and increasing product lifetimes. in the building sector the focus is on better design of new buildings, and higher levels of energy efficiency in retrofitting. the use of technologies like heat pumps can also increase building energy efficiency. agriculture and industry taking