Global warming
Global warming is the long-term rise in the averagetemperature of the Earth's climate system. It is a major
aspect of current climate change, and has been
demonstrated by direct temperature measurements and bymeasurements of various effects of the warming.[1][2] Theterm commonly refers to the mainly human-caused increase
inglobalsurfacetemperatures

and

its

projected

continuation.[3][4] In this context, the terms global warming
and climate change are often used interchangeably,[5] but
climate change includes both global warming and its
effects, such as changes in precipitation and impacts thatdiffer by region.[6] There were prehistoric periods of global
warming,[7] but observed changes since the mid-20thcentury have been much greater than those seen in previous
records covering decades to thousands of years.[1][8]The average annual temperature at the earth's surface
has risen since the late 1800s, with year-to-year
variations (shown in black) being smoothed out (shownin red) to show the general warming trend.

The Intergovernmental Panel on Climate Change (IPCC)
Fifth Assessment Report concluded, "It is extremely likelythat human influence has been the dominant cause of theobserved warming since the mid-20th century."[9] Thelargest human influence has been the emission ofgreenhouse gases such as carbon dioxide, methane, andnitrous oxide. Climate model projections summarized in thereport indicated that during the 21st century the global
surface temperature is likely to rise a further 0.3 to 1.7 °C(0.5 to 3.1 °F) in a moderate scenario, or as much as 2.6 to
4.8 °C (4.7 to 8.6 °F) in an extreme scenario, depending on
the rate of future greenhouse gas emissions and on climate
feedback effects.[10] These findings have been recognizedby the national science academies of the majorindustrialized nations[11] and are not disputed by any

Play media
Since the late 1800s, temperatures in different
geographic locations have increased by different
amounts, shown by a changing pattern of growing
intensities of red.

scientific body of national or international standing.[12][13]The effects of global warming include rising sea levels, regional changes in precipitation, more frequent extreme weather events
such as heat waves, and expansion of deserts.[14] Surface temperature increases are greatest in the Arctic, which has contributed
to the retreat of glaciers, permafrost, and sea ice. Overall, higher temperatures bring more rain and snowfall, but for some regions
droughts and wildfires increase instead.[15] Climate change threatens to diminish crop yields, harming food security, and rising
sea levels may flood coastal infrastructure and force the abandonment of many coastal cities.[16][17] Environmental impacts
include the extinction or relocation of many species as their ecosystems change, most immediately the environments of coral
reefs,[18] mountains, and the Arctic.[19] Because the climate system has a large "inertia" and greenhouse gases persist in theatmosphere, climatic changes and their effects will continue for many centuries even if greenhouse gas emissions are stopped.[20]Possible societal responses to global warming include mitigation by emissions reduction, adaptation to its effects, and maybe
climate engineering. Countries work together on climate change under the umbrella of the United Nations Framework
Convention on Climate Change (UNFCCC), which has near-universal membership. The ultimate goal of the convention is toprevent dangerous anthropogenic climate change.[21] Although the parties to the UNFCCC have agreed that deep cuts inemissions are required[22] and that global warming should be limited to well below 2 °C (3.6 °F) in the Paris Agreement,[23] theEarth's average surface temperature has already increased by about half this threshold.[24] and current pledges by countries to cutemissions are inadequate to limit future warming.[25] Some scientists question the feasibility, in higher emissions scenarios, ofclimate adaptation.[26]Contents
Observed temperature changes
Regional trends
Short-term slowdowns and surges
Physical drivers of recent climate change
Greenhouse gases
Land use change
Aerosols and soot
Minor forcings: the Sun and short-lived greenhouse gases
Climate change feedback
Climate models
Effects
Physical environment
Biosphere
HumansFood and water
Health and security
Livelihoods, industry, and infrastructure
Responses
Mitigation
Drivers of greenhouse gas emissions
Reducing greenhouse gases
Adaptation
Climate engineering
Society and culturePolitical response
UN Framework Convention
Other policy
Scientific discussion
Public opinion and disputes
Controversy
The climate movement
History of the science
Terminology
Climate crisis
See also
Notes
Sources