Difference between revisions of "Global warming"

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:''See also [[Counterexamples to Global Warming|Counterexamples to global warming]]''
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Contemporary climate change includes both global warming and its impacts on Earth's weather patterns. There have been previous periods of climate change, but the current changes are distinctly more rapid and not due to natural causes.[2] Instead, they are caused by the emission of greenhouse gases, mostly carbon dioxide (CO2) and methane. Burning fossil fuels for energy use creates most of these emissions. Certain agricultural practices, industrial processes, and forest loss are additional sources.[3] Greenhouse gases are transparent to sunlight, allowing it through to heat the Earth's surface. When the Earth emits that heat as infrared radiation the gases absorb it, trapping the heat near the Earth's surface. As the planet heats up it causes changes like the loss of sunlight-reflecting snow cover, amplifying global warming.[4]
[[File:Global temp chart.jpg|thumb|right|Graph showing temperature connections between solar activity and volcanic eruptions, against a backdrop of historical events.]]
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'''Anthropogenic global warming''' (AGW) is an unproven theory that insists human activity is causing the [[Earth]] to warm catastrophically. The theory posits that [[greenhouse gas]]es, including [[carbon dioxide]], methane, nitrous oxide, and water vapor, trap solar warmth on the planet. Computer models suggest that industrial and vehicular emissions could lead to catastrophic warming. [[Leftist]]s use this theory as a basis to propose cuts in energy production and consumption and to promote de-industrialization.
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The rate of warming predicted by AGW is far higher than what has been observed so far. Based on an average of 102 climate models, the UN's Intergovernment Panel of Climate Change (IPCC) predicts that the lower troposphere should be warming at a rate of 3.1 degrees per century.<ref name="SpencerCSP2">"[https://www.newcriterion.com//cm/images/THE%20CLIMATE%20SURPRISE%20PAMPHLET.pdf The Climate Surprise Pamphlet]", ''The New Criterion'', 2016. Taken from chart "All 3 Global Temperature Dataset Types Disagree with the Climate Model During the Period of Greatest Greenhouse Concentration."</ref> Satellite data shows that the lower troposphere warmed at a rate of 1.4 degrees per century between 1978 and 2021.<ref name="SpencerCSP">"[https://www.newcriterion.com//cm/images/THE%20CLIMATE%20SURPRISE%20PAMPHLET.pdf The Climate Surprise Pamphlet]", ''The New Criterion'', 2016.</ref><ref name=SpencerUAH>Spencer, Roy, "[https://www.drroyspencer.com/2021/ Archive for 2021]", 2019. This is data from the University of Alabama in Huntsville.</ref> Weather balloon data shows a warming trend of 1.6 degrees per century between 1958 and 2018.<ref>"[https://www1.ncdc.noaa.gov/pub/data/ratpac/ratpac-a/ RATPAC-A-annual-levels.txt.zip]", NOAA, National Centers for Environmental Information. Based on data for 850-300 mb.</ref>
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Due to climate change, deserts are expanding, while heat waves and wildfires are becoming more common.[5] Increased warming in the Arctic has contributed to melting permafrost, glacial retreat and sea ice loss.[6] Higher temperatures are also causing more intense storms, droughts, and other weather extremes.[7] Rapid environmental change in mountains, coral reefs, and the Arctic is forcing many species to relocate or become extinct.[8] Climate change threatens people with food and water scarcity, increased flooding, extreme heat, more disease, and economic loss. Human migration and conflict can be a result.[9] The World Health Organization (WHO) calls climate change the greatest threat to global health in the 21st century.[10] Even if efforts to minimise future warming are successful, some effects will continue for centuries. These include sea level rise, and warmer, more acidic oceans.[11]
  
An analysis of weather station data by U.S. climate researcher [[Roy Spencer]] shows no significant warming since 1943. Unlike the official weather station record, Spencer's data includes only those stations that recorded temperature at a consistent time of day.<ref name="Spencer" /> The heating predicted by AGW but not detected in the temperature record is sometimes said to be accumulating in the oceans. But a study by the Scripps Institution of Oceanography found that ocean temperature has risen by only 0.1 degree Celsius in the last fifty years.<ref>"[https://dailycaller.com/2018/01/05/new-study-shows-past-research-on-rising-ocean-temps-built-on-faulty-science/ New Study Shows Past Research On Rising Ocean Temps Built On Faulty Science]," ''The Daily Caller'', 01/05/2018.</ref>
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Many of these impacts are already felt at the current 1.2 °C (2.2 °F) level of warming. Additional warming will increase these impacts and may trigger tipping points, such as the melting of the Greenland ice sheet.[12] Under the 2015 Paris Agreement, nations collectively agreed to keep warming "well under 2 °C". However, with pledges made under the Agreement, global warming would still reach about 2.7 °C (4.9 °F) by the end of the century.[13] Limiting warming to 1.5 °C will require halving emissions by 2030 and achieving net-zero emissions by 2050.[14]
  
The theory that "greenhouse gases" have a greater warming effect than other gases goes back to the 19th century. The idea that carbon dioxide emissions might lead to catastrophic warming was introduced by Carl Sagan in the 1960s. He was inspired by research on the atmosphere of Venus. Around 1978, the environmental movement decided to promote Sagan's theory. The movement was already advocating energy conservation and renewables as a response to the "energy crisis." That is to say, a desired political outcome was agreed upon and then a "scientific" justification was developed.
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Bobcat Fire in Monrovia, CA, September 10, 2020
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Bleached colony of Acropora coral
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A dry riverbed in California, which is experiencing its worst megadrought in 1,200 years.[15]
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Some effects of climate change, clockwise from top left: Wildfire intensified by heat and drought, worsening droughts compromising water supplies, and bleaching of coral caused by ocean acidification and heating.
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Making deep cuts in emissions will require switching away from burning fossil fuels and towards using electricity generated from low-carbon sources. This includes phasing out coal-fired power plants, vastly increasing use of wind, solar, and other types of renewable energy, and taking measures to reduce energy use. Electricity will need to replace fossil fuels for powering transportation, heating buildings, and operating industrial facilities.[16][17] Carbon can also be removed from the atmosphere, for instance by increasing forest cover and by farming with methods that capture carbon in soil.[18] While communities may adapt to climate change through efforts like better coastline protection, they cannot avert the risk of severe, widespread, and permanent impacts.[19]
  
Proponents of the global warming theory advocate for conversion to electric vehicles without expanding the electric power grid, which can only be powered by coal-burning power plants, fossil fuel, or nuclear energy. So-called renewable energy sources, solar and wind, cannot provide enough capacity to recharge hundreds of millions of electric vehicles.
 
  
==Difficulties with the theory==
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Contents
*'''Carbon dioxide is insignificant as a greenhouse gas.''' The level of CO<sub>2</sub> in the Earth's atmosphere is only 400 parts per million. Ninety to 95 percent of the greenhouse effect is due to water vapor.<ref>Friedenreich and Ramaswamy, "Solar Radiation Absorption by Carbon Dioxide, Overlap with Water, and a Parameterization for General Circulation Models," Journal of Geophysical Research 98 (1993):7255-7264</ref> The IPCC claims that water vapor acts as a "positive feedback," i.e. warming creates more humidity, which leads to additional warming. There are humidity measurements going back to 1948, and they show no upward trend.<ref>"[https://wattsupwiththat.com/global-climate/ global climate]," ''Watt's Up with That''</ref> More humidity could lead to more clouds and therefore to cooling and to negative feedback. So why assume positive feedback? AGW works only if water vapor is a positive feedback, so that is what the IPCC must claim.<br/>Although Obama has denounced elevated carbon dioxide levels as "carbon pollution," greenhouse operators commonly increase the level of CO<sub>2</sub> to 1,000 ppm or more to enhance plant growth.<ref>"[https://www.sciencedaily.com/releases/2015/12/151210101819.htm Plant growth enhanced by increased carbon dioxide, but food webs give rise to significant variations]", ''Science News'', December 10, 2015.<br/>Harrison H. Schmitt and William Happer, "[http://arizonaskywatch.com/article/articles/In%20defense%20of%20carbon%20dioxide.pdf In Defense of Carbon Dioxide]," ''Wall Street Journal'', May 8, 2013.</ref>
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1 Terminology
[[Image:NASA-1024x933.jpg|thumb|right|A composite map of [[Antarctica]] showing areas of greatest warming in red. The Wilkins Ice Shelf lies off the peninsula in the top left corner, and shows extensive warming. Overall, Antarctica shows little warming, and many areas to the  East (right) are almost cooling.<ref>Roberts, Greg (April 18, 2009). [http://www.news.com.au/antarctic-ice-is-growing-not-melting-away/story-0-1225700043191 "Antarctic ice is growing, not melting away."] News.com.au.  Retrieved on September 25, 2014.</ref>]]
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2 Observed temperature rise
*'''The Earth has warmed or cooled many times. Historically, warm periods are associated with favorable climate.''' The [[Roman Warm Period]] (250 BC to 180 AD) featured temperatures comparable to those of modern times. This was followed by the Dark Ages Cold Period (450-950 AD).<ref>"[http://www.co2science.org/subject/d/summaries/dacpeurope.php Dark Ages Cold Period (Europe) - Summary]", ''CO<sub>2</sub> Science'', 1 June 2005.</ref> The Medieval Warm Period was even warmer than the Roman period and lasted from 950 to 1300.<ref>John P. Rafferty, "[https://global.britannica.com/science/medieval-warm-period Medieval warm period (MWP)]", ''Britannica''</ref> From the 14th century to the early 19th century, there was a Little Ice Age.<ref>John P. Rafferty, Stephen T. Jackson, "[https://global.britannica.com/science/Little-Ice-Age Little Ice Age (LIA)]", ''Britannica''.</ref><ref>See the graphs at "[http://www.climate4you.com/ Global temperatures]," Climate4you.</ref><ref>Bastasch, Michael, "[https://dailycaller.com/2013/12/13/study-earth-was-warmer-in-roman-medieval-times/ Study: Earth was warmer in Roman, Medieval times]", ''The Daily Caller''. For a peer-reviewed paper, see Moberg, A., et al. 2005 "[ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/moberg2005/nhtemp-moberg2005.txt 2,000-Year Northern Hemisphere Temperature Reconstruction]", ''World Data Center for Paleoclimatology''. The Moberg data set is charted [https://i0.wp.com/i90.photobucket.com/albums/k247/dhm1353/Moberg-1.png here].</ref>
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2.1 Regional aspects to temperature rises
*'''For leftists, the attraction of the theory is that it supports their agenda.''' The environmentalist agenda of renewables, solar energy, conservation, and world government was put together in the 1970s in response to the energy crisis and to the overpopulation scare. At that time, most scientists thought the Earth was cooling.<ref>"[http://realclimatescience.com/the-corrupt-history-of-nasa-temperature-history/ The corrupt history of NASA temperature history]", ''Real Climate Science''.</ref><ref name="Time" /> When AGW came along, it was treated as an additional justification for this agenda.<br/>Steven Schneider, founding father of the AGW movement, was a global cooling believer in the early 1970s. "We have to offer up scary scenarios, make simplified, dramatic statements, and make little mention of any doubts we might have," he explained.<ref>This is from an article Schneider wrote for ''Discover'' magazine in 1989.[http://www.creationworldview.org/articles_view.asp?id=67]</ref> To Schneider, global cooling and global warming were just two "scary scenarios." He could offer up whichever one was expedient.
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3 Drivers of recent temperature rise
*'''Carbon dioxide can be absorbed by promoting plant growth, an angle overlooked by the mainstream media.''' In fact, the increase in carbon dioxide in the atmosphere has already resulted in an increase in plant growth. If that's not enough, iron filings can be dumped at sea to encourage the growth of marine plants.<ref>Carrington, Damian, "[https://www.theguardian.com/environment/2012/jul/18/iron-sea-carbon Dumping iron at sea can bury carbon for centuries, study shows]" ''The Guardian'', 18 July 2012.</ref> Freeman Dyson, America's top physicist, has suggested genetically engineering trees to absorb more carbon.<ref>"[https://www.youtube.com/watch?v=BiKfWdXXfIs Freeman Dyson on the Global Warming Hysteria April, 2015]." Dyson recommends ''Cool It'' (2007) by Bjorn Lomborg as the best summary of the AGW issue.</ref>
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3.1 Greenhouse gases
*'''If the science were in fact settled, we would see less outrage at "deniers" and greater concern for scientific integrity.''' One climate science scandal after another has been exposed. The Climategate emails show hoaxers scurrying to "hide the decline."<ref name=MISH>"[http://globaleconomicanalysis.blogspot.com/2009/11/hackers-prove-global-warming-is-scam.html#quEdWPhB8b6cs07f.99 Beware The Ice Age Cometh: Hackers Prove Global Warming Is A Scam]", ''MISH'S Global Economic Trend Analysis''</ref> The "hockey stick" view of climate history, which holds that global temperature was constant for 2,000 years and then surged in the last century, has been repeatedly debunked.<ref>Muller, Richard A., "[http://www.technologyreview.com/Energy/13830/ A Global Warming Bombshell]", ''Technology Review'' , Oct. 2004; calls into question famous graph by Michael Mann.</ref> No one's reputation is tarnished by these bloopers, no one pays any price. The first response of AGW backers is name calling and attempts to shut down the discussion. Argument is a last resort.<ref>Phil Plait, columnist for ''Discover'', is a good example. Plait has only contempt for those who express concerns about scientific integrity in climate research: "yawn," "non-event," etc. With no sense of irony, he can write, "these denialist claims are largely ad hominems." If you fail to show "the scientists" enough respect, then you are a "global warming denier." This name-calling-as-argument strategy is typical of AGW hacks. (Phil Plait, "[http://blogs.discovermagazine.com/badastronomy/2009/11/30/the-global-warming-emails-non-event/#.WHMkC9J97cs The global warming emails non-event]," ''Discover'',  November 30, 2009.)</ref> The logical explanation is that they already know AGW is a hoax, and they don't care.
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3.2 Aerosols and clouds
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3.3 Land surface changes
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3.4 Solar and volcanic activity
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3.5 Climate change feedback
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4 Future warming and the carbon budget
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5 Impacts
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5.1 Environmental effects
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5.2 Tipping points and long-term impacts
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5.3 Nature and wildlife
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5.4 Humans
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6 Reducing and recapturing emissions
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6.1 Clean energy
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6.2 Energy conservation
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6.3 Agriculture and industry
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6.4 Carbon sequestration
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7 Adapting to a changing climate
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8 Policies and politics
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8.1 Policy options
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8.2 International climate agreements
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8.3 National responses
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9 Scientific consensus and society
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9.1 Scientific consensus
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9.2 Denial and misinformation
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9.3 Public awareness and opinion
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10 Discovery
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11 See also
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12 References
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12.1 Sources
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13 External links
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Terminology
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Before the 1980s, it was unclear whether warming by increased greenhouse gases would dominate aerosol-induced cooling. Scientists then often used the term inadvertent climate modification to refer to the human impact on the climate. In the 1980s, the terms global warming and climate change were popularised. The former refers only to increased surface warming, the latter describes the full effect of greenhouse gases on the climate.[20] Global warming became the most popular term after NASA climate scientist James Hansen used it in his 1988 testimony in the U.S. Senate.[21] In the 2000s, the term climate change increased in popularity.[22] Global warming usually refers to human-induced warming of the Earth system, whereas climate change can refer to natural or anthropogenic change.[23] The two terms are often used interchangeably.[24]
  
== How accurate are weather forecasts and climate forecasts? ==
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Various scientists, politicians and media figures have adopted the terms climate crisis or climate emergency to talk about climate change, and global heating instead of global warming.[25] The policy editor-in-chief of The Guardian said they included this language in their editorial guidelines "to ensure that we are being scientifically precise, while also communicating clearly with readers on this very important issue".[26] In 2019, Oxford Languages chose climate emergency as its word of the year, defining it as "a situation in which urgent action is required to reduce or halt climate change and avoid potentially irreversible environmental damage resulting from it".[27][28]
  
In 2013, ''Scientific American'' published an article entitled ''Why Are Weather Forecasts Often Wrong?''<ref>[https://www.scientificamerican.com/article/why-are-weather-forecasts-often-wrong/ ''Why Are Weather Forecasts Often Wrong?''] By Lee Falin PhD on January 9, 2013, ''Scientific American''</ref>
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Observed temperature rise
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Main articles: Temperature record of the last 2,000 years and Instrumental temperature record
  
In 2020, data from the National Oceanic and Atmospheric Administration suggests a seven-day weather forecast by a [[meteorology|meteorologist]] could accurately predict the weather about 80 percent of the time.<ref>[https://www.mprnews.org/story/2020/01/02/forecast-models-keep-hinting-at-subzero-air-ahead How accurate are forecast models 1 to 2 weeks ahead?]</ref><ref>[https://www.wral.com/how-accurate-are-weather-forecasts/19645159/#:~:text=Longer%2Drange%20forecasts%20are%20less,90%20percent%20of%20the%20time. How accurate are weather forecasts?], WRAL</ref> However, beyond 10 days, a weather forecast is only right about half the time.<ref>[https://www.wral.com/how-accurate-are-weather-forecasts/19645159/#:~:text=Longer%2Drange%20forecasts%20are%20less,90%20percent%20of%20the%20time. How accurate are weather forecasts?], WRAL</ref>
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Global surface temperature reconstruction over the last 2000 years using proxy data from tree rings, corals, and ice cores in blue.[29] Directly observed data is in red.[30]
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Multiple independent instrumental datasets show that the climate system is warming.[31] The 2011–2020 decade warmed to an average 1.09 °C [0.95–1.20 °C] compared to the pre-industrial baseline (1850–1900).[32] Surface temperatures are rising by about 0.2 °C per decade,[33] with 2020 reaching a temperature of 1.2 °C above the pre-industrial era.[34] Since 1950, the number of cold days and nights has decreased, and the number of warm days and nights has increased.[35]
  
The accuracy of the long-range forecasts of climate scientists' that are 10 years or decades ahead of time are of dubious value (See: [[Limitations of science]]).  In addition, environmentalists have a history of making alarmist statements that do not come to fruition (see: [https://www.aei.org/carpe-diem/50-years-of-failed-doomsday-eco-pocalyptic-predictions-the-so-called-experts-are-0-50/ 50 years of failed doomsday, eco-pocalyptic predictions; the so-called ‘experts’ are 0-50], American Enterprise Institute).
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There was little net warming between the 18th century and the mid-19th century. Climate information for that period comes from climate proxies, such as trees and ice cores.[36] Thermometer records began to provide global coverage around 1850.[37] Historical patterns of warming and cooling, like the Medieval Climate Anomaly and the Little Ice Age, did not occur at the same time across different regions. Temperatures may have reached as high as those of the late-20th century in a limited set of regions.[38] There have been prehistorical episodes of global warming, such as the Paleocene–Eocene Thermal Maximum.[39] However, the modern observed rise in temperature and CO2 concentrations has been so rapid that even abrupt geophysical events in Earth's history do not approach current rates.[40]
  
==History==
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Evidence of warming from air temperature measurements are reinforced with a wide range of other observations.[41][42] There has been an increase in the frequency and intensity of heavy precipitation, melting of snow and land ice, and increased atmospheric humidity.[43] Flora and fauna are also behaving in a manner consistent with warming; for instance, plants are flowering earlier in spring.[44] Another key indicator is the cooling of the upper atmosphere, which demonstrates that greenhouse gases are trapping heat near the Earth's surface and preventing it from radiating into space.[45]
The greenhouse effect was proposed by [[Joseph Fourier]] in 1827. Swedish scientist Svante Arrhenius is sometimes considered the father of global warming theory because of a paper he published in 1896 on the effect of carbon dioxide emissions. Arrhenius thought of global warming as a positive thing. The idea that carbon dioxide emissions might lead to catastrophe comes from research on the Venusian atmosphere in the 1960s by Karl Sagan and other NASA scientists. In the 1970s, global cooling theories were more prominent than global warming theories. Even Steven Schneider, later a promoter of global warming, published a paper on global cooling. As a result of the energy crisis of the 1970s, the environmentalist movement adopted an agenda of conservation and renewable energy. With global warming as its flagship theory, the movement could continue promoting its 1970s agenda long after the original justifications for it had disappeared. Schneider offered up "scary scenarios," as he called them, to promote the theory.
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===Origin===
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Regional aspects to temperature rises
In 1827, French scientist Joseph Fourier suggested that although the atmosphere allowed sunlight to pass through to warm the Earth, it blocked "dark heat" (infrared radiation) from the Earth and thus prevented energy from being transferred back into space.<ref name=Fourier>Fourier, Jean Baptist Joseph, "On the Temperatures of the Terrestrial Sphere in Interplanetary Space", Translated in ''The Warming Papers: The Scientific Foundation for Climate Change Forecast''. The relevant section is pp. 12-13.</ref> Fourier did make an unfortunate analogy between the Earth's atmosphere and a space enclosed by glass. All the same, it may not be fair to blame Fourier for the greenhouse effect meme. He also discussed convection as an alternative explanation and, as a good scientist, recommended an experiment to resolve the issue.  
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See also: Climate variability and change § Variability between regions
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Regions of the world warm at differing rates. The pattern is independent of where greenhouse gases are emitted, because the gases persist long enough to diffuse across the planet. Since the pre-industrial period, the average surface temperature over land regions has increased almost twice as fast as the global-average surface temperature.[46] This is because of the larger heat capacity of oceans, and because oceans lose more heat by evaporation.[47] The thermal energy in the global climate system has grown with only brief pauses since at least 1970, and over 90% of this extra energy has been stored in the ocean.[48][49] The rest has heated the atmosphere, melted ice, and warmed the continents.[50]
  
In 1861, Irish scientist John Tyndall measured the absorption of radiant energy by various gases in the atmosphere. He concluded that water vapor was the gas primarily responsible. It could therefore be considered the warming agent that Fourier hypothesized. Tyndall suggested that changes in humidity could bring about climate change.
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The Northern Hemisphere and the North Pole have warmed much faster than the South Pole and Southern Hemisphere. The Northern Hemisphere not only has much more land, but also more seasonal snow cover and sea ice. As these surfaces flip from reflecting a lot of light to being dark after the ice has melted, they start absorbing more heat.[51] Local black carbon deposits on snow and ice also contribute to Arctic warming.[52] Arctic temperatures are increasing at over twice the rate of the rest of the world.[53] Melting of glaciers and ice sheets in the Arctic disrupts ocean circulation, including a weakened Gulf Stream, further changing the climate.[54]
  
The AGW theory was first presented in 1896 in an article by Swedish scientist Svante Arrhenius. Arrhenius predicted that a doubling of CO<sub>2</sub> in the atmosphere due to fossil fuel burning would lead to a temperature increase of 3 to 4&nbsp;°C (about 5 to 7&nbsp;°F) after 500 years. Arrhenius attributes his misunderstanding of the science to Fourier: "Fourier maintained that the atmosphere acts like the glass of a hothouse."<ref>Arrhenius, Svante, "On the Influence of Carbonic Acid in the Air on the Temperature on the Ground", ''London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science,'' April 1896. Reprinted in ''The Warming Papers'', pp. 56-77.</ref>
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Drivers of recent temperature rise
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Main article: Attribution of recent climate change
  
The use of the Swedish word ''drivbänk'' (hothouse) by Arrhenius and his colleagues is likely to be the origin of the phrase "greenhouse effect." This phrase is first recorded in English in 1907.<ref>"[http://www.easterbrook.ca/steve/2015/08/who-first-coined-the-term-greenhouse-effect/ Who first coined the term “Greenhouse Effect”?]," ''Serendipity,'' August 2015</ref>
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Drivers of climate change from 1850–1900 to 2010–2019. There was no significant contribution from internal variability or solar and volcanic drivers.
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The climate system experiences various cycles on its own which can last for years (such as the El Niño–Southern Oscillation (ENSO)), decades or even centuries.[55] Other changes are caused by an imbalance of energy that is "external" to the climate system, but not always external to the Earth.[56] Examples of external forcings include changes in the concentrations of greenhouse gases, solar luminosity, volcanic eruptions, and variations in the Earth's orbit around the Sun.[57]
  
===The skeptics strike back===
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To determine the human contribution to climate change, known internal climate variability and natural external forcings need to be ruled out. A key approach is to determine unique "fingerprints" for all potential causes, then compare these fingerprints with observed patterns of climate change.[58] For example, solar forcing can be ruled out as a major cause. Its fingerprint would be warming in the entire atmosphere. Yet, only the lower atmosphere has warmed, consistent with greenhouse gas forcing.[59] Attribution of recent climate change shows that the main driver is elevated greenhouse gases, with aerosols having a dampening effect.[60]
Arrhenius ignored water vapor in his calculations, leading him to overestimate the effect of CO<sub>2</sub> by 96 percent, as Knut Ångström observed in 1901.<ref>"[https://realclimatescience.com/2016/12/climate-scientists-celebrating-115-years-of-debunked-science/ Climate Scientists Celebrating 115 Years Of Debunked Junk Science]"</ref> More controversially, Ångström questioned whether CO<sub>2</sub> could act as a greenhouse gas at all. He took a tube of carbon dioxide, shined black-body radiation on it, and varied the pressure on the gas. Increasing the pressure led to only a slight increase in absorption. He concluded that radiation absorption by CO<sub>2</sub> is already nearly saturated, so the emission of additional gas into the atmosphere would have little effect. Ångström thus became "the first denier."
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Nils Ekholm, an associate of Arrhenius, had an answer to Ångström's point about saturation.<ref>Ekholm, Nils, "On the Variations of the Geological and Historical Past their Causes, ''Quarterly Journal of the Royal Meteorological Society,'' January 1901. DOI: 10.1002/qj.49702711702.</ref> Ångström's tube was saturated because it was at ground level. High enough in the atmosphere, there must be an unsaturated layer of carbon dioxide capable of absorbing radiation. The greater the density of carbon dioxide in the atmosphere, the lower this layer would be. A lower layer would retransmit more radiation to the lower atmosphere and would therefore be responsible for greater warming. Ekholm's insight was lost on his fellow scientists. It was not rediscovered until the 1960s.<ref>"The Surface budget fallacy," ''The Warming Papers'', pp. 79-80.</ref>
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Greenhouse gases
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Main articles: Greenhouse gas, Greenhouse gas emissions, Greenhouse effect, and Carbon dioxide in Earth's atmosphere
  
