"Global warming" redirects here. For other uses, see Climate change


Tipping points and long-term impacts



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CLIMAGE CHANGE

Tipping points and long-term impacts
Greater degrees of global warming increase the risk of passing through 'tipping points'—thresholds beyond which certain impacts can no longer be avoided even if temperatures are reduced.[170][171] An example is the collapse of West Antarctic and Greenland ice sheets, where a temperature rise of 1.5 to 2 °C may commit the ice sheets to melt, although the time scale of melt is uncertain and depends on future warming.[172][173] Some large-scale changes could occur over a short time period, such as a shutdown of certain ocean currents like the Atlantic meridional overturning circulation (AMOC).[174] Tipping points can also include irreversible damage to ecosystems like the Amazon rainforest and coral reefs.[175]
The long-term effects of climate change on oceans include further ice melt, ocean warming, sea level rise, and ocean acidification.[176] On the timescale of centuries to millennia, the magnitude of climate change will be determined primarily by anthropogenic CO2 emissions. This is due to CO2's long atmospheric lifetime.[177] Oceanic CO2 uptake is slow enough that ocean acidification will continue for hundreds to thousands of years.[178] These emissions are estimated to have prolonged the current interglacial period by at least 100,000 years.[179] Sea level rise will continue over many centuries, with an estimated rise of 2.3 metres per degree Celsius (4.2 ft/°F) after 2000 years.[180]
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.[181] 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.[182] Climate change has contributed to the expansion of drier climate zones, such as the expansion of deserts in the subtropics.[183] The size and speed of global warming is making abrupt changes in ecosystems more likely.[184] Overall, it is expected that climate change will result in the extinction of many species.[185]
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.[186] 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.[187] Ocean acidification makes it harder for marine calcifying organisms such as musselsbarnacles and corals to produce shells and skeletons; and heatwaves have bleached coral reefs.[188] Harmful algal blooms enhanced by climate change and eutrophication lower oxygen levels, disrupt food webs and cause great loss of marine life.[189] Coastal ecosystems are under particular stress. Almost half of global wetlands have disappeared due to climate change and other human impacts.[190]


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