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Line 1: − :''See also [[Counterexamples to Global Warming|Counterexamples to global warming]]''+ + + + + − [[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>]]+ − '''Anthropogenic global warming''' (AGW) is a theory that suggests that human activity is causing the Earth to warm. The theory posits that greenhouse gases, 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 in the near future. Some leftists use this theory as a basis to propose cuts in energy production and consumption and promote de-industrialization.+ + + + + + + + − + − Difficulties with the theory:+ − *'''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 Intergovernmental Panel on Climate Change (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> − *'''The Earth has warmed or cooled many times. Historically, warm periods are associated with favorable climate.''' The [[Roman Warm Period]] (250 BC to 400 AD) 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 lasted from 900 to 1300. From the 14th century to the early 19th century, there was a Little Ice Age.<ref>Bastasch, Michael, "[http://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> − *'''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 senarios." He could offer up whichever one was expedient.<br/>If the problem was simply too much carbon dioxide in the atmosphere, this could be addressed by promoting plant growth in the oceans.<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> Such "geoengineering" doesn't appeal to liberals because AGW is less about the climate than about justifying the anti-energy cause. Scratch an AGW believer and there is an overpopulationist or a world government socialist underneath. − *'''If the science was 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. No one's reputation is tarnished, 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.<br/>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> It is a view at odds with several hypotheses considered well-established in this field, including the Medieval Warm Period<ref>John P. Rafferty, "[https://global.britannica.com/science/medieval-warm-period Medieval warm period (MWP)]", ''Britannica''</ref> and the 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> − + − + − 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 discusses convection as an alternative explanation and, as a good scientist, recommends an experiment to resolve the issue. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + − 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.+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + − 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 °C (about 5 to 7 °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>+ − 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>+ + + + + + + + + + + − + − Arrhenius ignored water vapor in his calculations, leading him 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." − 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>+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + − 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, ''1951 Compendium of Meteorology''.</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.+ + + + + + + + + − 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 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 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" />+ + + + + + + + + + + + − 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>+ − + − 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. http://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.+ − 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>+ + + + + + + + + + + + + − 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.+ + + + + + + + + + + + + + + + + + + + + − 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 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.+ + + + + + + + + + + + + + + + + + + + + − 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.+ + + + + + + + − 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>+ + + + + + + + + − 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:+ − Vol. 354, Issue 6309, pp. 225-229 DOI: 10.1126/science.aaf5466.</ref> − ===From cooling to warming===+ − 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: − {{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>}} − 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.+ + + + + + + + + + + + + + + + − 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:+ − + + + + + + + + + + − After Schneider abandoned his global cooling hobbyhorse and got on the global warming 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.+ + − ===The IPCC===+ − 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., "[http://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. − As for the main report, this is put together carelessly, according George Filippo: "I feel rather unconfortable 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>+ + − + − 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.+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + − + + + + + + + + + + + + + + + + + + − 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 coorelated 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>+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + − 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.+ + + + + + + + + + + + − + − 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>+ + − 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>+ + + − 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>+ + − 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>+ + + + + + + + + + + − + − 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.+ − 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.+ + + + + + + + + + + + + + + + + + + + + + + + + + − 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). [http://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.]+ − + − The following facts can help dissuade even the most illogical of liberals from believing in the flawed theory of anthropogenic global warming.+ + + + + + + + + + + + + + + + + + + + + + + + + + + + − + − The overall temperature has been flat for about 16 years.<ref name="Rose">Rose, David (October 13, 2012). [http://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>+ + + + + + + + + + + + + + + + + + + + + − + − Climate data stating otherwise has been proven to be manipulated.<ref>Multiple references: − *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. − *[http://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> − + − 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>+ − + − + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + − 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>+ − 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>[http://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.+ + + + + + + + + + + + + + + + + + + + − 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>+ + + + + + + + + + − But other scientists have disputed this claim of modern-day record-high carbon dioxide readings:<ref name="dissidents"/>+ − <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>+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + − ===The Modern Warm Period===+ − 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. − 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:+ − + + + + + + + + + + + + + + + + + + + + + + + + + + + + − 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.+ + + + + + + + + + + + − 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"/>+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + − + − <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>+ + + + + − The MailOnline article continued:+ + + + + + + + + + + + + + + + + + + + − <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>+ − ===Sunspots===+ − 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: − − 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. − ==Economics of global warming==+ − + − 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>+ + + + + + − ==Public stances on global warming==+ − + − 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]]'', + − <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> − <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>+ − 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?"+ + − 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> + − + − 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>+ + − And while, "When man was made in the image of God, he was fallen but redeemable", among these devotees of [[Gaia]], + − + + + + + + + + + + − + − {{main|Politics of global warming}} − 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>+ + − '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>+ + + + − 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. + − − Mark Steyn writes in "Why climate change is hot hot hot",<ref name="hot"/>+ − + − 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>+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + − 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. + + + + + − 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.+ + + + + − 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:+ − + + + + + + + + − + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + − :The present analysis suggests the models failure to predict other climatic phenomena arises from defects in its evaluation of radioactive forcing, no-feedbacks climate sensitivity parameter and feedback multiplier. In conclusion, that there may be no "Climate Crisis" and for governments to reduce emissions may be pointless or even harmful.+ + + − 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:+ − + + + + + + + + + + + + + + + + + − 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>[http://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>+ + − Dr. John S. Theon:+ − + + − 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>+ + − 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). [http://web.archive.org/web/20081215162025/http://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>[http://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>[http://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). [http://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!"+ − + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + − 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"/> + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + − + − 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). [http://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>+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + − + − 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==+ − + − + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + − 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>[http://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). [http://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). [http://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>[http://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.+ + + + + + + + + + + + + − + − + − 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). [http://www.theguardian.com/science/2001/jun/28/physicalsciences.highereducation "Breaking the ice"]. The Guardian website. Retrieved on September 30, 2014. See [[Guardian (UK)]].</ref>+ + − + − − 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.+ − + − 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>+ − + − + − + − 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> + − + − 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." + − + − 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>+ − + − ===Natural variability of the climate system===+ − 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. − − ===Natural climate change on other planets=== − − 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: − − − − 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> − − − − 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> − − 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. − − 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. − − 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. − + − [[File:Gore GlobalWarming.jpg|right|200px]]+ − 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: − *Sheppard, Marc (July 14, 2009). [http://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. − *Smith, Lewis (October 11, 2007). [http://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. − *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> − 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:+ + + − + + + + + + + − + + + + + + + + + − + + + + + + − + + + + + + + + + + − + + + + + + + + + + + + − + + + + + + + + + + + − + + + + + + + + + + + − + + + + + + + + + + + − + − + − 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." + + + + + + − 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.+ + + + + + + + − 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>+ + + + + + + + + + + + + + − In order for the film to be shown, the Government must first amend their Guidance Notes to Teachers to make clear that + + + + + + + + − + + + + + + + + + + + − + + + + + + + + − + + + + + + + + + + + − 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). [http://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>+ + + + + + + + + + + − 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,+ + + + + + + + + + + + + + + + + + + + + − + + + + + + + + + + − 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.+ + + + + + + + + + + + − + + + + + + + + + + − [[Image:Rogerrevelle.jpg|thumb|right|200px|Roger Revelle]]+ + + + + + + + − + − + − * [[Roger Revelle]]+ − * [[Achim Steiner]]+ − * [[Fred Singer]]+ − + − * [[Sallie Baliunas]]+ − * [[Lonnie Thompson]]+ − + − * [[James E. Hansen]]+ − * [[Michael Mann]]+ − * [[Charles Keeling]]+ − * [[Edwin A. Hernández-Delgado]]+ − |}+ + + + + + + − + − [[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). [http://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>+ + + + + + + + − + − ::''See also : [[Climategate#Hockey Stick Graph|Climategate: hockey stick graph]]''+ − <small>+ − *Shabecoff, Philip, [http://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. 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 − + − *Taylor, James (November 23, 2011). [http://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.+ − *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.+ − *Cole, Steve and McCarthy, Leslie (January 12, 2011). [http://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.+ − *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>+ − </small>+ + + + + + − ==Effects of global warming==+ − ===Beneficial effects of global warming=== − [[File:Autumn foliage.jpg|thumb|Canoing on a Colorful Day, (NY).]] − 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>[http://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>+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + − <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>+ + + + + + + + + − ===Reported effects of global warming===+ + + + + + + + − Reported past or expected/possible future environmental and societal consequences of man-made global warming include global cooling,<ref>72Jag (August 25, 2014). [http://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). [http://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). [http://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). [http://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]]. 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). [http://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). [http://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+ − + − + − {{liberalism}}+ − {{Climategate scandal}}+ − + − ==References==+ − {{reflist|2}}+ − + − == See also ==+ − *''[[Massachusetts v. EPA]]'' + − *[[Liberal hysteria#Global Warming Derangement Syndrome|Global Warming Derangement Syndrome]]+ − *[[Socialist Environmental Disasters]]+ − *[[Counterexamples to Global Warming]]+ − *[[Winter of 2010]]+ − *[[Reducing carbon dioxide emissions]]+ − *[[Essay:Global Warming]]+ − *[[Essay:Parallels between evolution and global warming]]+ − *[[Exaggeration of global warming]]+ − *[[Global warming and polar bears]]+ − *[[Global climate disruption]]+ − *[[Global warming research]] − *[[Global annual average temperature]] − *[[Warm period]] − + + + − *[http://www.creationworldview.org/articles_view.asp?id=67 Global Warming? Absolutely No Truth To It!]+ − *[http://www.aim.org/wls/category/global-warming/ What Liberals Say - Category: Global Warming], [[Accuracy In Media]] − *[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] − *[http://www.icr.org/creation-meteorology Clinate Change] by The Institute for Creation Research − *[http://environment.guardian.co.uk/climatechange/story/0,,2032821,00.html The appliance of science] by Mike Hulme. − *[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]] − *[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]. − *[http://www.independent.org/publications/tir/article.asp?issueID=25&articleID=296 "After Kyoto: A Global Scramble for Advantage," by Bruce Yandle]. − *[http://www.ncpa.org/sub/dpd/index.php?Article_ID=2319 The physical evidence of earth's unstoppable 1,500-year climate cycle] − *[http://www.independent.org/publications/article.asp?id=1714 "Is There a Basis for Global Warming Alarm?", by Richard Lindzen] − *[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"] − *[http://www.heartland.org/Article.cfm?artId=17181 Survey Shows Climatologists Are Split on Global Warming] − *[http://www.magma.ca/~hurleyp/FightingTheHoax.htm Fighting the Hoax] − *[http://www.globalwarminghoax.com/news.php Refuting the Myth of Man-made Global Warming] − *[http://www.climateaudit.org Climate Audit], Steve McIntyre's blog − *[http://www.realclimate.org Real Climate], blog by a group of climatologists including Michael Mann − *[http://www.americanthinker.com/2009/01/co2_fairytales_in_global_warmi.html "CO<sub>2</sub> Fairytales in Global Warming"] − *[http://www.numberwatch.co.uk/warmlist.htm A complete list of things caused by global warming] − *[http://globaleconomicanalysis.blogspot.com/2009/11/hackers-prove-global-warming-is-scam.html Hackers Prove Global Warming Is A Scam] − [[Category:Earth Sciences]]+ − [[Category:Environmentalism]]+ − + − + − + −
Updated some information
{{hatnote|This page is about the current warming of the Earth's climate system. "[[Climate change]]" can also refer to climate trends at any point in Earth's history. For other uses see [[Global warming (disambiguation)]]}}
{{pp-semi-indef}}
{{use dmy dates|date=November 2015}}
{{bots|deny=Citation bot}}
{{featured article}}{{Use British (Oxford) English|date=September 2016}}
{{Multiple image|align=right|direction=vertical|width=320|image1=Global Temperature Anomaly.svg|alt1=refer to caption|caption1=Global mean surface-temperature change from 1880 to 2016, relative to the 1951–1980 mean. The black line is the global annual mean and the red line is the five-year [[Local regression|lowess smooth]]. The blue [[Error bar|uncertainty bars]] show a 95% confidence limit.
|image2=World map showing surface temperature trends between 1950 and 2014.png
|alt2=Map of temperature changes across the world
|image3=Key to world map showing surface temperature trends between 1950 and 2014.svg
|alt3=key to map of temperature changes
|caption3=World map showing surface temperature trends (°C per decade) between 1950 and 2014.<ref>16 January 2015: [http://www.giss.nasa.gov/research/news/20150116/ NASA GISS: NASA GISS: NASA, NOAA Find 2014 Warmest Year in Modern Record], in: Research News. NASA Goddard Institute for Space Studies, New York, US. Retrieved 20 February 2015</ref>
|image4=Global Warming Observed CO2 Emissions from fossil fuel burning vs IPCC scenarios.svg|alt4=refer to caption|caption4=Fossil-fuel–related [[carbon dioxide in Earth's atmosphere|carbon-dioxide]] (CO<sub>2</sub>) emissions compared to five of the IPCC's "[[Special Report on Emissions Scenarios|SRES]]" emissions scenarios, published in 2000. The dips are related to global recessions.
|image5=TrendsGlobalEmissions.png|alt5=refer to caption|caption5=Fossil-fuel–related carbon-dioxide emissions over the 20th century.
|image6=2016 Was the Warmest Year on Record.webm|alt6=refer to caption|caption6=Eight of the 12 months of 2016 – from January through September, with the exception of June – were the hottest of those respective months on record. October, November and December of that year were the second hottest of those months on record – in all three cases, behind records set in 2015.}}
A reanalysis of weather station data for 1943 to 2012 by U.S. climate researcher Roy Spencer shows that after a cooler period in the 1960s and 1970s, U.S. temperatures returned to their earlier level.<ref name="Spencer" /> There are also temperature records based on weather balloon data and satellite readings, but these records do not go back far enough to reveal the full temperature cycle. Although recent climate trends are much discussed in the media, the temperature shifts that have been recorded are modest and should not be conflate with the various climate doomsday scenarios, which are based on computer modelling.
'''Global warming''' and '''climate change'''<!-- DO NOT WIKILINK "climate change" because here it is being used in the colloquial sense and means the current climate change; this is the article about that topic. A short explanation and wikilink for the article titled "Climate change" is in the hatnote right before this sentence.--> are terms for the observed century-scale rise in the average temperature of the Earth's [[climate|climate system]] and its related effects.<ref name="NYT-20151128-jg">{{cite news |last=Gillis |first=Justin |title=Short Answers to Hard Questions About Climate Change |url=http://www.nytimes.com/interactive/2015/11/28/science/what-is-climate-change.html |date=28 November 2015 |work=[[The New York Times]] |accessdate=29 November 2015 }}</ref><ref>{{Cite book|title=Oxford English Dictionary|last=Simpson|first=John|publisher=|year=|isbn=|location=|pages=|quote=(Global warming is a) gradual increase in the overall temperature of the earth’s atmosphere generally attributed to the greenhouse effect caused by increased levels of carbon dioxide, CFC’s, and other pollutants.|via=}}</ref> Multiple lines of scientific evidence show that the climate system is warming.<ref>{{cite report|chapter=2: Observations: Atmosphere and Surface|author=Hartmann, D. L.; Klein Tank, A. M. G.; Rusticucci, M.|year=2013|chapter-url=http://www.climatechange2013.org/images/report/WG1AR5_Chapter02_FINAL.pdf |page=198|quote=Evidence for a warming world comes from multiple independent climate indicators, from high up in the atmosphere to the depths of the oceans. They include changes in surface, atmospheric and oceanic temperatures; glaciers; snow cover; sea ice; sea level and atmospheric water vapour. Scientists from all over the world have independently verified this evidence many times.|title=IPCC WGI AR5}}</ref><ref>{{cite web|title=Myth vs Facts....|url=http://epa.gov/climatechange/endangerment/myths-facts.html|publisher=EPA (US)|year=2013}}The U.S. Global Change Research Program, the National Academy of Sciences, and the Intergovernmental Panel on Climate Change (IPCC) have each independently concluded that warming of the climate system in recent decades is 'unequivocal'. This conclusion is not drawn from any one source of data but is based on multiple lines of evidence, including three worldwide temperature datasets showing nearly identical warming trends as well as numerous other independent indicators of global warming (e.g., rising sea levels, shrinking Arctic sea ice).</ref><ref name="AP-20151129">{{cite news |last=Borenstein |first=Seth |title=Earth is a wilder, warmer place since last climate deal made |url=http://apnews.excite.com/article/20151129/eu-climate-countdown-since-1997-edf9d62e51.html |date=29 November 2015 |accessdate=29 November 2015 }}</ref> Although the increase of near-surface atmospheric temperature is the measure of global warming often reported in the popular press, most of the additional energy stored in the climate system since 1970 has gone into the oceans.<!-- ref for this sentence is the same as ref for the next so please don't tag CN --> The rest has melted ice and warmed the continents and [[atmosphere]].<ref>{{cite report|chapter=3: Observations: Ocean|author1=Rhein, M.|author2=Rintoul, S.R.|year=2013|chapter-url=http://www.climatechange2013.org/images/report/WG1AR5_Chapter03_FINAL.pdf|page=257|quote=Ocean warming dominates the global energy change inventory. Warming of the ocean accounts for about 93% of the increase in the Earth's energy inventory between 1971 and 2010 (high confidence), with warming of the upper (0 to 700 m) ocean accounting for about 64% of the total. Melting ice (including Arctic sea ice, ice sheets and glaciers) and warming of the continents and atmosphere account for the remainder of the change in energy.|title=IPCC WGI AR5}}</ref>{{efn|Scientific journals use "global warming" to describe an increasing global average temperature just at earth's surface, and most of these authorities further limit "global warming" to such increases caused by human activities or increasing greenhouse gases.}} Many of the observed changes since the 1950s are unprecedented over tens to thousands of years.<ref>IPCC, Climate Change 2013: The Physical Science Basis - Summary for Policymakers, Observed Changes in the Climate System, [http://www.climatechange2013.org/spm p. 2], in {{Harvnb|IPCC AR5 WG1|2013}}. "Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia."</ref>
[[Scientific opinion on climate change|Scientific understanding of global warming]] is increasing. The United Nations [[Intergovernmental Panel on Climate Change]] (IPCC) [[IPCC Fifth Assessment Report|reported in 2014]], that "It is ''extremely likely'' that human influence has been the dominant cause of the observed warming since the mid-20th century." <ref>IPCC, Climate Change 2013: The Physical Science Basis - Summary for Policymakers, Observed Changes in the Climate System, [http://www.climatechange2013.org/spm p. 15], in {{Harvnb|IPCC AR5 WG1|2013}}.</ref> Human activities have led to [[carbon dioxide]] [[Carbon dioxide in Earth's atmosphere|concentrations]] above levels not seen in hundreds of thousands of years. Currently, about half of the carbon dioxide released from the burning of [[fossil fuels]] remains in the atmosphere. The rest is absorbed by vegetation and the oceans.<ref name="NASA-20151112-ab" /> [[Climate model]] projections summarized in the report indicated that during the 21st century the global surface temperature is likely to rise a further {{convert|0.3|to|1.7|C-change|1}} for their lowest [[Representative Concentration Pathways|emissions scenario]] and {{convert|2.6|to|4.8|C-change|1}} for the highest emissions scenario.<ref>Stocker ''et al.'', [http://www.climatechange2013.org/images/report/WG1AR5_TS_FINAL.pdf Technical Summary], in {{Harvnb|IPCC AR5 WG1|2013}}.</ref> These findings have been recognized by the national science academies of the major industrialized nations<ref>{{cite web|url=http://nationalacademies.org/onpi/06072005.pdf |title=Joint Science Academies' Statement |format=PDF |accessdate=6 January 2014}}</ref>{{efn|The 2001 joint statement was signed by the national academies of science of Australia, Belgium, Brazil, Canada, the Caribbean, the People's Republic of China, France, Germany, India, Indonesia, Ireland, Italy, Malaysia, New Zealand, Sweden, and the UK.<ref>{{cite news|url=http://news.bbc.co.uk/1/hi/sci/tech/1335872.stm |title=Science academies back Kyoto |first=Alex |last=Kirby |publisher=BBC News |date=17 May 2001 |accessdate=27 July 2011}}</ref> The 2005 statement added Japan, Russia, and the U.S. The 2007 statement added Mexico and South Africa. The [[Network of African Science Academies]], and the [[Polish Academy of Sciences]] have issued separate statements. Professional scientific societies include [[American Astronomical Society]], [[American Chemical Society]], [[American Geophysical Union]], [[American Institute of Physics]], [[American Meteorological Society]], [[American Physical Society]], [[American Quaternary Association]], [[Australian Meteorological and Oceanographic Society]], [[Canadian Foundation for Climate and Atmospheric Sciences]], [[Canadian Meteorological and Oceanographic Society]], [[European Academy of Sciences and Arts]], [[European Geosciences Union]], [[European Science Foundation]], [[Geological Society of America]], [[Geological Society of Australia]], [[Geological Society of London]]-Stratigraphy Commission, [[InterAcademy Council]], [[International Union of Geodesy and Geophysics]], [[International Union for Quaternary Research]], [http://www.nagt.org/index.html National Association of Geoscience Teachers], [[United States National Research Council|National Research Council (US)]], [[Royal Meteorological Society]], and [[World Meteorological Organization]].}} and are not disputed by any scientific body of national or international standing.<ref name="The MIT Press">{{cite book |title= Climate Change: What It Means for Us, Our Children, and Our Grandchildren|last1= DiMento|first1= Joseph F. C.|last2= Doughman|first2= Pamela M.|year= 2007|publisher=The MIT Press|isbn= 978-0-262-54193-0|page= 68}}</ref>
==History==
Future climate change and associated impacts will differ from [[regional effects of global warming|region to region]] around the globe.<ref>
===Origin===
{{citation
| author=Parry, M.L.
