Global warming

2021-04-15T14:48:34Z

WikiWarrior:

'''Climate change''' includes both '''global warming''' driven by human emissions of [[greenhouse gas]]es and the resulting large-scale shifts in weather patterns. Though there have been [[Climate variability and change|previous periods of climatic change]], since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.<ref>{{Harvnb|IPCC AR5 WG1 Summary for Policymakers|2013|p=4|ps=: Warming of the climate system is unequivocal, and since the 1950s many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased}}; {{harvnb|IPCC SR15 Ch1|2018|p=54|ps=: Abundant empirical evidence of the unprecedented rate and global scale of impact of human influence on the Earth System (Steffen et al., 2016; Waters et al., 2016) has led many scientists to call for an acknowledgment that the Earth has entered a new geological epoch: the [[Anthropocene]].}}</ref>

The largest driver of warming is the [[Greenhouse gas emissions|emission of greenhouse gases]], of which more than 90% are [[carbon dioxide]] ({{CO2}}) and [[methane]].<ref>{{harvnb|EPA|2020|ps=: Carbon dioxide (76%), Methane (16%), Nitrous Oxide (6%).}}</ref> [[Fossil fuel]] burning ([[coal]], [[petroleum|oil]], and [[natural gas]]) for [[World energy consumption|energy consumption]] is the main source of these emissions, with additional contributions from agriculture, deforestation, and [[Industrial processes#Chemical processes by main basic material|manufacturing]].<ref>{{harvnb|EPA|2020|ps=: Carbon dioxide enters the atmosphere through burning fossil fuels (coal, natural gas, and oil), solid waste, trees and other biological materials, and also as a result of certain chemical reactions (e.g., manufacture of cement). Fossil fuel use is the primary source of {{CO2}}. {{CO2}} can also be emitted from direct human-induced impacts on forestry and other land use, such as through deforestation, land clearing for agriculture, and degradation of soils. Methane is emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from livestock and other agricultural practices and by the decay of organic waste in municipal solid waste landfills.}}</ref> The human cause of climate change is not disputed by any scientific body of national or international standing.<ref>{{cite web|title=Scientific Consensus: Earth's Climate is Warming|url=https://climate.nasa.gov/scientific-consensus/|url-status=live|archive-url=https://web.archive.org/web/20200328082109/https://climate.nasa.gov/scientific-consensus/|archive-date=28 March 2020|access-date=29 March 2020|work=Climate Change: Vital Signs of the Planet|publisher=[[NASA JPL]]}}; {{harvnb|Gleick, 7 January|2017}}.</ref> Temperature rise is accelerated or tempered by [[Climate change feedback|climate feedbacks]], such as loss of [[Albedo|sunlight-reflecting snow and ice cover]], increased [[Water vapor|water vapour]] (a greenhouse gas itself), and changes to [[Carbon sink|land and ocean carbon sinks]].

Temperature rise on land is about twice the global average increase, leading to desert expansion and more common [[heat wave]]s and [[wildfire]]s.<ref>{{harvnb|IPCC SRCCL|2019|p=7|ps=: Since the pre-industrial period, the land surface air temperature has risen nearly twice as much as the global average temperature (high confidence). Climate change... contributed to desertification and land degradation in many regions (high confidence).}}; {{harvnb|IPCC SRCCL|2019|p=45|ps=: Climate change is playing an increasing role in determining wildfire regimes alongside human activity (medium confidence), with future climate variability expected to enhance the risk and severity of wildfires in many biomes such as tropical rainforests (high confidence).}}</ref> Temperature rise is also [[polar amplification|amplified in the Arctic]], where it has contributed to melting [[permafrost]], [[retreat of glaciers since 1850|glacial retreat]] and sea ice loss.<ref>{{harvnb|IPCC SROCC|2019|p=16|ps=: Over the last decades, global warming has led to widespread shrinking of the cryosphere, with mass loss from ice sheets and glaciers (very high confidence), reductions in snow cover (high confidence) and Arctic sea ice extent and thickness (very high confidence), and increased permafrost temperature (very high confidence).}}</ref> Warmer temperatures are increasing rates of evaporation, causing [[Tropical cyclones and climate change|more intense storms]] and [[Extreme weather|weather extremes]].<ref name=":0" /> [[Climate change and ecosystems|Impacts on ecosystems]] include the relocation or [[Extinction risk from global warming|extinction]] of many species as their environment changes, most immediately in [[Environmental issues with coral reefs|coral reefs]], mountains, and [[Climate change in the Arctic|the Arctic]].<ref>{{cite web|author=EPA|date=19 January 2017|title=Climate Impacts on Ecosystems|url=https://19january2017snapshot.epa.gov/climate-impacts/climate-impacts-ecosystems_.html#Extinction|url-status=live|archive-url=https://web.archive.org/web/20180127185656/https://19january2017snapshot.epa.gov/climate-impacts/climate-impacts-ecosystems_.html#Extinction|archive-date=27 January 2018|access-date=5 February 2019|quote=Mountain and arctic ecosystems and species are particularly sensitive to climate change... As ocean temperatures warm and the acidity of the ocean increases, bleaching and coral die-offs are likely to become more frequent.}}</ref> Climate change [[Effects of climate change on humans|threatens people]] with [[Food security and climate change|food insecurity]], [[Water scarcity#Climate change|water scarcity]], flooding, infectious diseases, extreme heat, [[Economic impacts of climate change|economic losses]], and displacement. These impacts have led the [[World Health Organization]] to call climate change the greatest threat to global health in the 21st century.<ref>{{harvnb|IPCC AR5 SYR|2014|pp=13-16}}; {{harvnb|WHO, Nov|2015}}: "Climate change is the greatest threat to global health in the 21st century. Health professionals have a duty of care to current and future generations. You are on the front line in protecting people from climate impacts - from more heat-waves and other extreme weather events; from outbreaks of infectious diseases such as malaria, dengue and cholera; from the effects of malnutrition; as well as treating people that are affected by cancer, respiratory, cardiovascular and other non-communicable diseases caused by environmental pollution."</ref> Even if efforts to minimize future warming are successful, some effects will continue for centuries, including [[rising sea levels]], rising ocean temperatures, and [[ocean acidification]].<ref>{{harvnb|IPCC SR15 Ch1|2018|p=64|ps=: Sustained net zero anthropogenic emissions of {{CO2}} and declining net anthropogenic non-{{CO2}} radiative forcing over a multi-decade period would halt anthropogenic global warming over that period, although it would not halt sea level rise or many other aspects of climate system adjustment.}}</ref>

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Global warming