As for Ångström's point concerning water vapor, Arrhenius insisted that CO<sub>2</sub> rose higher in the atmosphere than water vapor could, so water vapor was not relevant. This argument never caught on. The idea that adding CO<sub>2</sub> would change the climate, "was never widely accepted and was abandoned when it was found that all the long-wave radiation [that would be] absorbed by CO<sub>2</sub> is [already] absorbed by water vapor," the American Meteorological Society concluded in 1951.<ref>American Meteorological Society, ''[https://www.questia.com/read/97549786/compendium-of-meteorology 1951 Compendium of Meteorology]'', p. 1016.</ref> Despite Ångström's debunking of his theory, Arrhenius won the Nobel prize for chemistry in 1903 for unrelated research. The Ångströms, meanwhile, are remembered for a miniscule unit of length named after Anders Ångström, Knut's dad.
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CO2 concentrations over the last 800,000 years as measured from ice cores (blue/green) and directly (black)
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The Earth absorbs sunlight, then radiates it as heat. Greenhouse gases in the atmosphere absorb and reemit infrared radiation, slowing the rate at which it can pass through the atmosphere and escape into space.[61] Before the Industrial Revolution, naturally-occurring amounts of greenhouse gases caused the air near the surface to be about 33 °C warmer than it would have been in their absence.[62][63] While water vapour (~50%) and clouds (~25%) are the biggest contributors to the greenhouse effect, they increase as a function of temperature and are therefore feedbacks. On the other hand, concentrations of gases such as CO2 (~20%), tropospheric ozone,[64] CFCs and nitrous oxide are not temperature-dependent, and are therefore external forcings.[65]
  
===Disproving the greenhouse effect===
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Human activity since the Industrial Revolution, mainly extracting and burning fossil fuels (coal, oil, and natural gas),[66] has increased the amount of greenhouse gases in the atmosphere, resulting in a radiative imbalance. In 2019, the concentrations of CO2 and methane had increased by about 48% and 160%, respectively, since 1750.[67] These CO2 levels are higher than they have been at any time during the last 2 million years. Concentrations of methane are far higher than they were over the last 800,000 years.[68]
Finally performing the experiment Fourier had recommended a century earlier, Robert Wood showed in 1909 that energy is transferred from the Earth's surface to the atmosphere primarily through convection currents. In Wood's experiment, the temperature in a glass box was compared to that in a box with a top made of halite (rock salt). Halite allows sunlight to enter, but blocks infrared. Infrared re-radiation and the greenhouse effect play "a very small part," both in the atmosphere and in literal greenhouses, Wood concluded.<ref>Wood, Robert, "[http://www.tech-know-group.com/papers/Note_on_the_Theory_of_the_Greenhouse.pdf Note on the Theory of the Greenhouse]", ''Philosphical Magazine'', January—June 1909.<br/>"[http://hockeyschtick.blogspot.jp/2010/06/greenhouse-theory-disproven-in-1909.html Greenhouse Theory disproven in 1909, 1963, 1966, 1973...but still refuses to die]," June 28, 2010.<br/>Gerhard Gerlich and Ralf D. Tscheuschner, "[https://arxiv.org/PS_cache/arxiv/pdf/0707/0707.1161v4.pdf Falsification Of The Atmospheric CO<sub>2</sub> Greenhouse Effects Within The Frame Of Physics]"</ref> A greenhouse is warmer than the air outside because the roof limits convection and the walls restrict wind. "The acquired heat is concentrated, because it is not dissipated immediately by renewing the air," as Fourier himself explained.<ref name="Fourier" />
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From 1909 until the 1960s, only a few additional papers on AGW were published. Research went forward as the lonely project of English scientist Guy Callendar. Callendar collected historical temperature readings and CO<sub>2</sub> measurements and published the results in 1938.<ref>Callendar, G.S. (1938). "The Artificial Production of Carbon Dioxide and Its Influence on Climate." ''Quarterly J. Royal Meteorological Society'' 64: 223-40. Reprinted in ''The Warming Papers'', pp. 261-273.</ref>
 
  
===Sagan and Venus===
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The Global Carbon Project shows how additions to CO2 since 1880 have been caused by different sources ramping up one after another.
In 1932, Venus was shown to have an atmosphere of carbon dioxide.<ref>"Carbon Dioxide Discovered in Atmosphere of Venus", Astronautics, Vol. 2, No. 21 (1932), pp. 6-7. https://dx.doi.org/10.2514/8.11921</ref> This finding prompted astronomer Rupert Wildt to propose in 1940 that a greenhouse effect operated on the planet. Radio telescope observations in 1958 showed that the temperature of Venus was even higher than Wildt's theory could explain. Astronomer Carl Sagan proposed in 1960 that the planet had a “very efficient greenhouse effect,” or runaway greenhouse as it later came to be called.<ref>Weart, Spencer, "[http://history.aip.org/history/climate/pdf/venus.pdf Venus & Mars]", June 2011.</ref><ref>Sagan, Carl, "[http://science.sciencemag.org/content/133/3456/849 The Planet Venus]", ''Science'', 24 March 1961.</ref> The Mariner 2 mission in 1962 measured the temperature of Venus as 500 degrees Celsius. The planet that had been considered "Earth's twin" just a few years earlier was revealed as a sulfurous vision of hell.
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Global anthropogenic greenhouse gas emissions in 2019 were equivalent to 59 billion tonnes of CO2. Of these emissions, 75% was CO2, 18% was methane, 4% was nitrous oxide, and 2% was fluorinated gases.[69] CO2 emissions primarily come from burning fossil fuels to provide energy for transport, manufacturing, heating, and electricity.[3] Additional CO2 emissions come from deforestation and industrial processes, which include the CO2 released by the chemical reactions for making cement, steel, aluminum, and fertiliser.[70] Methane emissions come from livestock, manure, rice cultivation, landfills, wastewater, and coal mining, as well as oil and gas extraction.[71] Nitrous oxide emissions largely come from the microbial decomposition of fertiliser.[72]
  
Mariner's findings were sensational because they had been predicted by Immanuel Velikovsky in ''Worlds in Collision'' (1950), which argues that Venus was ejected from Jupiter in mythological times. The scientific community had denounced Velikovsky and his theory in the strongest terms, and Sagan emerged as its champion. Sagan and Velikovsky faced off at a dramatic conference in San Francisco in 1974.<ref>AAAS Symposium: "Velikovsky's Challenge to Science" held on February 25, 1974.</ref>
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Despite the contribution of deforestation to greenhouse gas emissions, the Earth's land surface, particularly its forests, remain a significant carbon sink for CO2. Land-surface sink processes, such as carbon fixation in the soil and photosynthesis, remove about 29% of annual global CO2 emissions.[73] The ocean also serves as a significant carbon sink via a two-step process. First, CO2 dissolves in the surface water. Afterwards, the ocean's overturning circulation distributes it deep into the ocean's interior, where it accumulates over time as part of the carbon cycle. Over the last two decades, the world's oceans have absorbed 20 to 30% of emitted CO2.[74]
  
By portraying carbon dioxide as a doomsday chemical, Sagan put a radically new spin on the issue. Both Arrhenius and Callendar had assumed that greenhouse warming would be beneficial. With Rachel Carson's ''Silent Spring'' (1962), Paul R. Ehrlich's ''The Population Bomb'' (1968), and the Club of Rome's ''The Limits to Growth'' (1972), this was an era when the reading public had an enormous appetite for spurious theories concerning human-initiated global catastrophe.
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Aerosols and clouds
 +
Air pollution, in the form of aerosols, not only puts a large burden on human health, but also affects the climate on a large scale.[75] From 1961 to 1990, a gradual reduction in the amount of sunlight reaching the Earth's surface was observed, a phenomenon popularly known as global dimming,[76] typically attributed to aerosols from biofuel and fossil fuel burning.[77] Globally, aerosols have been declining since 1990, meaning that they no longer mask greenhouse gas warming as much.[78]
  
While the Venus discoveries ignited a burst of interest in AGW, they did nothing to shore up its scientific merits. In 1971, Russian climatologist Mikhail Budyko gave a speech to a large international conference in Leningrad in which he presented an alarmist AGW scenario. Reaction was strongly negative. It was clear that AGW was very much a minority opinion among scientists at this time. A quick look at Venus reveals that the atmosphere is opaque due to globe-spanning sulfur dioxide clouds. These clouds are 30 to 40&nbsp;km thick. No sunlight reaches the surface.<ref>NASA's "[http://nssdc.gsfc.nasa.gov/planetary/factsheet/venusfact.html Venus Fact Sheet]" gives the planet's diurnal temperature range as zero, i.e. no difference between night and day on the surface.</ref> It follows that the planet has no greenhouse effect whatsoever.
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Aerosols scatter and absorb solar radiation. They also have indirect effects on the Earth's radiation budget. Sulfate aerosols act as cloud condensation nuclei and lead to clouds that have more and smaller cloud droplets. These clouds reflect solar radiation more efficiently than clouds with fewer and larger droplets.[79] They also reduce the growth of raindrops, which makes clouds more reflective to incoming sunlight.[80] Indirect effects of aerosols are the largest uncertainty in radiative forcing.[81]
  
In a runaway greenhouse, the greenhouse effect vaporizes additional water, which in turn increases the greenhouse effect. This leads to even more water vaporization and so on in a cycle of positive feedback. Venus has very little water of any kind, so Sagan's runaway greenhouse is not possible.<ref name=pierre>*Raymond T. Pierrehumbert, ''[https://books.google.ca/books?id=bO_U8f5pVR8C&source=gbs_navlinks_s Principles of Planetary Climate]'', pp. 14-15.<br />*Anthony Watts explains why Sagan's theory is "beyond absurd" in "[https://wattsupwiththat.com/2010/05/06/hyperventilating-on-venus/ Hyperventilating on Venus]," May 6, 2010.</ref> Whatever the chemistry of the Venusian atmosphere, water vapor absorbs a wider spectrum of radiation than carbon dioxide does and remains the primary greenhouse gas in the terrestrial atmosphere, as Tyndall showed long ago.
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While aerosols typically limit global warming by reflecting sunlight, black carbon in soot that falls on snow or ice can contribute to global warming. Not only does this increase the absorption of sunlight, it also increases melting and sea-level rise.[82] Limiting new black carbon deposits in the Arctic could reduce global warming by 0.2 °C by 2050.[83]
  
Venus research proved to be an incubator for AGW showboaters. James “Boiling Oceans” Hansen, who emerged as the public face of AGW in the late 1980s, was a NASA Venus researcher in the 1960s. Overlooking Hansen's history of following one kook theory after another, the mainstream media treated his talk of "runaway greenhouse" and "Venus syndrome" as serious science.<ref>Sullivan, John, "[https://johnosullivan.wordpress.com/2012/05/20/top-scientists-vent-on-nasas-sub-prime-greenhouse-gas-hoaxere-optional/ Top Scientists Vent on NASA’s Sub Prime Greenhouse Gas Hoaxer]", May 20, 2012. "The oceans will begin to boil," Hansen announces in [https://wattsupwiththat.com/2012/01/12/quote-of-the-week-dr-james-hansen-of-nasa-giss-unhinged/ this video]. In his book, ''Storms of my Grandchildren'', Hansen writes: "[I]f we burn all reserves of oil, gas, and coal, there is a substantial chance we will initiate the runaway greenhouse. If we also burn the tar sands and tar shale, I believe the Venus syndrome is a dead certainty."</ref>
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Land surface changes
  
Hansen's claim that continued CO<sub>2</sub> emissions will trigger a runaway greenhouse on Earth is unlikely in view of the Earth's recovery after the Paleocene-Eocene Thermal Maximum (PETM), a huge natural spike in CO<sub>2</sub> that occurred 55.5 million years ago.<ref>Kunzig, Robert, "[http://news.nationalgeographic.com/news/2013/13/130729-runaway-greenhouse-global-warming-venus-ocean-climate-science/ Will Earth's Ocean Boil Away?]", ''National Geographic'', July 30, 2013.</ref> During PETM, the carbon dioxide level in the atmosphere increased by about 700 ppm over 20,000 years and the planet warmed by 5–8 degrees Celsius.<ref>McInherney, F.A..; Wing, S. (2011). "A perturbation of carbon cycle, climate, and biosphere with implications for the future". Annual Review of Earth and Planetary Sciences. 39: 489–516. Bibcode:2011AREPS..39..489M. doi:10.1146/annurev-earth-040610-133431</ref> Plant growth accelerated and there was a return to pre-PETM conditions after 200,000 years.<ref>Gabriel J. Bowen & James C. Zachos, "Rapid carbon sequestration at the termination of the Palaeocene–Eocene Thermal Maximum", ''Nature'' Geoscience 3, 866–869 (2010) doi:10.1038/ngeo1014</ref> Although this event is sometimes presented as confirmation of the greenhouse concept, warming preceded the CO<sub>2</sub> spike by about 3,000 years<ref>Sluijs, A.; Brinkhuis, H.; Schouten, S.; Bohaty, S.M.; John, C.M.; Zachos, J.C.; Reichart, G.J.; Sinninghe Damste, J.S.; Crouch, E.M.; Dickens, G.R. (2007). "Environmental precursors to rapid light carbon injection at the Palaeocene/Eocene boundary". Nature. 450 (7173): 1218–21. Bibcode:2007Natur.450.1218S. doi:10.1038/nature06400. PMID 18097406.</ref> and may have been initiated by a comet impact.<ref>[https://wattsupwiththat.com/tag/petm/ Study: Extraterrestrial impact preceded ancient global warming event]", October 13, 2016.<br/>Morgan F. Schaller, Megan K. Fung, James D. Wright, Miriam E. Katz, Dennis V. Kent, "[http://science.sciencemag.org/content/354/6309/225.full Impact ejecta at the Paleocene-Eocene boundary]", ''Science'', 14 Oct 2016:
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The rate of global tree cover loss has approximately doubled since 2001, to an annual loss approaching an area the size of Italy.[84]
Vol. 354, Issue 6309, pp. 225-229 DOI: 10.1126/science.aaf5466.</ref>
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Humans change the Earth's surface mainly to create more agricultural land. Today, agriculture takes up 34% of Earth's land area, while 26% is forests, and 30% is uninhabitable (glaciers, deserts, etc.).[85] The amount of forested land continues to decrease, which is the main land use change that causes global warming.[86] Deforestation releases CO2 contained in trees when they are destroyed, plus it prevents those trees from absorbing more CO2 in the future.[87] The main causes of deforestation are: permanent land-use change from forest to agricultural land producing products such as beef and palm oil (27%), logging to produce forestry/forest products (26%), short term shifting cultivation (24%), and wildfires (23%).[88]
  
===From cooling to warming===
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Land use changes not only affect greenhouse gas emissions. The type of vegetation in a region affects the local temperature. It impacts how much of the sunlight gets reflected back into space (albedo), and how much heat is lost by evaporation. For instance, the change from a dark forest to grassland makes the surface lighter, causing it to reflect more sunlight. Deforestation can also affect temperatures by modifying the release of chemical compounds that influence clouds, and by changing wind patterns.[89] In tropic and temperate areas the net effect is to produce significant warming, while at latitudes closer to the poles a gain of albedo (as forest is replaced by snow cover) leads to a cooling effect.[89] Globally, these effects are estimated to have led to a slight cooling, dominated by an increase in surface albedo.[90]
Despite Venus-related attention, AGW was overshadowed by a cooling scare in the 1970s. Steven Schneider, who later emerged as a key player in AGW politics, confidently predicted more cooling in 1971:
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{{cquote|[I]t is projected that man's potential to pollute will increase six- to eightfold in the next 50 years. If this increased rate of injection of particulate matter in the atmosphere should raise the present background opacity by a factor of 4, our calculations suggest a decrease in global temperature by as much as 3.5 ''°K''. Such a large decrease in the average temperature of Earth, sustained over a period of few years, is '''believed to be sufficient to trigger an ice age.''' However, by that time, nuclear power may have largely replaced fossil fuels as a means of energy production.<ref>{{cite journal |author=Rasool SI, Schneider SH |title=Atmospheric carbon dioxide and aerosols: effects of large increases on global climate |journal=Science |volume=173 |issue=3992 |pages=138–41 |date=July 1971 |pmid=17739641 |doi=10.1126/science.173.3992.138 |url= }}</ref>}}
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By the late 1970s, the cooling scare had tapered off and Schneider was actively promoting AGW. The energy crisis, which began in 1973, put energy policy in the center of the political debate. In response, the left adopted a platform of conservation, renewables, and solar energy. Schneider and others noticed that AGW provided an additional justification for this platform.
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Solar and volcanic activity
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Further information: Solar activity and climate
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Physical climate models are unable to reproduce the rapid warming observed in recent decades when taking into account only variations in solar output and volcanic activity.[91] As the Sun is the Earth's primary energy source, changes in incoming sunlight directly affect the climate system.[81] Solar irradiance has been measured directly by satellites,[92] and indirect measurements are available from the early 1600s onwards.[81] There has been no upward trend in the amount of the Sun's energy reaching the Earth.[93] Further evidence for greenhouse gases causing global warming comes from measurements that show a warming of the lower atmosphere (the troposphere), coupled with a cooling of the upper atmosphere (the stratosphere).[94] If solar variations were responsible for the observed warming, the troposphere and stratosphere would both warm.[59]
  
By the late 1980s, Schneider and his fellow activists had transformed global warming from a fringe concern to a central political issue. He explained how in a 1989 interview:
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Explosive volcanic eruptions represent the largest natural forcing over the industrial era. When the eruption is sufficiently strong (with sulfur dioxide reaching the stratosphere), sunlight can be partially blocked for a couple of years. The temperature signal lasts about twice as long. In the industrial era, volcanic activity has had negligible impacts on global temperature trends.[95] Present-day volcanic CO2 emissions are equivalent to less than 1% of current anthropogenic CO2 emissions.[96]
{{cquote|And like most people we’d like to see the world a better place, which in this context translates into our working to reduce the risk of potentially disastrous climate change. To do that we need to get some broad based support, to capture the public’s imagination. '''That, of course, means getting loads of media coverage. So we have to offer up scary scenarios,''' make simplified, dramatic statements, '''and make little mention of any doubts we might have'''. This “double ethical bind” we frequently find ourselves in cannot be solved by any formula. Each of us has to decide what the right balance is between being effective and being honest. I hope that means being both.<ref>The quote is from ''Discover'', pp. 45–48, October 1989. See [https://www.weeklystandard.com/climategate-part-ii/article/610926 this link].</ref>}}
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After Schneider abandoned his global cooling hobbyhorse and got on the global warming [[argumentum ad populum|bandwagon]], he never looked back. He was all about offering up "scary scenarios" in order to get "loads of media coverage." He had hoped to be honest, but, let's face it, nobody's perfect. Since he presents himself here as the high priest of climate science, it should be noted that Schneider's Ph.D. is in mechanical engineering.
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Climate change feedback
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Main articles: Climate change feedback and Climate sensitivity
  
According to Oxfam, "climate-related disasters has tripled in the last 30 years", and "more than 20 million people a year are forced from their homes".<ref>[https://www.oxfam.org/en/5-natural-disasters-beg-climate-action Oxfam]</ref>
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Sea ice reflects 50% to 70% of incoming solar radiation while the dark ocean surface only reflects 6%, so melting sea ice is a self-reinforcing feedback.[97]
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The response of the climate system to an initial forcing is modified by feedbacks: increased by self-reinforcing feedbacks and reduced by balancing feedbacks.[98] The main reinforcing feedbacks are the water-vapour feedback, the ice–albedo feedback, and the net effect of clouds.[99][100] The primary balancing mechanism is radiative cooling, as Earth's surface gives off more heat to space in response to rising temperature.[101] In addition to temperature feedbacks, there are feedbacks in the carbon cycle, such as the fertilizing effect of CO2 on plant growth.[102] Uncertainty over feedbacks is the major reason why different climate models project different magnitudes of warming for a given amount of emissions.[103]
===The IPCC===
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The Intergovernmental Panel on Climate Change, a UN agency that reports on climate science, was founded in 1988. IPCC reports are often cited as the gold standard of science in this field, proof that AGW is "settled science." But few journalists read the report itself. Instead, they rely on the "Executive Summary" or "Summary for Policymakers." This document is written, not by scientists, but by UN bureaucrats under the supervision of Rajendra Pachauri, the Indian railway economist who heads the IPCC. The Climategate II emails reveal that the summary is written first then material is added to the various chapters to support it.<ref>Hayward, Steven F., "[https://www.weeklystandard.com/climategate-part-ii/article/610926 Climategate (Part II)]," ''Weekly Standard'', Dec. 12, 2011</ref> This procedure makes a farce of the IPCC's stated mission, which is to review the published literature so as to determine the scientific consensus.  
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As for the main report, this is put together carelessly, according George Filippo: "I feel rather uncomfortable about using not only unpublished but also unreviewed material as the backbone of our conclusions (or any conclusions)....IPCC is not any more an assessment of published science (which is its proclaimed goal) but production of results....I feel that at this point there are very little rules and almost anything goes." Filippo was a vice chair of the group from 2002 to 2008 and has contributed to all five IPCC reports.<ref>"[http://tomnelson.blogspot.jp/2012/01/don-miss-this-devastating-criticism-of.html Don't miss this devastating criticism of the IPCC]," January 02, 2012</ref>
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As the air is warmed by greenhouse gases, it can hold more moisture. Water vapour is a potent greenhouse gas, so this further heats the atmosphere.[99] If cloud cover increases, more sunlight will be reflected back into space, cooling the planet. If clouds become higher and thinner, they act as an insulator, reflecting heat from below back downwards and warming the planet.[104] The effect of clouds is the largest source of feedback uncertainty.[105]
  
===Climategate===
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Another major feedback is the reduction of snow cover and sea ice in the Arctic, which reduces the reflectivity of the Earth's surface.[106] More of the Sun's energy is now absorbed in these regions, contributing to amplification of Arctic temperature changes.[107] Arctic amplification is also melting permafrost, which releases methane and CO2 into the atmosphere.[108] Climate change can also cause methane releases from wetlands, marine systems, and freshwater systems.[109] Overall, climate feedbacks are expected to become increasingly positive.[110]
The AGW industry was exposed as a hoax by the release of the "[[Climategate]]" emails in 2009. The Climate Research Unit of East Anglia University in Britain prepared 156 megaybytes of email by their researchers for release under the Freedom of Information Act. This database was somehow leaked, either prematurely or by a whistleblower after the institution had second thoughts.
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In the most notorious message, Phil Jones, director of the unit, wrote, "I've just completed '''Mike's ''Nature'' trick''' of adding in the real temps to each series for the last 20 years (ie from 1981 onwards) amd from 1961 for Keith's to '''hide the decline'''."<ref name=MISH /> This should not be understood to mean that real temperature was declining, but rather that the researchers were attempting to cover up flaws in their tree-ring based data set. The graph in question was a version of the famous "hockey stick" that shows global temperature constant for 2,000 years, followed by a dramatic warming in the last century. ''Nature'' is considered one of the most authoritative science journals. So this quote suggests that a chart prepared for the magazine was faked with the approval of Jones as supervisor. An email by CRU researcher Tim Osborn clarifies what the ''Nature'' trick was: "Also we have applied a completely artificial adjustment to the data after 1960, so they look closer to observed temperatures than the tree-ring data actually were."<ref>"[http://tomnelson.blogspot.jp/2011/12/in-case-you-missed-it-damning.html In case you missed it, damning ClimateGate emails from Tim Osborne]", Tom Nelson, Dec. 06, 2011.</ref>
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Around half of human-caused CO2 emissions have been absorbed by land plants and by the oceans.[111] On land, elevated CO2 and an extended growing season have stimulated plant growth. Climate change increases droughts and heat waves that inhibit plant growth, which makes it uncertain whether this carbon sink will continue to grow in the future.[112] Soils contain large quantities of carbon and may release some when they heat up.[113] As more CO2 and heat are absorbed by the ocean, it acidifies, its circulation changes and phytoplankton takes up less carbon, decreasing the rate at which the ocean absorbs atmospheric carbon.[114] Overall, at higher CO2 concentrations the Earth will absorb a reduced fraction of our emissions.[115]
  
What's wrong with using tree ring data to created a climate record? The CRU researchers assumed that a tree grows faster when it's warmer. But rainfall has a stronger influence on tree growth than temperature does. Temperature is correlated to tree growth only in the sense that it tends to rain more in warm eras. Critics call the CRU's approach the "tree-o-meter" theory.<ref>"[http://tomnelson.blogspot.jp/2012/02/email-3826-feb-2001-in-email-copied-to.html Email 3826, Feb 2001]," Tom Nelson, Feb. 04, 2012. "In one go, they tossed aside dozens of studies which confirmed the existence of the MWE [Medieval Warm Era] and LIA [Little Ice Age] as global events, and all on the basis of tree rings - a proxy which has all the deficiencies I have stated above."</ref>
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Future warming and the carbon budget
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Further information: Carbon budget, Climate model, and Climate change scenario
  
In another Climategate email, Jones enthusiastically demands that the IPCC review process be rigged: "I can't see either of these papers being in the next IPCC report. Kevin and I will keep them out somehow - even if we have to redefine what the peer-review literature is!" Jones also admitted that the reason he claims the Earth is warming is political: "The scientific community would come down on me in no uncertain terms if I said the world had cooled from 1998. Okay it has but it is only seven years of data and it isn't statistically significant."<ref name=steyn14>Steyn, Mark, "[http://www.steynonline.com/2697/how-the-science-got-settled How the Science Got Settled]", December 6, 2014.</ref> Jones is ignoring the fact that 1998 was an unusually warm year due to an El Niño event. All the same, it's clear that he runs the CRU to produce made-to-order results rather than as a scientist.
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Projected global surface temperature changes relative to 1850–1900, based on CMIP6 multi-model mean changes
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A climate model is a representation of the physical, chemical, and biological processes that affect the climate system.[116] Models are used to calculate the degree of warming future emissions will cause when accounting for the strength of climate feedbacks.[117][118] Models also include natural processes like changes in the Earth's orbit, historical changes in the Sun's activity, and volcanic forcing.[119] In addition to estimating future temperatures, they reproduce and predict the circulation of the oceans, the annual cycle of the seasons, and the flows of carbon between the land surface and the atmosphere.[120]
  