| url=http://www.ipcc.ch/publications_and_data/ar4/wg2/en/tssts-4-2.html |title=Box TS.6. The main projected impacts for regions
| chapter=Technical summary
| chapter-url=http://www.ipcc.ch/publications_and_data/ar4/wg2/en/ts.html
|display-authors=etal}}, in {{harvnb|IPCC AR4 WG2|2007|pp=59–63}}
</ref><ref>Solomon ''et al.'', [http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ts.html Technical Summary],
[http://www.ipcc.ch/publications_and_data/ar4/wg1/en/tssts-5-3.html Section TS.5.3: Regional-Scale Projections], in {{Harvnb|IPCC AR4 WG1|2007}}.</ref> Anticipated [[effects of global warming|effects]] include warming global temperature, [[Current sea level rise|rising sea levels]], changing [[precipitation (meteorology)|precipitation]], and expansion of [[desert]]s in the [[subtropics]].<ref>
{{Cite journal
|last1= Lu |first1= Jian
|last2= Vechhi |first2= Gabriel A.
|last3= Reichler |first3= Thomas
|title= Expansion of the Hadley cell under global warming
|journal= Geophysical Research Letters
|volume=34 |issue= 6 |page= L06805
|year= 2007
|url= http://onlinelibrary.wiley.com/doi/10.1029/2006GL028443/epdf
|format=PDF
|doi=10.1029/2006GL028443
|bibcode=2007GeoRL..3406805L
|ref= harv
}}
</ref> Warming is expected to be greater over land than over the oceans and [[Arctic shrinkage|greatest in the Arctic]], with the continuing [[retreat of glaciers since 1850|retreat of glaciers]], [[permafrost]] and [[sea ice]]. Other likely changes include more frequent [[extreme weather]] events including [[heat wave]]s, [[drought]]s, heavy [[rain]]fall with [[inundation|floods]] and heavy [[snow]]fall;<ref>On snowfall:
* {{cite news|url=http://www.npr.org/templates/story/story.php?storyId=123671588|title=Get This: Warming Planet Can Mean More Snow|date=15 February 2010|author=Christopher Joyce|publisher=NPR}}
* {{cite news|url=http://phys.org/news/2011-03-global-snowstorms-scientists.html|title=Global warming means more snowstorms: scientists|date=1 March 2011}}
* {{cite web|url=http://www.skepticalscience.com/Record-snowfall-disproves-global-warming.htm|title=Does record snowfall disprove global warming?|accessdate=14 December 2014|date=9 July 2010}}</ref> [[ocean acidification]]; and [[extinction risk from climate change|species extinctions]] due to shifting temperature regimes. Effects significant to humans include the threat to [[climate change and agriculture|food security]] from decreasing crop yields and the [[climate refugee|abandonment of populated areas]] due to [[sea level rise|rising sea levels]].<ref>{{cite journal
|last=Battisti|first=David
|author2=Naylor, Rosamund L. |title=Historical warnings of future food insecurity with unprecedented seasonal heat|journal=Science|year=2009
|url=http://www.sciencemag.org/content/323/5911/240.short|accessdate=13 April 2012|doi=10.1126/science.1164363
|volume=323
|issue=5911
|pages=240–4
|pmid=19131626
|ref=harv
}}</ref><ref>{{harvnb|US NRC|2012|p=26}}</ref> Because the climate system has a large "[[inertia]]" and greenhouse gases will stay in the atmosphere for a long time, many of these effects will not only exist for decades or centuries, but will persist for tens of thousands of years.<ref>{{cite journal | last1 = Peter | first1 = U. | display-authors = 1 | last2 = et al | year = | title = Clark ''et al.'' 2016 ''Consequences of twenty-first-century policy for multi-millennial climate and sea-level change'' | url = | journal = [[Nature Climate Change]] | volume = 6 | issue = | pages = 360–369 | doi = 10.1038/NCLIMATE2923 }}</ref>
Possible societal responses to global warming include [[Climate change mitigation|mitigation]] by emissions reduction, [[adaptation to global warming|adaptation]] to its effects, building systems [[climate resilience|resilient]] to its effects, and possible future [[climate engineering]]. Most countries are parties to the [[United Nations Framework Convention on Climate Change]] (UNFCCC),<ref>{{Cite journal
| year=2011
| author=[[United Nations Framework Convention on Climate Change]] (UNFCCC)
| title=Status of Ratification of the Convention
| url=http://unfccc.int/essential_background/convention/status_of_ratification/items/2631.php
| publisher=UNFCCC
| location=UNFCCC Secretariat: [[Bonn]], Germany
| ref=harv
}}. Most countries in the world are Parties to the [[United Nations Framework Convention on Climate Change]] (UNFCCC), which has adopted the {{val|2|u=°C}} limit. As of 25 November 2011, there are 195 parties (194 states and 1 regional economic integration organization (the [[European Union]])) to the UNFCCC.</ref>
whose ultimate objective is to [[Avoiding dangerous climate change|prevent dangerous anthropogenic climate change]].<ref>{{cite web
|title=Article 2
|work=The United Nations Framework Convention on Climate Change
|quote=The ultimate objective of this Convention and any related legal instruments that the Conference of the Parties may adopt is to achieve, in accordance with the relevant provisions of the Convention, stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. Such a level should be achieved within a time-frame sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner. Such a level should be achieved within a time-frame sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner
|url=http://unfccc.int/essential_background/convention/background/items/1353.php
|deadurl=yes
|archiveurl=https://web.archive.org/web/20051028023600/http://unfccc.int:80/essential_background/convention/background/items/1353.php
|archivedate=28 October 2005
|df=dmy
}}, excerpt from the founding international treaty that took force on 21 March 1994.
</ref> Parties to the UNFCCC have agreed that deep cuts in emissions are required<ref name="unfccc 2 degrees celsius target">
{{Cite journal
| year=2011
| author=[[United Nations Framework Convention on Climate Change]] (UNFCCC)
| title=Conference of the Parties – Sixteenth Session: Decision 1/CP.16: The Cancun Agreements: Outcome of the work of the Ad Hoc Working Group on Long-term Cooperative Action under the Convention (English): Paragraph 4
| publisher=UNFCCC
| location=UNFCCC Secretariat: [[Bonn]], Germany
| page=3
| url=http://unfccc.int/resource/docs/2010/cop16/eng/07a01.pdf#page=2
| format=PDF
| ref=harv
}} "(...) deep cuts in global greenhouse gas emissions are required according to science, and as documented in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, with a view to reducing global greenhouse gas emissions so as to hold the increase in global average temperature below {{val|2|u=°C}} above preindustrial levels"
</ref> and that global warming should be limited to well below {{convert|2.0|C-change|F-change|1}} relative to pre-industrial levels,{{efn
|Earth has already experienced almost 1/2 of the {{convert|2.0|C-change|F-change|1}} described in the Cancún Agreement. In the last 100 years, Earth's average surface temperature increased by about {{convert|0.8|C-change|F-change|1}} with about two thirds of the increase occurring over just the last three decades.<ref name = "AmericasClimateChoices-2011-FullReport">
{{Cite book
| publisher = The National Academies Press
| isbn = 978-0-309-14585-5
| title = America's Climate Choices
| location = Washington, D.C.
| year = 2011
| url = http://www.nap.edu/openbook.php?record_id=12781&page=1
| page = 15
| quote = The average temperature of the Earth's surface increased by about {{convert|1.4|F-change|1}} over the past 100 years, with about {{convert|1.0|F-change|1}} of this warming occurring over just the past three decades.
}}
</ref>}} with efforts made to limit warming to {{convert|1.5|C-change|1}}.<ref>
*{{cite web
|url=http://www.cnn.com/2015/12/12/world/global-climate-change-conference-vote/
|title=Final draft of climate deal formally accepted in Paris
|last1=Sutter
|first1=John D.
|last2=Berlinger
|first2=Joshua
|date=12 December 2015
|website=CNN
|publisher=Cable News Network, Turner Broadcasting System, Inc.
|access-date=12 December 2015
}}
*{{cite news
|url=https://www.theguardian.com/environment/2015/dec/12/paris-climate-deal-key-points
|title=Paris climate deal: key points at a glance
|author=Vaughan, A.
|date=12 December 2015
|newspaper=The Guardian
|location=London and Manchester, UK
|access-date=12 December 2015
|deadurl=bot: unknown
|archiveurl=https://web.archive.org/web/20151213005658/http://www.theguardian.com/environment/2015/dec/12/paris-climate-deal-key-points
|archivedate=13 December 2015
|df=dmy
}}. Archived .
</ref>
Public reactions to global warming and concern about its effects are also increasing. A global 2015 [[Pew Research Center]] report showed a [[median]] of 54% consider it "a very serious problem". There are significant regional differences, with [[Americans]] and [[Chinese people|Chinese]] (whose economies are responsible for [[List of countries by carbon dioxide emissions|the greatest annual CO<sub>2</sub> emissions]]) among the least concerned.<ref>{{cite web|first1=Bruce|last1=Stokes|first2=Richard|last2=Wike|first3=Jill|last3=Carle|title=Global Concern about Climate Change, Broad Support for Limiting Emissions: U.S., China Less Worried; Partisan Divides in Key Countries|date=5 November 2015|url=http://www.pewglobal.org/2015/11/05/global-concern-about-climate-change-broad-support-for-limiting-emissions/|website=Pew Research Center|access-date=18 June 2016}}</ref>
== Observed temperature changes ==
{{Main article|Instrumental temperature record}}
[[File:16-008-NASA-2015RecordWarmGlobalYearSince1880-20160120.png|thumb|400px|2015 – warmest year on record globally (since 1880) until 2016. Colours indicate temperature anomalies ([[NASA]]/[[NOAA]]; 20 January 2016).<ref name="NASA-20160120">{{cite web |last1=Brown |first1=Dwayne |last2=Cabbage |first2=Michael |last3=McCarthy |first3=Leslie |last4=Norton |first4=Karen |title=NASA, NOAA Analyses Reveal Record-Shattering Global Warm Temperatures in 2015 |url=http://www.nasa.gov/press-release/nasa-noaa-analyses-reveal-record-shattering-global-warm-temperatures-in-2015 |date=20 January 2016 |work=[[NASA]] |accessdate=21 January 2016 }}</ref>]]
[[File:Energy change inventory, 1971-2010.svg|thumb|250px|right|alt=refer to caption and image description|Earth has been in ''radiative imbalance'' since at least the 1970s, where less energy leaves the [[Atmosphere of Earth|atmosphere]] than enters it. Most of this extra energy has been absorbed by the oceans.<ref>
Rhein, M., ''et al''. (June 7, 2013): Box 3.1, in: [http://www.climatechange2013.org/images/uploads/WGIAR5_WGI-12Doc2b_FinalDraft_Chapter03.pdf Chapter 3: Observations: Ocean (final draft accepted by IPCC Working Group I)], pp.11-12 (pp.14-15 of PDF chapter), in: {{harvnb|IPCC AR5 WG1|2013}}
</ref> It is very likely that human activities substantially contributed to this increase in [[ocean heat content]].<ref>
IPCC (November 11, 2013): D.3 Detection and Attribution of Climate Change, in: [http://www.climatechange2013.org/spm Summary for Policymakers (finalized version)], p.15, in: {{harvnb|IPCC AR5 WG1|2013}}
</ref>]]
[[File:2000 Year Temperature Comparison.png|thumb|right|alt=refer to caption and adjacent text|Two millennia of mean surface temperatures according to different reconstructions from [[Proxy (climate)|climate proxies]], each smoothed on a decadal scale, with the [[instrumental temperature record]] overlaid in black.]]
[[File:Enso-global-temp-anomalies.png|thumb|right|alt=refer to caption and adjacent text|[[National Oceanic and Atmospheric Administration|NOAA]] graph of global annual temperature anomalies 1950–2012, showing the [[El Niño Southern Oscillation]]]]
The global average (land and ocean) surface temperature shows a warming of 0.85 [0.65 to 1.06] °C in the period 1880 to 2012, based on multiple independently produced datasets.<ref>{{cite web|work=WGI AR5|publisher=IPCC AR5|title=Climate Change 2013: The Physical Science Basis, IPCC Fifth Assessment Report (WGI AR5)|url=http://www.climatechange2013.org/images/report/WG1AR5_ALL_FINAL.pdf|format=PDF|page=5|year=2013}}</ref> [[Global average surface temperature|Earth's average surface temperature]] rose by {{val|0.74|0.18|u=°C}} over the period 1906–2005. The rate of warming almost doubled for the last half of that period ({{val|0.13|0.03|u=°C|s= per decade}}, versus {{val|0.07|0.02|u=°C|s= per decade}}).<ref>{{cite web|url=https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch3s3-es.html|title=Climate Change 2007: Working Group I: The Physical Science Basis|year=2007|publisher=IPCC AR4}}</ref>
===The skeptics strike back===
The average temperature of the lower [[troposphere]] has increased between {{convert|0.12|and|0.135|C-change}} per decade since 1979, according to [[satellite temperature measurements]].<ref name=":1">{{cite web|url=http://vortex.nsstc.uah.edu/data/msu/v6.0/tlt/uahncdc_lt_6.0.txt|title=UAH v6.0 TLT data|last=|first=|date=|website=nsstc.uah.edu|publisher=The National Space Science & Technology Center|format=trend data at bottom of file|archive-url=|archive-date=|dead-url=|accessdate=3 February 2017}}</ref><ref name=":0">{{cite web|url=http://www.remss.com/measurements/upper-air-temperature|title=Upper Air Temperature: Decadal Trends|website=remss.com|publisher=Remote Sensing Systems|accessdate=3 February 2017}}</ref> [[Proxy (climate)|Climate proxies]] show the temperature to have been relatively stable over the [[Temperature record of the past 1000 years|one or two thousand years]] before 1850, with regionally varying fluctuations such as the [[Medieval Warm Period]] and the [[Little Ice Age]].<ref>Jansen ''et al.'', [http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch6.html Ch. 6, Palaeoclimate], [http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch6s6-6.html#6-6-1 Section 6.6.1.1: What Do Reconstructions Based on Palaeoclimatic Proxies Show?], [http://www.ipcc-wg1.unibe.ch/publications/wg1-ar4/ar4-wg1-chapter6.pdf pp. 466–478], in {{Harvnb|IPCC AR4 WG1|2007}}.</ref>
The warming that is evident in the instrumental temperature record is consistent with a wide range of observations, as documented by many independent scientific groups.<ref name="kennedy evidence for global warming">
{{Cite journal
| author=Kennedy, J.J.| year=2010
| title=How do we know the world has warmed? in: 2. Global Climate, in: State of the Climate in 2009
| url= http://www.ncdc.noaa.gov/bams-state-of-the-climate/2009.php
| journal=Bull. Amer. Meteor. Soc.
| volume=91
| issue=7
| page=26
| ref=harv
|display-authors=etal}}
</ref> Examples include [[current sea level rise|sea level rise]],<ref>
{{Cite journal
| author=Kennedy, C.
