Global warming
Climate change includes both global warming driven by human emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been 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.[1]
The largest driver of warming is the emission of greenhouse gases, of which more than 90% are carbon dioxide (Template:CO2) and methane.[2] Fossil fuel burning (coal, oil, and natural gas) for energy consumption is the main source of these emissions, with additional contributions from agriculture, deforestation, and manufacturing.[3] The human cause of climate change is not disputed by any scientific body of national or international standing.[4] Temperature rise is accelerated or tempered by climate feedbacks, such as loss of sunlight-reflecting snow and ice cover, increased water vapour (a greenhouse gas itself), and changes to land and ocean carbon sinks.
Temperature rise on land is about twice the global average increase, leading to desert expansion and more common heat waves and wildfires.[5] Temperature rise is also amplified in the Arctic, where it has contributed to melting permafrost, glacial retreat and sea ice loss.[6] Warmer temperatures are increasing rates of evaporation, causing more intense storms and weather extremes.[7] Impacts on ecosystems include the relocation or extinction of many species as their environment changes, most immediately in coral reefs, mountains, and the Arctic.[8] Climate change threatens people with food insecurity, water scarcity, flooding, infectious diseases, extreme heat, 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.[9] 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.[10]
- â IPCC AR5 WG1 Summary for Policymakers 2013, p. 4; IPCC SR15 Ch1 2018, p. 54
- â EPA 2020
- â EPA 2020
- â Scientific Consensus: Earth's Climate is Warming. Climate Change: Vital Signs of the Planet. NASA JPL.; Gleick, 7 January 2017.
- â IPCC SRCCL 2019, p. 7; IPCC SRCCL 2019, p. 45
- â IPCC SROCC 2019, p. 16
- â Cite error: Invalid
<ref>tag; no text was provided for refs named:0 - â EPA (19 January 2017). Climate Impacts on Ecosystems. âMountain 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.â
- â IPCC AR5 SYR 2014, pp. 13-16; 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."
- â IPCC SR15 Ch1 2018, p. 64