==The temperature record==
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The physical realism of models is tested by examining their ability to simulate contemporary or past climates.[121] Past models have underestimated the rate of Arctic shrinkage[122] and underestimated the rate of precipitation increase.[123] Sea level rise since 1990 was underestimated in older models, but more recent models agree well with observations.[124] The 2017 United States-published National Climate Assessment notes that "climate models may still be underestimating or missing relevant feedback processes".[125]
Global temperatures are tracked by three methods: satellites, weather balloons, and weather stations. All three methods confirm a modest amount of warming in recent decades. Satellite data shows a warming trend of 0.11 K/decade for 1978 to 2015.<ref>Roy W. Spencer, John R. Christy, and William D. Braswell, "[http://www.drroyspencer.com/wp-content/uploads/Version-61.pdf Version 6.0 of the UAH Temperature Dataset Released]", 28 April 2015.</ref> Weather balloon data shows a warming trend of 0.18 K/decade for 1970 to 2015.<ref>The figure given is for RATPAC-A, surface to 700 mb. See "[https://wattsupwiththat.com/2015/12/14/gavins-admission-about-the-satellite-record-versus-the-surface-temperature-record/ Gavin’s admission about the satellite record versus the surface temperature record]," ''Watt's Up With That''. You can find a collection of global climate charts [https://wattsupwiththat.com/global-climate/ here].</ref>
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A reanalysis of weather station data for 1943 to 2012 by Roy Spencer shows that after a cooler period in the 1960s and 1970s, U.S. temperatures returned to their earlier level. Unlike CRU, NASA, and NOAA, Spencer corrects for the fact that at most stations measurement time of day has changed over the years.<ref name=Spencer>Spencer, Roy, "[http://www.drroyspencer.com/2012/08/a-new-analysis-of-u-s-temperature-trends-since-1943/ A New Analysis of U.S. Temperature Trends Since 1943]," August 6th, 2012.</ref> So Spencer's analysis implies that the warmest year on record was 1934, the warmest year of the 1930s, not 2016 as the climate establishment maintains. Spencer is a prominent skeptic and a professor at the University of Alabama in Huntsville. He maintains the UAH record, one of the two major satellite temperature records. As an active researcher at the center of the climate science community, Spencer is a standing rebuke to the claim that AGW represents the scientific consensus.<ref>Spencer, Roy, "[http://www.drroyspencer.com/my-global-warming-skepticism-for-dummies/ My Global Warming Skepticism, for Dummies]"</ref> While the cause is debatable, worldwide, 2016 was the warmest year on record, 2020 was the second-warmest, and 2011–2020 was the warmest decade on record since thermometer-based observations began. Eight of the top 10 warmest years on record for the contiguous 48 states have occurred since 1998, and 2012 and 2016 were the two warmest years on record.<ref>[https://www.epa.gov/climate-indicators/climate-change-indicators-us-and-global-temperature US and global temperatures]</ref>
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A subset of climate models add societal factors to a simple physical climate model. These models simulate how population, economic growth, and energy use affect – and interact with – the physical climate. With this information, these models can produce scenarios of future greenhouse gas emissions. This is then used as input for physical climate models and carbon cycle models to predict how atmospheric concentrations of greenhouse gases might change in the future.[126][127] Depending on the socioeconomic scenario and the mitigation scenario, models produce atmospheric CO2 concentrations that range widely between 380 and 1400 ppm.[128]
  
The temperature records preferred by the climate establishment were built up over many years and include numerous gaps, bugs, incompatible coding, and other errors. The problems of the CRU data set are memorably documented in the "Harry read me" file, part of the Climategate trove. According to this file, the premier global temperature record contains, "botch after botch after botch."<ref name=Brownlow>Brownlow, Andie, "[https://pjmedia.com/blog/climategates-harry_read_me-txt-we-all-really-should/?singlepage=true Climategate's Harry_Read_Me.txt: We All Really Should]", Dec. 11, 2009.</ref>
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The IPCC Sixth Assessment Report projects that global warming is very likely to reach 1.0 °C to 1.8 °C by the late 21st century under the very low GHG emissions scenario. In an intermediate scenario global warming would reach 2.1 °C to 3.5 °C, and 3.3 °C to 5.7 °C under the very high GHG emissions scenario.[129] These projections are based on climate models in combination with observations.[130]
  
AGW is hardly the only explanation that has been proposed for recent warming. There are also explanations involving natural cycles such as the 11-year-sunspot cycle, the Pacific decadal oscillation,<ref>Bratcher and Giese, "Tropical Pacific decadal variability and global warming", ''Geophysical Research Letters''.</ref> and the El Niño-Southern Oscillation (ENSO).<ref>*72 percent of global temperature variation since 1958 reflects the influence of a Pacific Ocean weather cycle called the El Niño-Southern Oscillation (McLean, J. D., C. R. de Freitas, and R. M. Carter--2009-07-23). "Influence of the Southern Oscillation on tropospheric temperature". ''Journal of Geophysical Research''<br/>*Spencer, R.W. & Braswell, W.D., "[http://link.springer.com/article/10.1007/s13143-014-0011-z The role of ENSO in global ocean temperature changes during 1955–2011 simulated with a 1D climate model]", Asia-Pacific J Atmos Sci (2014) 50: 229. doi:10.1007/s13143-014-0011-z</ref>
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The remaining carbon budget is determined by modelling the carbon cycle and the climate sensitivity to greenhouse gases.[131] According to the IPCC, global warming can be kept below 1.5 °C with a two-thirds chance if emissions after 2018 do not exceed 420 or 570 gigatonnes of CO2. This corresponds to 10 to 13 years of current emissions. There are high uncertainties about the budget. For instance, it may be 100 gigatonnes of CO2 smaller due to methane release from permafrost and wetlands.[132] However, it is clear that fossil fuel resources are too abundant for shortages to be relied on to limit carbon emissions in the 21st century.[133]
  
==Summary of arguments against anthropogenic global warming==
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Impacts
Natural periods of global warming and global cooling are expected to occur regardless of human activity, and not long ago liberals were demanding more government control to combat an alleged cooling in temperatures, with some scientists warning of a possible ice age.<ref name="Time">"Science: Another Ice Age?" (June 24, 1974).  ''Time'' magazine.  Retrieved on September 25, 2014.</ref>  [[Global cooling]], a theory that predates global warming, obviously occurs naturally many times throughout [[Earth|Earth's]] geological history.<ref name="dissidents">"After any given warming phase begins, thousands of years later the cyclical [[Milankovitch]] decrease in the sun's heat kicks in. The warming stops, reverses and an [[ice age]] ensues."  Cockburn, Alexander (June 9–11, 2007).  [http://www.counterpunch.org/cockburn06092007.html "Dissidents against dogma"].  Counterpunch.  Retrieved on September 25, 2014.</ref> The ease of refutation of anthropogenic global cooling claims foretells the eventual fate of the current global warming hysteria.
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Main article: Effects of climate change
  
Many political activists use the term "global warming" to refer to [[anthropogenic global warming theory]] (AGW), which asserts that human activity such as spewing "[[greenhouse gases]]" is causing an increase in temperature and is more significant than natural causes. The AGW theory is supported by left-leaning political parties, as well as a majority of sovereign states, national agencies, and an intergovernmental panel (see [[IPCC]]). The reality is that there is no immediate global crisis, and even dire warnings by the UN's [[Intergovernmental Panel on Climate Change]] (IPCC) admit that significant effects will not be manifested for at least 100 years. Predictions made by [[climate model]]s publicized by the IPCC have not come to pass in recent years. Many scientists, such as Hal Lewis, have decried global warming as a conspiracy for the purpose of securing trillions of dollars in grant money.
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The sixth IPCC Assessment Report projects changes in average soil moisture that can disrupt agriculture and ecosystems. A reduction in soil moisture by one standard deviation means that average soil moisture will approximately match the ninth driest year between 1850 and 1900 at that location.
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Environmental effects
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The environmental effects of climate change are broad and far-reaching, affecting oceans, ice, and weather. Changes may occur gradually or rapidly. Evidence for these effects comes from studying climate change in the past, from modelling, and from modern observations.[134] Since the 1950s, droughts and heat waves have appeared simultaneously with increasing frequency.[135] Extremely wet or dry events within the monsoon period have increased in India and East Asia.[136] The rainfall rate and intensity of hurricanes and typhoons is likely increasing.[137] Frequency of tropical cyclones has not increased as a result of climate change.[138] However, a study review article published in 2021 in Nature Geoscience concluded that the geographic range of tropical cyclones will probably expand poleward in response to climate warming of the Hadley circulation.[139]
  
In November 2009, emails were disclosed that implicated a wrongful manipulation and concealment of data by scientists who have insisted that there is dangerous man-made global warming. Prior to [[ClimateGate]], both the Republican and Democratic party Platforms in 2008 suggested that global warming is happening, that it is caused by human activity, and that it should be counteracted. For example, in 2007, the Republican presidential candidate Senator [[John McCain]] called global warming "an issue we can no longer afford to ignore".<ref>"Issues" (September 1, 2007).  www.JohnMcCain.com [2008 senate campaign website] quoted in [http://www.ontheissues.org/domestic/John_McCain_Environment.htm "John McCain on environment"]  OnTheIssues.org.  Retrieved on September 25, 2014.</ref>  In 2010, an independent analysis cleared the scientists involved of any wrongdoing ''as scientists'', but remarked upon their omissions as data-presenters.  Accordingly, the effects of the scandal still linger.<ref>Whiteman, Hilary (July 7, 2010). [https://www.cnn.com/2010/WORLD/europe/07/07/climategate.email.review/?hpt=Sbin "'Climategate' review clears scientists of dishonesty"]. CNN World.  Retrieved on September 26, 2014.</ref>
 
  
Former Vice President [[Al Gore]] won a [[Nobel Prize]] in 2007 for claiming that there is a dangerous man-made global warming that threatens the world. However, it has since been revealed that he convinced many people through inaccurate information in his "documentary," i.e., he only won the Nobel Prize by lying. [See [[#Al_Gore.27s_Claims|Al Gore's claims]] below.]
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Historical sea level reconstruction and projections up to 2100 published in 2017 by the U.S. Global Change Research Program[140]
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Global sea level is rising as a consequence of glacial melt, melt of the ice sheets in Greenland and Antarctica, and thermal expansion. Between 1993 and 2020, the rise increased over time, averaging 3.3 ± 0.3 mm per year.[141] Over the 21st century, the IPCC projects that in a very high emissions scenario the sea level could rise by 61–110 cm.[142] Increased ocean warmth is undermining and threatening to unplug Antarctic glacier outlets, risking a large melt of the ice sheet[143] and the possibility of a 2-meter sea level rise by 2100 under high emissions.[144]
The following facts can help dissuade even the most illogical of liberals from believing in the flawed theory of anthropogenic global warming.
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=== Temperature flat ===
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Climate change has led to decades of shrinking and thinning of the Arctic sea ice.[145] While ice-free summers are expected to be rare at 1.5 °C degrees of warming, they are set to occur once every three to ten years at a warming level of 2 °C.[146] Higher atmospheric CO2 concentrations have led to changes in ocean chemistry. An increase in dissolved CO2 is causing oceans to acidify.[147] In addition, oxygen levels are decreasing as oxygen is less soluble in warmer water.[148] Dead zones in the ocean, regions with very little oxygen, are expanding too.[149]
The overall temperature has been flat for about 16 years.<ref name="Rose">Rose, David (October 13, 2012). [https://www.dailymail.co.uk/sciencetech/article-2217286/Global-warming-stopped-16-years-ago-reveals-Met-Office-report-quietly-released--chart-prove-it.html "Global warming stopped 16 years ago, reveals Met Office report quietly released...and here is the chart to prove it"]. MailOnline.  Retrieved on September 26, 2014.</ref>
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=== Data manipulation ===
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Tipping points and long-term impacts
Climate data stating otherwise has been proven to be manipulated.<ref>Multiple references:
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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.[150] 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.[151][152] 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).[153] Tipping points can also include irreversible damage to ecosystems like the Amazon rainforest and coral reefs.[154]
*KUSI-TV (January 14, 2010).  [http://www.spaceref.com/news/viewpr.html?pid=30000 "NASA caught in climate data manipulation; new revelations headlined on KUSI-TV climate special"]. SpaceRef.  Retrieved on September 26, 2014.
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*[https://www.youtube.com/watch?v=2jasZcNQqsw "Climategate 2-US Government involved in data manipulation"] (January 16, 2010). YouTube video, 10:00, posted by Bigone5555J. Retrieved on September 26, 2014.</ref>
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=== Alternate causation ===
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The long-term effects of climate change include further ice melt, ocean warming, sea level rise, and ocean acidification.[155] 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.[156] Oceanic CO2 uptake is slow enough that ocean acidification will continue for hundreds to thousands of years.[157] These emissions are estimated to have prolonged the current interglacial period by at least 100,000 years.[158] 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.[159]
Even if global warming did actually exist, the overall effect of human activities on global warming are minimal, if not nonexistent.<ref>Byrne, Dennis (August 30, 2011). [http://articles.chicagotribune.com/2011-08-30/news/ct-oped-0830-byrne-20110830_1_cosmic-rays-aerosols-magnetic-field "The real science trashers"]. ChicagoTribune.  Retrieved on September 26, 2014.</ref>
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==Science of global warming==
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Nature and wildlife
===Presence of CO<sub>2</sub>===
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Main article: Climate change and ecosystems
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Recent warming has driven many terrestrial and freshwater species poleward and towards higher altitudes.[160] 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.[161] Climate change has contributed to the expansion of drier climate zones, such as the expansion of deserts in the subtropics.[162] The size and speed of global warming is making abrupt changes in ecosystems more likely.[163] Overall, it is expected that climate change will result in the extinction of many species.[164]
  
One of the primary concerns of Global Warming research is the increased presence of carbon dioxide (CO<sub>2</sub>) in the atmosphere. Original claims stated that the increase in carbon dioxide—which is a greenhouse gas—were caused primarily through the burning of [[fossil fuels]], and that such increases were the foremost cause of global temperatures rising. Historically, Global temperature changes precede changes in carbon dioxide in the atmosphere.<ref>[http://www.skepticalscience.com/co2-lags-temperature.htm "CO2 lags temperature-what does it mean?"] (2007). SkepticalScience. Retrieved on September 26, 2014.</ref>
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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.[165] 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.[166] Ocean acidification makes it harder for organisms such as mussels, barnacles and corals to produce shells and skeletons; and heatwaves have bleached coral reefs.[167] Harmful algal blooms enhanced by climate change and eutrophication lower oxygen levels, disrupt food webs and cause great loss of marine life.[168] Coastal ecosystems are under particular stress. Almost half of global wetlands have disappeared due to climate change and other human impacts.[169]
  
The most obvious way that this would occur would be through the heating of ocean water. The oceans are the single largest storage unit for carbon dioxide gas on the planet, containing about 93% of the Earth's carbon dioxide.<ref>[http://www.waterencyclopedia.com/Bi-Ca/Carbon-Dioxide-in-the-Ocean-and-Atmosphere.html "Carbon dioxide in the ocean and atmosphere"] (2007).  Water Encyclopedia.  Retrieved on September 26, 2014</ref> As the temperature rises, the [[solubility]] of carbon dioxide in ocean water is reduced,<ref>[https://science.nasa.gov/earth-science/oceanography/ocean-earth-system/ocean-carbon-cycle/ "Carbon cycle"] (2010).  NASA Science.  Retrieved on September 26, 2014.</ref> causing the dissolved carbon dioxide gas to enter the atmosphere, and begin trapping radiation from the sun. Scientists now believe that this cycle causes a sort of chain effect, where increased temperature causes more carbon dioxide to enter the atmosphere, which in turn causes more temperature rise.
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Climate change impacts on the environment
 +
Underwater photograph of branching coral that is bleached white
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Ecological collapse. Bleaching has damaged the Great Barrier Reef and threatens reefs worldwide.[170]
  
It is also noteworthy to point out that carbon dioxide, while not as abundant in the atmosphere, has a more significant effect on global warming than water vapor does. Carbon dioxide cannot form clouds, as water vapor does. When water vapor forms clouds, those clouds actually block some of the sun's radiation from reaching the Earth, causing water vapor to both contribute positively and negatively to global temperature rise. Carbon dioxide can only act as a greenhouse gas, causing the above-mentioned cyclic effect. According to the IPCC and others, the current concentration of carbon dioxide in the Earth's atmosphere is about 392 ppm, which is the highest it has been in at about 800,000 years.<ref>Tans, Pieter and Keeling, Ralph (2010).  [http://www.esrl.noaa.gov/gmd/ccgg/trends/mlo.html "Trends in atmospheric carbon dioxide"].  NOAA/Earth System Research Laboratory Global Monitoring Division.  Retrieved on September 26, 2014.</ref>
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 +
Photograph of evening in a valley settlement. The skyline in the hills beyond is lit up red from the fires.
 +
Extreme weather. Drought and high temperatures worsened the 2020 bushfires in Australia.[171]
  
But other scientists have disputed this claim of modern-day record-high carbon dioxide readings:<ref name="dissidents"/>
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<blockquote>Take Warsaw-based Professor Zbigniew Jaworowski, famous for his critiques of ice-core data. He’s devastating on the IPCC rallying cry that CO<sub>2</sub> is higher now than it has ever been over the past 650,000 years. In his 1997 paper in the Spring ''21st Century Science and Technology'', he demolishes this proposition. In particular, he’s very good on pointing out the enormous inaccuracies in the ice-core data and the ease with which a CO<sub>2</sub> reading from any given year is contaminated by the CO<sub>2</sub> from entirely different eras. He also points out that from 1985 on there’s been some highly suspect editing of the CO<sub>2</sub> data, presumably to reinforce the case for the "unprecedented levels" of modern CO<sub>2</sub>. In fact, in numerous papers prior to 1985, there were plenty of instances of CO<sub>2</sub> levels much higher than current CO<sub>2</sub> measurements, some even six times higher. He also points out that it is highly unscientific to merge ice-core temperature measurements with modern temperature measurements.</blockquote>
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The green landscape is interrupted by a huge muddy scar where the ground has subsided.
 +
Arctic warming. Permafrost thaws undermine infrastructure and release methane, a greenhouse gas.[108]
  
===The Modern Warm Period===
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According to temperature reconstruction made within an [[Old Earth]] paradigm, there have been many cycles of naturally-caused global warming and cooling over many millions of years (see [[climate cycles]]). Some scientists, including [[Richard Lindzen]] of [[MIT]], [[Sallie Baliunas]] of [[Harvard]] and [[Fred Singer]] (independent), say that the recent warming could be part of another natural cycle or random fluctuations in the atmosphere.
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An emaciated polar bear stands atop the remains of a melting ice floe.
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Habitat destruction. Many arctic animals rely on sea ice, which has been disappearing in a warming Arctic.[172]
  
Recent studies of the Milankovitch Cycles, which predict Earth's climate by studying changes in its orbit and axial tilt, suggest that we are currently 18,000 years into a 150,000 year period between ice ages. This would imply that we should expect the temperature to be rising anyway. A 2002 study by Berger and Loutre suggests 50,000 years of warmer weather before Earth begins to cool again, but that model incorporated anthropogenic forces and concluded:
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<blockquote>While combinations of natural forcings produce a gradual warming up to about 1960, none of them leads to a warming over the last 30 years (this period containing three major volcanic eruptions). In contrast, simulations incorporating only anthropogenic forcings reproduce the warming over the last three decades at a rate consistent with that observed, but underestimate the early 20th century warming. As a consequence, only the use of both natural and anthropogenic forcings allows to reproduce much of the observed decadal scale variations of the annual mean hemispheric temperature over the last 150 years.<ref>Bertrand, Cédric, Loutre, Marie-France et al. (May 2002). [http://onlinelibrary.wiley.com/doi/10.1034/j.1600-0870.2002.00287.x/full "Climate of the last millennium: a sensitivity study"]. ''Tellus'' [Stockholm], vol. 54, iss. 3, pp. 221-244.  Retrieved from Wiley Online Library on September 26, 2014.</ref></blockquote>
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Photograph of a large area of forest. The green trees are interspersed with large patches of damaged or dead trees turning purple-brown and light red.
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Pest propagation. Mild winters allow more pine beetles to survive to kill large swaths of forest.[173]
  
It should be noted, however, that computer simulated climate models are often tweaked so they agree with the historical temperature record. There is no way to completely simulate all of the Earth's climate with a computer program.
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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
  
After a major set of temperature readings was found to be an incompatible mix of older and recent data (in the Climategate II scandal) in 2010, Judith Curry, chair of the School of Earth and Atmospheric Science at America's Georgia Tech university examined new data causing her to state (as quoted by MailOnline):<ref name="Rose"/>
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The IPCC Sixth Assessment Report (2021) projects that extreme weather will be progressively more common as the Earth warms.[174]
 +
The effects of climate change on humans have been observed worldwide. They are mostly due to warming and shifts in precipitation. Impacts can now be observed on all continents and ocean regions,[175] with low-latitude, less developed areas facing the greatest risk.[176] Continued warming has potentially “severe, pervasive and irreversible impacts” for people and ecosystems.[177] The risks are unevenly distributed, but are generally greater for disadvantaged people in developing and developed countries.[178]
  
<blockquote>'Natural variability  [the impact of factors such as long-term temperature cycles in the oceans and the output of the sun] has been shown over the past two decades to have a magnitude that dominates the greenhouse warming effect.</blockquote>
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Food and health
 +
The WHO has classified climate change as the greatest threat to global health in the 21st century.[179] Extreme weather leads to injury and loss of life,[180] and crop failures to undernutrition.[181] Various infectious diseases are more easily transmitted in a warmer climate, such as dengue fever and malaria.[182] Young children are the most vulnerable to food shortages. Both children and older people are vulnerable to extreme heat.[183] 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 undernutrition.[184] Over 500,000 more adult deaths are projected yearly by 2050 due to reductions in food availability and quality.[185]
  
<blockquote>'It is becoming increasingly apparent that our attribution of warming since 1980 and future projections of climate change needs to consider natural internal variability as a factor of fundamental importance.'</blockquote>
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Climate change is affecting food security. It has caused reduction in global yields of maize, wheat, and soybeans between 1981 and 2010.[186] Future warming could further reduce global yields of major crops.[187] Crop production will probably be negatively affected in low-latitude countries, while effects at northern latitudes may be positive or negative.[188] Up to an additional 183 million people worldwide, particularly those with lower incomes, are at risk of hunger as a consequence of these impacts.[189] Climate change also impacts fish populations. Globally, less will be available to be fished.[190] Regions dependent on glacier water, regions that are already dry, and small islands have a higher risk of water stress due to climate change.[191]
  
The MailOnline article continued:
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Livelihoods
 +
Economic damages due to climate change may be severe and there is a chance of disastrous consequences.[192] Climate change has likely already increased global economic inequality, and this trend is projected to continue.[193] Most of the severe impacts are expected in sub-Saharan Africa, where most of the local inhabitants are dependent upon natural and agricultural resources[194], and South-East Asia.[195] The World Bank estimates that climate change could drive over 120 million people into poverty by 2030.[196]
  
<blockquote>Professor Phil Jones, director of the Climate Research Unit at the University of East Anglia, who found himself at the centre of the ‘Climategate’ scandal over leaked emails three years ago, would not normally be expected to agree with her....  Prof Jones also admitted that the climate models were imperfect: ‘We don’t fully understand how to input things like changes in the oceans, and because we don’t fully understand it you could say that natural variability is now working to suppress the warming. We don’t know what natural variability is doing.’</blockquote>
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Current inequalities based on wealth and social status have worsened due to climate change.[197] Major difficulties in mitigating, adapting, and recovering to climate shocks are faced by marginalized people who have less control over resources.[198][194] Indigenous people, who are subsistent on their land and ecosystems, will face endangerment to their wellness and lifestyles due to climate change.[199] 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.[200]
  
==Polar bears==
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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.[201] This could lead to statelessness for people in island nations, such as the Maldives and Tuvalu.[202] In some regions, the rise in temperature and humidity may be too severe for humans to adapt to.[203] 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.[204] These factors can drive environmental migration, both within and between countries.[9] 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.[205]
It was announced on the news that polar bears risk going extinct by the end of the twenty-first century if current carbon emissions continue.
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===Sunspots===
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Climate change impacts on people
Sunspot activity is a factor in climate fluctuations, however, little details were known about how much of an impact these fluctuations had on the Earth's climate. During the deepest solar minimum ever recorded, from 2005 to 2010, NASA measured the Earth's energy balance, i.e. the amount of energy absorbed by the sun subtract the amount of energy lost to radiation into space. They concluded:
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Environmental migration. Sparser rainfall leads to desertification that harms agriculture and can displace populations. Shown: Telly, Mali (2008).[206]
<blockquote>If the Sun were the only climate forcing or the dominant climate forcing, then the planet would gain energy during the solar maxima, but lose energy during solar minima. The fact that Earth gained energy at a rate 0.58 W/m<sup>2</sup> during a deep prolonged solar minimum reveals that there is a strong positive forcing overwhelming the negative forcing by below-average solar irradiance. That result is not a surprise, given knowledge of other forcings, but it provides unequivocal refutation of assertions that the Sun is the dominant climate forcing.<ref>Hansen, James, Sato, Makiko et al. (January 2012). [http://www.giss.nasa.gov/research/briefs/hansen_16/ "Earth's energy imbalance"] nasa.gov/Goddard Institute for Space Studies.  Retrieved on September 26, 2014.</ref></blockquote>
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Environmental migration. Sparser rainfall leads to desertification that harms agriculture and can displace populations. Shown: Telly, Mali (2008).[206]
But heat energy is not the only force of the Sun affecting the Earth. The Sun also produces magnetic activity, the effect of which was not measured in this study, and which could affect the Earth's climate in little-understood ways. British astrophysicist Piers Corbyn, speaking in May 2017, claimed that low sunspot activity heralds a mini ice age which could last for 20 years.<ref>https://abruptearthchanges.com/2017/06/14/mini-ice-age-is-here-to-stay-says-astrophysicist/</ref>
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==Economics of global warming==
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While the marriage of anti-capitalists and alleged climate science is nothing new, Rep. [[Alexandria Ocasio-Cortez]] has introduced legislation as part of her [[Green New Deal]], [[reparations]] for minorities, a basic income, and [[Medicare for All]] as part of her "[[climate justice]]" program.<ref>https://news.grabien.com/story-ocasio-cortezs-green-new-deal-radical-mandate-government-con</ref>
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Agricultural changes. Droughts, rising temperatures, and extreme weather negatively impact agriculture. Shown: Texas, US (2013).[207]
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Agricultural changes. Droughts, rising temperatures, and extreme weather negatively impact agriculture. Shown: Texas, US (2013).[207]
  