| date=10 July 2012
| title=ClimateWatch Magazine >> State of the Climate: 2011 Global Sea Level
| url=http://www.climatewatch.noaa.gov/article/2012/2011-state-of-the-climate-sea-level
| publisher=NOAA Climate Services Portal
| ref=harv
}}
</ref> widespread melting of snow and land ice,<ref>
{{Cite book
| url=http://www.ipcc.ch/publications_and_data/ar4/wg1/en/spmsspm-direct-observations.html |title=Direct Observations of Recent Climate Change
| chapter=Summary for Policymakers
| chapter-url=http://www.ipcc.ch/publications_and_data/ar4/wg1/en/spm.html
| ref=harv
}}, in {{harvnb|IPCC AR4 WG1|2007}}
</ref> increased [[Ocean heat content|heat content of the oceans]],<ref name="kennedy evidence for global warming"/> increased [[specific humidity|humidity]],<ref name="kennedy evidence for global warming"/> and the earlier [[phenology|timing]] of spring events,<ref>
{{Cite book
| url=http://www.ipcc.ch/publications_and_data/ar4/wg2/en/spmsspm-b.html|title= B. Current knowledge about observed impacts of climate change on the natural and human environment
| chapter=Summary for Policymakers
| chapter-url=http://www.ipcc.ch/publications_and_data/ar4/wg2/en/spm.html
| ref=harv
}}, in {{harvnb|IPCC AR4 WG2|2007}}
</ref> e.g., the [[flowering]] of plants.<ref>
{{Cite book
| url=http://www.ipcc.ch/publications_and_data/ar4/wg2/en/ch1s1-3-5-1.html |title=Sec 1.3.5.1 Changes in phenology
| author=Rosenzweig, C.| chapter=Ch 1: Assessment of Observed Changes and Responses in Natural and Managed Systems
| chapter-url=http://www.ipcc.ch/publications_and_data/ar4/wg2/en/ch1.html
| ref=harv
|display-authors=etal}}, in {{harvnb|IPCC AR4 WG2|2007|p=99}}
</ref> The [[probability]] that these changes could have occurred by chance is virtually zero.<ref name="kennedy evidence for global warming"/>
=== Trends ===
Temperature changes vary over the globe. Since 1979, land temperatures have increased about twice as fast as ocean temperatures ({{val|0.25|u=°C|s= per decade}} against {{val|0.13|u=°C|s= per decade}}).<ref>Trenberth ''et al.'', [http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch3.html Chap 3, Observations: Atmospheric Surface and Climate Change], [http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch3s3-es.html Executive Summary], [http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter3.pdf p. 237], in {{Harvnb|IPCC AR4 WG1|2007}}.</ref> Ocean temperatures increase more slowly than land temperatures because of the larger effective [[heat capacity]] of the oceans and because the ocean loses more heat by evaporation.<ref>{{Cite journal
|title = Land/sea warming ratio in response to climate change: IPCC AR4 model results and comparison with observations
|author1=Rowan T. Sutton |author2=Buwen Dong |author3=Jonathan M. Gregory |journal=Geophysical Research Letters|volume=34
|url = http://www.agu.org/pubs/crossref/2007/2006GL028164.shtml|doi=10.1029/2006GL028164
|issue = 2 |pages = L02701 |year=2007
|accessdate =19 September 2007
|bibcode = 2007GeoRL..3402701S
|ref = harv }}</ref> Since the [[Industrial Revolution|beginning of industrialisation]] the temperature difference between the [[Hemispheres of the Earth|hemispheres]] has increased due to melting of sea ice and snow in the North.<ref>{{cite journal|last=Feulner|first=Georg|author2=Rahmstorf, Stefan|author3=Levermann, Anders|author4=Volkwardt, Silvia |title=On the Origin of the Surface Air Temperature Difference Between the Hemispheres in Earth's Present-Day Climate|journal=Journal of Climate|date=March 2013|doi=10.1175/JCLI-D-12-00636.1|url=http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00636.1|accessdate=25 April 2013|pages=130325101629005|ref=harv|volume=26}}</ref> Average arctic temperatures have been increasing at almost twice the rate of the rest of the world in the past 100 years; however arctic temperatures are also highly variable.<ref>[http://www.ipcc.ch/publications_and_data/ar4/wg1/en/tssts-3-1-2.html TS.3.1.2 Spatial Distribution of Changes in Temperature, Circulation and Related Variables - AR4 WGI Technical Summary<!-- Bot generated title -->]</ref> Although more greenhouse gases are emitted in the Northern than Southern Hemisphere this does not contribute to the difference in warming because the major greenhouse gases persist long enough to mix between hemispheres.<ref>Ehhalt ''et al.'', [http://www.grida.no/climate/ipcc_tar/wg1/127.htm Chapter 4: Atmospheric Chemistry and Greenhouse Gases], [http://www.grida.no/climate/ipcc_tar/wg1/139.htm#4231 Section 4.2.3.1: Carbon monoxide (CO) and hydrogen (H<sub>2</sub>)], [http://www.grida.no/climate/ipcc_tar/wg1/pdf/TAR-04.pdf p. 256], in {{Harvnb|IPCC TAR WG1|2001}}.</ref>
The [[Climate inertia#Thermal inertia|thermal inertia]] of the oceans and slow responses of other indirect effects mean that climate can take centuries or longer to adjust to changes in forcing. One [[climate commitment]] study concluded that if greenhouse gases were stabilized at year 2000 levels, surface temperatures would still increase by about one-half degree Celsius,<ref>{{Cite journal
|last=Meehl|first=Gerald A.
|authorlink=Gerald Meehl
|author2=Washington, Warren M. |author3=Collins, William D. |author4=Arblaster, Julie M. |author5=Hu, Aixue |author6=Buja, Lawrence E. |author7=Strand, Warren G. |author8=Teng, Haiyan
|date = 18 March 2005
|title = How Much More Global Warming and Sea Level Rise
|journal=Science|volume=307|issue=5716
|pages =1769–1772|doi=10.1126/science.1106663
|url = http://science.sciencemag.org/content/307/5716/1769|format=PDF
|accessdate =11 February 2007|pmid=15774757| bibcode=2005Sci...307.1769M
|ref=harv
}}</ref> and another found that if they were stabilized at 2005 levels surface warming could exceed a whole degree Celsius. Some of this surface warming will be driven by past natural forcings which are still seeking [[Earth's energy budget#Climate forcings and global warming|equilibrium in the climate system]]. One study using a highly simplified climate model indicates these past natural forcings may account for as much as 64% of the committed 2050 surface warming and their influence will fade with time compared to the human contribution.<ref>{{cite web|title=The Climate Change Commitment|url=ftp://ftp.soest.hawaii.edu/coastal/Climate%20Articles/Wigley_2005%20Sea%20level%20commitment.pdf|author= T. M. L. Wigley|DOI=10.1126/science.1103934 |year= 2005 |quote= Even if atmospheric composition were fixed today, global-mean temperature and sea level rise would continue due to oceanic thermal inertia. These constant-composition (CC) commitments and their uncertainties are quantified. Constant-emissions (CE) commitments are also considered. The CC warming commitment could exceed 1C. The CE warming commitment is 2 to 6C by the year 2400." (...) "A breakdown of the natural and anthropogenic components of the CC commitment, together with uncertainties arising from ocean mixing (Kz) uncertainties, is given in table S1. Past natural forcing (inclusion of which is the default case here) has a marked effect. The natural forcing component is surprisingly large, 64% of the total commitment in 2050, reducing to 52% by 2400.}}</ref>
Global temperature is subject to short-term fluctuations that overlay long-term trends and can temporarily mask them. The relative stability in surface temperature from 2002 to 2009, which has been dubbed the [[global warming hiatus]] by the media and some scientists,<ref>{{cite journal | title=Recent intensification of wind-driven circulation in the Pacific and the ongoing warming hiatus | author=England, Matthew | journal=[[Nature Climate Change]] |date=February 2014 | doi=10.1038/nclimate2106 | volume=4 | pages=222–227|bibcode = 2014NatCC...4..222E }}</ref> is consistent with such an episode.<ref>{{Cite journal| url = http://www.metoffice.gov.uk/media/pdf/j/j/global_temperatures_09.pdf | title = Do Global Temperature Trends Over the Last Decade Falsify Climate Predictions? [in "State of the Climate in 2008"] |first=J.|last=Knight|first2=J.J.|last2=Kenney|first3=C.|last3=Folland|first4=G.|last4=Harris|first5=G.S.|last5=Jones|first6=M.|last6=Palmer|first7=D.|last7=Parker|first8=A.|last8=Scaife|first9=P.|last9=Stott |work=Bull. Amer. Meteor. Soc.|volume=90|issue=8| pages =S75–S79|date=August 2009|format=PDF|accessdate =13 August 2011| ref = harv}}</ref><ref>{{Cite book | title = Global temperature slowdown – not an end to climate change|publisher=UK Met Office| url = http://webarchive.nationalarchives.gov.uk/+/http:/www.metoffice.gov.uk/climatechange/policymakers/policy/slowdown.html|accessdate =20 March 2011}}</ref> 2015 updates to account for differing methods of measuring ocean surface temperature measurements show a positive trend over the recent decade.<ref>{{cite web|url=http://www.realclimate.org/index.php/archives/2015/06/noaa-temperature-record-updates-and-the-hiatus/|title=NOAA temperature record updates and the ‘hiatus’|date=4 June 2015|author=Gavin Schmidt}}</ref><ref>{{cite web|url=http://www.noaanews.noaa.gov/stories2015/noaa-analysis-journal-science-no-slowdown-in-global-warming-in-recent-years.html|author=NOAA|date=4 June 2015|title=Science publishes new NOAA analysis: Data show no recent slowdown in global warming}}</ref>
===Sagan and Venus===
=== Warmest years ===
Sixteen of the 17 warmest years on record have occurred since 2000.<ref>[https://www.washingtonpost.com/news/energy-environment/wp/2017/01/18/u-s-scientists-officially-declare-2016-the-hottest-year-on-record-that-makes-three-in-a-row/?utm_term=.cb42cba96765 "U.S. scientists officially declare 2016 the hottest year on record. That makes three in a row."]</ref> While record-breaking years attract considerable public interest, individual years are less significant than the overall trend. Some climatologists have criticized the attention that the popular press gives to "warmest year" statistics. In particular, ocean oscillations such as the [[El Niño Southern Oscillation]] (ENSO) can cause temperatures of a given year to be abnormally warm or cold for reasons unrelated to the overall trend of climate change. [[Gavin Schmidt]] stated "the long-term trends or the expected sequence of records are far more important than whether any single year is a record or not."<ref name="Gavin Schmidt 201501">{{cite web |last=Schmidt |first=Gavin |authorlink=Gavin Schmidt | title=Thoughts on 2014 and ongoing temperature trends | website=RealClimate | date=22 January 2015 | url=http://www.realclimate.org/index.php/archives/2015/01/thoughts-on-2014-and-ongoing-temperature-trends/ | accessdate=4 September 2015}}</ref>
== Initial causes of temperature changes (external forcings) ==
{{Main article|Attribution of recent climate change}}
{{Multiple image
| align = right
| direction = vertical
| width = 200
| image1 = Greenhouse Effect.svg
| alt1 = refer to caption and adjacent text
| caption1 = Greenhouse effect schematic showing energy flows between space, the atmosphere, and Earth's surface. Energy exchanges are expressed in watts per square metre (W/m<sup>2</sup>).
| image2 = Mauna Loa CO2 monthly mean concentration.svg
| alt2 = refer to caption and adjacent text
| caption2 = This graph, known as the [[Keeling Curve]], documents the increase of atmospheric [[carbon dioxide]] concentrations from 1958–2015. Monthly CO<sub>2</sub> measurements display seasonal oscillations in an upward trend; each year's maximum occurs during the [[Northern Hemisphere]]'s late spring, and declines during its growing season as plants remove some atmospheric CO<sub>2</sub>.
}}
The climate system can spontaneously generate changes in global temperature for years to decades at a time but long-term changes in global temperature require ''external forcings.''<ref>
{{cite web
| author=Group
| title=Forcings (filed under: Glossary)
| url=http://www.realclimate.org/index.php/archives/2004/11/forcings/
| publisher=RealClimate
| date=28 November 2004
}}
</ref><ref>
{{Cite journal
| author=Pew Center on Global Climate Change / Center for Climate and Energy Solutions
| title=Science Brief 1: The Causes of Global Climate Change
| url=http://www.c2es.org/docUploads/PewSB1-Attribution-SMALL_102606.pdf
| publisher=Center for Climate and Energy Solutions
| location=Arlington, Virginia, USA
| date=September 2006
| ref=harv
}}, p.2
</ref><ref>{{Cite journal|last=Brown|first=Patrick T.|last2=Li|first2=Wenhong|last3=Jiang|first3=Jonathan H.|last4=Su|first4=Hui|date=2015-12-07|title=Unforced Surface Air Temperature Variability and Its Contrasting Relationship with the Anomalous TOA Energy Flux at Local and Global Spatial Scales|url=http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0384.1|journal=Journal of Climate|volume=29|issue=3|pages=925–940|doi=10.1175/JCLI-D-15-0384.1|issn=0894-8755}}</ref> These forcings are "external" to the climate system but not necessarily external to Earth.<ref>
{{harvnb|US NRC|2012|p=9}}
</ref> Examples of external forcings include changes in atmospheric composition (e.g., increased concentrations of [[greenhouse gas]]es), [[solar luminosity]], [[volcano|volcanic]] eruptions, and [[orbital forcing|variations in Earth's orbit]] around the Sun.<ref name="Hegerl-2001">Hegerl ''et al.'', [http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch9.html Chapter 9: Understanding and Attributing Climate Change], [http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch9s9-4-1-5.html Section 9.4.1.5: The Influence of Other Anthropogenic and Natural Forcings], in {{Harvnb|IPCC AR4 WG1|2007|pp=690–691}}. "Recent estimates indicate a relatively small combined effect of natural forcings on the global mean temperature evolution of the second half of the 20th century, with a small net cooling from the combined effects of solar and volcanic forcings." [http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter9.pdf p. 690]</ref>
=== Greenhouse gases ===
{{Main article|Greenhouse gas|Greenhouse effect|Radiative forcing|Carbon dioxide in Earth's atmosphere|Earth's energy budget}}
{{See also|List of countries by carbon dioxide emissions|History of climate change science}}
The greenhouse effect is the process by which [[Absorption (electromagnetic radiation)|absorption]] and [[Emission spectrum|emission]] of [[infrared]] radiation by gases in a planet's [[atmosphere]] warm its lower atmosphere and surface. It was proposed by [[Joseph Fourier]] in 1824, discovered in 1860 by [[John Tyndall]],<ref>{{cite journal|last=Tyndall|first=John|title=On the Absorption and Radiation of Heat by Gases and Vapours, and on the Physical Connection of Radiation, Absorption, and Conduction|journal=Philosophical Magazine|year=1861|volume=22|series=4|pages=169–94, 273–85|url=http://rstl.royalsocietypublishing.org/content/151/1.full.pdf+html|accessdate=8 May 2013|ref=harv}}</ref> was first investigated quantitatively by [[Svante Arrhenius]] in 1896,<ref>{{cite web
|title = The Carbon Dioxide Greenhouse Effect
|work=The Discovery of Global Warming
|url = http://history.aip.org/climate/co2.htm|accessdate =21 April 2009|year=2008
|publisher=American Institute of Physics
|first=Spencer|last=Weart | authorlink=Spencer R. Weart
}}</ref> and was developed in the 1930s through 1960s by [[Guy Stewart Callendar]].<ref>The Callendar Effect: the life and work of Guy Stewart Callendar (1898–1964) Amer Meteor Soc., Boston. ISBN 978-1-878220-76-9</ref>
{{Multiple image
| direction=vertical
| align=left
| image1=Annual greenhouse gas emissions by sector, in 2010 (color) png.png
| alt1=refer to caption and image description
| image2= Percentage share of global cumulative energy-related carbon dioxide emissions between 1751 and 2012 across different regions.svg
| alt2=refer to caption and image description
| width=220
| caption1=Annual world greenhouse gas emissions, in 2010, by sector.
| caption2= Percentage share of global cumulative energy-related {{CO2}} emissions between 1751 and 2012 across different regions.
}}
On Earth, naturally occurring amounts of greenhouse gases cause air temperature near the surface to be about {{convert|33|C-change|0}} warmer than it would be in their absence.<ref>{{Cite book
|author=Le Treut
|chapter-url= http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch1.html
|chapter= Chapter 1: Historical Overview of Climate Change Science
|url= http://www.ipcc.ch/publications_and_data/ar4/wg1/en/faq-1-2.html |title=FAQ 1.1
|ref=harv
|display-authors=etal}}, [http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter1.pdf p. 97], in {{Harvnb|IPCC AR4 WG1|2007}}: "To emit 240 W m–2, a surface would have to have a temperature of around −19 °C. This is much colder than the conditions that actually exist at the Earth's surface (the global mean surface temperature is about 14 °C). Instead, the necessary −19 °C is found at an altitude about 5 km above the surface."</ref>{{efn|The greenhouse effect produces an average worldwide temperature ''increase'' of about {{convert|33|C-change|0}} compared to [[black body]] predictions without the greenhouse effect, not an average ''surface temperature'' of {{convert|33|°C|0}}. The average worldwide surface temperature is about {{convert|14|°C|0}}.}} Without the Earth's atmosphere, the Earth's average temperature would be well below the freezing temperature of water.<ref name=Blue>{{cite news|last=Blue|first=Jessica|title=What is the Natural Greenhouse Effect?|url=http://education.nationalgeographic.org/encyclopedia/greenhouse-effect/|accessdate=1 Jan 2015|newspaper=[[National Geographic (magazine)|National Geographic]]}}</ref> The major greenhouse gases are [[water vapor|water vapour]], which causes about 36–70% of the greenhouse effect; [[carbon dioxide]] (CO<sub>2</sub>), which causes 9–26%; [[methane]] (CH<sub>4</sub>), which causes 4–9%; and [[ozone]] (O<sub>3</sub>), which causes 3–7%.<ref>{{Cite journal| url = http://www.atmo.arizona.edu/students/courselinks/spring04/atmo451b/pdf/RadiationBudget.pdf| archiveurl = https://web.archive.org/web/20080624223905/http://www.atmo.arizona.edu/students/courselinks/spring04/atmo451b/pdf/RadiationBudget.pdf| archivedate = 24 June 2008 | title = Earth's Annual Global Mean Energy Budget|first=J.T. | last=Kiehl | first2=K.E. | last2=Trenberth | authorlink2=Kevin Trenberth |format=PDF|journal=Bulletin of the American Meteorological Society| pages =197–208|volume=78|issue=2|year=1997|accessdate =21 April 2009|doi=10.1175/1520-0477(1997)078<0197:EAGMEB>2.0.CO;2 | bibcode=1997BAMS...78..197K| issn = 1520-0477| ref = harv}}</ref><ref>{{cite web| url = http://www.realclimate.org/index.php?p=142|date=6 April 2005 | title = Water vapour: feedback or forcing?|first=Gavin | last=Schmidt | authorlink=Gavin Schmidt |publisher=[[RealClimate]]|accessdate =21 April 2009}}</ref><ref>
{{cite web | first=Randy | last=Russell | publisher=[[University Corporation for Atmospheric Research]] Windows to the Universe | url = http://www.windows.ucar.edu/tour/link=/earth/climate/greenhouse_effect_gases.html&edu=high | title = The Greenhouse Effect & Greenhouse Gases | date=16 May 2007 | accessdate=27 December 2009}}</ref> Clouds also affect the radiation balance through [[cloud forcing]]s similar to greenhouse gases.
Human activity since the Industrial Revolution has increased the amount of greenhouse gases in the atmosphere, leading to increased radiative forcing from CO<sub>2</sub>, methane, [[tropospheric ozone]], [[Chlorofluorocarbon|CFCs]] and [[nitrous oxide]]. According to work published in 2007, the [[Greenhouse gas#Anthropogenic greenhouse gases|concentrations]] of CO<sub>2</sub> and methane had increased by 36% and 148% respectively since 1750.<ref>{{Cite web |url=http://www.epa.gov/climatechange/science/recentac.html |title=Recent Climate Change: Atmosphere Changes |last=EPA |year=2007 |website=Climate Change Science Program |publisher=United States Environmental Protection Agency |archive-url=https://web.archive.org/web/20090510053004/http://www.epa.gov/climatechange/science/recentac.html |archive-date=10 May 2009 |dead-url=yes |access-date=21 April 2009}}</ref> These levels are much higher than at any time during the last 800,000 years, the period for which reliable data has been extracted from [[ice core]]s.<ref>{{Cite journal|last=Spahni|first=Renato|author2=Jérôme Chappellaz |author3=Thomas F. Stocker |author4=Laetitia Loulergue |author5=Gregor Hausammann |author6=Kenji Kawamura |author7=Jacqueline Flückiger |author8=Jakob Schwander |author9=Dominique Raynaud |author10=Valérie Masson-Delmotte |author11=Jean Jouzel|date = November 2005| title = Atmospheric Methane and Nitrous Oxide of the Late Pleistocene from Antarctic Ice Cores|journal=Science|volume=310|issue=5752| pages =1317–1321|doi=10.1126/science.1120132|pmid=16311333|bibcode = 2005Sci...310.1317S|ref=harv}}</ref><ref>{{Cite journal|author=Siegenthaler, Urs|date = November 2005| title = Stable Carbon Cycle–Climate Relationship During the Late Pleistocene|journal=Science|volume=310|issue=5752| pages =1313–1317| url = http://www.sciencemag.org/cgi/content/abstract/310/5752/1313|format=PDF|doi=10.1126/science.1120130|accessdate =25 August 2010|pmid=16311332|bibcode = 2005Sci...310.1313S|ref=harv
|display-authors=etal}}</ref><ref>{{Cite journal|author=Petit, J. R.
|date=3 June 1999
|title = Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica
|journal=Nature|volume=399|issue=6735| pages =429–436
|url = http://www.daycreek.com/dc/images/1999.pdf|format=PDF
|accessdate =27 December 2009|doi=10.1038/20859|bibcode = 1999Natur.399..429P|ref=harv
|display-authors=etal}}</ref><ref>{{Cite journal | last1 = Lüthi | first1 = D. | last2 = Le Floch | first2 = M. | last3 = Bereiter | first3 = B. | last4 = Blunier | first4 = T. | last5 = Barnola | first5 = J. M. | last6 = Siegenthaler | first6 = U. | last7 = Raynaud | first7 = D. | last8 = Jouzel | first8 = J. | last9 = Fischer | first9 = H. | last10 = Kawamura | first10 = K. | last11 = Stocker | first11 = T. F. | doi = 10.1038/nature06949 | title = High-resolution carbon dioxide concentration record 650,000–800,000 years before present | journal = Nature | volume = 453 | issue = 7193 | pages = 379–382 | year = 2008 | pmid = 18480821|bibcode = 2008Natur.453..379L }}</ref> Less direct geological evidence indicates that CO<sub>2</sub> values higher than this were last seen about 20 million years ago.<ref>{{Cite journal|journal=Nature | title = Atmospheric carbon dioxide concentrations over the past 60 million years|year=2000|volume=406|issue=6797| pages =695–699|doi=10.1038/35021000|pmid=10963587|last1=Pearson|first1=PN|last2=Palmer|first2=MR|ref=harv
}}</ref>
[[Fossil fuel]] burning has produced about three-quarters of the increase in CO<sub>2</sub> from human activity over the past 20 years. The rest of this increase is caused mostly by changes in land-use, [[deforestation and climate change|particularly deforestation]].<ref>IPCC, [http://www.grida.no/climate/ipcc_tar/wg1/005.htm Summary for Policymakers], [http://www.grida.no/climate/ipcc_tar/wg1/006.htm Concentrations of atmospheric greenhouse gases ...], [http://www.grida.no/climate/ipcc_tar/wg1/pdf/WG1_TAR-FRONT.pdf p. 7], in {{Harvnb|IPCC TAR WG1|2001}}.</ref> Another significant non-fuel source of anthropogenic CO<sub>2</sub> emissions is the [[calcination]] of [[limestone]] for [[clinker (cement)|clinker]] production, a chemical process which releases CO<sub>2</sub>.<ref>IPCC (2007) AR4. Climate Change 2007: Working Group III: Mitigation of Climate Change, section 7.4.5.1. https://www.ipcc.ch/publications_and_data/ar4/wg3/en/ch7s7-4-5.html</ref> Estimates of global CO<sub>2</sub> emissions in 2011 from fossil fuel combustion, including cement production and [[gas flaring]], was 34.8 billion tonnes (9.5 ± 0.5 PgC), an increase of 54% above emissions in 1990. Coal burning was responsible for 43% of the total emissions, oil 34%, gas 18%, cement 4.9% and gas flaring 0.7%<ref>{{cite journal|author1=Le Quéré, C.;|author2=Andres, R.J.|author3=Boden, T.|author4=Conway, T.|author5=Houghton, R.A.|author6=House, J.I.|author7=Marland, G.|author8=Peters, G.P.|author9=van der Werf, G.|author10=Ahlström, A.|author11=Andrew, R.M.|author12=Bopp, L.|author13=Canadell, J.G.|author14=Ciais, P.|author15=Doney, S.C.|author16=Enright, C.|author17=Friedlingstein, P.|author18=Huntingford, C.|author19=Jain, A.K.|author20=Jourdain, C.|author21=Kato, E.|author22=Keeling, R.F.|author23=Klein Goldewijk, K.|author24=Levis, S.|author25=Levy, P.|author26=Lomas, M.|author27=Poulter, B.|author28=Raupach, M.R.|author29=Schwinger, J.|author30=Sitch, S.|author31=Stocker, B.D.|author32=Viovy, N.|author33=Zaehle, S.|author34=Zeng, N.|title=The global carbon budget 1959–2011|journal=Earth System Science Data Discussions|date=2 December 2012|volume=5|issue=2|pages=1107–1157|doi=10.5194/essdd-5-1107-2012|ref=harv|bibcode = 2012ESSDD...5.1107L }}</ref>
[[File:Evidence CO2.jpg|thumb|alt=refer to caption and body text|Atmospheric CO<sub>2</sub> concentration from 650,000 years ago to near present, using ice core proxy data and direct measurements.]]
In May 2013, it was reported that readings for CO<sub>2</sub> taken at the world's primary benchmark site in [[Mauna Loa Observatory|Mauna Loa]] surpassed 400 [[Parts per million|ppm]]. According to professor [[Brian Hoskins]], this is likely the first time CO<sub>2</sub> levels have been this high for about 4.5 million years.<ref>
{{cite news
|url= http://www.bbc.co.uk/news/science-environment-22486153
|title= Carbon dioxide passes symbolic mark
|publisher= [[BBC]]
|date = 10 May 2013
|accessdate= 27 May 2013
}}
</ref><ref>{{Cite news
|url= http://www.ft.com/cms/s/0/e00ba374-b9a4-11e2-bc57-00144feabdc0.html
|title= CO<sub>2</sub> at highest level for millions of years
|work= [[Financial Times]]
|author= Pilita Clark
|date = 10 May 2013
|accessdate= 27 May 2013
|registration=yes}}</ref> Monthly global CO<sub>2</sub> concentrations exceeded 400 ppm in March 2015, probably for the first time in several million years.<ref>{{Cite web|url = http://www.nature.com/news/climate-scientists-discuss-future-of-their-field-1.17917|title = Climate scientists discuss future of their field|date = 7 July 2015|website = }}</ref> On 12 November 2015, [[NASA|NASA scientists]] reported that human-made carbon dioxide [[Carbon dioxide in Earth's atmosphere|continues to increase]] above levels not seen in hundreds of thousands of years: currently, about half of the carbon dioxide released from the burning of fossil fuels is not absorbed by vegetation and the oceans and remains in the atmosphere.<ref name="NASA-20151112-ab">{{cite web |last1=Buis |first1=Alan |last2=Ramsayer |first2=Kate |last3=Rasmussen |first3=Carol |title=A Breathing Planet, Off Balance |url=http://www.jpl.nasa.gov/news/news.php?feature=4769 |date=12 November 2015 |work=[[NASA]] |accessdate=13 November 2015 }}</ref>
Over the last three decades of the twentieth century, [[gross domestic product]] per capita and [[population growth]] were the main drivers of increases in greenhouse gas emissions.<ref>Rogner, H.-H., ''et al''., [http://www.ipcc.ch/publications_and_data/ar4/wg3/en/ch1.html Chap. 1, Introduction], [http://www.ipcc.ch/publications_and_data/ar4/wg3/en/ch1s1-3-1-2.html Section 1.3.1.2: Intensities], in {{Harvnb|IPCC AR4 WG3|2007}}.</ref> CO<sub>2</sub> emissions are continuing to rise due to the burning of fossil fuels and land-use change.<ref name=nrc2008/><ref name=worldbank2010>{{cite book
{{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 [http://www.weeklystandard.com/climategate-part-ii/article/610926 this link].</ref>}}
| year = 2010
| author=World Bank
| title = World Development Report 2010: Development and Climate Change
| publisher=The International Bank for Reconstruction and Development / The World Bank, 1818 H Street NW, Washington, D.C. 20433
| url = http://econ.worldbank.org/WBSITE/EXTERNAL/EXTDEC/EXTRESEARCH/EXTWDRS/EXTWDR2010/0,,contentMDK:21969137~menuPK:5287816~pagePK:64167689~piPK:64167673~theSitePK:5287741,00.html
| isbn = 978-0-8213-7987-5
| doi=10.1596/978-0-8213-7987-5
| accessdate =6 April 2010
| archiveurl =https://web.archive.org/web/20100305081236/http://econ.worldbank.org/WBSITE/EXTERNAL/EXTDEC/EXTRESEARCH/EXTWDRS/EXTWDR2010/0,,contentMDK:21969137~menuPK:5287816~pagePK:64167689~piPK:64167673~theSitePK:5287741,00.html <!--Added by H3llBot-->
| archivedate =5 March 2010}}</ref>{{Rp|71|date=November 2012}} Emissions can be [[greenhouse gas#Regional and national attribution of emissions|attributed to different regions]]. Attributions of emissions due to land-use change are subject to considerable uncertainty.<ref>Banuri ''et al.'', Chapter 3: Equity and Social Considerations, Section 3.3.3: Patterns of greenhouse gas emissions, and Box 3.1, [http://www.ipcc.ch/ipccreports/sar/wg_III/ipcc_sar_wg_III_full_report.pdf pp. 92–93] in {{Harvnb|IPCC SAR WG3|1996}}.</ref><ref name=liverman/>{{Rp|289|date=November 2012}}
[[climate change scenario#Emissions scenarios|Emissions scenarios]], estimates of changes in future emission levels of greenhouse gases, have been projected that depend upon uncertain economic, [[sociology|sociological]], [[technology|technological]], and natural developments.<ref>Fisher ''et al''., [http://www.ipcc.ch/publications_and_data/ar4/wg3/en/ch3.html Chapter 3: Issues related to mitigation in the long-term context], [http://www.ipcc.ch/publications_and_data/ar4/wg3/en/ch3s3-1.html Section 3.1: Emissions scenarios: Issues related to mitigation in the long term context] in {{Harvnb|IPCC AR4 WG3|2007}}.</ref> In most scenarios, emissions continue to rise over the century, while in a few, emissions are reduced.<ref>Morita, [http://www.grida.no/climate/ipcc_tar/wg3/068.htm Chapter 2: Greenhouse Gas Emission Mitigation Scenarios and Implications], [http://www.grida.no/climate/ipcc_tar/wg3/081.htm#2514 Section 2.5.1.4: Emissions and Other Results of the SRES Scenarios], in {{Harvnb|IPCC TAR WG3|2001}}.</ref><ref>Rogner ''et al''., [http://www.ipcc.ch/publications_and_data/ar4/wg3/en/ch1.html Ch. 1: Introduction], [http://www.ipcc.ch/publications_and_data/ar4/wg3/en/ch1s1-3-2-2.html Figure 1.7], in {{Harvnb|IPCC AR4 WG3|2007}}.</ref> Fossil fuel reserves are abundant, and will not limit carbon emissions in the 21st century.<ref>IPCC, [http://www.grida.no/climate/ipcc_tar/wg3/003.htm Summary for Policymakers], [http://www.grida.no/climate/ipcc_tar/wg3/004.htm Introduction, paragraph 6], in {{Harvnb|IPCC TAR WG3|2001}}.</ref>
Emission scenarios, combined with modelling of the [[carbon cycle]], have been used to produce estimates of how atmospheric concentrations of greenhouse gases might change in the future. Using the six IPCC [[Special Report on Emissions Scenarios|SRES]] "marker" scenarios, models suggest that by the year 2100, the atmospheric concentration of CO<sub>2</sub> could range between 541 and 970 ppm.<ref>Prentence ''et al.'', [http://www.grida.no/climate/ipcc_tar/wg1/095.htm Chapter 3: The Carbon Cycle and Atmospheric Carbon Dioxide] [http://www.grida.no/climate/ipcc_tar/wg1/096.htm Executive Summary], in {{Harvnb|IPCC TAR WG1|2001}}.</ref> This is 90–250% above the concentration in the year 1750.
The popular media and the public often confuse global warming with [[ozone depletion]], i.e., the destruction of [[ozone layer|stratospheric ozone (e.g., the ozone layer)]] by [[chlorofluorocarbons]].<ref>Newell, P.J., 2000: '' Climate for change: non-state actors and the global politics of greenhouse.'' Cambridge University Press, ISBN 0-521-63250-1.</ref><ref>{{cite web|author=Talk of the Nation |url=http://www.npr.org/2010/12/03/131785444/Americans-Fail-The-Climate-Quiz |title=Americans Fail the Climate Quiz |publisher=NPR |accessdate=27 December 2011}}</ref> Although there are a few [[Ozone depletion#Ozone depletion and global warming|areas of linkage]], the relationship between the two is not strong. Reduced stratospheric ozone has had a slight cooling influence on surface temperatures, while increased tropospheric ozone has had a somewhat larger warming effect.<ref>{{Cite journal|doi=10.1029/2005JD006348 | title = Role of tropospheric ozone increases in 20th-century climate change|year=2006|author=Shindell, Drew|journal=[[Journal of Geophysical Research]]|volume=111|issue=D8| pages =D08302|last2=Faluvegi|first2=Greg|last3=Lacis|first3=Andrew|last4=Hansen|first4=James|last5=Ruedy|first5=Reto|last6=Aguilar|first6=Elliot|bibcode=2006JGRD..11108302S|ref=harv}}</ref>
=== Aerosols and soot ===
[[File:ShipTracks MODIS 2005may11.jpg|left|thumb|alt=Refer to caption|[[Ship tracks]] can be seen as lines in these clouds over the Atlantic Ocean on the east coast of the United States. Atmospheric particles from these and other sources could have a large effect on climate through the aerosol indirect effect.]]