===Unnecessary expansion of government===
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The idea of dangerous anthropogenic (man-made) global warming (AGW) is promoted by liberals and socialists seeking greater government control over the production and use of energy, which is a substantial percentage of the economy. In economic terms, they would like to 'internalize' the 'externality,' which is to say that they think that producers of emissions should be directly connected to the consequences of those emissions, leading syndicated columnist [[Charles Krauthammer]] to warn of an impending "environmental shakedown".<ref>Krauthammer, Charles (December 11, 2009). [http://www.realclearpolitics.com/articles/2009/12/11/copenhagen_shakedown.html "The environmental shakedown"].  Real Clear Politics.  Retrieved on September 27, 2014.</ref>
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Tidal flooding. Sea-level rise increases flooding in low-lying coastal regions. Shown: Venice, Italy (2004).[208]
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Tidal flooding. Sea-level rise increases flooding in low-lying coastal regions. Shown: Venice, Italy (2004).[208]
  
==Public stances on global warming==
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In 2021 72% of American believed that global warming is real and 14# believed that was not.<ref>[https://climatecommunication.yale.edu/visualizations-data/ycom-us/]</ref> However, the ''Daily Mail'' gives  a figure of 63% of Americans who believe in climate change. Another survey in March 2021  conducted in the United States, some 70 percent of the respondents said they believed that global warming was happening. A much smaller share, 15 percent, believed global warming was not happening.<ref>[https://www.statista.com/statistics/663247/belief-of-global-warming-according-to-us-adults/]</ref> In the UK, according to a ''Daily Mail'' poll, "the public strongly supportsc [Conservative] [[Boris Johnson]]’s bid to curb climate change – but they are not prepared to pay more than £5 extra a week in tax to fund his trillion-pound green energy plans".<ref>[https://www.dailymail.co.uk/news/article-10146089/Daily-Mail-poll-shows-strong-support-PMs-bid-curb-climate-change-public-fears-Cop26-flop.html]></ref> While little is known about public opinion in Russia, the Russian government is beginning to take climate change seriously. Vladimir Putin, who was for long a sceptic, said in 2021 that "climate change is one of the greatest challenges facing humanity. He reiterated this in connection with the climate summit in Glasgow in November this year".<ref>[https://sciencenorway.no/climate-policy-russia-society-and-culture/have-russian,-climate-scientists-convinced-vladimir-putin-that-climate-change-is-real/1956249]</ref>
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Storm intensification. Bangladesh after Cyclone Sidr (2007) is an example of catastrophic flooding from increased rainfall.[209]
 +
Storm intensification. Bangladesh after Cyclone Sidr (2007) is an example of catastrophic flooding from increased rainfall.[209]
  
===Climate change as a cult===
+
   
The zeal of climate-change advocates and lack of objectivity has led some observers to see it as a core belief in a new eco-theology, using themes of traditional Judeo-Christian beliefs. Columnist Deon Feder warns,<ref>Feder, Don (July 31, 2007). [http://archive.frontpagemag.com/readArticle.aspx?ARTID=27579 "The cult of global warming"].  GrassTopsUSA.com.  Retrieved from archive at FrontPageMag.com on September 27, 2014.</ref> that following other attempts such as Marxism, overpopulation, ''[[Silent Spring]]'',
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Heat wave intensification. Events like the June 2019 European heat wave are becoming more common.[210]
<blockquote>now we have the Church of Global Warming, under the leadership of Pope Albert I and his college of cardinals (the [[Natural Resources Defense Council]], [[Sierra Club]] and editorial board of ''The New York Times'').</blockquote>
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Heat wave intensification. Events like the June 2019 European heat wave are becoming more common.[210]
 
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<blockquote>Its Office for the Propagation of the Faith works overtime, churning out books, movies (from the fictional “The Day After Tomorrow” to the fictional [[An Inconvenient Truth|“An Inconvenient Truth”]]), textbooks, concerts, congressional hearings, media pleading and inquisitions.</blockquote>
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Commenting on the tendency to hastily issue dire warnings of Climate Change, seen in the coming [[Ice Age]] scare of the 70's, Maurizio Morabito<ref>Morabito, Maurizio (December 5, 2009). [http://www.spectator.co.uk/features/5592803/the-cias-global-cooling-files/ "The CIA’s ‘global cooling’ file"]. ''The Spectator''.  Retrieved from The Spectator website on September 27, 2014.</ref> asked, "Is the problem with the general public, who cannot talk about climate except in doom-laden terms, and for whom the sky is the last animist god?"
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Mark Steyn writes in ''Macleans'',<ref name="hot">Steyn, Mark (December 24, 2009). [http://www2.macleans.ca/2009/12/24/why-climate-change-is-hot-hot-hot/2/ "Why climate change is hot hot hot"].  Macleans.  Retrieved on September 27, 2014.</ref>
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<blockquote>
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Forty years ago conventional religious belief was certainly in decline in what we once knew as Christendom, but the hole was not yet ozone-layer sized. Once the sea of faith had receded far from shore, the post-Christian West looked at what remained and found “Gaia.”</blockquote>
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And while, "When man was made in the image of God, he was fallen but redeemable", among these devotees of [[Gaia]], 
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<blockquote>Anti-humanism is everywhere, not least in the barely concealed admiration for China’s (demographically disastrous) “One Child” policy advanced by everyone from the ''National Post''’s Diane Francis to Sir David Attenborough, the world’s leading telly naturalist but also a BBC exec who once long ago commissioned the great series ''The Ascent of Man''. If Sir David’s any guide, the great thing about man’s ascent is it gives him a higher cliff to nosedive off.</blockquote>
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===Politics of global warming and dissent===
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{{main|Politics of global warming}}
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[[File:Global carbon emissions.PNG|right|300px|thumb|The [[Peoples Republic of China]] is responsible for 27% of global carbon emissions, more than all other developed nations combined.]]
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Christine Stewart—Canadian Environment Ministry, "'''No matter if the science is all phony''', there are collateral environmental benefits....  [C]limate change [provides] the greatest chance to bring about justice and equality in the world." <ref>Stewart, Christine (December 14, 1998). ''Calgary Herald''.  Reprinted at "Match these quotes" (December 2004).  ''Resource Roundup'', p. 8.  Reprinted at [http://www.aim.org/wls/use-environmentalism-to-change-the-world/ "Use environmentalism to change the world"].  Accuracy in Media, "What liberals say" series.  Retrieved on September 27, 2014.</ref>
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'Global Warming Now World's Most Boring Topic' <ref>Sheppard, Noel (July 17, 2007). [http://newsbusters.org/node/14467 "Hysterical satire: 'Global warming now world's most boring topic'"].  MRC NewsBusters.  Retrieved on September 27, 2014.</ref>
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The need to fight "global warming" has become part of the dogma of the liberal conscience.<ref name="cato">Lindzen, Richard (Spring 1992).  [http://www.cato.org/regulation/spring-1992 "Global warming: The origin and nature of the alleged scientific consensus"].  ''Regulation'', vol. 15, no. 2.  Retrieved from Cato Institute website on September 29, 2014.</ref>
+
 
+
Clearly, "global warming" is a tempting issue for many very important groups to exploit.
+
... dealing with the threat of warming fits in with a great variety of preexisting agendas [like] dissatisfaction with industrial society (neopastoralism), ... governmental desires for enhanced revenues (carbon taxes), and bureaucratic desires for enhanced power.<ref name="cato"/>
+
 
+
Mark Steyn writes in "Why climate change is hot hot hot",<ref name="hot"/>
+
<blockquote>
+
What’s also changed since the seventies is the nature of the UN and the transnational bureaucracies...“Aid” is a discredited word these days and comes with too many strings attached. But eco-credits sluiced through an oil-for-food program on steroids offers splendid new opportunities for bulking up an ambitious dictator’s Swiss bank accounts.</blockquote>
+
 
+
The IPCC is desperate to claim the 20th century—the warmest on record. Thus, tying the progress of modern mankind to our supposed planet imbalance problem. Unfortunately for the IPCC, that point is disputed as well. In 2008, it was discovered that tree rings in Finland were more accurate record of the warmest century. The current era was not the warmest period—it was the period between 931 and 1180.<ref>Birdnow, Timothy (June 24, 2008).  [http://tbirdnow.mee.nu/archive/2008/6?page=2 "The trees of Finland; temperature readings and historical reconstruction"]. Birdnow's Aviary blog.  Retrieved on September 29, 2014.  With links to actual data sources.</ref>
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Assessments of climate science by the [[United Nations]] (see [[IPCC]] — ''Intergovernmental Panel on Climate Change'') have claimed that scientists are 90% sure that over 50% of the observed global warming in recent decades is human-caused, and that continued global warming should be expected over at least the next century.
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Several prominent scientists have pointed out the [[politicized science]] of the UN's assessment methods. The scientific reports are submitted to a panel of representatives appointed by each country in the IPCC. Several scientists whose research demonstrates that climate change is taking place have complained about their work being misrepresented by the U.N.
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In addition, a number of the participants have testified to the pressures placed on them to emphasize results supportive of the current scenario and to suppress other results. That pressure has frequently been effective, and a survey of participants reveals substantial disagreement with the final report.<ref name="cato" />
+
 
+
Richard Lindzen wrote:
+
:Perhaps more important are the pressures being brought to bear on scientists to get the "right" results. Such pressures are inevitable, given how far out on a limb much of the scientific community has gone. The situation is compounded by the fact that some of the strongest proponents of "global warming" in Congress are also among the major supporters of science (Sen. Gore is notable among those).<ref name="cato"/>
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+
[[Christopher Monckton]] wrote an article entitled "Climate sensitivity reconsidered" which states that the Intergovernmental Panel on Climate Change studies are flawed.<ref>Monckton, Christopher (July 2008). [http://www.aps.org/units/fps/newsletters/200807/monckton.cfm "Climate sensitivity reconsidered"].  ''Physics & Society'' newsletter.  Retrieved from American Physical Society/Forum on Physics and Society website on September 29, 2014.</ref>
+
 
+
:The present analysis suggests that the failure of the IPCC's models to predict this and many other climatic phenomena arises from defects in its evaluation of the three factors whose product is climate sensitivity:
+
 
+
::Radiative forcing ΔF;
+
::The no-feedbacks climate sensitivity parameter κ; and
+
::The feedback multiplier ƒ.
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+
:Some reasons why the IPCC’s estimates may be excessive and unsafe are explained. More importantly, the conclusion is that, perhaps, there is no “climate crisis”, and that currently-fashionable efforts by governments to reduce anthropogenic CO<sub>2</sub> emissions are pointless, may be ill-conceived, and could even be harmful.
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+
This was published on a forum of the American Physical Society with the following disclaimers:  "The article has not undergone any scientific peer review" and "the APS disagrees with the article's conclusions".  In fact, the APS disagrees with the article without ever reviewing it.
+
 
+
Ryan N. Maue:
+
:A doctoral student at the Department of Meteorology at Florida State University did a study of global tropical cyclone activity. Its conclusions state that  global warming might be greatly overblown.<ref>Tribune-Review, The (March 21, 2009). [http://www.pittsburghlive.com/x/pittsburghtrib/opinion/s_617111.html# "Global warming? More doubts"].  TribLive [''Pittsburgh Tribune'' website].  Retrieved on September 29, 2014.</ref> Mr. Maue found that tropical cyclone activity worldwide "has completely and utterly collapsed" during the past two to three years with energy levels sinking to those of the late 1970s.
+
 
+
Dr. Vincent Gray:
+
:A member of the IPCC’s expert reviewers’ panel asserts, "There is no relationship between warming and the level of gases in the atmosphere," and "there is no serious threat to the climate" <ref>Hendrickson, Mark W. (May 25, 2009). [https://townhall.com/columnists/markwhendrickson/2009/05/25/a_closer_look_at_climate_change "A closer look at climate change"]. Townhall.com.  Retrieved on September 29, 2014.  "The panic over global warming is totally unjustified" says Vice Chair, IPCC.</ref>
+
 
+
Joe D’Aleo: Climatologist:
+
:The International Climate and Environmental Change Assessment Project says new data "show that in five of the last seven decades since World War II, including this one, global temperatures have cooled while carbon dioxide has continued to rise," and "'''The data suggest cooling''', not warming, in Earth's future." <ref>[https://www.wnd.com/index.php?fa=PAGE.view&pageId=92557 "Shocker: 'Global warming' simply no longer happening"] (March 22, 2009).  WND.  Retrieved on September 29, 2014.</ref>
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+
Dr. John S. Theon:
+
:Retired senior NASA atmospheric [[scientist]], Dr. John S. Theon, the former boss of global warming alarmist James Hansen of [[NASA]], rebukes him declaring “climate models are useless.” “My own belief concerning anthropogenic climate change is that the models do not realistically simulate the climate system because there are many very important sub-grid scale processes that the models either replicate poorly or completely omit,” “Furthermore, some scientists have manipulated the observed data to justify their model results." <ref>Blumer, Tom (January 28, 2009).  [http://newsbusters.org/blogs/tom-blumer/2009/01/28/former-boss-rebukes-nasa-global-warming-alarmist-hansen-agw-skeptic "Former boss rebukes NASA global warming alarmist Hansen, is AGW skeptic"].  MRC NewsBusters.  Retrieved on September 29, 2014.</ref>
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+
Sammy Wilson—Ireland's environment minister
+
:He argues that global weather patterns are naturally cooling, not warming. He calls television ads that promote global warming as "an insidious propaganda campaign" peddling "patent nonsense." <ref>Pogatchnik, Shawn (February 9, 2009).  [http://cnsnews.com/news/article/belfast-environment-chief-bans-climate-change-ads "Belfast environment chief bans climate change ads"].  Associated Press.  Retrieved from CNSNews.com on September 29, 2014.</ref>
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After the broadcast of his movie '[[The Great Global Warming Swindle]]', filmmaker Martin Durkin's statements read <ref>Goodenough, Patrick (July 22, 2008).  [http://cnsnews.com/news/article/uk-broadcaster-scolded-film-global-warming-swindle "UK broadcaster scolded for film on global warming"].  CNSNews.  Retrieved on September 29, 2014.</ref>
+
 
+
*“Everywhere you are told that man-made [[climate change]] is proved beyond doubt,”  “But you are being told lies.”
+
*“This is a story of how a theory about climate turned into a political [[ideology]] ... it is the story of the distortion of a whole area of [[science]].”
+
*“as the frenzy over man-made global warming grows shriller, many senior scientists say the actual scientific basis for the [[theory]] is crumbling.”
+
 
+
In late 2008, the [[AP]] published an article by its Science Writer Seth Borenstein, which is seen by skeptics as another example of one-sided, uncritical reporting on the issue by [[liberal media]]. The report stated that global warming was "a ticking time bomb that President-elect Barack Obama can't avoid", and that  "We're out of time", with Al Gore calling the situation "the equivalent of a five-alarm fire that has to be addressed immediately."<ref>Borenstein, Seth (December 14, 2008).  [https://web.archive.org/web/20081215162025/https://www.breitbart.com/article.php?id=D952LKOO1&show_article=1 "Obama left with little time to curb global warming"].  Associated Press.  Reprinted at Breitbart.com.  Retrieved from December 15, 2008 archive at Internet Archive on September 29, 2014.</ref>  In response, Fox News (December 16, 2008) reported that scientists skeptical of anthropogenic global warming criticized the report as "irrational hysteria," "horrifically bad" and "incredibly biased", containing sweeping scientific errors and being a one-sided portrayal of a complicated issue. Geology professor [[David Deming]] stated, "If the issues weren't so serious and the ramifications so profound, I would have to laugh at it", and accused Borenstein of "writing a polemic and reporting it as fact." Deming noted that "the mean global temperature, at least as measured by satellite, is now the same as it was in the year 1980. In the last couple of years sea level has stopped rising. Hurricane and cyclone activity in the northern hemisphere is at a 24-year low and sea ice globally is also the same as it was in 1980." The AP responded to criticism by stating that, "It’s a news story, based on fact and the clearly expressed views of President-elect Barack Obama and others."<ref>[https://www.foxnews.com/story/0,2933,468084,00.html "Scientists call AP Report on global warming 'hysteria'"] (December 16, 2008).  Fox News website.  Retrieved on September 29, 2014.</ref>
+
 
+
Also in the discussion of the biased AP report, Michael R. Fox, a retired nuclear scientist and chemistry professor from the University of Idaho stated, "There is little evidence to believe that man-made carbon dioxide is causing temperature fluctuation. Other factors, including sun spots, solar winds, variations in the solar magnetic field and solar irradiation, could all be affecting temperature changes."
+
 
+
The year 2008 turned out to be the coolest year since 2000, yet the seventh to tenth warmest year on record, according to the NASA Goddard Institute for Space Studies.<ref>[https://web.archive.org/web/20110725075133/http://news.eoportal.org/research/090127_res3.html "2008 global temperature"] (January 21, 2009).  EO [Earth Observation].  Retrieved from July 25, 2011 archive at Internet Archive on September 29, 2014.</ref>  According to a preliminary analysis by NOAA's National Climatic Data Center, the average June–August 2009 summer temperature for the contiguous United States was below average—the 34th coolest on record.<ref>[http://www.noaanews.noaa.gov/stories2009/20090910_summerstats.html "NOAA: Summer temperature below average for U.S."] (September 10, 2009).  NOAA.  Retrieved on September 29, 2014.</ref>
+
 
+
Richard S. Courtney, a U.N. Intergovernmental Panel on Climate Change (IPCC) expert reviewer and a U.K.-based climate and atmospheric science consultant says  "Rubbish! Global warming is not 'accelerating," and "...that anybody who proclaims that 'Global warming is accelerating' is a liar, a fool, or both."<ref>Brennan, Phil (December 16, 2008). [https://www.newsmax.com/brennan/global-warming-debunked/2009/12/12/id/341719/ "Global warming’s last gasp"].  NewsMax.  Retrieved on September 29, 2014.</ref>
+
 
+
Don J. Easterbrook, Ph.D., emeritus professor of geology at Western Washington University, asked, "What does it take to ignore 10 years of global cooling....? The answer is really quite simple—just follow the money!"
+
==== Belief in global warming and political and religious views ====
+
 
+
The more religious an individual is, the more likely they are to disbelieve in global warming. In 2014, whereas 80% of American [[Atheism|atheists]] believed in climate change, only 56% of all very religious Americans did.<ref name="randalolson.com">[http://www.randalolson.com/2014/09/13/who-are-the-climate-change-deniers/ Statistics on belief in climate change], Randal S. Olson</ref>
+
 
+
In 2014, 86% of [[Democrats]] accepted climate change, whereas half of all [[Republican]]s disbelieve in global warming.<ref name="randalolson.com"/>
+
 
+
===== Evangelicals =====
+
In 2008 86 evangelical pastors, including Rev. Dr.[[Rick Warren]] signed a statement titled "Climate Change: An Evangelical Call to Action", which called on Christians to acknowledge the moral importance of action to counteract man-made climate change. the statement includes specific support for market-based CO<sub>2</sub> reductions such as a cap-and-trade program.<ref>Evangelical Climate Initiative (2006).  [https://web.archive.org/web/20140201232519/http://christiansandclimate.org/statement/ "ECI Statement"].  Climate Change: An Evangelical Call to Action.  Retrieved from February 1, 2014 archive at Internet Archive on September 29, 2014.</ref> In contrast, a group of evangelical scholars, comprised of scientists, economists and theologians, contend that the liberal view of pending catastrophe caused by climate change is  misleading and/or exaggerated.<ref>Vu, Michelle A. (December 4, 2009).  [http://www.christianpost.com/article/20091204/evangelicals-push-back-against-climate-change-hoax/pageall.html "Evangelicals push back against global warming doom"]  The Christian Post website.  Retrieved on September 29, 2014.</ref>
+
 
+
===The Bill Nye challenge===
+
 
+
In April 2016 science popularizer "[[Bill Nye|Bill Nye the Science Guy]]" took the debate up to the "put your money where your mouth is" level.  He issued two bets, of $10,000 each, with Joe Bastardi, a "climate change contrarian" and frequent critic of Nye.  One bet was that "2016 will be in the top 10 of hottest years on record", and that "this current decade will be the warmest ever recorded".<ref>[http://time.com/4301258/bill-nye-sarah-palin-climate-change-bet/ The Bill Nye climate change bet].</ref> As of late May Mr. Bastardi has not taken up the offer.
+
 
+
==Inaccuracies of global warming evidence==
+
===Climate "science" fraud===
+
{{main|Climategate}}
+
 
+
The [[Climategate#Climategate scandal|Climategate scandal]] revealed how liberal scientists appeared to be deceiving the public with the use of fraudulent data for use as climate science. The [[liberal media]] has attempted to bury the story and discount it as the work of computer hackers illegally stealing data. However, [[FOIA|Freedom of Information]] requests is likely what led to the data being leaked — intentionally.<ref>[https://web.archive.org/web/20091212190817/http://www.junkscience.com/ JunkScience.com] (December 12, 2009).  Retrieved from December 12, 2009 archive at Internet Archive on September 29, 2014.</ref> Dr. Willie Soon, a [[physicist]], [[astronomer]] and climate researcher at the solar and stellar physics division of the [[Harvard University]]-Smithsonian Center for Astrophysics, said in an interview, "[The Climatic Research Unit climate scientists] are making scientific progress more difficult now. This is a shameful, dark day for science." Dr. Soon also suggested that there has been systemic suppression of dissenting opinion among scientists in the climate change community, ranging from social snubs to e-mail stalking and even threats of harm.<ref>Koprowski, Gene J. (December 1, 2009). [https://www.foxnews.com/story/0,2933,578368,00.html "Global warming scandal makes scientific progress more difficult, experts say"].  Fox News website.  Retrieved on September 30, 2014.  See [[Fox News]].</ref>
+
 
+
[[Image:GoreFireBreathing.jpg|thumb|left|250px|Al Gore's [[Schlockumentary]] under fire; ''[[An Inconvenient Truth]]'' found to be an inconvenient [[lie]] based on [[junk science]] and digitally enhanced, totally faked scenes of polar icecaps melting.]]
+
 
+
===Liberal claims of "consensus"===
+
Reports of a scientific "consensus" among scientists are similar to their one-sided support of other [[liberal]] policies and beliefs.  For example, nearly 100% of political donations from professors are to [[Democrats]] rather than Republicans.  Similarly, according to NASA, 97% of climate scientists believe that climate-warming trends over the past century are very likely due to human activities.<ref>NASA's Jet Propulsion Laboratory-California Institute of Technology Earth Science Communications Team (2013).  [http://climate.nasa.gov/scientific-consensus "Consensus"].  NASA website/Global Climate Change.  Retrieved on September 30, 2014.</ref>  These liberal scientists believe, or say they believe, that the Earth is warming overall, and that this warming, as well as other changes in climate patterns, is largely caused by human activities.<ref>Multiple references:
+
*Anderegg, William R. L., Prall, James W. et al. (July 6, 2010).  [http://www.pnas.org/content/early/2010/06/04/1003187107.full.pdf+html "Expert credibility in climate change."]  ''Proceedings of the National Academy of Sciences'', vol. 107, no. 27, pp. 12107-12109.  Retrieved from PNAS.org on September 30, 2014.
+
*[http://www.ipcc.ch/publications_and_data/ar4/wg1/en/spmsspm-understanding-and.html "Working group I: The physical science basis/Summary for policy makers/Understanding and attributing climate change"] (2007).  ''IPCC Fourth Assessment Report: Climate Change 2007.''  Retrieved from Intergovernmental Panel on Climate Change website on September 30, 2014.</ref> These allegations do not necessarily make the consensus true, as discussed throughout the referenced citation. Numerous scientists, especially those outside of university faculties, have been critical of anthropogenic global warming. However, according to some researchers, scientists who do not support the anthropogenic global warming theory offer a general lack of comparative credentials; proponents of man-made global warming argue that this has led to agreement that, among authorities in scientific disciplines, there is a "[[scientific consensus]]" supporting the theory for greater government control. Scientists skeptical of the theory question whether there is a financial incentive for supporting research.<ref>Chesser, Paul (October 25, 2007).  [http://www.seattlepi.com/local/opinion/article/Be-wary-of-climate-policy-development-1253536.php "Be wary of climate policy development"].  Seattle Post-Intelligencer website.  Retrieved on September 30, 2014.</ref> It has also been documented that on most college campuses criticism of the global warming theory is silenced or censored; evidence shows that scientists skeptical of AGW are being suppressed.<ref>Multiple references:
+
*O'Neill, Brendan (October 6, 2006).  [http://www.spiked-online.com/index.php?/site/article/1782/ "Global warming:  The chilling effect on free speech"].  Sp!ked.  Retrieved on September 30, 2014.
+
*Schilling, Chelsea (June 24, 2009).  [https://www.wnd.com/index.php?fa=PAGE.view&pageId=102031 "EPA's own research expert 'shut up' on climate change"].  WND.  Retrieved on September 30, 2014.</ref>
+
 
+
It is well understood that most media companies do not offer balanced reporting. Many politicians have bought into the liberal claim of consensus, for example Barack Obama's views, "Few challenges facing America and the world are more urgent than fighting climate change. The science is beyond dispute and the facts are clear." <ref>[https://web.archive.org/web/20090331121618/http://www.cato.org/special/climatechange/ "Climate change reality"] (March 2009).  Cato Institute website.  Retrieved on September 30, 2014.</ref> In fact, many scientists disagree with the "facts," their certainty, and their interpretation. Over 100 of them have signed the statement that appears in the Cato Institute's newspaper ad. Liberals have failed to back up their claims with any scientific facts.
+
 
+
[[File:ad.jpg|center]]
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According to 80 graphs published in 58 peer-reviewed scientific papers in the first five months of 2017 alone, catastrophic anthropogenic global warming does not exist.<ref>Delingpole, James (June 6, 2017). [https://www.breitbart.com/big-government/2017/06/06/delingpole-global-warming-is-myth-58-scientific-papers-2017/ DELINGPOLE: ‘Global Warming’ Is a Myth, Say 58 Scientific Papers in 2017]. ''Breitbart News''. Retrieved June 7, 2017.</ref> By October 2017, the number of peer-reviewed papers rejecting global warming had increased to 400.<ref>Delingpole, James (October 24, 2017). [https://www.breitbart.com/big-government/2017/10/24/delingpole-now-400-scientific-papers-in-2017-say-global-warming-is-a-myth/ Delingpole: Now 400 Scientific Papers in 2017 Say ‘Global Warming’ Is a Myth]. ''Breitbart News''. Retrieved October 24, 2017.</ref>
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+
===Past speculation===
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+
Speculation and warnings of catastrophic climate change are not unprecedented.  In 2001 the ''Guardian'' noted that some 70s headlines shouted, "Brace yourself for another ice age". In 1971 the journal ''Science'' reported that the subsequent cooling effect resulting from a possible eightfold increased from atmospheric aerosol concentrations, "if sustained over a period of several years—is believed to be sufficient to trigger an ice age." <ref>George, Alison (June 28, 2001).  [https://www.theguardian.com/science/2001/jun/28/physicalsciences.highereducation "Breaking the ice"].  The Guardian website.  Retrieved on September 30, 2014.  See [[Guardian (UK)]].</ref>
+
 