===Climategate===
[[Global dimming]], a gradual reduction in the amount of global direct [[irradiance]] at the Earth's surface, was observed from 1961 until at least 1990.<ref>{{Cite book
| isbn = 978-0-521-88009-1
| title = Climate Change 2007: Working Group I: The Physical Science Basis
| year = 2007
| editor-last = Solomon
| editor-first = S
| editor2 = D. Qin
| editor3 = M. Manning
| editor4 = Z. Chen
| editor5 = M. Marquis
| editor6 = K.B. Averyt
| editor7 = M. Tignor
| editor8 = H.L. Miller
| chapter = 3.4.4.2 Surface Radiation
| chapterurl = http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch3s3-4-4-2.html
}}</ref> [[Particulates#Climate effects|Solid and liquid particles]] known as ''aerosols'', produced by volcanoes and human-made [[pollutant]]s, are thought to be the main cause of this dimming. They exert a cooling effect by increasing the reflection of incoming sunlight. The effects of the products of fossil fuel combustion – CO<sub>2</sub> and aerosols – have partially offset one another in recent decades, so that net warming has been due to the increase in non-CO<sub>2</sub> greenhouse gases such as methane.<ref name="pmid10944197">
{{Cite journal
|title = Global warming in the twenty-first century: an alternative scenario
|journal=Proc. Natl. Acad. Sci. U.S.A.
|volume=97 |issue=18 |pages= 9875–80
|year= 2000
|last1=Hansen |first1=J
|last2=Sato |first2=M
|last3=Ruedy |first3=R
|last4=Lacis |first4=A
|last5=Oinas |first5=V
|doi=10.1073/pnas.170278997|pmid=10944197
|pmc=27611|bibcode=2000PNAS...97.9875H
|ref = harv
}}</ref> Radiative forcing due to aerosols is temporally limited due to the processes that remove aerosols from the atmosphere. [[Wet deposition|Removal by clouds and precipitation]] gives tropospheric aerosols an [[atmospheric lifetime]] of only about a week, while [[stratosphere|stratospheric]] aerosols can remain for a few years. Carbon dioxide has a lifetime of a century or more, and as such, changes in aerosols will only delay climate changes due to carbon dioxide.<ref>
{{cite journal
|last1=Ramanathan |first1=V.
|last2=Carmichael |first2=G.
|title = Global and regional climate changes due to black carbon
|journal=Nature Geoscience
|volume=1 |issue=4 | pages =221–227
|year=2008
|doi=10.1038/ngeo156|bibcode = 2008NatGe...1..221R
|ref=harv
}}</ref> [[Black carbon]] is second only to carbon dioxide for its contribution to global warming.<ref>V. Ramanathan and G. Carmichael, ''supra'' note 1, at 221 (". . . emissions of black carbon are the second strongest contribution to current global warming, after carbon dioxide emissions.") Numerous scientists also calculate that black carbon may be second only to CO<sub>2</sub> in its contribution to climate change, including Tami C. Bond & Haolin Sun, ''Can Reducing Black Carbon Emissions Counteract Global Warming'', ENVIRON. SCI. TECHN. (2005), at 5921 ("BC is the second or third largest individual warming agent, following carbon dioxide and methane."); ''and'' J. Hansen, ''A Brighter Future'', 53 CLIMATE CHANGE 435 (2002), ''available at'' http://pubs.giss.nasa.gov/docs/2002/2002_Hansen_1.pdf (calculating the climate forcing of BC at 1.0±0.5 W/m<sup>2</sup>).</ref>
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>
In addition to their direct effect by scattering and absorbing solar radiation, aerosols have indirect effects on the [[Earth's energy budget|Earth's radiation budget]]. Sulfate aerosols act as [[cloud condensation nuclei]] and thus lead to clouds that have more and smaller cloud droplets. These clouds reflect solar radiation more efficiently than clouds with fewer and larger droplets, a phenomenon known as the [[Twomey effect]].<ref>
{{Cite journal
|author=Twomey, S.|year= 1977
|title = Influence of pollution on shortwave albedo of clouds
|journal=J. Atmos. Sci.|volume=34 |issue=7 |pages= 1149–1152
|doi=10.1175/1520-0469(1977)034<1149:TIOPOT>2.0.CO;2
|bibcode=1977JAtS...34.1149T |issn= 1520-0469
|ref=harv
}}</ref> This effect also causes droplets to be of more uniform size, which reduces [[Cloud physics#Collision-coalescence|growth of raindrops]] and makes the cloud more reflective to incoming sunlight, known as the [[Albrecht effect]].<ref>
{{Cite journal
|author= Albrecht, B.
|year=1989
|title = Aerosols, cloud microphysics, and fractional cloudiness
|journal=Science |volume=245 |issue=4923 |pages =1227–1239
|doi=10.1126/science.245.4923.1227
|pmid=17747885 |bibcode=1989Sci...245.1227A
|ref= harv
}}</ref> Indirect effects are most noticeable in marine stratiform clouds, and have very little radiative effect on convective clouds. Indirect effects of aerosols represent the largest uncertainty in radiative forcing.<ref>IPCC, "[http://www.ipcc.ch/ipccreports/tar/wg1/pdf/TAR-05.PDF Aerosols, their Direct and Indirect Effects]", pp. 291–292 in {{Harvnb|IPCC TAR WG1|2001}}.</ref>
[[Soot]] may either cool or warm Earth's [[climate|climate system]], depending on whether it is airborne or deposited. Atmospheric soot directly absorbs solar radiation, which heats the atmosphere and cools the surface. In isolated areas with high soot production, such as rural India, as much as 50% of surface warming due to greenhouse gases may be masked by [[atmospheric brown cloud]]s.<ref>{{Cite journal
| doi = 10.1073/pnas.0500656102
| pmid = 15749818
| last1 = Ramanathan | first1 = V.
| last2 = Chung | first2 = C.
| last3 = Kim | first3 = D.
| last4 = Bettge | first4 = T.
| last5 = Buja | first5 = L.
| last6 = Kiehl | first6 = J. T.
| last7 = Washington | first7 = W. M.
| last8 = Fu | first8 = Q.
| last9 = Sikka | first9 = D. R.
| last10 = Wild | first10 = M.
| title = Atmospheric brown clouds: Impacts on South Asian climate and hydrological cycle
| year = 2005
| journal = Proceedings of the National Academy of Sciences
| volume = 102
| pages = 5326–5333
| url = http://www.pnas.org/content/102/15/5326.full
| format = Full free text
| issue = 15
| pmc = 552786
|bibcode = 2005PNAS..102.5326R }}</ref> When deposited, especially on glaciers or on ice in arctic regions, the lower surface [[albedo]] can also directly heat the surface.<ref>
{{cite web
|author= Ramanathan, V.|title = Report Summary
|year= 2008
|work= Atmospheric Brown Clouds: Regional Assessment Report with Focus on Asia
|publisher= United Nations Environment Programme
|url= http://www.rrcap.unep.org/abc/impact/files/ABC_Report_Summary_Final.pdf |format=PDF
|display-authors=etal}}</ref> The influences of atmospheric particles, including black carbon, are most pronounced in the tropics and sub-tropics, particularly in Asia, while the effects of greenhouse gases are dominant in the extratropics and southern hemisphere.<ref>
{{cite web
|author= Ramanathan, V.|title= Part III: Global and Future Implications
|year= 2008
|work= Atmospheric Brown Clouds: Regional Assessment Report with Focus on Asia
|publisher= United Nations Environment Programme
|url= http://www.rrcap.unep.org/abc/publication/Part%20III.pdf |format=PDF
|display-authors=etal}}</ref>
[[File:Changes in total solar irradiance and monthly sunspot numbers, 1975-2013.png|thumb|alt=Refer to caption and adjacent text|Changes in [[total solar irradiance]] (TSI) and monthly [[sunspot]] numbers since the mid-1970s.]]
[[File:Radiative-forcings.svg|thumb|alt=Refer to caption|Contribution of natural factors and human activities to [[radiative forcing]] of climate change.<ref name="ipcc radiative forcing">IPCC, [http://www.ipcc.ch/publications_and_data/ar4/wg1/en/spm.html Summary for Policymakers], [http://www.ipcc.ch/publications_and_data/ar4/wg1/en/spmsspm-human-and.html Human and Natural Drivers of Climate Change], Figure SPM.2, in {{Harvnb|IPCC AR4 WG1|2007}}.
</ref> Radiative forcing values are for the year 2005, relative to the pre-industrial era (1750).<ref name="ipcc radiative forcing"/> The contribution of solar irradiance to radiative forcing is 5% the value of the combined radiative forcing due to increases in the atmospheric concentrations of carbon dioxide, [[Atmospheric methane|methane]] and nitrous oxide.<ref name="epa solar activity">{{cite book
| year=2009
| contribution=3.2.2 Solar Irradiance
| title=Volume 3: Attribution of Observed Climate Change
| series=Endangerment and Cause or Contribute Findings for Greenhouse Gases under Section 202(a) of the Clean Air Act. EPA's Response to Public Comments
| publisher= US Environmental Protection Agency
| author=US Environmental Protection Agency
| url=http://www.epa.gov/climatechange/endangerment/comments/volume3.html#2-2
| accessdate=June 23, 2011| archiveurl= https://web.archive.org/web/20110616210216/http://www.epa.gov/climatechange/endangerment/comments/volume3.html| archivedate=16 June 2011 | deadurl= no}}
</ref>]]
==The temperature record==
=== Solar activity ===
<!-- [[Sun global warming]] redirects here -->
{{Main article|Solar activity and climate}}
Since 1978, [[solar variation|solar irradiance]] has been measured by [[satellite]]s.<ref>
{{harvnb|US NRC|2008|p=6}}
</ref> These measurements indicate that the Sun's radiative output has not increased during that time, so the warming during the past 40 years cannot be attributed to an increase in solar energy reaching the Earth.
Climate models have been used to examine the role of the Sun in recent climate change.<ref>Hegerl, ''et al''., [http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch9.html Chapter 9: Understanding and Attributing Climate Change], [http://www.ipcc.ch/publications_and_data/ar4/wg1/en/faq-9-2.html Frequently Asked Question 9.2: Can the Warming of the 20th century be Explained by Natural Variability?], in {{Harvnb|IPCC AR4 WG1|2007}}.
</ref> Models are unable to reproduce the rapid warming observed in recent decades when they only take into account variations in solar output and volcanic activity. Models are, however, able to simulate the observed 20th century changes in temperature when they include all of the most important external forcings, including human influences and natural forcings.
Another line of evidence is differing temperature changes at different levels in the Earth's atmosphere.<ref>{{cite web
|date=November 2009
|author1=Simmon, R. |author2=D. Herring
| title=Notes for slide number 7, titled "Satellite evidence also suggests greenhouse gas warming," in presentation, "Human contributions to global climate change"
| url=http://www.climate.gov/#understandingClimate/presentationLibrary
| publisher=Presentation library on the U.S. National Oceanic and Atmospheric Administration's Climate Services website
| accessdate=23 June 2011| archiveurl= https://web.archive.org/web/20110703210729/http://www.climate.gov/| archivedate= 3 July 2011 | deadurl= no}}
</ref> Basic physical principles require that the greenhouse effect produces warming of the lower atmosphere (the troposphere) but cooling of the upper atmosphere (the stratosphere).<ref>Hegerl ''et al.'', [http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch9.html Chapter 9: Understanding and Attributing Climate Change], [http://www.ipcc.ch/publications_and_data/ar4/wg1/en/faq-9-2.html Frequently Asked Question 9.2: Can the Warming of the 20th century be Explained by Natural Variability?], in {{Harvnb|IPCC AR4 WG1|2007}}. <!-- Hegerl -->
</ref><ref name=Randel2009>{{Cite journal|doi=10.1029/2008JD010421 | title = An update of observed stratospheric temperature trends|year=2009|author=Randel, William J.|journal=Journal of Geophysical Research|volume=114|issue=D2| pages =D02107|last2=Shine|first2=Keith P.|authorlink2=Keith Shine|last3=Austin|first3=John|last4=Barnett|first4=John|last5=Claud|first5=Chantal|last6=Gillett|first6=Nathan P.|last7=Keckhut|first7=Philippe|last8=Langematz|first8=Ulrike|last9=Lin|first9=Roger|displayauthors=3|bibcode=2009JGRD..11402107R|ref=harv}}
</ref> Depletion of the ozone layer by chemical [[refrigerant]]s has also resulted in a strong cooling effect in the stratosphere. If solar variations were responsible for observed warming, warming of both the troposphere and stratosphere would be expected.<ref>{{Harvnb|USGCRP|2009|p=20}}
</ref>
==Summary of arguments against anthropogenic global warming==
===Variations in Earth's orbit===
{{Main article|Milankovitch cycles}}
The tilt of the Earth’s axis and the shape of its orbit around the Sun vary slowly over tens of thousands of years. This changes climate by changing the seasonal and latitudinal distribution of incoming [[insolation|solar energy]] at Earth's surface.<ref>{{Cite book
|isbn=3-540-42402-4
|title=Paleoclimate, global change and the future
|year=2003
|publisher=Springer
|editor1=K.D. Alverson
|editor2=R.S. Bradley
|editor3=T.F. Pederson
|chapter=The climate of the last millennium
|author1=R.S. Bradley
|author2=K.R. Briffa
|author3=J. Cole
|author4=M.K. Hughes
|author5=T.J. Osborn
|pages=105–141}}</ref>
During the last few thousand years, this phenomenon contributed to a slow cooling trend at high latitudes of the Northern Hemisphere during summer, a trend that was reversed by greenhouse-gas-induced warming during the 20th century.<ref>{{Cite journal
|last1 = Kaufman | first1 = D. S.| last2 = Schneider | first2 = D. P.| last3 = McKay | first3 = N. P.| last4 = Ammann | first4 = C. M.| last5 = Bradley | first5 = R. S.| last6 = Briffa | first6 = K. R.| last7 = Miller | first7 = G. H.| last8 = Otto-Bliesner | first8 = B. L.| last9 = Overpeck | first9 = J. T.| last10 = Vinther | first10 = B. M.| author32 = Arctic Lakes 2k Project Members| last11 = Abbott | first11 = M.| last12 = Axford | first12 = M.| last13 = Bird | first13 = Y.| last14 = Birks | first14 = B.| last15 = Bjune | first15 = H. J. B.| last16 = Briner | first16 = A. E.| last17 = Cook | first17 = J.| last18 = Chipman | first18 = T.| last19 = Francus | first19 = M.| last20 = Gajewski | first20 = P.| last21 = Geirsdottir | first21 = K.| last22 = Hu | first22 = A.| last23 = Kutchko | first23 = F. S.| last24 = Lamoureux | first24 = B.| last25 = Loso | first25 = S.| last26 = MacDonald | first26 = M.| last27 = Peros | first27 = G.| last28 = Porinchu | first28 = M.| last29 = Schiff | first29 = D.| last30 = Seppa | first30 = C.| last31 = Seppa | first31 = H.| title = Recent Warming Reverses Long-Term Arctic Cooling| doi = 10.1126/science.1173983| journal = Science| volume = 325| issue = 5945| pages = 1236–1239| year = 2009| pmid = 19729653|bibcode = 2009Sci...325.1236K }}</ref><ref>{{cite web | title = Arctic Warming Overtakes 2,000 Years of Natural Cooling | url = http://www2.ucar.edu/news/846/arctic-warming-overtakes-2000-years-natural-cooling | publisher=UCAR | date =3 September 2009 | accessdate =8 June 2011}}</ref><ref>{{Cite news | last =Bello | first = David | title = Global Warming Reverses Long-Term Arctic Cooling | url = http://www.scientificamerican.com/article.cfm?id=global-warming-reverses-arctic-cooling | work=Scientific American | date = 4 September 2009 | accessdate =8 June 2011}}</ref><ref>{{Cite journal | last1 = Mann | first1 = M. E. | last2 = Zhang | first2 = Z. | last3 = Hughes | first3 = M. K. | last4 = Bradley | first4 = R. S. | last5 = Miller | first5 = S. K. | last6 = Rutherford | first6 = S. | last7 = Ni | first7 = F. | doi = 10.1073/pnas.0805721105 | title = Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia | journal = Proceedings of the National Academy of Sciences | volume = 105 | issue = 36 | pages = 13252–7 | year = 2008 | pmid = 18765811| pmc = 2527990|bibcode = 2008PNAS..10513252M }}</ref> Orbital cycles favorable for glaciation are not expected within the next 50,000 years.<ref>{{Cite journal | doi = 10.1126/science.1076120| title = CLIMATE: An Exceptionally Long Interglacial Ahead?| journal = Science| volume = 297| issue = 5585| pages = 1287–8| year = 2002| last1 = Berger | first1 = A.| pmid=12193773}}</ref><ref>{{Cite book
|isbn=978-1-107-66182-0
|title=Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change
|year=2013
|publisher=Cambridge University Press
|editors=Stocker T.F. |display-editors=etal
|chapter=Information from paleoclimate archives
|author=Masson-Delmotte V.M.
|pages=383–464
|display-authors=etal}}</ref>
== Feedback ==
{{Main article|Climate change feedback|Climate sensitivity}}
[[File:Aerial view of the edge of the ice in Nunavut 2.jpg|thumb|left|Sea ice, shown here in [[Nunavut]], in northern Canada, reflects more sunshine, while open ocean absorbs more, accelerating melting.]]
The climate system includes a range of ''[[feedback]]s'', which alter the response of the system to changes in external forcings. Positive feedbacks increase the response of the climate system to an initial forcing, while negative feedbacks reduce it.<ref name="jackson feedbacks">
{{Cite journal
|author1=Jackson, R. |author2=A. Jenkins
| title=Vital signs of the planet: global climate change and global warming: uncertainties
| date=17 November 2012
| url=http://climate.nasa.gov/uncertainties
| publisher=Earth Science Communications Team at NASA's Jet Propulsion Laboratory / California Institute of Technology
| ref=harv
}}
</ref>
There are a range of feedbacks in the climate system, including [[water vapor feedback|water vapour]], changes in [[ice-albedo feedback|ice-albedo]] (snow and ice cover affect how much the Earth's surface absorbs or reflects incoming sunlight), clouds, and changes in the Earth's carbon cycle (e.g., the release of carbon from [[soil]]).<ref>
{{Cite journal
| title=The Carbon Cycle: Feature Articles: Effects of Changing the Carbon Cycle
| author=Riebeek, H.
| date=16 June 2011
| url=http://www.earthobservatory.nasa.gov/Features/CarbonCycle/page5.php
| publisher=Earth Observatory, part of the EOS Project Science Office located at NASA Goddard Space Flight Center
| ref=harv
}}
</ref> The main negative feedback is the energy the Earth's surface [[radiative cooling|radiates]] into space as [[infrared radiation]].<ref>
{{Cite book
| author=US National Research Council
| year=2003
| title=Understanding Climate Change Feedbacks
| chapter=Ch. 1 Introduction
| url=http://www.nap.edu/openbook.php?record_id=10850&page=19
| publisher=National Academies Press
| location=Washington, D.C., USA
| ref=harv
}}, p.19
</ref> According to the [[Stefan-Boltzmann law]], if the [[thermodynamic temperature|absolute temperature]] (as measured in [[kelvin]]) doubles,{{efn|A rise in temperature from 10 °C to 20 °C is ''not'' a doubling of [[Thermodynamic temperature|absolute temperature]]; a rise from (273 + 10) K {{=}} 283 K to (273 + 20) K {{=}} 293 K is an increase of (293 − 283)/283 {{=}} 3.5 %.}} radiated energy increases by a factor of 16 (2 to the 4th power).<ref>
{{Cite journal
| author=Lindsey, R.
| date=14 January 2009
| url=http://earthobservatory.nasa.gov/Features/EnergyBalance/page4.php
| title=Earth's Energy Budget (p.4), in: Climate and Earth's Energy Budget: Feature Articles
| publisher=Earth Observatory, part of the EOS Project Science Office, located at NASA Goddard Space Flight Center
| ref=harv
}}
</ref>
=== Temperature flat ===
Feedbacks are an important factor in determining the sensitivity of the climate system to increased atmospheric greenhouse gas concentrations. Other factors being equal, a higher ''[[climate sensitivity]]'' means that more warming will occur for a given increase in greenhouse gas forcing.<ref>
{{Cite book
| author=US National Research Council
| year=2006
| title=Surface Temperature Reconstructions for the Last 2,000 Years
| chapter=Ch. 1 Introduction to Technical Chapters
| url=http://books.nap.edu/openbook.php?record_id=11676&page=26
| publisher=National Academies Press
| location=Washington, D.C., USA
| ref=harv
}}, pp.26-27
</ref> Uncertainty over the effect of feedbacks is a major reason why different climate models project different magnitudes of warming for a given forcing scenario. More research is needed to understand the role of clouds<ref name="jackson feedbacks"/> and carbon cycle feedbacks in climate projections.<ref>
{{Cite journal
| title=2012 American Meteorological Society (AMS) Information Statement on Climate Change
| author=AMS Council
| date=20 August 2012
| url=http://www.ametsoc.org/policy/2012climatechange.html
| publisher=AMS
| location=Boston, Massachusetts, USA
| ref=harv
}}
</ref>
=== Data manipulation ===
The IPCC projections previously mentioned span the "likely" range (greater than 66% probability, based on expert judgement)<ref name="IPCC-Def-Of-Certainty">{{Cite web | quote=The following terms have been used to indicate the assessed likelihood of an outcome or a result: virtually certain 99–100% probability, very likely 90–100%, likely 66–100%, about as likely as not 33–66%, unlikely 0–33%, very unlikely 0–10%, exceptionally unlikely 0–1%. Additional terms (extremely likely: 95–100%, more likely than not >50–100%, more unlikely than likely 0–<50% and extremely unlikely 0–5%) may also be used when appropriate. | publisher=IPCC | url=http://www.ipcc.ch/pdf/assessment-report/ar5/syr/AR5_SYR_FINAL_SPM.pdf | title=CLIMATE CHANGE 2014: Synthesis Report. Summary for Policymakers | accessdate=1 November 2015}}</ref> for the selected emissions scenarios. However, the IPCC's projections do not reflect the full range of uncertainty.<ref name="meehl 2007 global warming projections"/> The lower end of the "likely" range appears to be better constrained than the upper end.<ref name="meehl 2007 global warming projections"/>
=== Alternate causation ===
== Climate models ==
{{Main article|Global climate model}}
==Science of global warming==
{{Multiple image
===Presence of CO<sub>2</sub>===
|direction=vertical
|align=right
|image1=Global Warming Predictions.png
|alt1=refer to caption
|image2= Projected change in annual mean surface air temperature from the late 20th century to the middle 21st century, based on SRES emissions scenario A1B.png
|alt2= refer to caption and image description
|width=220
|caption1=Calculations of global warming prepared in or before 2001 from a range of climate models under the [[Special Report on Emissions Scenarios|SRES]] A2 emissions scenario, which assumes no action is taken to reduce emissions and regionally divided economic development.
|caption2=Projected change in annual mean surface air temperature from the late 20th century to the middle 21st century, based on a medium [[Economics of global warming#Emissions scenarios|emissions scenario]] (SRES A1B).<ref>
{{Cite journal
| author=NOAA
| date= January 2007
| work=GFDL Climate Modeling Research Highlights
| title=Patterns of greenhouse warming
| url=http://www.gfdl.noaa.gov/cms-filesystem-action/user_files/kd/pdf/gfdlhighlight_vol1n6.pdf
| volume=1
| issue=6
| publisher=The National Oceanic and Atmospheric Administration (NOAA) Geophysical Fluid Dynamics Laboratory (GFDL)
| location=Princeton, New Jersey, USA
| ref=harv
}}, revision 2 February 2007, 8:50.08 AM.
</ref> This scenario assumes that no future policies are adopted to limit greenhouse gas emissions. Image credit: [[NOAA]] [[Geophysical Fluid Dynamics Laboratory|GFDL]].<ref>
{{Cite journal
| url=http://www.gfdl.noaa.gov/patterns-of-greenhouse-warming-ar4
| title=NOAA GFDL Climate Research Highlights Image Gallery: Patterns of Greenhouse Warming
| publisher=NOAA GFDL
| date=9 October 2012
| author=NOAA Geophysical Fluid Dynamics Laboratory (GFDL)
| ref=harv
}}
</ref>
}}
A [[climate model]] is a [[mathematical models|representation]] of the physical, chemical and biological processes that affect the climate system.<ref>IPCC, [http://www.ipcc.ch/publications_and_data/ar4/syr/en/annexessglossary-a-d.html Glossary A-D]: "Climate Model", in {{Harvnb|IPCC AR4 SYR|2007}}.</ref> Such models are based on scientific disciplines such as [[fluid dynamics]] and [[thermodynamics]] as well as physical processes such as [[radiative transfer]]. The models may be used to predict a range of variables such as local air movement, temperature, clouds, and other atmospheric properties; ocean temperature, [[salinity|salt content]], and [[ocean circulation|circulation]]; ice cover on land and sea; the transfer of heat and moisture from soil and vegetation to the atmosphere; and chemical and biological processes, among others.
Although researchers attempt to include as many processes as possible, simplifications of the actual climate system are inevitable because of the constraints of available computer power and limitations in knowledge of the climate system. Results from models can also vary due to different greenhouse gas inputs and the model's climate sensitivity. For example, the uncertainty in IPCC's 2007 projections is caused by (1) the use of multiple models<ref name="meehl 2007 global warming projections">
{{Cite book
| url=http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch10s10-5-4-6.html |title=Sec 10.5.4.6 Synthesis of Projected Global Temperature at Year 2100]
| author=Meehl, G.A.| chapter=Ch 10: Global Climate Projections
| ref=harv
|display-authors=etal}}, in {{harvnb|IPCC AR4 WG1|2007}}
</ref> with differing sensitivity to greenhouse gas concentrations,<ref>
{{Cite book
| year=2009
| title=Global Climate Change Impacts in the United States
| chapter=Global Climate Change
| url=http://www.globalchange.gov/publications/reports/scientific-assessments/us-impacts/full-report/global-climate-change
| editor=Karl, TR| publisher=Cambridge University Press
| isbn=978-0-521-14407-0
| ref=harv
|display-editors=etal}}
</ref> (2) the use of differing estimates of humanity's future greenhouse gas emissions,<ref name="meehl 2007 global warming projections"/> (3) any additional emissions from climate feedbacks that were not included in the models IPCC used to prepare its report, i.e., greenhouse gas releases from permafrost.<ref name="NSDIC_permafrost_study">{{Cite journal |journal=Tellus Series B
|author1=KEVIN SCHAEFER |author2=TINGJUN ZHANG |author3=LORI BRUHWILER |author4=ANDREW P. BARRETT |title = Amount and timing of permafrost carbon release in response to climate warming
|year=2011|volume=63|issue=2|pages= 165–180|doi=10.1111/j.1600-0889.2011.00527.x
|bibcode = 2011TellB..63..165S |ref=harv}}</ref>
The models do not assume the climate will warm due to increasing levels of greenhouse gases. Instead the models predict how greenhouse gases will interact with radiative transfer and other physical processes. Warming or cooling is thus a result, not an assumption, of the models.<ref>{{Cite book
|last=Hansen |first=James
|contribution= Climatic Change: Understanding Global Warming
|title=One World: The Health & Survival of the Human Species in the 21st century
|accessdate =18 August 2007
|year=2000 |publisher=Health Press (New Mexico) |editor=Robert Lanza
|pages=173–190
|isbn = 0-929173-33-3
|url= https://books.google.com/?id=sx6DFr8rbpIC&dq=robert+lanza&printsec=frontcover
}}</ref>
Clouds and their effects are especially difficult to predict. Improving the models' representation of clouds is therefore an important topic in current research.<ref>Stocker ''et al.'', [http://www.grida.no/climate/ipcc_tar/wg1/260.htm Chapter 7: Physical Climate Processes and Feedbacks], [http://www.grida.no/climate/ipcc_tar/wg1/271.htm Section 7.2.2: Cloud Processes and Feedbacks], in {{Harvnb|IPCC TAR WG1|2001}}.</ref> Another prominent research topic is expanding and improving representations of the carbon cycle.<ref>{{Cite journal
|last=Torn|first=Margaret
|author2=Harte, John|year=2006
|title= Missing feedbacks, asymmetric uncertainties, and the underestimation of future warming
|journal=Geophysical Research Letters
|volume=33|issue=10
|pages =L10703
|url= http://www.webpages.uidaho.edu/envs501/downloads/Torn%20%26%20Harte%202006.pdf
|accessdate =4 March 2007|doi=10.1029/2005GL025540
|bibcode=2006GeoRL..3310703T
|ref=harv
}}</ref><ref>{{Cite journal
|last=Harte|first=John
|author2=Saleska, Scott |author3=Shih, Tiffany|year=2006
|title = Shifts in plant dominance control carbon-cycle responses to experimental warming and widespread drought
|journal=Environmental Research Letters
|volume=1|issue=1|page =014001
|accessdate =2 May 2007
|doi=10.1088/1748-9326/1/1/014001
| bibcode=2006ERL.....1a4001H
|url = http://www.iop.org/EJ/article/1748-9326/1/1/014001/erl6_1_014001.html
|ref=harv
}}</ref><ref>{{Cite journal
|last=Scheffer|first=Marten
|author2=Brovkin, Victor
|author3=Cox, Peter
|title= Positive feedback between global warming and atmospheric CO<sub>2</sub> concentration inferred from past climate change
|journal=Geophysical Research Letters
|volume=33|issue=10|year=2006|pages= L10702
|bibcode=2006GeoRL..3310702S
|doi=10.1029/2005gl025044
|accessdate =4 May 2007
|url = http://www.pik-potsdam.de/~victor/recent/scheffer_etal_T_CO2_GRL_in_press.pdf
|ref=harv
}}</ref>
Models are also used to help investigate the [[Attribution of recent climate change|causes of recent climate change]] by comparing the observed changes to those that the models project from various natural and human causes. Although these models do not unambiguously attribute the warming that occurred from approximately 1910 to 1945 to either natural variation or human effects, they do indicate that the warming since 1970 is dominated by anthropogenic greenhouse gas emissions.<ref name="Hegerl-2001"/>
The physical realism of models is tested by examining their ability to simulate contemporary or past climates.<ref>Randall ''et al.'', [http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch8.html Chapter 8, Climate Models and Their Evaluation], Sec. FAQ 8.1 in {{Harvnb|IPCC AR4 WG1|2007}}.</ref> Climate models produce a good match to observations of global temperature changes over the last century, but do not simulate all aspects of climate.<ref>IPCC, [http://www.grida.no/climate/ipcc_tar/wg1/pdf/WG1_TAR-FRONT.pdf Technical Summary], p. 54, in {{Harvnb|IPCC TAR WG1|2001}}.</ref> Not all [[effects of global warming]] are accurately predicted by the climate models used by the IPCC. Observed [[Arctic shrinkage]] has been faster than that predicted.<ref>{{Cite journal
<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>
|author=Stroeve, J.
|title = Arctic sea ice decline: Faster than forecast
|year=2007
|journal=Geophysical Research Letters
|volume=34|issue=9|pages= L09501
|doi=10.1029/2007GL029703
|bibcode=2007GeoRL..3409501S
|ref=harv
|display-authors=etal}}</ref> Precipitation increased proportionally to atmospheric humidity, and hence significantly faster than global climate models predict.<ref>{{Cite journal
|author=Wentz,FJ
|title = How Much More Rain Will Global Warming Bring?
|year=2007|pages=233–5|issue=5835|volume=317
|journal=Science
|doi=10.1126/science.1140746
|pmid=17540863
|bibcode = 2007Sci...317..233W
|url=http://www.sciencemag.org/cgi/content/abstract/317/5835/233
|ref=harv
|display-authors=etal}}</ref><ref>{{cite journal
|last=Liepert|first=Beate G.|author2=Previdi, Michael
|title=Do Models and Observations Disagree on the Rainfall Response to Global Warming?
|journal=Journal of Climate
|year=2009|pages=3156–3166|volume= 22|issue=11
|doi=10.1175/2008JCLI2472.1|bibcode = 2009JCli...22.3156L
|url=http://journals.ametsoc.org/doi/abs/10.1175/2008JCLI2472.1
|quote=Recently analyzed satellite-derived global precipitation datasets from 1987 to 2006 indicate an increase in global-mean precipitation of 1.1%–1.4% decade−1. This trend corresponds to a hydrological sensitivity (HS) of 7% K−1 of global warming, which is close to the Clausius–Clapeyron (CC) rate expected from the increase in saturation water vapor pressure with temperature. Analysis of two available global ocean evaporation datasets confirms this observed intensification of the atmospheric water cycle. The observed hydrological sensitivity over the past 20-yr period is higher by a factor of 5 than the average HS of 1.4% K−1 simulated in state-of-the-art coupled atmosphere–ocean climate models for the twentieth and twenty-first centuries.
|ref=harv
}}</ref> Since 1990, sea level has also risen considerably faster than models predicted it would.<ref>{{cite journal|last1=Rahmstorf|first1=S.|last2=Cazenave|first2=A.|last3=Church|first3=J. A.|last4=Hansen|first4=J. E.|last5=Keeling|first5=R. F.|last6=Parker|first6=D. E.|last7=Somerville|first7=R. C. J.|title=Recent Climate Observations Compared to Projections|journal=Science|date=4 May 2007|volume=316|issue=5825|pages=709–709|doi=10.1126/science.1136843|pmid=17272686|bibcode = 2007Sci...316..709R }}</ref>
== Observed and expected environmental effects ==
{{Main article|Effects of global warming}}
[[File:Projections of global mean sea level rise by Parris et al. (2012).png|thumb|right|350px|alt=Refer to caption and adjacent text|Projections of global mean sea level rise by Parris and others.<ref name="parris sea level rise"/> Probabilities have not been assigned to these projections.<ref>
Executive Summary, in {{harvnb|Parris|others|2012|p=1}}
</ref> Therefore, none of these projections should be interpreted as a "best estimate" of future sea level rise. Image credit: NOAA.]]Anthropogenic forcing has likely contributed to some of the observed changes, including sea level rise, changes in climate [[extreme weather|extremes]] (such as the number of warm and cold days), [[Arctic sea ice decline|declines in Arctic sea ice]] extent, [[Retreat of glaciers since 1850|glacier retreat]], and greening of the [[Sahara]].<ref>
{{Cite book
| url=http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch9s9-es.html |title=Executive Summary
| chapter=Ch 9: Understanding and Attributing Climate Change
| chapter-url=http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch9.html
| author=Hegerl, G.C.| ref=harv
|display-authors=etal}}, in {{harvnb|IPCC AR4 WG1|2007}}
</ref><ref>{{cite web|url=http://news.nationalgeographic.com/news/2009/07/090731-green-sahara.html |title=Sahara Desert Greening Due to Climate Change? |work=National Geographic |accessdate=12 June 2010}}</ref>
During the 21st century, [[glacier]]s<ref>
{{Cite book
| author=Meehl, G.A.| chapter=Ch 10: Global Climate Projections
| chapter-url=http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch10.html
| url=http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch10s10-3-4.html|title= Box 10.1: Future Abrupt Climate Change, ‘Climate Surprises’, and Irreversible Changes: Glaciers and ice caps
| ref=harv
|display-authors=etal}}, in {{harvnb|IPCC AR4 WG1|2007|p=776}}
</ref> and snow cover<ref>
{{Cite book
| author=Meehl, G.A.| chapter=Ch 10: Global Climate Projections
| chapter-url=http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch10.html
| url=http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch10s10-3-3-2.html |title=Sec 10.3.3.2 Changes in Snow Cover and Frozen Ground
| ref=harv
|display-authors=etal}}, in {{harvnb|IPCC AR4 WG1|2007|pp=770, 772}}
</ref> are projected to continue their widespread retreat. Projections of declines in Arctic sea ice vary.<ref>
{{Cite book
| author=Meehl, G.A.| chapter=Ch 10: Global Climate Projections
| chapter-url=http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch10.html
| url=http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch10s10-3-2-4.html#10-3-3|title= Sec 10.3.3.1 Changes in Sea Ice Cover
| ref=harv
|display-authors=etal}}, in {{harvnb|IPCC AR4 WG1|2007|p=770}}
</ref><ref>
{{cite journal|last=Wang|first=M.|author2=Overland, J. E.|journal=Geophys. Res. Lett.|year=2009|volume=36|doi=10.1029/2009GL037820|url=http://www.pmel.noaa.gov/publications/search_abstract.php?fmContributionNum=3261
|accessdate=2 May 2011|bibcode=2009GeoRL..3607502W|title=A sea ice free summer Arctic within 30 years?|issue=7|ref=harv
}}
</ref> Recent projections suggest that Arctic summers could be ice-free (defined as ice extent less than 1 million [[square km]]) as early as 2025-2030.<ref>
{{Cite journal
| title=Arctic sea ice 2012
| author=Met Office
| publisher=Met Office
| location=Exeter, UK
| url=http://www.metoffice.gov.uk/research/news/sea-ice-2012
| ref=harv
}}</ref>
<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>
"Detection" is the process of demonstrating that climate has changed in some defined [[statistics|statistical]] sense, without providing a reason for that change. Detection does not imply attribution of the detected change to a particular cause. "Attribution" of causes of climate change is the process of establishing the most likely causes for the detected change with some defined level of confidence.<ref>IPCC, [http://www.ipcc.ch/publications_and_data/ar4/wg1/en/annexessglossary-a-d.html Glossary A-D]: "Detection and attribution", in {{Harvnb|IPCC AR4 WG1|2007}}. See also Hegerl ''et al.'', [http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch9s9-1-2.html Section 9.1.2: What are Climate Change Detection and Attribution?], in {{Harvnb|IPCC AR4 WG1|2007}}.</ref> Detection and attribution may also be applied to observed changes in physical, ecological and social systems.<ref>Rosenzweig ''et al.'', [http://www.ipcc.ch/publications_and_data/ar4/wg2/en/ch1.html Chapter 1: Assessment of Observed Changes and Responses in Natural and Managed Systems] [http://www.ipcc.ch/publications_and_data/ar4/wg2/en/ch1s1-2.html Section 1.2 Methods of detection and attribution of observed changes], in {{Harvnb|IPCC AR4 WG2|2007}} .</ref>
=== Extreme weather ===
{{Main article|Extreme weather|Physical impacts of climate change#Extreme events}}
Changes in regional climate are expected to include greater warming over land, with most warming at high northern [[latitudes]], and least warming over the [[Southern Ocean]] and parts of the North Atlantic Ocean.<ref name="IPCC AR4 SYR 2007">
IPCC, [http://www.ipcc.ch/publications_and_data/ar4/syr/en/spm.html Synthesis Report Summary for Policymakers], [http://www.ipcc.ch/publications_and_data/ar4/syr/en/spms3.html Section 3: Projected climate change and its impacts], in {{Harvnb|IPCC AR4 SYR|2007}}.
</ref>
Future changes in [[precipitation (meteorology)|precipitation]] are expected to follow existing trends, with reduced precipitation over [[subtropical]] land areas, and increased precipitation at subpolar latitudes and some [[equator]]ial regions.<ref>
{{Cite journal
| author=NOAA
| date=February 2007
| url=http://www.gfdl.noaa.gov/cms-filesystem-action/user_files/kd/pdf/gfdlhighlight_vol1n5.pdf
| title=Will the wet get wetter and the dry drier?
| work=GFDL Climate Modeling Research Highlights
| volume=1
| issue=5
| publisher=National Oceanic and Atmospheric Administration (NOAA) Geophysical Fluid Dynamics Laboratory (GFDL)
| location=Princeton, New Jersey, USA
| ref=harv
}}, p.1. Revision 15 October 2008, 4:47:16 PM.