+
[[Richard Lindzen]] wrote in 1992 on the doubtfulness of man-caused warming on Earth.
+
{{Cquote|Indeed, a recent Gallup poll of climate scientists in the American Meteorological Society and in the American Geophysical Union shows that a vast majority doubts that there has been any identifiable man-caused warming to date (49 percent asserted no, 33 percent did not know, 18 percent thought some has occurred; however, among those actively involved in research and publishing frequently in peer-reviewed research journals, none believes that any man-caused global warming has been identified so far).<ref name="cato"/>}}
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Oddly enough, even though 82% of US climate scientists refused to support the global warming theory then, [[liberal]] activists were already claiming a scientific consensus for [[anthropogenic global warming]]. (It's hard to understand how 18 percent credence in ''any'' global warming translates into "consensus" support for ''human-caused'' global warming.)
+
 
+
The campaign to convince the public (and their elected representatives) that the "science is settled" began in 1988 or 1989.
+
  
By the 2008 elections both candidates for the Presidency of the United States were proposing plans to mitigate climate change.
+
Reducing and recapturing emissions
 +
Main article: Climate change mitigation
  
Over 31,000 American scientists have signed the petition rejecting global warming.<ref>[http://www.petitionproject.org/ "Global warming petition project"] (2008). Global Warming Petition Project. Retrieved on September 30, 2014.</ref>
+
Scenarios of global greenhouse gas emissions. If all countries achieve their current Paris Agreement pledges, average warming by 2100 would still significantly exceed the maximum 2 °C target set by the Agreement.
 +
Climate change can be mitigated by reducing greenhouse gas emissions and by enhancing sinks that absorb greenhouse gases from the atmosphere.[211] In order to limit global warming to less than 1.5 °C with a high likelihood of success, global greenhouse gas emissions needs to be net-zero by 2050, or by 2070 with a 2 °C target.[132] This requires far-reaching, systemic changes on an unprecedented scale in energy, land, cities, transport, buildings, and industry.[212] 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.[213] With pledges made under the 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.[13]
  
[[Image:Teller_Card_100dpi.jpg|600px|center|thumb| Global Warming Petition]]
+
Although there is no single pathway to limit global warming to 1.5 or 2 °C,[214] 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.[215] To reduce pressures on ecosystems and enhance their carbon sequestration capabilities, changes would also be necessary in agriculture and forestry,[216] such as preventing deforestation and restoring natural ecosystems by reforestation.[217]
  
In June, 1974, ''[[Time]]'' magazine published its front-page article, ''Science: Another Ice Age?'',<ref name="Time"/> while a report by the [[CIA]] in the same year stated that, "The western world's leading climatologists have confirmed recent reports of a detrimental global climatic change”, noting such things as that the "world's snow and ice cover had increased by at least 10 to 15 percent", and in the "Canadian area of [[Arctic]] Greenland, below normal temperatures were recorded for 19 consecutive months", which was unique during the last 100 years.  A "major climatic shift" was speculated, which would threaten the "the stability of most nations.” It further warned that "Scientists are confident that unless man is able to effectively modify the climate, the northern regions, such as Canada" to "major areas in northern China, will again be covered with 100 to 200 feet of ice and snow", within the next 2500 years—or sooner.<ref>Central Intelligence Agency (August 1974).  [http://www.climatemonitor.it/wp-content/uploads/2009/12/1974.pdf ''A Study of Climatological Research as it Pertains to Intelligence Problems''], pp. 1, 5, 7, 16. Retrieved from Climatemonitor [Italy] on September 30, 2014.</ref>
+
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.[218] There are concerns, though, about over-reliance on these technologies, and environmental impacts.[219] Solar radiation management (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.[220]
  
Also in 1974, Nigel Calder, former editor of ''New Scientist'' and atmospheric researcher wrote in his book ''The Weather Machine'', "One might argue that there is a virtual certainty of the next ice age starting some time in the next 2000 years. Then the odds are only about 20-to-1 against it beginning in the next 100 years."
+
Clean energy
 +
Main articles: Sustainable energy and Sustainable transport
  
In 1975 the liberal magazine ''[[Newsweek]]'' reported that "Meteorologists disagree about the cause and extent of the cooling trend,...but they are almost unanimous in the view that the trend will reduce agricultural productivity for the rest of the century." These authorities were skeptical that political leaders would take any positive action to compensate for the [[climate change]], and they conceded that the more dramatic solutions, such as melting the arctic ice cap, might create worse problems than that which they were designed to solve.<ref>Gwynne, Peter (April 28, 1975). [http://denisdutton.com/newsweek_coolingworld.pdf "The cooling world"].  ''Newsweek''.  Retrieved from DenisDutton.com on September 30, 2014.  Caution:  Copyrighted material; for fair educational use only.</ref>
+
Coal, oil, and natural gas remain the primary global energy sources even as renewables have begun rapidly increasing.[221]
  
===Natural variability of the climate system===
+
Economic sectors with more greenhouse gas contributions have a greater stake in climate change policies.
It is virtually universally accepted amongst secular climatologists that the earth has experienced numerous [[Ice Age|ice age]]s over two million years, during which global temperatures fluctuated created glacial and inter-glacial periods. The frigid temperatures allowed ice sheets to expand southward, covering much of [[Asia]], [[Europe]], and [[North America]]. The cooling associated with ice ages is gradual, while the terminations are relatively rapid. However, even the rapid terminations of ice ages take centuries to millennia.
+
Renewable energy is key to limiting climate change.[222] 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).[223] That mix is projected to change significantly over the next 30 years.[215] Solar panels and onshore wind are now among the cheapest forms of adding new power generation capacity in many locations.[224] Renewables represented 75% of all new electricity generation installed in 2019, nearly all solar and wind.[225] 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.[226]
  
===Natural climate change on other planets===
+
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.[227][228]
  
Since the [[Viking spacecraft]] reached [[Mars]] in the 1970s until recent readings were taken, the average temperature on Mars has risen {{temperature|0.6|1.1}} just as the average temperature on the earth has risen.  Since human industrialization is clearly not to blame for the change on Mars, other causes are being considered. One possibility is that dust storms are changing the albedo of the planet, allowing it to warm, while another possibility is that solar variations from the sun are causing the warming.<ref>Multiple references:
+
Electricity would also need to become the main energy source for heating and transport.[229] In transport, emissions can be reduced fast by a switch to electric vehicles.[230] Public transport and active transport (cycling and walking) also produce less CO2.[231] For shipping and flying, low-carbon fuels can be used to reduce emissions.[230] Heating would be increasingly decarbonised with technologies like heat pumps.[232]
*Than, Ker (April 4, 2007). [http://www.space.com/scienceastronomy/070404_gw_mars.html "Dust storms fuel global warming on Mars"].  Space.com.  Retrieved on September 30, 2014.
+
*Taylor, James M. (November 1, 2005). [http://www.heartland.org/Article.cfm?artId=17977 "Mars is warming, NASA scientists report"].  Heartlander Magazine.  Retrieved on September 30, 2014.</ref>
+
  
Recently, it has also been found that similar to the Earth and Mars, [[Neptune]] is also undergoing global warming. Measurements taken at the Lowell observatory in [[Arizona]] have shown an increase in Neptune's brightness and temperature since 1980 following the same pattern seen on Earth and Mars. The researchers who discovered this warming suggest there may be a correlation between the warming and solar variations.<ref>Hammel, H. B. and Lockwood, G. W. (April 8, 2007). [http://www.agu.org/pubs/crossref/2007.../2006GL028764.shtml "Suggestive correlations between the brightness of Neptune, solar variability, and Earth's temperature"]. ''Geophysical Research Letters''.  Retrieved from Wiley Online Library on September 30, 2014.</ref>
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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.[233] 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.[222] Bioenergy is often not carbon-neutral and may have negative consequences for food security.[234] The growth of nuclear power is constrained by controversy around nuclear waste, nuclear weapon proliferation, and accidents.[235][236] Hydropower growth is limited by the fact that the best sites have been developed, and new projects are confronting increased social and environmental concerns.[237]
  
[[Pluto]] has also been found to be undergoing global warming. The overall temperature increase on Pluto has been greater than that on the earth.<ref>Britt, Robert Roy (October 9, 2002).  [http://www.space.com/scienceastronomy/pluto_warming_021009.html "Global warming on Pluto puzzles scientists"]. Space.com.  Retrieved on September 30, 2014.</ref>
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Low-carbon energy improves human health by minimising climate change. It also has the near-term benefit of reducing air pollution deaths,[238] which were estimated at 7 million annually in 2016.[239] 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.[240]
  
On the other hand, [[Uranus]] has had no net change in temperature since 1977.  A rapid increase in temperature reversed itself.  The reasons for this are not understood.<ref>Young, Leslie A., Bosh, Amanda S. et al. (October 2001). [http://www.boulder.swri.edu/~layoung/eprint/ur149/Young2001Uranus.pdf "Uranus after solstice:  Results from the 1998 November 6 occultation"].  ''Icarus'', vol. 153, iss. 2, pp. 236-247.  Retrieved from Southwest Research Institute [Boulder, CO] website on September 30, 2014.</ref>
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Energy conservation
 +
Main articles: Efficient energy use and Energy conservation
 +
Reducing energy demand is another major aspect of reducing emissions.[241] 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.[242] Major increases in energy efficiency investment will be required to achieve climate goals, comparable to the level of investment in renewable energy.[243] Several COVID-19 related changes in energy use patterns, energy efficiency investments, and funding have made forecasts for this decade more difficult and uncertain.[244]
  
Global temperatures change on other planets even when there is no life, something which strongly supports the idea that humans are not necessarily the cause of earth's global warming. Moreover, the temperature on Uranus has fluctuated back and forth. There is no reason that fluctuations cannot occur on earth, too.
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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.[245] Industrial strategies to reduce energy demand include improving heating systems and motors, designing less energy-intensive products, and increasing product lifetimes.[246] In the building sector the focus is on better design of new buildings, and higher levels of energy efficiency in retrofitting.[247] The use of technologies like heat pumps can also increase building energy efficiency.[248]
  
Although measurements have been made of the temperatures of other planets these are by no means thorough or comparable with the measurements used for earth. The short space of time over which measurements have been taken and the very limited spatial coverage means that reliable average figures have not been obtained. They have certainly not been taken extensively enough to produce a five-year average temperature, which is the standard when determining temperature trends on earth.  
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Agriculture and industry
 +
See also: Sustainable agriculture and Green industrial policy
 +
Agriculture and forestry face a triple challenge of limiting greenhouse gas emissions, preventing the further conversion of forests to agricultural land, and meeting increases in world food demand.[249] A set of actions could reduce agriculture and forestry-based emissions by two thirds from 2010 levels. These include reducing growth in demand for food and other agricultural products, increasing land productivity, protecting and restoring forests, and reducing greenhouse gas emissions from agricultural production.[250]
  
However, if accurate measurements could be made, and their accuracy and reliability is improving over time, then they may prove useful to climate science. Their different atmospheres and distances from the sun provide natural laboratories to study climatic changes without human influences. Though of course they will not be directly comparable due to the vast differences.
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On the demand side, a key component of reducing emissions is shifting people towards plant-based diets.[251] Eliminating the production of livestock for meat and dairy would eliminate about 3/4ths of all emissions from agriculture and other land use.[252] Livestock also occupy 37% of ice-free land area on Earth and consume feed from the 12% of land area used for crops, driving deforestation and land degradation.[253]
  
===Al Gore's claims===
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Steel and cement production are responsible for about 13% of industrial CO2 emissions. In these industries, carbon-intensive materials such as coke and lime play an integral role in the production, so that reducing CO2 emissions requires research into alternative chemistries.[254]
[[File:Gore GlobalWarming.jpg|right|200px]]
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The decision by the government to distribute Al Gore's film, ''An Inconvenient Truth'', became the subject of a legal challenge by [[New Party]] member Stewart Dimmock. A school governor from Dover and father of two, Dimmock charged the Government with brainwashing children with propaganda by presenting Gore's sci-fi film as science. In October 2007, Mr Justice Burton of London's High Court found that while the film was "broadly accurate", it contained nine significant errors,“in which statements were made that were not supported by the current mainstream scientific consensus”, some of which had arisen in “the context of alarmism and exaggeration”. He also found the Guidance Notes drafted by the Education Secretary's advisers only worked to exacerbate the political propaganda in the film.<ref>Multiple references:
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*Sheppard, Marc (July 14, 2009). [https://www.americanthinker.com/blog/2009/07/clearly_its_al_gore_whos_in_de.html "Clearly it's Al Gore who's in denial"].  American Thinker.  Retrieved on October 1, 2014.
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*Smith, Lewis (October 11, 2007).  [https://www.thetimes.co.uk/tto/law/article2210175.ece "Al Gore’s inconvenient judgment"].  The Times website.  Retrieved on October 1, 2014.  Fee required to see article.
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*Smith, Lewis (October 11, 2007).  [http://www.uio.no/studier/emner/matnat/ifi/MNSES9100/h11/undervisningsmateriale/literature/Al%20Gore%E2%80%99s%20inconvenient%20judgement%20times%202007.pdf "Al Gore’s inconvenient judgment"].  The Times website.  Retrieved from University of Oslo/Faculty of Mathematics and Natural Science website on October 1, 2014.  Caution:  Copyrighted; for fair educational use only.</ref>
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Taken from the official transcript,<ref>Burton, Mr Justice Michael (October 10, 2007). [http://noteviljustwrong.com/images/nejw/docs/22161.pdf "Stuart Dimmock and Secretary of State for Education and Skills"].  United Kingdom of Great Britain's High Court of Justice/Queen's Bench Division/Administrative Court.  Retrieved from Not Evil Just Wrong on October 1, 2014.</ref> the nine errors the judge found were:
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Carbon sequestration
 +
Main articles: Carbon dioxide removal and Carbon sequestration
  
*1. Sea  level  rise  of  up  to  20  feet  (7 metres) will  be caused  by melting  of either West Antarctica or Greenland in the near future. This is distinctly alarmist, and part of Mr Gore's 'wake-up call'. It is common ground that if indeed Greenland melted, it would release this amount of water, but only after, and over, millennia,  so  that  the  Armageddon  scenario  he  predicts,  insofar  as it suggests that sea level rises of 7 metres might occur in the immediate future, is not in line with the scientific consensus.
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Most CO2 emissions have been absorbed by carbon sinks, including plant growth, soil uptake, and ocean uptake (2020 Global Carbon Budget).
 +
Natural carbon sinks can be enhanced to sequester significantly larger amounts of CO2 beyond naturally occurring levels.[255] Reforestation and tree planting on non-forest lands are among the most mature sequestration techniques, although the latter raises food security concerns.[256] Farmers can promote sequestration of carbon in soils through practices such as use of winter cover crops, reducing the intensity and frequency of tillage, and using compost and manure as soil amendments.[257] Restoration/recreation of coastal wetlands and seagrass meadows increases the uptake of carbon into organic matter (blue carbon).[258] When carbon is sequestered in soils and in organic matter such as trees, there is a risk of the carbon being re-released into the atmosphere later through changes in land use, fire, or other changes in ecosystems.[259]
  
*2. Low  lying  inhabited  Pacific  atolls  are  being  inundated  because  of anthropogenic global warming. In scene 20, Mr Gore states "that's why the citizens of these Pacific nations have all had to evacuate to New Zealand". There is no evidence of any such evacuation having yet happened.  
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Where energy production or CO2-intensive heavy industries continue to produce waste CO2, the gas can be captured and stored instead of released to the atmosphere. Although its current use is limited in scale and expensive,[260] carbon capture and storage (CCS) may be able to play a significant role in limiting CO2 emissions by mid-century.[261] This technique, in combination with bio-energy (BECCS) can result in net negative emissions: CO2 is drawn from the atmosphere.[262] It remains highly uncertain whether carbon dioxide removal techniques, such as BECCS, will be able to play a large role in limiting warming to 1.5 °C. Policy decisions that rely on carbon dioxide removal increase the risk of global warming rising beyond international goals.[263]
  
*3. Shutting down of the "Ocean Conveyor". According  to  the  IPCC, it  is very  unlikely  that  the  Ocean  Conveyor (known  technically  as  the Meridional  Overturning  Circulation  or  thermohaline circulation)  will  shut  down  in the  future, though  it  is considered  likely  that thermohaline circulation may slow down.  
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Adapting to a changing climate
 +
Main article: Climate change adaptation
 +
Adaptation is "the process of adjustment to current or expected changes in climate and its effects".[264] Without additional mitigation, adaptation cannot avert the risk of "severe, widespread and irreversible" impacts.[265] More severe climate change requires more transformative adaptation, which can be prohibitively expensive.[264] The capacity and potential for humans to adapt is unevenly distributed across different regions and populations, and developing countries generally have less.[266] The first two decades of the 21st century saw an increase in adaptive capacity in most low- and middle-income countries with improved access to basic sanitation and electricity, but progress is slow. Many countries have implemented adaptation policies. However, there is a considerable gap between necessary and available finance.[267]
  
*4. Direct coincidence between rise in CO<sub>2</sub> in the atmosphere and in temperature, by reference to two graphs. In scenes 8 and 9, Mr Gore shows  two graphs relating  to a period of 650,000 years, one  showing  rise  in  CO<sub>2</sub>  and one  showing  rise  in  temperature,  and  asserts  (by ridiculing  the  opposite  view)  that  they  show  an  exact  fit. Although  there  is  general scientific agreement  that  there  is a connection, the  two graphs do not establish what Mr Gore asserts.  
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Adaptation to sea level rise consists of avoiding at-risk areas, learning to live with increased flooding and protection. If that fails, managed retreat may be needed.[268] There are economic barriers for tackling dangerous heat impact. Avoiding strenuous work or having air conditioning is not possible for everybody.[269] In agriculture, adaptation options include a switch to more sustainable diets, diversification, erosion control and genetic improvements for increased tolerance to a changing climate.[270] Insurance allows for risk-sharing, but is often difficult to get for people on lower incomes.[271] Education, migration and early warning systems can reduce climate vulnerability.[272]
  
*5. The snows of Kilimanjaro. The film asserted that melting snows on Mount Kilimanjaro evidenced global warming. The Government's expert was had to admit that this is not correct. Mr  Gore  asserts  in  scene  7  that  the  disappearance  of  snow  on Mt  Kilimanjaro  is expressly  attributable  to global  warming. It  is  noteworthy  that  this  is  a point  that specifically  impressed Mr Milliband  (see  the  press  release  quoted  at  paragraph  6 above). However, it is common ground that, the scientific consensus is that it cannot be established that the recession of snows on Mt Kilimanjaro is mainly attributable to human-induced climate change.
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Ecosystems adapt to climate change, a process that can be supported by human intervention. By increasing connectivity between ecosystems, species can migrate to more favourable climate conditions. Species can also be introduced to areas acquiring a favorable climate. Protection and restoration of natural and semi-natural areas helps build resilience, making it easier for ecosystems to adapt. Many of the actions that promote adaptation in ecosystems, also help humans adapt via ecosystem-based adaptation. For instance, restoration of natural fire regimes makes catastrophic fires less likely, and reduces human exposure. Giving rivers more space allows for more water storage in the natural system, reducing flood risk. Restored forest acts as a carbon sink, but planting trees in unsuitable regions can exacerbate climate impacts.[273]
  
*6. Lake Chad etc. The drying up of Lake Chad  is used  as  a prime  example of  a  catastrophic  result of global  warming.  However,  it  is  generally  accepted  that  the  evidence  remains insufficient to establish such an attribution. It is apparently considered to be far more likely  to result from other factors, such as population  increase and over-grazing, and regional climate variability.
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There are synergies and trade-offs between adaptation and mitigation. Adaptation often offer short-term benefits, whereas mitigation has longer-term benefits.[274] Increased use of air conditioning allows people to better cope with heat, but increases energy demand. Compact urban development may lead to reduced emissions from transport and construction. At the same time, it may increase the urban heat island effect, leading to higher temperatures and increased exposure.[275] Increased food productivity has large benefits for both adaptation and mitigation.[276]
  
*7. Hurricane Katrina. In  scene  12  Hurricane  Katrina  and the  consequent  devastation  in  New  Orleans  is ascribed to global warming. It is common ground that there is insufficient evidence to show that.
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Policies and politics
 +
Main article: Politics of climate change
  
*8. Death of polar bears. In scene 16, by reference to a dramatic graphic of a polar bear desperately swimming through  the water  looking  for  ice, Mr Gore says: "A new scientific study shows  that for  the  first  time  they are finding polar bears  that have actually drowned swimming long distances up to 60 miles to find the ice. They did not find that before." The only scientific  study  that  either  side  before me  can  find  is one which indicates  that  four polar bears have recently been found drowned because of a storm.
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The Climate Change Performance Index ranks countries by greenhouse gas emissions (40% of score), renewable energy (20%), energy use (20%), and climate policy (20%).
 +
  High
 +
  Medium
 +
  Low
 +
  Very Low
 +
Countries that are most vulnerable to climate change have typically been responsible for a small share of global emissions. This raises questions about justice and fairness.[277] Climate change is strongly linked to sustainable development. Limiting global warming makes it easier to achieve sustainable development goals, such as eradicating poverty and reducing inequalities. The connection is recognised in Sustainable Development Goal 13 which is to "take urgent action to combat climate change and its impacts".[278] The goals on food, clean water and ecosystem protection have synergies with climate mitigation.[279]
  
*9. Coral reefs. In scene 19, Mr Gore says: "Coral reefs all over the world because of global warming and  other  factors  are  bleaching  and  they  end  up  like  this. All  the  fish  species  that depend on  the coral reef are also  in  jeopardy as a result. Overall specie loss  is now occurring at a rate 1000 times greater than the natural background rate." The actual scientific view, as recorded in the IPCC report, is that, if the temperature were to rise by 1-3 degrees Centigrade, there would be  increased coral bleaching and widespread coral  mortality,  unless  corals  could  adapt or climatize, but  that  separating  the impacts  of  climate  change-related  stresses  from other  stresses,  such  as  over-fishing and polluting, is difficult.  
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The geopolitics of climate change is complex. It has often been framed as a free-rider problem, in which all countries benefit from mitigation done by other countries, but individual countries would lose from switching to a low-carbon economy themselves. This framing has been challenged. For instance, the benefits of a coal phase-out to public health and local environments exceed the costs in almost all regions.[280] Furthermore, net importers of fossil fuels win economically from switching to clean energy, causing net exporters to face stranded assets: fossil fuels they cannot sell.[281]
 
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Dimmock's lawyer, Mr. Downes, argued that by schools making available such film to its teachers, and if teachers then showed such  film  to  their pupils, then  this would inevitably result "in  the promotion of partisan political views  in the  teaching of any  subject  in  the  school, which  is  thus not only not being forbidden  by  the  local  education  authority  (and  the  DES), but  being  positively facilitated by them."
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Mr Justice Barton stressed that the “apocalyptic vision” presented in the film was politically partisan and not an impartial analysis of the science of climate change. “It is now common ground that it is not simply a science film—although it is clear that it is based substantially on scientific research and opinion—but that it is a political film.
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Policy options
 +
A wide range of policies, regulations, and laws are being used to reduce emissions. As of 2019, carbon pricing covers about 20% of global greenhouse gas emissions.[282] Carbon can be priced with carbon taxes and emissions trading systems.[283] Direct global fossil fuel subsidies reached $319 billion in 2017, and $5.2 trillion when indirect costs such as air pollution are priced in.[284] Ending these can cause a 28% reduction in global carbon emissions and a 46% reduction in air pollution deaths.[285] Subsidies could be used to support the transition to clean energy instead.[286] More direct methods to reduce greenhouse gases include vehicle efficiency standards, renewable fuel standards, and air pollution regulations on heavy industry.[287] Several countries require utilities to increase the share of renewables in power production.[288]
  
Justice Barton also stated that, “I conclude that the claimant substantially won this case by virtue of my finding that, but for the new guidance note, the film would have been distributed in breach of sections 406 and 407 of the 1996 Education Act.”<ref>[http://news.bbc.co.uk/2/hi/7037671.stm "Gore climate film's nine 'errors'"] (October 11, 2007). BBC News website.  Retrieved on October 1, 2014.</ref>
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Policy designed through the lens of climate justice tries to address human rights issues and social inequality. For instance, wealthy nations responsible for the largest share of emissions would have to pay poorer countries to adapt.[289] As the use of fossil fuels is reduced, jobs in the sector are being lost. To achieve a just transition, these people would need to be retrained for other jobs. Communities with many fossil fuel workers would need additional investments.[290]
  
In order for the film to be shown, the Government must first amend their Guidance Notes to Teachers to make clear that
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International climate agreements
 +
Further information: United Nations Framework Convention on Climate Change
  
*1.  The Film is a political work and promotes only one side of the argument.  
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Since 2000, rising CO2 emissions in China and the rest of world have surpassed the output of the United States and Europe.[291]
  
*2. If teachers present the Film without making this plain they may be in breach of section 406 of the Education Act 1996 and guilty of political indoctrination.  
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Per person, the United States generates CO2 at a far faster rate than other primary regions.[291]
 +
Nearly all countries in the world are parties to the 1994 United Nations Framework Convention on Climate Change (UNFCCC).[292] The goal of the UNFCCC is to prevent dangerous human interference with the climate system.[293] As stated in the convention, this requires that greenhouse gas concentrations are stabilised in the atmosphere at a level where ecosystems can adapt naturally to climate change, food production is not threatened, and economic development can be sustained.[294] The UNFCCC does not itself restrict emissions but rather provides a framework for protocols that do. Global emissions have risen since the UNFCCC was signed.[295] Its yearly conferences are the stage of global negotiations.[296]
  