</ref> Projections suggest a probable increase in the frequency and severity of some extreme weather events, such as [[heat wave]]s.<ref>
{{Cite book|title=MANAGING THE RISKS OF EXTREME EVENTS AND DISASTERS TO ADVANCE CLIMATE CHANGE ADAPTATION
| chapter=D. Future Climate Extremes, Impacts, and Disaster Losses, in: Summary for policymakers
| url=https://docs.google.com/file/d/0B1gFp6Ioo3akYklZcWkwWHJud00/edit?pli=1
| ref=harv
}}, in {{harvnb|IPCC SREX|2012|pp=9–13}}
</ref>
A 2015 study published in ''[[Nature Climate Change]]'', states: {{cquote|About 18% of the moderate daily precipitation extremes over land are attributable to the observed temperature increase since pre-industrial times, which in turn primarily results from human influence. For 2 °C of warming the fraction of precipitation extremes attributable to human influence rises to about 40%. Likewise, today about 75% of the moderate daily hot extremes over land are attributable to warming. It is the most rare and extreme events for which the largest fraction is anthropogenic, and that contribution increases nonlinearly with further warming.<ref name=NYT42715>{{cite news|author1=Justin Gillis|title=New Study Links Weather Extremes to Global Warming|url=http://www.nytimes.com/2015/04/28/science/new-study-links-weather-extremes-to-global-warming.html|accessdate=27 April 2015|work=The New York Times|date=27 April 2015|quote=“The bottom line is that things are not that complicated,” Dr. Knutti said. “You make the world a degree or two warmer, and there will be more hot days. There will be more moisture in the atmosphere, so that must come down somewhere.”}}</ref><ref name=NatureCC42715>{{cite journal|author1=E. M. Fischer|author2=R. Knutti|title=Anthropogenic contribution to global occurrence of heavy-precipitation and high-temperature extremes|journal=Nature Climate Change|date=27 April 2015|doi=10.1038/nclimate2617|url=http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2617.html|accessdate=27 April 2015|format=online|quote=We show that at the present-day warming of 0.85 °C about 18% of the moderate daily precipitation extremes over land are attributable to the observed temperature increase since pre-industrial times, which in turn primarily results from human influence. … Likewise, today about 75% of the moderate daily hot extremes over land are attributable to warming.|bibcode = 2015NatCC...5..560F|volume=5|pages=560–564}}</ref>}}
Data analysis of extreme events from 1960 till 2010 suggests that droughts and heat waves appear simultaneously with increased frequency.<ref>{{cite web|url=http://news.uci.edu/press-releases/uci-study-finds-dramatic-increase-in-concurrent-droughts-heat-waves/|title=UCI study finds dramatic increase in concurrent droughts, heat waves|publisher=UCI|year=2015}}</ref> Extremely wet or dry events within the [[monsoon]] period have increased since 1980.<ref>{{cite web|url=http://www.scientificamerican.com/article/indian-monsoons-are-becoming-more-extreme/|title=Indian Monsoons Are Becoming More Extreme|year=2014|publisher=Scientific American}}</ref>
<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>
=== Sea level rise ===
===Unnecessary expansion of government===
[[File:6m Sea Level Rise.jpg|thumb|250px|Map of the Earth with a six-metre sea level rise represented in red.]]
{{Main article|Sea level rise|Retreat of glaciers since 1850}}
[[File:Glacier Mass Balance.png|thumb|right|alt=refer to caption|250px|Sparse records indicate that glaciers have been retreating since the early 1800s. In the 1950s measurements began that allow the monitoring of glacial mass balance, reported to the [[World Glacier Monitoring Service]] (WGMS) and the [[National Snow and Ice Data Center]] (NSIDC).]]
The sea level rise since 1993 has been estimated to have been on average 2.6 mm and 2.9 mm per year ± 0.4 mm. Additionally, sea level rise has accelerated from 1995 to 2015.<ref>{{cite journal|url=http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2635.html|title=Unabated global mean sea-level rise over the satellite altimeter era|author1=Christopher S. Watson|author2=Neil J. White|author3=John A. Church|author4=Matt A. King|author5=Reed J. Burgette|author6=Benoit Legresy|date=11 May 2015|journal=Nature Climate Change|doi=10.1038/nclimate2635|bibcode = 2015NatCC...5..565W|volume=5|pages=565–568}}</ref> Over the 21st century, the IPCC projects for a high emissions scenario, that global mean [[sea level rise|sea level]] could rise by 52–98 cm.<ref name=IPCC_SLR2013>{{cite web|last1=Churchs|first1=John|last2=Clark|first2=Peter|title=Chapter 13: Sea Level Change - Final Draft Underlying Scientific-Technical Assessment|url=http://www.climatechange2013.org/images/uploads/WGIAR5_WGI-12Doc2b_FinalDraft_Chapter13.pdf|publisher=IPCC Working Group I|accessdate=21 January 2015}}</ref> The IPCC's projections are conservative, and may underestimate future sea level rise.<ref>PROJECTIONS OF FUTURE SEA LEVEL RISE, [http://www.nap.edu/openbook.php?record_id=12782&page=243 pp.243-244], in: Ch. 7. Sea Level Rise and the Coastal Environment, in {{harvnb|National Research Council|2010}}
</ref> Other estimates suggest that for the same period, global mean sea level could rise by 0.2 to 2.0 m (0.7–6.6 ft), relative to mean sea level in 1992.<ref name="parris sea level rise">
4. Global Mean Sea Level Rise Scenarios, in: Main Report, in {{harvnb|Parris|others|2012|p=12}}
</ref>
Widespread [[coastal flood]]ing would be expected if several degrees of warming is sustained for millennia.<ref name="us nrc 2011 long term slr">
===Climate change as a cult===
BOX SYN-1: SUSTAINED WARMING COULD LEAD TO SEVERE IMPACTS, [http://www.nap.edu/openbook.php?record_id=12877&page=5 p.5], in: Synopsis, in {{harvnb|National Research Council|2011}}
</ref> For example, sustained global warming of more than 2 °C (relative to pre-industrial levels) could lead to eventual sea level rise of around 1 to 4 m due to thermal expansion of sea water and the melting of glaciers and small [[ice cap]]s.<ref name="us nrc 2011 long term slr"/> Melting of the [[Greenland ice sheet]] could contribute an additional 4 to 7.5 m over many thousands of years.<ref name="us nrc 2011 long term slr"/> It has been estimated that we are already committed to a sea-level rise of approximately 2.3 metres for each degree of temperature rise within the next 2,000 years.<ref>{{cite journal|url=http://www.pnas.org/content/110/34/13745.abstract?sid=26fd1d37-7276-46e2-9192-0931e6ebf6ab|title=The multimillennial sea-level commitment of global warming|author1=Anders Levermann|author2=Peter U. Clark|author3=Ben Marzeion|author4=Glenn A. Milne|author5=David Pollard|author6=Valentina Radic|author7=Alexander Robinson|date=13 June 2013|journal=PNAS|doi=10.1073/pnas.1219414110|volume=110|pages=13745–13750|bibcode = 2013PNAS..11013745L }}</ref>
Warming beyond the 2 °C target would potentially lead to rates of sea-level rise dominated by ice loss from [[Antarctica]]. Continued CO<sub>2</sub> emissions from fossil sources could cause additional tens of metres of sea level rise, over the next millennia and eventually ultimately eliminate the entire Antarctic ice sheet, causing about 58 metres of sea level rise.<ref>{{cite web|url=http://advances.sciencemag.org/content/1/8/e1500589.full|doi=10.1126/sciadv.1500589|author1=Ricarda Winkelmann|author2=Anders Levermann|author3=Andy Ridgwell|author4=Ken Caldeira|date=11 September 2015|title=Combustion of available fossil fuel resources sufficient to eliminate the Antarctic Ice Sheet}}</ref>
=== Ecological systems ===
{{Main article|Climate change and ecosystems}}
In terrestrial [[ecosystem]]s, the earlier timing of spring events, as well as poleward and upward shifts in plant and animal ranges, have been linked with high confidence to recent warming.<ref name="ipcc.ch">IPCC, [http://www.ipcc.ch/publications_and_data/ar4/syr/en/spm.html Synthesis Report Summary for Policymakers], [http://www.ipcc.ch/publications_and_data/ar4/syr/en/spms1.html Section 1: Observed changes in climate and their effects], in {{Harvnb|IPCC AR4 SYR|2007}}.</ref>
<blockquote>
Future climate change is expected to affect particular ecosystems, including [[tundra]], [[mangrove]]s, [[coral reef]]s.,<ref name="IPCC AR4 SYR 2007" /> and [[cave]]s.<ref>{{Cite journal|last=Mammola|first=Stefano|last2=Goodacre|first2=Sara L.|last3=Isaia|first3=Marco|date=2017-01-01|title=Climate change may drive cave spiders to extinction|url=http://onlinelibrary.wiley.com/doi/10.1111/ecog.02902/abstract|journal=Ecography|language=en|pages=n/a–n/a|doi=10.1111/ecog.02902|issn=1600-0587}}</ref> It is expected that most ecosystems will be affected by higher atmospheric CO<sub>2</sub> levels, combined with higher global temperatures.<ref>Fischlin, ''et al''., [http://www.ipcc.ch/publications_and_data/ar4/wg2/en/contents.html Chapter 4: Ecosystems, their Properties, Goods and Services],
[http://www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-chapter4.pdf Executive Summary, p. 213], in {{Harvnb|IPCC AR4 WG2|2007}}. Executive summary not present in on-line text; see pdf.</ref> Overall, it is expected that climate change will result in the [[extinction]] of many species and reduced diversity of ecosystems.<ref>
Schneider ''et al.'', [http://www.ipcc.ch/publications_and_data/ar4/wg2/en/ch19.html Chapter 19: Assessing Key Vulnerabilities and the Risk from Climate Change], [http://www.ipcc.ch/publications_and_data/ar4/wg2/en/ch19s19-3-4.html Section 19.3.4: Ecosystems and biodiversity], in {{Harvnb|IPCC AR4 WG2|2007}}.</ref>
Increases in atmospheric CO<sub>2</sub> concentrations have led to an increase in [[ocean acidification|ocean acidity]].<ref name="ncadac 2013 climate">
<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>
Ocean Acidification, in: [http://ncadac.globalchange.gov/download/NCAJan11-2013-publicreviewdraft-chap2-climate.pdf Ch. 2. Our Changing Climate], in {{harvnb|NCADAC|2013|pp=69–70}}
</ref> Dissolved CO<sub>2</sub> increases ocean acidity, measured by lower [[pH]] values.<ref name="ncadac 2013 climate"/> Between 1750 and 2000, surface-ocean pH has decreased by ≈0.1, from ≈8.2 to ≈8.1.<ref name="zeebe ocean acidification">
Introduction, in {{harvnb|Zeebe|2012|p=142}}
</ref> Surface-ocean pH has probably not been below ≈8.1 during the past 2 million years.<ref name="zeebe ocean acidification"/> Projections suggest that surface-ocean pH could decrease by an additional 0.3–0.4 units by 2100.<ref>
Ocean acidification, in: Executive summary, in {{harvnb|Good|others|2010|p=14}}
</ref> Future ocean acidification could threaten [[Environmental issues with coral reefs|coral reefs]], [[fishery|fisheries]], [[protected species]], and other [[natural resource]]s of value to society.<ref name="ncadac 2013 climate"/><ref>
* {{harvnb|UNEP|2010}}
* 5. Ocean acidification, in {{harvnb|Good|others|2010|pp=73–81}}
* {{harvnb|IAP|2009}}
</ref>
===Politics of global warming and dissent===
[[Ocean deoxygenation]] is projected to increase [[Hypoxia (environmental)|hypoxia]] by 10%, and triple suboxic waters (oxygen concentrations 98% less than the mean surface concentrations), for each 1 °C of upper ocean warming.<ref>{{cite journal | bibcode=2011Sci...333..336D | display-authors=etal | url=http://people.atmos.ucla.edu/hbrix/papers/science.1202422.full.pdf | title=Climate-Forced Variability of Ocean Hypoxia | author=Deutsch | journal=Science | year=2011 | volume=333 | pages=336–339 | doi=10.1126/science.1202422}}</ref>
=== Long-term effects ===
{{Main article|Long-term effects of global warming}}
On the timescale of centuries to millennia, the magnitude of global warming will be determined primarily by anthropogenic CO<sub>2</sub> emissions.<ref name="long-term effects of global warming">
* Summary, [http://www.nap.edu/openbook.php?record_id=12877&page=14 pp.14-19], in {{harvnb|National Research Council|2011}}
* FAQ 12.3, in: [http://www.climatechange2013.org/images/uploads/WGIAR5_WGI-12Doc2b_FinalDraft_Chapter12.pdf Chapter 12: Long-term Climate Change: Projections, Commitments and Irreversibility], in {{harvnb|IPCC AR5 WG1|2013}}, pp.88-89 (pp.90-91 of PDF chapter)
</ref> This is due to carbon dioxide's very long lifetime in the atmosphere.<ref name="long-term effects of global warming"/>
Stabilizing the global average temperature would require large reductions in CO<sub>2</sub> emissions,<ref name="long-term effects of global warming"/> as well as reductions in emissions of other greenhouse gases such as methane and nitrous oxide.<ref name="long-term effects of global warming"/><ref>[http://www.nap.edu/openbook.php?record_id=12877&page=65 BOX 2.1: STABILIZATION AND NON-CO<sub>2</sub> GREENHOUSE GASES (p.65)], in: [http://www.nap.edu/openbook.php?record_id=12877&page=59 Chapter 2: Emissions, Concentrations, and Related Factors], in {{harvnb|National Research Council|2011}}
</ref> Emissions of CO<sub>2</sub> would need to be reduced by more than 80% relative to their peak level.<ref name="long-term effects of global warming"/> Even if this were achieved, global average temperatures would remain close to their highest level for many centuries.<ref name="long-term effects of global warming"/> As of 2016, emissions of CO<sub>2</sub> from burning fossil fuels had stopped increasing, but the Guardian reports they need to be "reduced to have a real impact on climate change". Meanwhile, this greenhouse gas continues to accumulate in the atmosphere.<ref>{{cite news|title=The world’s carbon-dioxide emissions have stabilised|url=http://www.economist.com/news/business-and-finance/21694972-they-need-fall-have-real-impact-climate-change-worlds-carbon|accessdate=12 December 2016|work=The Economist|date=16 March 2016}}</ref> Also, CO<sub>2</sub> is not the only factor driving climate change. Concentrations of atmospheric methane, another greenhouse gas, rose dramatically between 2006-2016 for unknown reasons. This undermines efforts to combat global warming and there is a risk of an uncontrollable [[runaway greenhouse effect]].<ref>[https://www.theguardian.com/environment/2016/dec/12/rapid-rise-methane-emissions-10-years-surprises-scientists Rapid rise in methane emissions in 10 years surprises scientists] ''[[The Guardian]]''</ref>
Long-term effects also include a response from the Earth's crust, due to ice melting and deglaciation, in a process called [[post-glacial rebound]], when land masses are no longer depressed by the weight of ice. This could lead to [[landslide]]s and increased seismic and volcanic activities. Tsunamis could be generated by submarine landslides caused by warmer ocean water thawing ocean-floor permafrost or releasing [[Clathrate hydrate|gas hydrates]].<ref>{{cite journal|journal=Philosophical Transactions A|publisher=Royal Society|url=http://rsta.royalsocietypublishing.org/content/368/1919/2311|doi=10.1098/rsta.2010.0077|title=Climate forcing of geological and geomorphological hazards|author=Bill McGuire|volume=368|pages=2311–2315|bibcode = 2010RSPTA.368.2311M }}</ref> Some world regions, such as the French Alps, already show signs of an increase in landslide frequency.<ref>{{cite journal|title=Climate change increases frequency of shallow spring landslides in the French Alps|url=http://geology.gsapubs.org/content/41/5/619.short|doi=10.1130/G34098.1|author1=Jérôme Lopez Saez|author2=Christophe Corona|author3=Markus Stoffel|author4=Frédéric Berger|volume=41|journal=Geology|pages=619–622}}</ref>
... 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"/>
=== Large-scale and abrupt impacts ===
<blockquote>
{{main article|Abrupt climate change}}
{{See also|Cold blob (North Atlantic)}}
Climate change could result in global, large-scale changes in [[natural environment|natural]] and [[society|social systems]].<ref>
{{Cite book
| url=http://www.grida.no/climate/ipcc_tar/wg2/679.htm |title=Sec 19.6. Extreme and Irreversible Effects
| chapter-url=http://www.grida.no/climate/ipcc_tar/wg2/657.htm
| chapter=Ch. 19. Vulnerability to Climate Change and Reasons for Concern: A Synthesis
| author=Smith, J.B.| ref=harv
|display-authors=etal}}, in {{harvnb|IPCC TAR WG2|2001}}
</ref> Examples include the possibility for the [[Atlantic Meridional Overturning Circulation]] to slow- or shutdown, which in the instance of a shutdown would change weather in Europe and North America considerably, ocean acidification caused by increased atmospheric concentrations of carbon dioxide, and the long-term melting of [[ice sheet]]s, which contributes to sea level rise.<ref>{{Cite journal
| last1 = Smith | first1 = J. B.
| last2 = Schneider | first2 = S. H.
| last3 = Oppenheimer | first3 = M.
| last4 = Yohe | first4 = G. W.
| last5 = Hare | first5 = W.
| last6 = Mastrandrea | first6 = M. D.
| last7 = Patwardhan | first7 = A.
| last8 = Burton | first8 = I.
| last9 = Corfee-Morlot | first9 = J.