*3. Nine inaccuracies have to be specifically drawn to the attention of school children.<ref>[http://www.newparty.co.uk/articles/inaccuracies-gore.html "Inaccuracies in Al Gore's 'An Inconvenient Truth'"] (October 2007). The New Party [U.K.].  Retrieved on October 1, 2014.</ref>
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The 1997 Kyoto Protocol extended the UNFCCC and included legally binding commitments for most developed countries to limit their emissions.[297] During the negotiations, the G77 (representing developing countries) pushed for a mandate requiring developed countries to "[take] the lead" in reducing their emissions,[298] since developed countries contributed most to the accumulation of greenhouse gases in the atmosphere. Per-capita emissions were also still relatively low in developing countries and developing countries would need to emit more to meet their development needs.[299]
  
Science and Public Policy took issue with the response to the ruling by Al Gore's spokesman and  environment adviser, and asserted that his film contains ''35 Inconvenient Truths''.<ref>Monckton, Christopher (October 19, 2007).  [https://web.archive.org/web/20140915002809/http://scienceandpublicpolicy.org/monckton/goreerrors.html "35 inconvenient truths: The errors in Al Gore's movie"]The Science and Public Policy Institute website. Retrieved from September 15, 2014 archive at Internet Archive on October 1, 2014.</ref>
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The 2009 Copenhagen Accord has been widely portrayed as disappointing because of its low goals, and was rejected by poorer nations including the G77.[300] Associated parties aimed to limit the global temperature rise to below 2 °C.[301] The Accord set the goal of sending $100 billion per year to developing countries for mitigation and adaptation by 2020, and proposed the founding of the Green Climate Fund.[302] As of 2020, the fund has failed to reach its expected target, and risks a shrinkage in its funding.[303]
  
Regarding his claims that the snow cap atop Africa's Mt. Kilimanjaro is shrinking and that global warming is to blame, the November 23, 2003, issue of ''Nature'' magazine stated,
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In 2015 all UN countries negotiated the Paris Agreement, which aims to keep global warming well below 2.0 °C and contains an aspirational goal of keeping warming under 1.5 °C.[304] The agreement replaced the Kyoto Protocol. Unlike Kyoto, no binding emission targets were set in the Paris Agreement. Instead, a set of procedures was made binding. Countries have to regularly set ever more ambitious goals and reevaluate these goals every five years.[305] The Paris Agreement restated that developing countries must be financially supported.[306] As of October 2021, 194 states and the European Union have signed the treaty and 191 states and the EU have ratified or acceded to the agreement.[307]
  
:Although it's tempting to blame the ice loss on global warming, researchers think that deforestation of the mountain's foothills is the more likely culprit. Without the forests' humidity, previously moisture-laden winds blew dry. No longer replenished with water, the ice is evaporating in the strong equatorial sunshine."
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The 1987 Montreal Protocol, an international agreement to stop emitting ozone-depleting gases, may have been more effective at curbing greenhouse gas emissions than the Kyoto Protocol specifically designed to do so.[308] The 2016 Kigali Amendment to the Montreal Protocol aims to reduce the emissions of hydrofluorocarbons, a group of powerful greenhouse gases which served as a replacement for banned ozone-depleting gases. This made the Montreal Protocol a stronger agreement against climate change.[309]
  
Many conservatives see Al Gore as an example of [[liberals]] using [[deceit]]ful tactics in important debates, in order to make a position seem more solid than it is.
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National responses
 +
In 2019, the United Kingdom parliament became the first national government to declare a climate emergency.[310] Other countries and jurisdictions followed suit.[311] That same year, the European Parliament declared a "climate and environmental emergency".[312] The European Commission presented its European Green Deal with the goal of making the EU carbon-neutral by 2050.[313] Major countries in Asia have made similar pledges: South Korea and Japan have committed to become carbon-neutral by 2050, and China by 2060.[314] In 2021, the European Commission released its “Fit for 55” legislation package, which contains guidelines for the car industry; all new cars on the European market must be zero-emission vehicles from 2035.[315] While India has strong incentives for renewables, it also plans a significant expansion of coal in the country.[316]
  
===Scientists===
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As of 2021, based on information from 48 national climate plans, which represent 40% of the parties to the Paris Agreement, estimated total greenhouse gas emissions will be 0.5% lower compared to 2010 levels, below the 45% or 25% reduction goals to limit global warming to 1.5 °C or 2 °C, respectively.[317]
  
[[Image:Rogerrevelle.jpg|thumb|right|200px|Roger Revelle]]
+
Scientific consensus and society
 +
Scientific consensus
 +
Main article: Scientific consensus on climate change
  
{|
+
Academic studies of scientific consensus[318][319][320] reflect that the level of consensus correlates with expertise in climate science.[321]
| valign="top" width="35%"|
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There is a near-complete scientific consensus that the climate is warming and that this is caused by human activities. As of 2019, agreement in recent literature reached over 99%.[322][319] No scientific body of national or international standing disagrees with this view.[323] Consensus has further developed that some form of action should be taken to protect people against the impacts of climate change. National science academies have called on world leaders to cut global emissions.[324]
* [[Roger Revelle]]
+
* [[Achim Steiner]]
+
* [[Fred Singer]]
+
* [[Richard Lindzen]]
+
* [[Sallie Baliunas]]
+
* [[Lonnie Thompson]]
+
| valign="top" width="33%"|
+
* [[James E. Hansen]]
+
* [[Michael Mann]]
+
* [[Charles Keeling]]
+
* [[Edwin A. Hernández-Delgado]]
+
|}
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====Hal Lewis====
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Scientific discussion takes place in journal articles that are peer-reviewed. Scientists assess these every few years in the Intergovernmental Panel on Climate Change reports.[325] The 2021 IPCC Assessment Report stated that it is "unequivocal" that climate change is caused by humans.[319]
[[Liberal]] claims of global warming led to the resignation in October 2010 by Professor Hal Lewis from The American Physical Society because of "the global warming scam, with the (literally) trillions of dollars driving it, that has corrupted so many scientists, and has carried APS before it like a rogue wave. '''It is the greatest and most successful pseudoscientific fraud I have seen in my long life as a physicist'''."<ref>Lewis, Hal (October 8, 2010). [https://web.archive.org/web/20140212001321/http://www.thegwpf.org/hal-lewis-my-resignation-from-the-american-physical-society/ "Hal Lewis:  My resignation from the American Physical Society"].  The Global Warming Policy Foundation website.  Retrieved from February 12, 2014 archive at Internet Archive on October 1, 2014.</ref>
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===Critique of the "Hockey Stick" reconstruction===
 
::''See also : [[Climategate#Hockey Stick Graph|Climategate: hockey stick graph]]''
 
<small>
 
*Shabecoff, Philip, [https://www.nytimes.com/1989/01/26/us/us-data-since-1895-fail-to-show-warming-trend.html U.S. Data Since 1895 Fail To Show Warming Trend]", ''New York Times'', January 26, 1989
 
*[http://blogs.nature.com/climatefeedback/2007/05/the_decay_of_the_hockey_stick.html The Decay of the Hockey Stick by Von Storch] published on the journal ''Nature'''s blog, May 3, 2007.
 
*Stephen McIntyre and Ross McKitrick, "[http://climateaudit.files.wordpress.com/2005/09/mcintyre.mckitrick.2003.pdf Corrections To The Mann et. al. (1998) Proxy Data Base And Northern Hemispheric Average Temperature Series], ''Energy & Enviornment'' volume 14, 2003.
 
*[http://www.technologyreview.com/Energy/13830/ A Global Warming Bombshell] by Richard A. Muller, ''Technology Review'' , Oct. 2004; calls into question famous graph by Michael Mann.
 
*[http://www.sciencemag.org/cgi/content/abstract/306/5696/679 Reconstructing Past Climate from Noisy Data] by Hans von Storch, Eduardo Zorita, Julie M. Jones, Yegor Dimitriev, Fidel González-Rouco, Simon F. B. Tett, ''Science'' magazine, 22 October 2004.
 
*[http://www.image.ucar.edu/~boli/manuscripts/2007-LNA-TeA.pdf The ‘hockey stick’ and the 1990s: a statistical perspective on reconstructing hemispheric temperatures] by Bo Li, Douglas W. Nychka and Casper M. Ammann, ''Institute for Mathmatics Applied to Geosciences''; (Manuscript received 22 March 2007; in final form 28 June 2007).
 
*[http://www.21stcenturysciencetech.com/2006_articles/IceCoreSprg97.pdf Ice Core Data Show No Carbon Dioxide Increase] by Zbigniew Jaworowski, Ph.D., Spring 1997; this article examines one of the main pillars of the global warming thesis.
 
*[http://climateaudit.files.wordpress.com/2005/09/mcintyre.ee.2005.pdf The M&M Critique of the MBH98 Northern Hemisphere Climate Index: Update and Implications] (''Energy & Environment'', vol. 16, no. 1, pp.&nbsp;69–100, January 2005) - Stephen McIntyre, Ross McKitrick
 
*[http://climateaudit.files.wordpress.com/2005/09/mcintyre.grl.2005.pdf Hockey sticks, principal components, and spurious significance] (''Geophysical Research Letters'', vol. 32, February 2005) - Stephen McIntyre, Ross McKitrick
 
  
*Dalmia, Shikha (December 2, 2009). [https://www.forbes.com/2009/12/01/climategate-scandal-science-obama-opinions-columnists-shikha-dalmia.html "Cringing over Climategate"].  Forbes website.  Retrieved on September 25, 2014.
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Data has been cherry picked from short periods to falsely assert that global temperatures are not rising. Blue trendlines show short periods that mask longer-term warming trends (red trendlines). Blue dots show the so-called global warming hiatus.[326]
*Taylor, James (November 23, 2011). [https://www.forbes.com/sites/jamestaylor/2011/11/23/climategate-2-0-new-e-mails-rock-the-global-warming-debate/ "Climategate 2.0: New e-mails rock the global warming debate"]. Forbes website.  Retrieved on September 25, 2014.
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Denial and misinformation
*Bailey, Ronald (December 26, 2012). [http://reason.com/blog/2012/12/26/34-years-of-satellite-temperature-data-s "34 years of satellite temperature data show global warming is on a plateau"].  Hit & Run Blog/Reason.com.  Retrieved on September 25, 2014.
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Further information: Global warming controversy, Fossil fuels lobby, Climate change denial, and Global warming conspiracy theory
*Cole, Steve and McCarthy, Leslie (January 12, 2011). [https://www.nasa.gov/topics/earth/features/2010-warmest-year.html "NASA research finds 2010 tied for warmest year on record"].  NASA website.  Retrieved on September 25, 2014.
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Public debate about climate change has been strongly affected by climate change denial and misinformation, which originated in the United States and has since spread to other countries, particularly Canada and Australia. The actors behind climate change denial form a well-funded and relatively coordinated coalition of fossil fuel companies, industry groups, conservative think tanks, and contrarian scientists.[327] Like the tobacco industry, the main strategy of these groups has been to manufacture doubt about scientific data and results.[328] Many who deny, dismiss, or hold unwarranted doubt about the scientific consensus on anthropogenic climate change are labelled as "climate change skeptics", which several scientists have noted is a misnomer.[329]
*Tisdale, Bob (August 10, 2012).  [http://wattsupwiththat.com/2012/08/10/not-hot-ocean-sst-around-the-usa-not-anywhere-near-record-levels/ "Not so hot—ocean temperatures around the USA are not anywhere near record levels"].  Watts Up with That?  Retrieved on September 25, 2014.</ref>
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</small>
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==Effects of global warming==
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There are different variants of climate denial: some deny that warming takes place at all, some acknowledge warming but attribute it to natural influences, and some minimise the negative impacts of climate change.[330] Manufacturing uncertainty about the science later developed into a manufactured controversy: creating the belief that there is significant uncertainty about climate change within the scientific community in order to delay policy changes.[331] Strategies to promote these ideas include criticism of scientific institutions,[332] and questioning the motives of individual scientists.[330] An echo chamber of climate-denying blogs and media has further fomented misunderstanding of climate change.[333]
===Beneficial effects of global warming===
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[[File:Autumn foliage.jpg|thumb|Canoing on a Colorful Day, (NY).]]
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Some researchers point out that benefits of health global warming have been overlooked, or minimized. As far back as 1996, Thomas Gale Moore, Senior Fellow at Hoover Institution (Stanford University) contended that positive health and amenity effects would be a result of projected increases in temperature.<ref>Moore, Thomas Gale (May 30, 1996).  [http://www.stanford.edu/~moore/health.html "Health and amenity effects of global warming"].  Stanford University/Thomas Gale Moore webpage.  Retrieved on October 1, 2014.</ref>
+
  
Another source notes,<ref>[https://web.archive.org/web/20081223011000/http://www.bionomicfuel.com/what-are-the-benefits-of-global-warming/ "What are the benefits of global warming?"] (November 3, 2008).  Bionomicfuel.com.  Retrieved from December 21, 2008 archive at Internet Archive on October 1, 2014.</ref>
+
Public awareness and opinion
 +
Further information: Climate communication, Media coverage of climate change, and Public opinion on climate change
 +
Climate change came to international public attention in the late 1980s.[334] Due to media coverage in the early 1990s, people often confused climate change with other environmental issues like ozone depletion.[335] In popular culture, the climate fiction movie The Day After Tomorrow (2004) and the Al Gore documentary An Inconvenient Truth (2006) focused on climate change.[334]
  
<blockquote>In areas that see extreme cold temperatures, deaths related to colder weather would drop significantly, leading to decreased health care costs, while areas that already have hot climates will see no increase. Warmer temperatures would also mean less energy use to heat homes and buildings, helping to conserve energy as cooling is much more energy efficient. With the changes brought about by global warming more land that is not lost to desert and/or rising sea levels would become available for uses like farming and living. Forests and plants would grow stronger, healthier, and more abundant because of the warmer weather, and this would mean more oxygen being released into the atmosphere.</blockquote>
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Significant regional, gender, age and political differences exist in both public concern for, and understanding of, climate change. More highly educated people, and in some countries, women and younger people, were more likely to see climate change as a serious threat.[336] Partisan gaps also exist in many countries,[337] and countries with high CO2 emissions tend to be less concerned.[338] Views on causes of climate change vary widely between countries.[339] Concern has increased over time,[337] to the point where in 2021 a majority of citizens in many countries express a high level of worry about climate change, or view it as a global emergency.[340] Higher levels of worry are associated with stronger public support for policies that address climate change.[341]
  
===Reported effects of global warming===
+
Climate movement
 +
Main articles: Climate movement and Climate change litigation
  
Reported past or expected/possible future environmental and societal consequences of man-made global warming include global cooling,<ref>72Jag (August 25, 2014).  [https://web.archive.org/web/20090827143311/http://www.nowpublic.com/environment/global-warming-causing-global-cooling "Is global warming causing global cooling?"] NowPublic.  Retrieved on October 1, 2014.</ref> decreased food production,<ref>Fred Pearce (April 26, 2005).  [http://www.newscientist.com/article/dn7310-climate-change-warning-over-food-production.html "Climate change warning over food production"]  Newscientist website.  Retrieved on October 1, 2014.</ref> increased food production,<ref>Booth, William (May 17, 1990). [http://www.highbeam.com/doc/1P2-1127111.html "Global heating could benefit U.S. farmers; prices seen rising as production falls"].  ''The Washington Post''.  Retrieved from HighBeam Research website on October 1, 2014.</ref> shrinking forest.,<ref>Adam, David (March 11, 2009).  [http://www.guardian.co.uk/environment/2009/mar/11/amazon-global-warming-trees/print "Amazon could shrink by 85% due to climate change"].  Theguardian [U. K.].  Retrieved on October 1, 2014.  See [[The Guardian]].</ref> increased tree foliage,<ref>[http://www.greenfingers.com/articledisplay.asp?id=1734 "Global warming causes greening"] (2008).  Greenfingers.com.  Retrieved on October 1, 2014.</ref> increased productivity of high-elevation forests,<ref>Oregon State University (Oct. 20, 2009). [https://www.sciencedaily.com/releases/2009/10/091019163020.htm "Global warming may spur increased growth in Pacific northwest forests"].  ScienceDaily.  Retrieved on October 1, 2014.</ref> melting glaciers.,<ref>Asian News International (June 6, 2007).  [http://www.andhranews.net/Intl/2007/June/6/Global-warming-causing-3633.asp "Global warming causing hundreds of Antarctic Peninsula glaciers to melt"]. AndhraNews.net.  Retrieved on October 1, 2014.</ref> growing glaciers,<ref>[http://www.cbc.ca/news/technology/global-warming-causing-california-glacier-to-grow-scientists-say-1.749761?ref=rss "Global warming causing California glacier to grow, scientists say"] (July 9, 2008).  CBCnews.  Retrieved on October 1, 2014.  Located by Sub-Driver of [http://www.freerepublic.com/focus/news/2043047/posts?page=51 Free Republic].</ref> increasing landmass in Antarctica,<ref>[http://www.worldclimatereport.com/index.php/2005/05/27/antarctic-ice-a-global-warming-snow-job/ "Antarctic ice:  A global warming snow job?"] (May 27, 2005).  World Climate Report.  Retrieved on October 2, 2014.</ref> colder winters,<ref>[http://www.cbc.ca/news/technology/climate-change-could-bring-colder-winters-1.363574 "Climate change could bring colder winters"] (March 13, 2003).  CBCNews.  Retrieved on October 2, 2014.</ref> a new ice age,<ref>McGuire, Bill (November 13, 2003).  [http://www.guardian.co.uk/environment/2003/nov/13/comment.research "Will global warming trigger a new ice age?"]  The Guardian website.  Retrieved on October 2, 2014.</ref> prevention of an ice age,<ref>Thompson, Andrea (September 10, 2007).  [https://www.foxnews.com/printer_friendly_story/0,3566,296060,00.html "Global warming may cancel next ice age"].  Fox News website.  Retrieved on October 2, 2014.</ref> taller mountains.,<ref>Than, Ker (August 4, 2006).  [http://www.livescience.com/938-taller-mountains-blamed-global-warming.html "Taller mountains blamed on global warming, too"]. LiveScience.  Retrieved on October 2, 2014.</ref> a lop-sided planet,<ref>Britt, Robert Roy (June 29, 2005). [http://www.livescience.com/3884-global-warming-create-lopsided-planet.html "Global warming might create lopsided planet"].  LiveScience.  Retrieved on October 2, 2014.</ref> stronger hurricanes,<ref>Florida State University (Sep. 4, 2008).  [https://www.sciencedaily.com/releases/2008/09/080903134323.htm "Global warming: Warmer seas linked to strengthening hurricanes, according to new research"].  ScienceDaily.  Retrieved on October 2, 2014.</ref> weaker hurricanes,<ref>Schmid, Randolph E., AP Science Writer (April 17, 2007).  [http://usatoday30.usatoday.com/weather/research/2007-04-17-globalwarming-hurricanes_N.htm "Study: Global warming may diminish Atlantic hurricane activity"].  USA Today.  Retrieved on October 2, 2014.</ref> shorter days,<ref>Atkins, William (April 11, 2007).  [http://www.itwire.com/science-news/climate/11220-researchers-say-global-warming-should-cause-shorter-days "Researchers say global warming should cause shorter days"]. iTWire.  Retrieved on October 2, 2014.</ref> earthquakes and volcanoes, and other geological disasters. Attempts to prevent climate change may do the same,<ref>Fisher, Richard.  (September 23, 2009).  [http://www.newscientist.com/article/mg20327273.800-climate-change-may-trigger-earthquakes-and-volcanoes.html "Climate change may trigger earthquakes and volcanoes" [preview&#93;].  Newscientist website.  Preview retrieved on October 2, 2014.  Subscription required for full article.</ref> shrinking brains,<ref>[http://www.albany.edu/campusnews/releases_286.htm "Study: Global warming could be reversing a trend that led to bigger human brains"] (March 15, 2007).  State University of New York at Albany.  Retrieved on October 2, 2014.</ref> shrinking sheep,<ref>Connor, Steve (July 3, 2009). [http://www.independent.co.uk/news/science/how-global-warming-shrank-st-kildas-sheep-1729609.html "How global warming shrank St Kilda's sheep"].  The Independent [U. K.] website.  Retrieved on October 2, 2014.</ref> tiger attacks.,<ref>Dhar, Sujoy (October 20, 2008). [http://southasia.oneworld.net/news/tiger-attacks-linked-to-global-warming "Tiger attacks linked to global warming"].  Reuters.  Retrieved from OneWorld South Asia on October 2, 2014.</ref> shark attacks,<ref>Johnston, Bruce (August 31, 1998).  [http://junksciencearchive.com/news3/shark.html "Shark attack on boat 'result of global warming'"].  Electronic Telegraph (U.K.)  Retrieved from JunkScienceArchive on October 3, 2014.</ref> walrus stampede deaths,<ref>Associated Press (December 17, 2007).  [https://web.archive.org/web/20141003042107/http://6abc.com/archive/5839622/ "Global warming is blamed for walrus stampede deaths"].  6abc Action News website.  Retrieved from October 3, 2014 archive at Internet Archive on October 3, 2014.  Located by digger48 of [http://www.freerepublic.com/focus/f-news/1939754/posts Free Republic]</ref> imminent cannibalism,<ref>Baker, Brent (April 2, 2008).  [http://newsbusters.org/blogs/brent-baker/2008/04/02/turner-iraqi-insurgents-patriots-inaction-warming-cannibalism "Turner: Global warming will cause mass cannibalism, insurgents are patriots"].  MRC NewsBusters.  Retrieved on October 2, 2014.</ref> the need for a drastic reduction of the earth's population,<ref>[http://thisistheendoftheworldasweknowit.com/archives/one-less-child-environmental-extremists-warn-that-overpopulation-is-causing-climate-change-and-will-ultimately-destroy-the-earth "One less child? Environmental extremists warn that overpopulation is causing climate change and will ultimately destroy the Earth"] (November 17, 2009).  The End of the World.  Retrieved on October 2, 2014.</ref> a strong increase in people dying of [[AIDS]],<ref>McLean, Tamara (April 29, 2008).  [https://web.archive.org/web/20110831093248/http://news.theage.com.au/national/global-warming-set-to-fan-the-hiv-fire-20080430-29eh.html "Global warming hoax set to fan the HIV fire"].  Theage.com.au.  Retrieved from August 31, 2011 archive at Internet Archive on October 1, 2014. Located by
+
The 2017 People's Climate March took place in hundreds of locations.[342] Shown: the Washington, D.C. march, protesting policies of then-U.S. President Trump.[342]
[https://web.archive.org/web/20110725075338/http://www.skepticsglobalwarming.com/?p=608 Skeptics Global Warning].</ref> increased risk of civil war in Africa,<ref>[http://news.stanford.edu/news/2009/november23/climate-civil-wars-112309.html "Global warming increases risk of civil war in Africa"] (November 23, 2009).  Stanford Report.  Retrieved from Stanford News on October 1, 2014.</ref> child ''climate cops'',<ref>[https://www.wnd.com/index.php?fa=PAGE.view&pageId=70811 "Beware your children: They might be 'climate cops'"] (July 28, 2008).  WND.  Retrieved on October 1, 2014.</ref> increase in depression,<ref>Sohn, Emily (December 10, 2009). [http://www.google.com/search?q=%22Deadly+heat+waves%2C+home-wrecking+hurricanes%22&hl=en&gbv=2&oq=&gs_l=  “Mental health to decline with climate change”].  Discovery.com News.  Retrieved from Google Search on October 1, 2014.</ref> increase in psychiatric illness<ref>Press Trust of India (April 8, 2008).  [http://www.sify.com/news/climate-change-leads-to-psychiatric-illness-news-national-jegnGhfjihasi.html "'Climate change leads to psychiatric illness'"].  Sify News.  Retrieved on October 1, 2014.</ref> and increased anxiety and loss of sleep among many children.<ref>Jones, Alan (February 22, 2007).  [http://www.scotsman.com/news/uk/children-losing-sleep-over-global-warming-1-683217 "Children losing sleep over global warming"].  The Scotsman website.  Retrieved on September 30, 2014.</ref>
+
Climate protests demand that political leaders take action to prevent climate change. They can take the form of public demonstrations, fossil fuel divestment, lawsuits and other activities.[343] Prominent demonstrations include the School Strike for Climate. In this initiative, young people across the globe have been protesting since 2018 by skipping school on Fridays, inspired by Swedish teenager Greta Thunberg.[344] Mass civil disobedience actions by groups like Extinction Rebellion have protested by disrupting roads and public transport.[345] Litigation is increasingly used as a tool to strengthen climate action from public institutions and companies. Activists also initiate lawsuits which target governments and demand that they take ambitious action or enforce existing laws on climate change.[346] Lawsuits against fossil-fuel companies generally seek compensation for loss and damage.[347]
  
==References==
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Discovery
{{Reflist|colwidth=35em}}
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For broader coverage of this topic, see History of climate change science.
  
== See also ==
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Tyndall's ratio spectrophotometer (drawing from 1861) measured how much infrared radiation was absorbed and emitted by various gases filling its central tube.
*''[[Massachusetts v. EPA]]''
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In the 1820s, Joseph Fourier proposed the greenhouse effect to explain why Earth's temperature was higher than the sun's energy alone could explain. Earth's atmosphere is transparent to sunlight, so sunlight reaches the surface where it is converted to heat. However, the atmosphere is not transparent to heat radiating from the surface, and captures some of that heat which warms the planet.[348] In 1856 Eunice Newton Foote demonstrated that the warming effect of the sun is greater for air with water vapour than for dry air, and the effect is even greater with carbon dioxide. She concluded that "An atmosphere of that gas would give to our earth a high temperature..."[349][350] Starting in 1859,[351] John Tyndall established that nitrogen and oxygen—together totalling 99% of dry air—are transparent to radiated heat. However, water vapour and some gases (in particular methane and carbon dioxide) absorb radiated heat and re-radiate that heat within the atmosphere. Tyndall proposed that changes in the concentrations of these gases may have caused climatic changes in the past, including ice ages.[352]
*[[Liberal hysteria#Global Warming Derangement Syndrome|Global Warming Derangement Syndrome]]
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*[[Socialist Environmental Disasters]]
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*[[Counterexamples to Global Warming]]
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*[[Winter of 2010]]
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*[[Reducing carbon dioxide emissions]]
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*[[Essay:Global Warming]]
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*[[Essay:Parallels between evolution and global warming]]
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*[[Exaggeration of global warming]]
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*[[Global warming and polar bears]]
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*[[Global climate disruption]]
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*[[Global warming research]]
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*[[Global annual average temperature]]
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*[[Warm period]]
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*[[Liberal lies]]
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*[[War on Science]]
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*[[Lysenkoism]]
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==External links==
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Svante Arrhenius noted that water vapour in air continuously varied, but the CO2 concentration in air was influenced by long-term geological processes. At the end of an ice age, warming from increased CO2 levels would increase the amount of water vapour, amplifying warming in a feedback loop. In 1896, he published the first climate model of its kind, showing that halving of CO2 levels could have produced the drop in temperature initiating the ice age. Arrhenius calculated the temperature increase expected from doubling CO2 to be around 5–6 °C.[353] Other scientists were initially sceptical and believed the greenhouse effect to be saturated so that adding more CO2 would make no difference. They thought climate would be self-regulating.[354] From 1938 onwards Guy Stewart Callendar published evidence that climate was warming and CO2 levels rising,[355] but his calculations met the same objections.[354]
*[http://www.creationworldview.org/articles_view.asp?id=67 Global Warming? Absolutely No Truth To It!]
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*[http://www.aim.org/wls/category/global-warming/ What Liberals Say - Category: Global Warming], [[Accuracy In Media]]
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*[http://global-warming.accuweather.com/2007/12/attempting_to_stop_global_warm_1.html Attempting to Stop Global Warming is Futile and a Mistake, says letter to the UN]
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*[https://www.icr.org/creation-meteorology Clinate Change] by The Institute for Creation Research
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*[http://environment.guardian.co.uk/climatechange/story/0,,2032821,00.html The appliance of science] by Mike Hulme.
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*[http://www.cato.org/pubs/regulation/regv15n2/reg15n2g.html Global Warming: The Origin and Nature of the Alleged Scientific Consensus] - [[Richard S. Lindzen]], Alfred P. Sloan Professor of Meteorology at the [[Massachusetts Institute of Technology]]
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*[http://www.independent.org/publications/tir/article.asp?issueID=47&articleID=604 "Should We Have Acted Thirty Years Ago to Prevent Climate Change?", by Randall G. Holcombe].
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*[http://www.independent.org/publications/tir/article.asp?issueID=25&articleID=296 "After Kyoto: A Global Scramble for Advantage," by Bruce Yandle].
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*[http://www.ncpa.org/sub/dpd/index.php?Article_ID=2319 The physical evidence of earth's unstoppable 1,500-year climate cycle]
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*[http://www.independent.org/publications/article.asp?id=1714 "Is There a Basis for Global Warming Alarm?", by Richard Lindzen]
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*[http://www.independent.org/publications/policy_reports/detail.asp?type=full&id=5 "New Perspectives in Climate Change: What the EPA Isn’t Telling Us"]
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*[http://www.heartland.org/Article.cfm?artId=17181 Survey Shows Climatologists Are Split on Global Warming]
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*[http://www.magma.ca/~hurleyp/FightingTheHoax.htm Fighting the Hoax]
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*[http://www.globalwarminghoax.com/news.php Refuting the Myth of Man-made Global Warming]
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*[http://www.climateaudit.org Climate Audit], Steve McIntyre's blog
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*[http://www.realclimate.org Real Climate], blog by a group of climatologists including Michael Mann
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*[https://www.americanthinker.com/2009/01/co2_fairytales_in_global_warmi.html "CO<sub>2</sub> Fairytales in Global Warming"]
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*[http://www.numberwatch.co.uk/warmlist.htm A complete list of things caused by global warming]
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*[http://globaleconomicanalysis.blogspot.com/2009/11/hackers-prove-global-warming-is-scam.html Hackers Prove Global Warming Is A Scam]
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*[http://www.frontpagemag.com/fpm/266930/i-dont-believe-science-daniel-greenfield]
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{{liberalism}}
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In the 1950s, Gilbert Plass created a detailed computer model that included different atmospheric layers and the infrared spectrum. This model predicted that increasing CO2 levels would cause warming. Around the same time, Hans Suess found evidence that CO2 levels had been rising, and Roger Revelle showed that the oceans would not absorb the increase. The two scientists subsequently helped Charles Keeling to begin a record of continued increase, which has been termed the "Keeling Curve".[354] Scientists alerted the public,[356] and the dangers were highlighted at James Hansen's 1988 Congressional testimony.[21] The Intergovernmental Panel on Climate Change, set up in 1988 to provide formal advice to the world's governments, spurred interdisciplinary research.[357]
{{Climategate scandal}}
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[[Category:Earth Sciences]]
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See also
[[Category:Environmentalism]]
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icon Climate change portal
[[Category:Liberal Bias]]
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icon Environment portal
[[Category:Liberal Falsehoods]]
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icon Science portal
[[Category:Featured articles]]
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World portal
[[Category:Man-Made Disasters]]
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2020s in environmental history
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Anthropocene – proposed new geological time interval in which humans are having significant geological impact
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Global cooling – minority view held by scientists in the 1970s that imminent cooling of the Earth would take place

Revision as of 21:28, July 4, 2022

Contemporary climate change includes both global warming and its impacts on Earth's weather patterns. There have been previous periods of climate change, but the current changes are distinctly more rapid and not due to natural causes.[2] Instead, they are caused by the emission of greenhouse gases, mostly carbon dioxide (CO2) and methane. Burning fossil fuels for energy use creates most of these emissions. Certain agricultural practices, industrial processes, and forest loss are additional sources.[3] Greenhouse gases are transparent to sunlight, allowing it through to heat the Earth's surface. When the Earth emits that heat as infrared radiation the gases absorb it, trapping the heat near the Earth's surface. As the planet heats up it causes changes like the loss of sunlight-reflecting snow cover, amplifying global warming.[4]

Due to climate change, deserts are expanding, while heat waves and wildfires are becoming more common.[5] Increased warming in the Arctic has contributed to melting permafrost, glacial retreat and sea ice loss.[6] Higher temperatures are also causing more intense storms, droughts, and other weather extremes.[7] Rapid environmental change in mountains, coral reefs, and the Arctic is forcing many species to relocate or become extinct.[8] Climate change threatens people with food and water scarcity, increased flooding, extreme heat, more disease, and economic loss. Human migration and conflict can be a result.[9] The World Health Organization (WHO) calls climate change the greatest threat to global health in the 21st century.[10] Even if efforts to minimise future warming are successful, some effects will continue for centuries. These include sea level rise, and warmer, more acidic oceans.[11]

Many of these impacts are already felt at the current 1.2 °C (2.2 °F) level of warming. Additional warming will increase these impacts and may trigger tipping points, such as the melting of the Greenland ice sheet.[12] Under the 2015 Paris Agreement, nations collectively agreed to keep warming "well under 2 °C". However, with pledges made under the Agreement, global warming would still reach about 2.7 °C (4.9 °F) by the end of the century.[13] Limiting warming to 1.5 °C will require halving emissions by 2030 and achieving net-zero emissions by 2050.[14]

Bobcat Fire in Monrovia, CA, September 10, 2020 Bleached colony of Acropora coral A dry riverbed in California, which is experiencing its worst megadrought in 1,200 years.[15] Some effects of climate change, clockwise from top left: Wildfire intensified by heat and drought, worsening droughts compromising water supplies, and bleaching of coral caused by ocean acidification and heating. Making deep cuts in emissions will require switching away from burning fossil fuels and towards using electricity generated from low-carbon sources. This includes phasing out coal-fired power plants, vastly increasing use of wind, solar, and other types of renewable energy, and taking measures to reduce energy use. Electricity will need to replace fossil fuels for powering transportation, heating buildings, and operating industrial facilities.[16][17] Carbon can also be removed from the atmosphere, for instance by increasing forest cover and by farming with methods that capture carbon in soil.[18] While communities may adapt to climate change through efforts like better coastline protection, they cannot avert the risk of severe, widespread, and permanent impacts.[19]


Contents 1 Terminology 2 Observed temperature rise 2.1 Regional aspects to temperature rises 3 Drivers of recent temperature rise 3.1 Greenhouse gases 3.2 Aerosols and clouds 3.3 Land surface changes 3.4 Solar and volcanic activity 3.5 Climate change feedback 4 Future warming and the carbon budget 5 Impacts 5.1 Environmental effects 5.2 Tipping points and long-term impacts 5.3 Nature and wildlife 5.4 Humans 6 Reducing and recapturing emissions 6.1 Clean energy 6.2 Energy conservation 6.3 Agriculture and industry 6.4 Carbon sequestration 7 Adapting to a changing climate 8 Policies and politics 8.1 Policy options 8.2 International climate agreements 8.3 National responses 9 Scientific consensus and society 9.1 Scientific consensus 9.2 Denial and misinformation 9.3 Public awareness and opinion 10 Discovery 11 See also 12 References 12.1 Sources 13 External links Terminology Before the 1980s, it was unclear whether warming by increased greenhouse gases would dominate aerosol-induced cooling. Scientists then often used the term inadvertent climate modification to refer to the human impact on the climate. In the 1980s, the terms global warming and climate change were popularised. The former refers only to increased surface warming, the latter describes the full effect of greenhouse gases on the climate.[20] Global warming became the most popular term after NASA climate scientist James Hansen used it in his 1988 testimony in the U.S. Senate.[21] In the 2000s, the term climate change increased in popularity.[22] Global warming usually refers to human-induced warming of the Earth system, whereas climate change can refer to natural or anthropogenic change.[23] The two terms are often used interchangeably.[24]

Various scientists, politicians and media figures have adopted the terms climate crisis or climate emergency to talk about climate change, and global heating instead of global warming.[25] The policy editor-in-chief of The Guardian said they included this language in their editorial guidelines "to ensure that we are being scientifically precise, while also communicating clearly with readers on this very important issue".[26] In 2019, Oxford Languages chose climate emergency as its word of the year, defining it as "a situation in which urgent action is required to reduce or halt climate change and avoid potentially irreversible environmental damage resulting from it".[27][28]

Observed temperature rise Main articles: Temperature record of the last 2,000 years and Instrumental temperature record

Global surface temperature reconstruction over the last 2000 years using proxy data from tree rings, corals, and ice cores in blue.[29] Directly observed data is in red.[30] Multiple independent instrumental datasets show that the climate system is warming.[31] The 2011–2020 decade warmed to an average 1.09 °C [0.95–1.20 °C] compared to the pre-industrial baseline (1850–1900).[32] Surface temperatures are rising by about 0.2 °C per decade,[33] with 2020 reaching a temperature of 1.2 °C above the pre-industrial era.[34] Since 1950, the number of cold days and nights has decreased, and the number of warm days and nights has increased.[35]

There was little net warming between the 18th century and the mid-19th century. Climate information for that period comes from climate proxies, such as trees and ice cores.[36] Thermometer records began to provide global coverage around 1850.[37] Historical patterns of warming and cooling, like the Medieval Climate Anomaly and the Little Ice Age, did not occur at the same time across different regions. Temperatures may have reached as high as those of the late-20th century in a limited set of regions.[38] There have been prehistorical episodes of global warming, such as the Paleocene–Eocene Thermal Maximum.[39] However, the modern observed rise in temperature and CO2 concentrations has been so rapid that even abrupt geophysical events in Earth's history do not approach current rates.[40]

Evidence of warming from air temperature measurements are reinforced with a wide range of other observations.[41][42] There has been an increase in the frequency and intensity of heavy precipitation, melting of snow and land ice, and increased atmospheric humidity.[43] Flora and fauna are also behaving in a manner consistent with warming; for instance, plants are flowering earlier in spring.[44] Another key indicator is the cooling of the upper atmosphere, which demonstrates that greenhouse gases are trapping heat near the Earth's surface and preventing it from radiating into space.[45]

Regional aspects to temperature rises See also: Climate variability and change § Variability between regions Regions of the world warm at differing rates. The pattern is independent of where greenhouse gases are emitted, because the gases persist long enough to diffuse across the planet. Since the pre-industrial period, the average surface temperature over land regions has increased almost twice as fast as the global-average surface temperature.[46] This is because of the larger heat capacity of oceans, and because oceans lose more heat by evaporation.[47] The thermal energy in the global climate system has grown with only brief pauses since at least 1970, and over 90% of this extra energy has been stored in the ocean.[48][49] The rest has heated the atmosphere, melted ice, and warmed the continents.[50]

The Northern Hemisphere and the North Pole have warmed much faster than the South Pole and Southern Hemisphere. The Northern Hemisphere not only has much more land, but also more seasonal snow cover and sea ice. As these surfaces flip from reflecting a lot of light to being dark after the ice has melted, they start absorbing more heat.[51] Local black carbon deposits on snow and ice also contribute to Arctic warming.[52] Arctic temperatures are increasing at over twice the rate of the rest of the world.[53] Melting of glaciers and ice sheets in the Arctic disrupts ocean circulation, including a weakened Gulf Stream, further changing the climate.[54]

Drivers of recent temperature rise Main article: Attribution of recent climate change

Drivers of climate change from 1850–1900 to 2010–2019. There was no significant contribution from internal variability or solar and volcanic drivers. The climate system experiences various cycles on its own which can last for years (such as the El Niño–Southern Oscillation (ENSO)), decades or even centuries.[55] Other changes are caused by an imbalance of energy that is "external" to the climate system, but not always external to the Earth.[56] Examples of external forcings include changes in the concentrations of greenhouse gases, solar luminosity, volcanic eruptions, and variations in the Earth's orbit around the Sun.[57]

To determine the human contribution to climate change, known internal climate variability and natural external forcings need to be ruled out. A key approach is to determine unique "fingerprints" for all potential causes, then compare these fingerprints with observed patterns of climate change.[58] For example, solar forcing can be ruled out as a major cause. Its fingerprint would be warming in the entire atmosphere. Yet, only the lower atmosphere has warmed, consistent with greenhouse gas forcing.[59] Attribution of recent climate change shows that the main driver is elevated greenhouse gases, with aerosols having a dampening effect.[60]

Greenhouse gases Main articles: Greenhouse gas, Greenhouse gas emissions, Greenhouse effect, and Carbon dioxide in Earth's atmosphere

CO2 concentrations over the last 800,000 years as measured from ice cores (blue/green) and directly (black) The Earth absorbs sunlight, then radiates it as heat. Greenhouse gases in the atmosphere absorb and reemit infrared radiation, slowing the rate at which it can pass through the atmosphere and escape into space.[61] Before the Industrial Revolution, naturally-occurring amounts of greenhouse gases caused the air near the surface to be about 33 °C warmer than it would have been in their absence.[62][63] While water vapour (~50%) and clouds (~25%) are the biggest contributors to the greenhouse effect, they increase as a function of temperature and are therefore feedbacks. On the other hand, concentrations of gases such as CO2 (~20%), tropospheric ozone,[64] CFCs and nitrous oxide are not temperature-dependent, and are therefore external forcings.[65]

Human activity since the Industrial Revolution, mainly extracting and burning fossil fuels (coal, oil, and natural gas),[66] has increased the amount of greenhouse gases in the atmosphere, resulting in a radiative imbalance. In 2019, the concentrations of CO2 and methane had increased by about 48% and 160%, respectively, since 1750.[67] These CO2 levels are higher than they have been at any time during the last 2 million years. Concentrations of methane are far higher than they were over the last 800,000 years.[68]


The Global Carbon Project shows how additions to CO2 since 1880 have been caused by different sources ramping up one after another. Global anthropogenic greenhouse gas emissions in 2019 were equivalent to 59 billion tonnes of CO2. Of these emissions, 75% was CO2, 18% was methane, 4% was nitrous oxide, and 2% was fluorinated gases.[69] CO2 emissions primarily come from burning fossil fuels to provide energy for transport, manufacturing, heating, and electricity.[3] Additional CO2 emissions come from deforestation and industrial processes, which include the CO2 released by the chemical reactions for making cement, steel, aluminum, and fertiliser.[70] Methane emissions come from livestock, manure, rice cultivation, landfills, wastewater, and coal mining, as well as oil and gas extraction.[71] Nitrous oxide emissions largely come from the microbial decomposition of fertiliser.[72]

Despite the contribution of deforestation to greenhouse gas emissions, the Earth's land surface, particularly its forests, remain a significant carbon sink for CO2. Land-surface sink processes, such as carbon fixation in the soil and photosynthesis, remove about 29% of annual global CO2 emissions.[73] The ocean also serves as a significant carbon sink via a two-step process. First, CO2 dissolves in the surface water. Afterwards, the ocean's overturning circulation distributes it deep into the ocean's interior, where it accumulates over time as part of the carbon cycle. Over the last two decades, the world's oceans have absorbed 20 to 30% of emitted CO2.[74]

Aerosols and clouds Air pollution, in the form of aerosols, not only puts a large burden on human health, but also affects the climate on a large scale.[75] From 1961 to 1990, a gradual reduction in the amount of sunlight reaching the Earth's surface was observed, a phenomenon popularly known as global dimming,[76] typically attributed to aerosols from biofuel and fossil fuel burning.[77] Globally, aerosols have been declining since 1990, meaning that they no longer mask greenhouse gas warming as much.[78]

Aerosols scatter and absorb solar radiation. They also have indirect effects on the Earth's radiation budget. Sulfate aerosols act as cloud condensation nuclei and lead to clouds that have more and smaller cloud droplets. These clouds reflect solar radiation more efficiently than clouds with fewer and larger droplets.[79] They also reduce the growth of raindrops, which makes clouds more reflective to incoming sunlight.[80] Indirect effects of aerosols are the largest uncertainty in radiative forcing.[81]

While aerosols typically limit global warming by reflecting sunlight, black carbon in soot that falls on snow or ice can contribute to global warming. Not only does this increase the absorption of sunlight, it also increases melting and sea-level rise.[82] Limiting new black carbon deposits in the Arctic could reduce global warming by 0.2 °C by 2050.[83]

Land surface changes

The rate of global tree cover loss has approximately doubled since 2001, to an annual loss approaching an area the size of Italy.[84] Humans change the Earth's surface mainly to create more agricultural land. Today, agriculture takes up 34% of Earth's land area, while 26% is forests, and 30% is uninhabitable (glaciers, deserts, etc.).[85] The amount of forested land continues to decrease, which is the main land use change that causes global warming.[86] Deforestation releases CO2 contained in trees when they are destroyed, plus it prevents those trees from absorbing more CO2 in the future.[87] The main causes of deforestation are: permanent land-use change from forest to agricultural land producing products such as beef and palm oil (27%), logging to produce forestry/forest products (26%), short term shifting cultivation (24%), and wildfires (23%).[88]

Land use changes not only affect greenhouse gas emissions. The type of vegetation in a region affects the local temperature. It impacts how much of the sunlight gets reflected back into space (albedo), and how much heat is lost by evaporation. For instance, the change from a dark forest to grassland makes the surface lighter, causing it to reflect more sunlight. Deforestation can also affect temperatures by modifying the release of chemical compounds that influence clouds, and by changing wind patterns.[89] In tropic and temperate areas the net effect is to produce significant warming, while at latitudes closer to the poles a gain of albedo (as forest is replaced by snow cover) leads to a cooling effect.[89] Globally, these effects are estimated to have led to a slight cooling, dominated by an increase in surface albedo.[90]

Solar and volcanic activity Further information: Solar activity and climate Physical climate models are unable to reproduce the rapid warming observed in recent decades when taking into account only variations in solar output and volcanic activity.[91] As the Sun is the Earth's primary energy source, changes in incoming sunlight directly affect the climate system.[81] Solar irradiance has been measured directly by satellites,[92] and indirect measurements are available from the early 1600s onwards.[81] There has been no upward trend in the amount of the Sun's energy reaching the Earth.[93] Further evidence for greenhouse gases causing global warming comes from measurements that show a warming of the lower atmosphere (the troposphere), coupled with a cooling of the upper atmosphere (the stratosphere).[94] If solar variations were responsible for the observed warming, the troposphere and stratosphere would both warm.[59]

Explosive volcanic eruptions represent the largest natural forcing over the industrial era. When the eruption is sufficiently strong (with sulfur dioxide reaching the stratosphere), sunlight can be partially blocked for a couple of years. The temperature signal lasts about twice as long. In the industrial era, volcanic activity has had negligible impacts on global temperature trends.[95] Present-day volcanic CO2 emissions are equivalent to less than 1% of current anthropogenic CO2 emissions.[96]

Climate change feedback Main articles: Climate change feedback and Climate sensitivity

Sea ice reflects 50% to 70% of incoming solar radiation while the dark ocean surface only reflects 6%, so melting sea ice is a self-reinforcing feedback.[97] The response of the climate system to an initial forcing is modified by feedbacks: increased by self-reinforcing feedbacks and reduced by balancing feedbacks.[98] The main reinforcing feedbacks are the water-vapour feedback, the ice–albedo feedback, and the net effect of clouds.[99][100] The primary balancing mechanism is radiative cooling, as Earth's surface gives off more heat to space in response to rising temperature.[101] In addition to temperature feedbacks, there are feedbacks in the carbon cycle, such as the fertilizing effect of CO2 on plant growth.[102] Uncertainty over feedbacks is the major reason why different climate models project different magnitudes of warming for a given amount of emissions.[103]

As the air is warmed by greenhouse gases, it can hold more moisture. Water vapour is a potent greenhouse gas, so this further heats the atmosphere.[99] If cloud cover increases, more sunlight will be reflected back into space, cooling the planet. If clouds become higher and thinner, they act as an insulator, reflecting heat from below back downwards and warming the planet.[104] The effect of clouds is the largest source of feedback uncertainty.[105]

Another major feedback is the reduction of snow cover and sea ice in the Arctic, which reduces the reflectivity of the Earth's surface.[106] More of the Sun's energy is now absorbed in these regions, contributing to amplification of Arctic temperature changes.[107] Arctic amplification is also melting permafrost, which releases methane and CO2 into the atmosphere.[108] Climate change can also cause methane releases from wetlands, marine systems, and freshwater systems.[109] Overall, climate feedbacks are expected to become increasingly positive.[110]

Around half of human-caused CO2 emissions have been absorbed by land plants and by the oceans.[111] On land, elevated CO2 and an extended growing season have stimulated plant growth. Climate change increases droughts and heat waves that inhibit plant growth, which makes it uncertain whether this carbon sink will continue to grow in the future.[112] Soils contain large quantities of carbon and may release some when they heat up.[113] As more CO2 and heat are absorbed by the ocean, it acidifies, its circulation changes and phytoplankton takes up less carbon, decreasing the rate at which the ocean absorbs atmospheric carbon.[114] Overall, at higher CO2 concentrations the Earth will absorb a reduced fraction of our emissions.[115]

Future warming and the carbon budget Further information: Carbon budget, Climate model, and Climate change scenario

Projected global surface temperature changes relative to 1850–1900, based on CMIP6 multi-model mean changes A climate model is a representation of the physical, chemical, and biological processes that affect the climate system.[116] Models are used to calculate the degree of warming future emissions will cause when accounting for the strength of climate feedbacks.[117][118] Models also include natural processes like changes in the Earth's orbit, historical changes in the Sun's activity, and volcanic forcing.[119] In addition to estimating future temperatures, they reproduce and predict the circulation of the oceans, the annual cycle of the seasons, and the flows of carbon between the land surface and the atmosphere.[120]

The physical realism of models is tested by examining their ability to simulate contemporary or past climates.[121] Past models have underestimated the rate of Arctic shrinkage[122] and underestimated the rate of precipitation increase.[123] Sea level rise since 1990 was underestimated in older models, but more recent models agree well with observations.[124] The 2017 United States-published National Climate Assessment notes that "climate models may still be underestimating or missing relevant feedback processes".[125]

A subset of climate models add societal factors to a simple physical climate model. These models simulate how population, economic growth, and energy use affect – and interact with – the physical climate. With this information, these models can produce scenarios of future greenhouse gas emissions. This is then used as input for physical climate models and carbon cycle models to predict how atmospheric concentrations of greenhouse gases might change in the future.[126][127] Depending on the socioeconomic scenario and the mitigation scenario, models produce atmospheric CO2 concentrations that range widely between 380 and 1400 ppm.[128]

The IPCC Sixth Assessment Report projects that global warming is very likely to reach 1.0 °C to 1.8 °C by the late 21st century under the very low GHG emissions scenario. In an intermediate scenario global warming would reach 2.1 °C to 3.5 °C, and 3.3 °C to 5.7 °C under the very high GHG emissions scenario.[129] These projections are based on climate models in combination with observations.[130]

The remaining carbon budget is determined by modelling the carbon cycle and the climate sensitivity to greenhouse gases.[131] According to the IPCC, global warming can be kept below 1.5 °C with a two-thirds chance if emissions after 2018 do not exceed 420 or 570 gigatonnes of CO2. This corresponds to 10 to 13 years of current emissions. There are high uncertainties about the budget. For instance, it may be 100 gigatonnes of CO2 smaller due to methane release from permafrost and wetlands.[132] However, it is clear that fossil fuel resources are too abundant for shortages to be relied on to limit carbon emissions in the 21st century.[133]

Impacts Main article: Effects of climate change

The sixth IPCC Assessment Report projects changes in average soil moisture that can disrupt agriculture and ecosystems. A reduction in soil moisture by one standard deviation means that average soil moisture will approximately match the ninth driest year between 1850 and 1900 at that location. Environmental effects The environmental effects of climate change are broad and far-reaching, affecting oceans, ice, and weather. Changes may occur gradually or rapidly. Evidence for these effects comes from studying climate change in the past, from modelling, and from modern observations.[134] Since the 1950s, droughts and heat waves have appeared simultaneously with increasing frequency.[135] Extremely wet or dry events within the monsoon period have increased in India and East Asia.[136] The rainfall rate and intensity of hurricanes and typhoons is likely increasing.[137] Frequency of tropical cyclones has not increased as a result of climate change.[138] However, a study review article published in 2021 in Nature Geoscience concluded that the geographic range of tropical cyclones will probably expand poleward in response to climate warming of the Hadley circulation.[139]


Historical sea level reconstruction and projections up to 2100 published in 2017 by the U.S. Global Change Research Program[140] Global sea level is rising as a consequence of glacial melt, melt of the ice sheets in Greenland and Antarctica, and thermal expansion. Between 1993 and 2020, the rise increased over time, averaging 3.3 ± 0.3 mm per year.[141] Over the 21st century, the IPCC projects that in a very high emissions scenario the sea level could rise by 61–110 cm.[142] Increased ocean warmth is undermining and threatening to unplug Antarctic glacier outlets, risking a large melt of the ice sheet[143] and the possibility of a 2-meter sea level rise by 2100 under high emissions.[144]

Climate change has led to decades of shrinking and thinning of the Arctic sea ice.[145] While ice-free summers are expected to be rare at 1.5 °C degrees of warming, they are set to occur once every three to ten years at a warming level of 2 °C.[146] Higher atmospheric CO2 concentrations have led to changes in ocean chemistry. An increase in dissolved CO2 is causing oceans to acidify.[147] In addition, oxygen levels are decreasing as oxygen is less soluble in warmer water.[148] Dead zones in the ocean, regions with very little oxygen, are expanding too.[149]

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.[150] 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.[151][152] 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).[153] Tipping points can also include irreversible damage to ecosystems like the Amazon rainforest and coral reefs.[154]

The long-term effects of climate change include further ice melt, ocean warming, sea level rise, and ocean acidification.[155] 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.[156] Oceanic CO2 uptake is slow enough that ocean acidification will continue for hundreds to thousands of years.[157] These emissions are estimated to have prolonged the current interglacial period by at least 100,000 years.[158] 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.[159]

Nature and wildlife Main article: Climate change and ecosystems Recent warming has driven many terrestrial and freshwater species poleward and towards higher altitudes.[160] 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.[161] Climate change has contributed to the expansion of drier climate zones, such as the expansion of deserts in the subtropics.[162] The size and speed of global warming is making abrupt changes in ecosystems more likely.[163] Overall, it is expected that climate change will result in the extinction of many species.[164]

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.[165] 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.[166] Ocean acidification makes it harder for organisms such as mussels, barnacles and corals to produce shells and skeletons; and heatwaves have bleached coral reefs.[167] Harmful algal blooms enhanced by climate change and eutrophication lower oxygen levels, disrupt food webs and cause great loss of marine life.[168] Coastal ecosystems are under particular stress. Almost half of global wetlands have disappeared due to climate change and other human impacts.[169]

Climate change impacts on the environment Underwater photograph of branching coral that is bleached white Ecological collapse. Bleaching has damaged the Great Barrier Reef and threatens reefs worldwide.[170]


Photograph of evening in a valley settlement. The skyline in the hills beyond is lit up red from the fires. Extreme weather. Drought and high temperatures worsened the 2020 bushfires in Australia.[171]


The green landscape is interrupted by a huge muddy scar where the ground has subsided. Arctic warming. Permafrost thaws undermine infrastructure and release methane, a greenhouse gas.[108]


An emaciated polar bear stands atop the remains of a melting ice floe. Habitat destruction. Many arctic animals rely on sea ice, which has been disappearing in a warming Arctic.[172]


Photograph of a large area of forest. The green trees are interspersed with large patches of damaged or dead trees turning purple-brown and light red. Pest propagation. Mild winters allow more pine beetles to survive to kill large swaths of forest.[173]

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

The IPCC Sixth Assessment Report (2021) projects that extreme weather will be progressively more common as the Earth warms.[174] The effects of climate change on humans have been observed worldwide. They are mostly due to warming and shifts in precipitation. Impacts can now be observed on all continents and ocean regions,[175] with low-latitude, less developed areas facing the greatest risk.[176] Continued warming has potentially “severe, pervasive and irreversible impacts” for people and ecosystems.[177] The risks are unevenly distributed, but are generally greater for disadvantaged people in developing and developed countries.[178]

Food and health The WHO has classified climate change as the greatest threat to global health in the 21st century.[179] Extreme weather leads to injury and loss of life,[180] and crop failures to undernutrition.[181] Various infectious diseases are more easily transmitted in a warmer climate, such as dengue fever and malaria.[182] Young children are the most vulnerable to food shortages. Both children and older people are vulnerable to extreme heat.[183] 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 undernutrition.[184] Over 500,000 more adult deaths are projected yearly by 2050 due to reductions in food availability and quality.[185]

Climate change is affecting food security. It has caused reduction in global yields of maize, wheat, and soybeans between 1981 and 2010.[186] Future warming could further reduce global yields of major crops.[187] Crop production will probably be negatively affected in low-latitude countries, while effects at northern latitudes may be positive or negative.[188] Up to an additional 183 million people worldwide, particularly those with lower incomes, are at risk of hunger as a consequence of these impacts.[189] Climate change also impacts fish populations. Globally, less will be available to be fished.[190] Regions dependent on glacier water, regions that are already dry, and small islands have a higher risk of water stress due to climate change.[191]

Livelihoods Economic damages due to climate change may be severe and there is a chance of disastrous consequences.[192] Climate change has likely already increased global economic inequality, and this trend is projected to continue.[193] Most of the severe impacts are expected in sub-Saharan Africa, where most of the local inhabitants are dependent upon natural and agricultural resources[194], and South-East Asia.[195] The World Bank estimates that climate change could drive over 120 million people into poverty by 2030.[196]

Current inequalities based on wealth and social status have worsened due to climate change.[197] Major difficulties in mitigating, adapting, and recovering to climate shocks are faced by marginalized people who have less control over resources.[198][194] Indigenous people, who are subsistent on their land and ecosystems, will face endangerment to their wellness and lifestyles due to climate change.[199] 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.[200]

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.[201] This could lead to statelessness for people in island nations, such as the Maldives and Tuvalu.[202] In some regions, the rise in temperature and humidity may be too severe for humans to adapt to.[203] 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.[204] These factors can drive environmental migration, both within and between countries.[9] 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.[205]

Climate change impacts on people Environmental migration. Sparser rainfall leads to desertification that harms agriculture and can displace populations. Shown: Telly, Mali (2008).[206] Environmental migration. Sparser rainfall leads to desertification that harms agriculture and can displace populations. Shown: Telly, Mali (2008).[206]


Agricultural changes. Droughts, rising temperatures, and extreme weather negatively impact agriculture. Shown: Texas, US (2013).[207] Agricultural changes. Droughts, rising temperatures, and extreme weather negatively impact agriculture. Shown: Texas, US (2013).[207]


Tidal flooding. Sea-level rise increases flooding in low-lying coastal regions. Shown: Venice, Italy (2004).[208] Tidal flooding. Sea-level rise increases flooding in low-lying coastal regions. Shown: Venice, Italy (2004).[208]


Storm intensification. Bangladesh after Cyclone Sidr (2007) is an example of catastrophic flooding from increased rainfall.[209] Storm intensification. Bangladesh after Cyclone Sidr (2007) is an example of catastrophic flooding from increased rainfall.[209]


Heat wave intensification. Events like the June 2019 European heat wave are becoming more common.[210] Heat wave intensification. Events like the June 2019 European heat wave are becoming more common.[210]

Reducing and recapturing emissions Main article: Climate change mitigation

Scenarios of global greenhouse gas emissions. If all countries achieve their current Paris Agreement pledges, average warming by 2100 would still significantly exceed the maximum 2 °C target set by the Agreement. Climate change can be mitigated by reducing greenhouse gas emissions and by enhancing sinks that absorb greenhouse gases from the atmosphere.[211] In order to limit global warming to less than 1.5 °C with a high likelihood of success, global greenhouse gas emissions needs to be net-zero by 2050, or by 2070 with a 2 °C target.[132] This requires far-reaching, systemic changes on an unprecedented scale in energy, land, cities, transport, buildings, and industry.[212] 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.[213] With pledges made under the 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.[13]

Although there is no single pathway to limit global warming to 1.5 or 2 °C,[214] 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.[215] To reduce pressures on ecosystems and enhance their carbon sequestration capabilities, changes would also be necessary in agriculture and forestry,[216] such as preventing deforestation and restoring natural ecosystems by reforestation.[217]

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.[218] There are concerns, though, about over-reliance on these technologies, and environmental impacts.[219] Solar radiation management (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.[220]

Clean energy Main articles: Sustainable energy and Sustainable transport

Coal, oil, and natural gas remain the primary global energy sources even as renewables have begun rapidly increasing.[221]

Economic sectors with more greenhouse gas contributions have a greater stake in climate change policies. Renewable energy is key to limiting climate change.[222] 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).[223] That mix is projected to change significantly over the next 30 years.[215] Solar panels and onshore wind are now among the cheapest forms of adding new power generation capacity in many locations.[224] Renewables represented 75% of all new electricity generation installed in 2019, nearly all solar and wind.[225] 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.[226]

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.[227][228]

Electricity would also need to become the main energy source for heating and transport.[229] In transport, emissions can be reduced fast by a switch to electric vehicles.[230] Public transport and active transport (cycling and walking) also produce less CO2.[231] For shipping and flying, low-carbon fuels can be used to reduce emissions.[230] Heating would be increasingly decarbonised with technologies like heat pumps.[232]

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.[233] 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.[222] Bioenergy is often not carbon-neutral and may have negative consequences for food security.[234] The growth of nuclear power is constrained by controversy around nuclear waste, nuclear weapon proliferation, and accidents.[235][236] Hydropower growth is limited by the fact that the best sites have been developed, and new projects are confronting increased social and environmental concerns.[237]

Low-carbon energy improves human health by minimising climate change. It also has the near-term benefit of reducing air pollution deaths,[238] which were estimated at 7 million annually in 2016.[239] 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.[240]

Energy conservation Main articles: Efficient energy use and Energy conservation Reducing energy demand is another major aspect of reducing emissions.[241] 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.[242] Major increases in energy efficiency investment will be required to achieve climate goals, comparable to the level of investment in renewable energy.[243] Several COVID-19 related changes in energy use patterns, energy efficiency investments, and funding have made forecasts for this decade more difficult and uncertain.[244]

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.[245] Industrial strategies to reduce energy demand include improving heating systems and motors, designing less energy-intensive products, and increasing product lifetimes.[246] In the building sector the focus is on better design of new buildings, and higher levels of energy efficiency in retrofitting.[247] The use of technologies like heat pumps can also increase building energy efficiency.[248]

Agriculture and industry See also: Sustainable agriculture and Green industrial policy Agriculture and forestry face a triple challenge of limiting greenhouse gas emissions, preventing the further conversion of forests to agricultural land, and meeting increases in world food demand.[249] A set of actions could reduce agriculture and forestry-based emissions by two thirds from 2010 levels. These include reducing growth in demand for food and other agricultural products, increasing land productivity, protecting and restoring forests, and reducing greenhouse gas emissions from agricultural production.[250]

On the demand side, a key component of reducing emissions is shifting people towards plant-based diets.[251] Eliminating the production of livestock for meat and dairy would eliminate about 3/4ths of all emissions from agriculture and other land use.[252] Livestock also occupy 37% of ice-free land area on Earth and consume feed from the 12% of land area used for crops, driving deforestation and land degradation.[253]

Steel and cement production are responsible for about 13% of industrial CO2 emissions. In these industries, carbon-intensive materials such as coke and lime play an integral role in the production, so that reducing CO2 emissions requires research into alternative chemistries.[254]

Carbon sequestration Main articles: Carbon dioxide removal and Carbon sequestration

Most CO2 emissions have been absorbed by carbon sinks, including plant growth, soil uptake, and ocean uptake (2020 Global Carbon Budget). Natural carbon sinks can be enhanced to sequester significantly larger amounts of CO2 beyond naturally occurring levels.[255] Reforestation and tree planting on non-forest lands are among the most mature sequestration techniques, although the latter raises food security concerns.[256] Farmers can promote sequestration of carbon in soils through practices such as use of winter cover crops, reducing the intensity and frequency of tillage, and using compost and manure as soil amendments.[257] Restoration/recreation of coastal wetlands and seagrass meadows increases the uptake of carbon into organic matter (blue carbon).[258] When carbon is sequestered in soils and in organic matter such as trees, there is a risk of the carbon being re-released into the atmosphere later through changes in land use, fire, or other changes in ecosystems.[259]

Where energy production or CO2-intensive heavy industries continue to produce waste CO2, the gas can be captured and stored instead of released to the atmosphere. Although its current use is limited in scale and expensive,[260] carbon capture and storage (CCS) may be able to play a significant role in limiting CO2 emissions by mid-century.[261] This technique, in combination with bio-energy (BECCS) can result in net negative emissions: CO2 is drawn from the atmosphere.[262] It remains highly uncertain whether carbon dioxide removal techniques, such as BECCS, will be able to play a large role in limiting warming to 1.5 °C. Policy decisions that rely on carbon dioxide removal increase the risk of global warming rising beyond international goals.[263]

Adapting to a changing climate Main article: Climate change adaptation Adaptation is "the process of adjustment to current or expected changes in climate and its effects".[264] Without additional mitigation, adaptation cannot avert the risk of "severe, widespread and irreversible" impacts.[265] More severe climate change requires more transformative adaptation, which can be prohibitively expensive.[264] The capacity and potential for humans to adapt is unevenly distributed across different regions and populations, and developing countries generally have less.[266] The first two decades of the 21st century saw an increase in adaptive capacity in most low- and middle-income countries with improved access to basic sanitation and electricity, but progress is slow. Many countries have implemented adaptation policies. However, there is a considerable gap between necessary and available finance.[267]

Adaptation to sea level rise consists of avoiding at-risk areas, learning to live with increased flooding and protection. If that fails, managed retreat may be needed.[268] There are economic barriers for tackling dangerous heat impact. Avoiding strenuous work or having air conditioning is not possible for everybody.[269] In agriculture, adaptation options include a switch to more sustainable diets, diversification, erosion control and genetic improvements for increased tolerance to a changing climate.[270] Insurance allows for risk-sharing, but is often difficult to get for people on lower incomes.[271] Education, migration and early warning systems can reduce climate vulnerability.[272]

Ecosystems adapt to climate change, a process that can be supported by human intervention. By increasing connectivity between ecosystems, species can migrate to more favourable climate conditions. Species can also be introduced to areas acquiring a favorable climate. Protection and restoration of natural and semi-natural areas helps build resilience, making it easier for ecosystems to adapt. Many of the actions that promote adaptation in ecosystems, also help humans adapt via ecosystem-based adaptation. For instance, restoration of natural fire regimes makes catastrophic fires less likely, and reduces human exposure. Giving rivers more space allows for more water storage in the natural system, reducing flood risk. Restored forest acts as a carbon sink, but planting trees in unsuitable regions can exacerbate climate impacts.[273]

There are synergies and trade-offs between adaptation and mitigation. Adaptation often offer short-term benefits, whereas mitigation has longer-term benefits.[274] Increased use of air conditioning allows people to better cope with heat, but increases energy demand. Compact urban development may lead to reduced emissions from transport and construction. At the same time, it may increase the urban heat island effect, leading to higher temperatures and increased exposure.[275] Increased food productivity has large benefits for both adaptation and mitigation.[276]

Policies and politics Main article: Politics of climate change

The Climate Change Performance Index ranks countries by greenhouse gas emissions (40% of score), renewable energy (20%), energy use (20%), and climate policy (20%).

 High
 Medium
 Low
 Very Low

Countries that are most vulnerable to climate change have typically been responsible for a small share of global emissions. This raises questions about justice and fairness.[277] Climate change is strongly linked to sustainable development. Limiting global warming makes it easier to achieve sustainable development goals, such as eradicating poverty and reducing inequalities. The connection is recognised in Sustainable Development Goal 13 which is to "take urgent action to combat climate change and its impacts".[278] The goals on food, clean water and ecosystem protection have synergies with climate mitigation.[279]

The geopolitics of climate change is complex. It has often been framed as a free-rider problem, in which all countries benefit from mitigation done by other countries, but individual countries would lose from switching to a low-carbon economy themselves. This framing has been challenged. For instance, the benefits of a coal phase-out to public health and local environments exceed the costs in almost all regions.[280] Furthermore, net importers of fossil fuels win economically from switching to clean energy, causing net exporters to face stranded assets: fossil fuels they cannot sell.[281]

Policy options A wide range of policies, regulations, and laws are being used to reduce emissions. As of 2019, carbon pricing covers about 20% of global greenhouse gas emissions.[282] Carbon can be priced with carbon taxes and emissions trading systems.[283] Direct global fossil fuel subsidies reached $319 billion in 2017, and $5.2 trillion when indirect costs such as air pollution are priced in.[284] Ending these can cause a 28% reduction in global carbon emissions and a 46% reduction in air pollution deaths.[285] Subsidies could be used to support the transition to clean energy instead.[286] More direct methods to reduce greenhouse gases include vehicle efficiency standards, renewable fuel standards, and air pollution regulations on heavy industry.[287] Several countries require utilities to increase the share of renewables in power production.[288]

Policy designed through the lens of climate justice tries to address human rights issues and social inequality. For instance, wealthy nations responsible for the largest share of emissions would have to pay poorer countries to adapt.[289] As the use of fossil fuels is reduced, jobs in the sector are being lost. To achieve a just transition, these people would need to be retrained for other jobs. Communities with many fossil fuel workers would need additional investments.[290]

International climate agreements Further information: United Nations Framework Convention on Climate Change

Since 2000, rising CO2 emissions in China and the rest of world have surpassed the output of the United States and Europe.[291]

Per person, the United States generates CO2 at a far faster rate than other primary regions.[291] Nearly all countries in the world are parties to the 1994 United Nations Framework Convention on Climate Change (UNFCCC).[292] The goal of the UNFCCC is to prevent dangerous human interference with the climate system.[293] As stated in the convention, this requires that greenhouse gas concentrations are stabilised in the atmosphere at a level where ecosystems can adapt naturally to climate change, food production is not threatened, and economic development can be sustained.[294] The UNFCCC does not itself restrict emissions but rather provides a framework for protocols that do. Global emissions have risen since the UNFCCC was signed.[295] Its yearly conferences are the stage of global negotiations.[296]

The 1997 Kyoto Protocol extended the UNFCCC and included legally binding commitments for most developed countries to limit their emissions.[297] During the negotiations, the G77 (representing developing countries) pushed for a mandate requiring developed countries to "[take] the lead" in reducing their emissions,[298] since developed countries contributed most to the accumulation of greenhouse gases in the atmosphere. Per-capita emissions were also still relatively low in developing countries and developing countries would need to emit more to meet their development needs.[299]

The 2009 Copenhagen Accord has been widely portrayed as disappointing because of its low goals, and was rejected by poorer nations including the G77.[300] Associated parties aimed to limit the global temperature rise to below 2 °C.[301] The Accord set the goal of sending $100 billion per year to developing countries for mitigation and adaptation by 2020, and proposed the founding of the Green Climate Fund.[302] As of 2020, the fund has failed to reach its expected target, and risks a shrinkage in its funding.[303]

In 2015 all UN countries negotiated the Paris Agreement, which aims to keep global warming well below 2.0 °C and contains an aspirational goal of keeping warming under 1.5 °C.[304] The agreement replaced the Kyoto Protocol. Unlike Kyoto, no binding emission targets were set in the Paris Agreement. Instead, a set of procedures was made binding. Countries have to regularly set ever more ambitious goals and reevaluate these goals every five years.[305] The Paris Agreement restated that developing countries must be financially supported.[306] As of October 2021, 194 states and the European Union have signed the treaty and 191 states and the EU have ratified or acceded to the agreement.[307]

The 1987 Montreal Protocol, an international agreement to stop emitting ozone-depleting gases, may have been more effective at curbing greenhouse gas emissions than the Kyoto Protocol specifically designed to do so.[308] The 2016 Kigali Amendment to the Montreal Protocol aims to reduce the emissions of hydrofluorocarbons, a group of powerful greenhouse gases which served as a replacement for banned ozone-depleting gases. This made the Montreal Protocol a stronger agreement against climate change.[309]

National responses In 2019, the United Kingdom parliament became the first national government to declare a climate emergency.[310] Other countries and jurisdictions followed suit.[311] That same year, the European Parliament declared a "climate and environmental emergency".[312] The European Commission presented its European Green Deal with the goal of making the EU carbon-neutral by 2050.[313] Major countries in Asia have made similar pledges: South Korea and Japan have committed to become carbon-neutral by 2050, and China by 2060.[314] In 2021, the European Commission released its “Fit for 55” legislation package, which contains guidelines for the car industry; all new cars on the European market must be zero-emission vehicles from 2035.[315] While India has strong incentives for renewables, it also plans a significant expansion of coal in the country.[316]

As of 2021, based on information from 48 national climate plans, which represent 40% of the parties to the Paris Agreement, estimated total greenhouse gas emissions will be 0.5% lower compared to 2010 levels, below the 45% or 25% reduction goals to limit global warming to 1.5 °C or 2 °C, respectively.[317]

Scientific consensus and society Scientific consensus Main article: Scientific consensus on climate change

Academic studies of scientific consensus[318][319][320] reflect that the level of consensus correlates with expertise in climate science.[321] There is a near-complete scientific consensus that the climate is warming and that this is caused by human activities. As of 2019, agreement in recent literature reached over 99%.[322][319] No scientific body of national or international standing disagrees with this view.[323] Consensus has further developed that some form of action should be taken to protect people against the impacts of climate change. National science academies have called on world leaders to cut global emissions.[324]

Scientific discussion takes place in journal articles that are peer-reviewed. Scientists assess these every few years in the Intergovernmental Panel on Climate Change reports.[325] The 2021 IPCC Assessment Report stated that it is "unequivocal" that climate change is caused by humans.[319]


Data has been cherry picked from short periods to falsely assert that global temperatures are not rising. Blue trendlines show short periods that mask longer-term warming trends (red trendlines). Blue dots show the so-called global warming hiatus.[326] Denial and misinformation Further information: Global warming controversy, Fossil fuels lobby, Climate change denial, and Global warming conspiracy theory Public debate about climate change has been strongly affected by climate change denial and misinformation, which originated in the United States and has since spread to other countries, particularly Canada and Australia. The actors behind climate change denial form a well-funded and relatively coordinated coalition of fossil fuel companies, industry groups, conservative think tanks, and contrarian scientists.[327] Like the tobacco industry, the main strategy of these groups has been to manufacture doubt about scientific data and results.[328] Many who deny, dismiss, or hold unwarranted doubt about the scientific consensus on anthropogenic climate change are labelled as "climate change skeptics", which several scientists have noted is a misnomer.[329]

There are different variants of climate denial: some deny that warming takes place at all, some acknowledge warming but attribute it to natural influences, and some minimise the negative impacts of climate change.[330] Manufacturing uncertainty about the science later developed into a manufactured controversy: creating the belief that there is significant uncertainty about climate change within the scientific community in order to delay policy changes.[331] Strategies to promote these ideas include criticism of scientific institutions,[332] and questioning the motives of individual scientists.[330] An echo chamber of climate-denying blogs and media has further fomented misunderstanding of climate change.[333]

Public awareness and opinion Further information: Climate communication, Media coverage of climate change, and Public opinion on climate change Climate change came to international public attention in the late 1980s.[334] Due to media coverage in the early 1990s, people often confused climate change with other environmental issues like ozone depletion.[335] In popular culture, the climate fiction movie The Day After Tomorrow (2004) and the Al Gore documentary An Inconvenient Truth (2006) focused on climate change.[334]

Significant regional, gender, age and political differences exist in both public concern for, and understanding of, climate change. More highly educated people, and in some countries, women and younger people, were more likely to see climate change as a serious threat.[336] Partisan gaps also exist in many countries,[337] and countries with high CO2 emissions tend to be less concerned.[338] Views on causes of climate change vary widely between countries.[339] Concern has increased over time,[337] to the point where in 2021 a majority of citizens in many countries express a high level of worry about climate change, or view it as a global emergency.[340] Higher levels of worry are associated with stronger public support for policies that address climate change.[341]

Climate movement Main articles: Climate movement and Climate change litigation

The 2017 People's Climate March took place in hundreds of locations.[342] Shown: the Washington, D.C. march, protesting policies of then-U.S. President Trump.[342] Climate protests demand that political leaders take action to prevent climate change. They can take the form of public demonstrations, fossil fuel divestment, lawsuits and other activities.[343] Prominent demonstrations include the School Strike for Climate. In this initiative, young people across the globe have been protesting since 2018 by skipping school on Fridays, inspired by Swedish teenager Greta Thunberg.[344] Mass civil disobedience actions by groups like Extinction Rebellion have protested by disrupting roads and public transport.[345] Litigation is increasingly used as a tool to strengthen climate action from public institutions and companies. Activists also initiate lawsuits which target governments and demand that they take ambitious action or enforce existing laws on climate change.[346] Lawsuits against fossil-fuel companies generally seek compensation for loss and damage.[347]

Discovery For broader coverage of this topic, see History of climate change science.

Tyndall's ratio spectrophotometer (drawing from 1861) measured how much infrared radiation was absorbed and emitted by various gases filling its central tube. In the 1820s, Joseph Fourier proposed the greenhouse effect to explain why Earth's temperature was higher than the sun's energy alone could explain. Earth's atmosphere is transparent to sunlight, so sunlight reaches the surface where it is converted to heat. However, the atmosphere is not transparent to heat radiating from the surface, and captures some of that heat which warms the planet.[348] In 1856 Eunice Newton Foote demonstrated that the warming effect of the sun is greater for air with water vapour than for dry air, and the effect is even greater with carbon dioxide. She concluded that "An atmosphere of that gas would give to our earth a high temperature..."[349][350] Starting in 1859,[351] John Tyndall established that nitrogen and oxygen—together totalling 99% of dry air—are transparent to radiated heat. However, water vapour and some gases (in particular methane and carbon dioxide) absorb radiated heat and re-radiate that heat within the atmosphere. Tyndall proposed that changes in the concentrations of these gases may have caused climatic changes in the past, including ice ages.[352]

Svante Arrhenius noted that water vapour in air continuously varied, but the CO2 concentration in air was influenced by long-term geological processes. At the end of an ice age, warming from increased CO2 levels would increase the amount of water vapour, amplifying warming in a feedback loop. In 1896, he published the first climate model of its kind, showing that halving of CO2 levels could have produced the drop in temperature initiating the ice age. Arrhenius calculated the temperature increase expected from doubling CO2 to be around 5–6 °C.[353] Other scientists were initially sceptical and believed the greenhouse effect to be saturated so that adding more CO2 would make no difference. They thought climate would be self-regulating.[354] From 1938 onwards Guy Stewart Callendar published evidence that climate was warming and CO2 levels rising,[355] but his calculations met the same objections.[354]

In the 1950s, Gilbert Plass created a detailed computer model that included different atmospheric layers and the infrared spectrum. This model predicted that increasing CO2 levels would cause warming. Around the same time, Hans Suess found evidence that CO2 levels had been rising, and Roger Revelle showed that the oceans would not absorb the increase. The two scientists subsequently helped Charles Keeling to begin a record of continued increase, which has been termed the "Keeling Curve".[354] Scientists alerted the public,[356] and the dangers were highlighted at James Hansen's 1988 Congressional testimony.[21] The Intergovernmental Panel on Climate Change, set up in 1988 to provide formal advice to the world's governments, spurred interdisciplinary research.[357]

See also icon Climate change portal icon Environment portal icon Science portal World portal 2020s in environmental history Anthropocene – proposed new geological time interval in which humans are having significant geological impact Global cooling – minority view held by scientists in the 1970s that imminent cooling of the Earth would take place