|first10=C. H. D. |last10=Magadza
|first11=H.-M. |last11=Füssel
|first12=A. B. |last12=Pittock
|first13=A. |last13=Rahman
|first14=A. |last14=Suarez
|first15=J.-P. |last15=van Ypersele
| title = Assessing dangerous climate change through an update of the Intergovernmental Panel on Climate Change (IPCC) 'reasons for concern'
| journal = Proceedings of the National Academy of Sciences
| volume = 106
| issue = 11
| pages = 4133–7
| date = 17 March 2009
| doi = 10.1073/pnas.0812355106 | pmid=19251662 | pmc=2648893|bibcode = 2009PNAS..106.4133S }}</ref>
Some large-scale changes could occur [[abrupt climate change|abruptly]], i.e., over a short time period, and might also be [[effects of global warming#Irreversibilities|irreversible]]. Examples of abrupt climate change are the rapid release of methane and carbon dioxide from [[permafrost]], which would lead to amplified global warming, or the [[shutdown of thermohaline circulation]].<ref name="ccsp abrupt climate change">
{{Cite book
| author=Clark, P.U.| date=December 2008
| chapter=Executive Summary
| title=Abrupt Climate Change. A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research
| url=http://www.globalchange.gov/browse/reports/sap-34-abrupt-climate-change
| publisher=U.S. Geological Survey
| location=Reston, Virginia, USA
| ref=harv
|display-authors=etal}}, pp. 1–7. [http://www.climatescience.gov/Library/sap/sap3-4/final-report/default.htm Report website] {{webarchive |url=https://web.archive.org/web/20130504113820/http://www.climatescience.gov/Library/sap/sap3-4/final-report/default.htm |date=4 May 2013 }}
</ref><ref>{{cite web|url=http://www.bbc.co.uk/news/science-environment-21549643|title=Siberian permafrost thaw warning sparked by cave data|publisher=BBC|date=22 February 2013|accessdate=24 February 2013}}</ref> Scientific understanding of abrupt climate change is generally poor.<ref>
{{Cite journal
| author=US National Research Council
| year=2010
| title=Advancing the Science of Climate Change: Report in Brief
| url=http://nas-sites.org/americasclimatechoices/sample-page/panel-reports/87-2/
| publisher=National Academies Press
| location=Washington, D.C., USA
| ref=harv
}}, p.3. [http://dels.nas.edu/resources/static-assets/materials-based-on-reports/reports-in-brief/Science-Report-Brief-final.pdf PDF of Report]
</ref> The probability of abrupt change for some climate related feedbacks may be low.<ref name="ccsp abrupt climate change"/><ref name="tar large scale impacts">
{{Cite book
| author=IPCC
| chapter=Summary for Policymakers
| chapter-url=http://www.grida.no/climate/ipcc_tar/wg2/005.htm
| url=http://www.grida.no/climate/ipcc_tar/wg2/009.htm|title= Sec. 2.6. The Potential for Large-Scale and Possibly Irreversible Impacts Poses Risks that have yet to be Reliably Quantified
| ref=harv
}}, in {{harvnb|IPCC TAR WG2|2001}}
</ref> Factors that may increase the probability of abrupt climate change include higher magnitudes of global warming, warming that occurs more rapidly, and warming that is sustained over longer time periods.<ref name="tar large scale impacts"/>
== Observed and expected effects on social systems ==
{{Further information|Effects of global warming#Social systems|Regional effects of global warming#Regional impacts}}
{{See also|Climate change and national security}}
The [[effects of climate change on humans|effects of climate change on human systems]], mostly due to warming or shifts in [[precipitation]] patterns, or both, have been detected worldwide. Production of wheat and maize globally has been impacted by climate change. While crop production has increased in some mid-latitude regions such as the UK and Northeast China, economic losses due to extreme weather events have increased globally. There has been a shift from cold- to heat-related mortality in some regions as a result of warming. Livelihoods of [[Circumpolar peoples|indigenous peoples of the Arctic]] have been altered by climate change, and there is emerging evidence of climate change impacts on livelihoods of [[indigenous peoples]] in other regions. Regional impacts of climate change are now observable at more locations than before, on all continents and across ocean regions.<ref>Cramer, W., ''et al''., Executive summary, in: [http://ipcc-wg2.gov/AR5/images/uploads/WGIIAR5-Chap18_FGDall.pdf Chapter 18: Detection and attribution of observed impacts] (archived [https://web.archive.org/web/20140708062559/http://ipcc-wg2.gov/AR5/images/uploads/WGIIAR5-Chap18_FGDall.pdf 8 July 2014]), pp.3-4, in {{harvnb|IPCC AR5 WG2 A|2014}}
</ref>
The future social impacts of climate change will be uneven.<ref>FAQ 7 and 8, in: [http://ipcc-wg2.gov/AR5/images/uploads/WGIIAR5-Volume-FAQs_FGD.pdf Volume-wide Frequently Asked Questions (FAQs)] (archived [https://web.archive.org/web/20140708062559/http://ipcc-wg2.gov/AR5/images/uploads/WGIIAR5-Volume-FAQs_FGD.pdf 8 July 2014]), pp.2-3, in {{harvnb|IPCC AR5 WG2 A|2014}}
</ref> Many risks are expected to increase with higher magnitudes of global warming.<ref>Oppenheimer, M., ''et al''., Section 19.6.3: Updating Reasons for Concern, in: [http://ipcc-wg2.gov/AR5/images/uploads/WGIIAR5-Chap19_FGDall.pdf Chapter 19: Emergent risks and key vulnerabilities] (archived [https://web.archive.org/web/20140708062559/http://ipcc-wg2.gov/AR5/images/uploads/WGIIAR5-Chap19_FGDall.pdf 8 July 2014]), pp.39-46, in {{harvnb|IPCC AR5 WG2 A|2014}}
</ref> All regions are at risk of experiencing negative impacts.<ref>Field, C., ''et al''., B-3: Regional Risks and Potential for Adaptation, in: [http://ipcc-wg2.gov/AR5/images/uploads/WGIIAR5-TS_FGDall.pdf Technical Summary] (archived [https://web.archive.org/web/20140708062559/http://ipcc-wg2.gov/AR5/images/uploads/WGIIAR5-TS_FGDall.pdf 8 July 2014]), pp.27-30, in {{harvnb|IPCC AR5 WG2 A|2014}}
</ref> Low-latitude, less developed areas face the greatest risk.<ref>Oppenheimer, M., ''et al''., Section 19.6.3: Updating Reasons for Concern, in: [http://ipcc-wg2.gov/AR5/images/uploads/WGIIAR5-Chap19_FGDall.pdf Chapter 19: Emergent risks and key vulnerabilities] (archived [https://web.archive.org/web/20140708062559/http://ipcc-wg2.gov/AR5/images/uploads/WGIIAR5-Chap19_FGDall.pdf 8 July 2014]), pp.42-43, in {{harvnb|IPCC AR5 WG2 A|2014}}
</ref> A study from 2015 concluded that economic growth (gross domestic product) of poorer countries is much more impaired with projected future climate warming, than previously thought.<ref>{{cite web|title=Climate change could impact the poor much more than previously thought|url=https://www.theguardian.com/environment/climate-consensus-97-per-cent/2015/jan/26/climate-change-could-impact-poor-much-more-than-previously-thought|author=Dana Nuccitelli|work=The Guardian|date=26 January 2015}}</ref>
A [[meta-analysis]] of 56 studies concluded in 2014 that each degree of temperature rise will increase violence by up to 20%, which includes fist fights, violent crimes, civil unrest or wars.<ref>{{cite web|url=http://www.washingtonpost.com/blogs/wonkblog/wp/2014/10/22/the-surprisingly-strong-link-between-climate-change-and-violence/|title=There’s a surprisingly strong link between climate change and violence|author=Chris Mooney|work=The Washington Post|date=22 October 2014}}</ref>
Examples of impacts include:
: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"/>
* ''[[Climate change and agriculture|Food]]'': [[crop productivity|Crop production]] will probably be negatively affected in low latitude countries, while effects at northern latitudes may be positive or negative.<ref>Porter, J.R., ''et al''., Executive summary, in: [http://ipcc-wg2.gov/AR5/images/uploads/WGIIAR5-Chap7_FGDall.pdf Chapter 7: Food security and food production systems] (archived [https://web.archive.org/web/20140708062559/http://ipcc-wg2.gov/AR5/images/uploads/WGIIAR5-Chap7_FGDall.pdf 8 July 2014]), p.3, in {{harvnb|IPCC AR5 WG2 A|2014}}
</ref> Global warming of around 4.6 °C relative to pre-industrial levels could pose a large risk to global and regional food security.<ref>Reference temperature period converted from late-20th century to pre-industrial times (approximated in the source as 1850-1900).
* Assessment Box SPM-1 (p.14) and B-2. Sectoral Risks and Potential for Adaptation: Food security and food production systems (p.18), in: [http://ipcc-wg2.gov/AR5/images/uploads/WG2AR5_SPM_FINAL.pdf Summary for Policymakers] (archived [https://web.archive.org/web/20140708062559/http://ipcc-wg2.gov/AR5/images/uploads/WG2AR5_SPM_FINAL.pdf 8 July 2014]), in {{harvnb|IPCC AR5 WG2 A|2014}}
</ref>
* ''[[Effects of global warming on human health|Health]]'': Generally impacts will be more negative than positive.<ref>Smith, K.R., ''et al''., FAQ 11.2, in: [http://ipcc-wg2.gov/AR5/images/uploads/WGIIAR5-Chap11_FGDall.pdf Chapter 11: Human health: impacts, adaptation, and co-benefits] (archived [https://web.archive.org/web/20140708062559/http://ipcc-wg2.gov/AR5/images/uploads/WGIIAR5-Chap11_FGDall.pdf 8 July 2014]), p.37, in {{harvnb|IPCC AR5 WG2 A|2014}}
</ref><ref name=lancet2009/><ref name=lancet2015/> Impacts include: the effects of extreme weather, leading to injury and loss of life;<ref>Smith, K.R., ''et al''., Section 11.4: Direct Impacts of Climate and Weather on Health, in: [http://ipcc-wg2.gov/AR5/images/uploads/WGIIAR5-Chap11_FGDall.pdf Chapter 11: Human health: impacts, adaptation, and co-benefits] (archived [https://web.archive.org/web/20140708062559/http://ipcc-wg2.gov/AR5/images/uploads/WGIIAR5-Chap11_FGDall.pdf 8 July 2014]), pp.10-13, in {{harvnb|IPCC AR5 WG2 A|2014}}
</ref> and indirect effects, such as [[undernutrition]] brought on by [[crop failure]]s.<ref name=lancet2009>{{cite journal|last1=Costello|first1=Anthony|last2=Abbas|first2=Mustafa|last3=Allen|first3=Adriana|last4=Ball|first4=Sarah|last5=Bell|first5=Sarah|last6=Bellamy|first6=Richard|last7=Friel|first7=Sharon|last8=Groce|first8=Nora|last9=Johnson|first9=Anne|last10=Kett|first10=Maria|last11=Lee|first11=Maria|last12=Levy|first12=Caren|last13=Maslin|first13=Mark|last14=McCoy|first14=David|last15=McGuire|first15=Bill|last16=Montgomery|first16=Hugh|last17=Napier|first17=David|last18=Pagel|first18=Christina|last19=Patel|first19=Jinesh|last20=de Oliveira|first20=Jose Antonio Puppim|last21=Redclift|first21=Nanneke|last22=Rees|first22=Hannah|last23=Rogger|first23=Daniel|last24=Scott|first24=Joanne|last25=Stephenson|first25=Judith|last26=Twigg|first26=John|last27=Wolff|first27=Jonathan|last28=Patterson|first28=Craig|title=Managing the health effects of climate change|journal=The Lancet|date=May 2009|volume=373|issue=9676|pages=1693–1733|doi=10.1016/S0140-6736(09)60935-1|url=http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2809%2960935-1/fulltext}}</ref><ref name=lancet2015>{{cite journal|last1=Watts|first1=Nick|last2=Adger|first2=W Neil|last3=Agnolucci|first3=Paolo|last4=Blackstock|first4=Jason|last5=Byass|first5=Peter|last6=Cai|first6=Wenjia|last7=Chaytor|first7=Sarah|last8=Colbourn|first8=Tim|last9=Collins|first9=Mat|last10=Cooper|first10=Adam|last11=Cox|first11=Peter M|last12=Depledge|first12=Joanna|last13=Drummond|first13=Paul|last14=Ekins|first14=Paul|last15=Galaz|first15=Victor|last16=Grace|first16=Delia|last17=Graham|first17=Hilary|last18=Grubb|first18=Michael|last19=Haines|first19=Andy|last20=Hamilton|first20=Ian|last21=Hunter|first21=Alasdair|last22=Jiang|first22=Xujia|last23=Li|first23=Moxuan|last24=Kelman|first24=Ilan|last25=Liang|first25=Lu|last26=Lott|first26=Melissa|last27=Lowe|first27=Robert|last28=Luo|first28=Yong|last29=Mace|first29=Georgina|last30=Maslin|first30=Mark|last31=Nilsson|first31=Maria|last32=Oreszczyn|first32=Tadj|last33=Pye|first33=Steve|last34=Quinn|first34=Tara|last35=Svensdotter|first35=My|last36=Venevsky|first36=Sergey|last37=Warner|first37=Koko|last38=Xu|first38=Bing|last39=Yang|first39=Jun|last40=Yin|first40=Yongyuan|last41=Yu|first41=Chaoqing|last42=Zhang|first42=Qiang|last43=Gong|first43=Peng|last44=Montgomery|first44=Hugh|last45=Costello|first45=Anthony|title=Health and climate change: policy responses to protect public health|journal=The Lancet|date=November 2015|volume=386|issue=10006|pages=1861–1914|doi=10.1016/S0140-6736(15)60854-6|url=http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2815%2960854-6/fulltext|accessdate=4 January 2016|pmid=26111439}}</ref><ref>Smith, K.R., ''et al''., Section 11.6.1. Nutrition, in: [http://ipcc-wg2.gov/AR5/images/uploads/WGIIAR5-Chap11_FGDall.pdf Chapter 11: Human health: impacts, adaptation, and co-benefits] (archived [https://web.archive.org/web/20140708062559/http://ipcc-wg2.gov/AR5/images/uploads/WGIIAR5-Chap11_FGDall.pdf 8 July 2014]), pp.10-13, in {{harvnb|IPCC AR5 WG2 A|2014}}
</ref>
[[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>
=== Habitat inundation ===
{{Further information|Effects of climate change on humans#Displacement/migration}}
{{See also|Climate refugee}}
In small islands and [[mega delta]]s, [[inundation]] as a result of sea level rise is expected to threaten vital infrastructure and human settlements.<ref>
{{cite book
| title=3.3.3 Especially affected systems, sectors and regions
| series=Synthesis report
| url=http://www.ipcc.ch/publications_and_data/ar4/syr/en/mains3-3-3.html
| author={{harvnb|IPCC AR4 SYR|2007}}
}}
</ref><ref>
{{cite book
| year=2007
| author=Mimura, N.
| contribution=Executive summary
| title=Chapter 16: Small Islands
| series= Climate change 2007: impacts, adaptation and vulnerability: contribution of Working Group II to the fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC)
| editors=Parry, M.L. |display-editors=etal
| url=http://www.ipcc.ch/publications_and_data/ar4/wg2/en/ch16s16-es.html
| publisher=Print version: CUP. This version: IPCC website
| location=Cambridge University Press (CUP): Cambridge, UK
| isbn=0521880106
| accessdate=15 September 2011
|display-authors=etal}}
</ref> This could lead to issues of [[climate refugee|homelessness]] in countries with low-lying areas such as [[Bangladesh]], as well as [[statelessness]] for populations in countries such as the [[Maldives]] and [[Tuvalu]].<ref>
{{cite web|url= http://www.unhcr.org/4df9cb0c9.pdf
|title=Climate change and the risk of statelessness
|format=PDF
|date=May 2011
|accessdate=13 April 2012
}}
</ref>
===Economy===
{{See also|Economics of global warming}}
Estimates based on the IPCC A1B emission scenario from additional CO<sub>2</sub> and CH<sub>4</sub> greenhouse gases released from permafrost, estimate associated impact damages by US$43 trillion.<ref>{{cite journal|journal=Nature|url=http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2807.html|doi=10.1038/nclimate2807|author1=Chris Hope|author2=Kevin Schaefer|year=2015|title=Economic impacts of carbon dioxide and methane released from thawing permafrost|volume=6|pages=56–59|bibcode = 2016NatCC...6...56H }}</ref>
===Infrastructure===
Continued permafrost degradation will likely result in unstable infrastructure in Arctic regions, or Alaska before 2100. Thus, impacting roads, pipelines and buildings, as well as water distribution, and cause [[Slope stability|slope failures]].<ref>{{cite web|url=http://news.uaf.edu/north_slope_permafrost_agu15/|year=2015|title=North Slope permafrost thawing sooner than expected|publisher=University of Alaska Fairbanks}}</ref>
== Possible responses to global warming ==
<!-- [[Climate security]] redirects here -->
{{See also|Climate action}}
=== Mitigation ===
: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). [http://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>
{{main article|Climate change mitigation}}
[[File:Limiting global warming to 2 degrees Celsius - options to reduce greenhouse gas emissions (PBL).png|thumb|300px|alt=Refer to caption and image description|The graph on the right shows three "pathways" to meet the UNFCCC's 2 °C target, labelled "global technology", "decentralized solutions", and "consumption change". Each pathway shows how various measures (e.g., improved energy efficiency, increased use of renewable energy) could contribute to emissions reductions. Image credit: PBL [[Netherlands Environmental Assessment Agency]].<ref>
{{Cite book
| date=June 15, 2012
| author=PBL Netherlands Environment Agency
| editor=van Vuuren, D. |editor2=M. Kok
| title=Roads from Rio+20
| chapter=Figure 6.14, in: Chapter 6: The energy and climate challenge
| url=http://www.pbl.nl/sites/default/files/cms/publicaties/pbl-2012-roads-from-rio-pathways-to-achieve-global-sustainability-goals-by-2050_0.pdf
| isbn=978-90-78645-98-6
| ref=harv
}}, p.177, Report no: 500062001. [http://www.pbl.nl/en/publications/2012/roads-from-rio20 Report website.]
</ref>]]
Mitigation of climate change are actions to reduce greenhouse gas emissions, or enhance the capacity of carbon sinks to absorb GHGs from the atmosphere.<ref>[http://www.globalchange.gov/climate-change/glossary Mitigation], in {{harvnb|USGCRP|2015}}
</ref> There is a large potential for future reductions in emissions by a combination of activities, including: [[energy conservation]] and increased [[Efficient energy use|energy efficiency]]; the use of [[low-carbon energy]] technologies, such as [[renewable energy]], [[nuclear power|nuclear energy]], and [[carbon capture and storage]];<ref name="autogenerated2007">IPCC, [http://www.ipcc.ch/publications_and_data/ar4/syr/en/spm.html Synthesis Report Summary for Policymakers], [http://www.ipcc.ch/publications_and_data/ar4/syr/en/spms4.html Section 4: Adaptation and mitigation options], in {{Harvnb|IPCC AR4 SYR|2007}}.</ref><ref name="2014 mitigation options">Edenhofer, O., ''et al''., Table TS.3, in: [http://report.mitigation2014.org/report/ipcc_wg3_ar5_technical-summary.pdf Technical summary] (archived [https://web.archive.org/web/20141230092610/http://report.mitigation2014.org/report/ipcc_wg3_ar5_technical-summary.pdf 30 December 2014)], in: {{harvnb|IPCC AR5 WG3|2014|p=68}}
</ref> and enhancing carbon sinks through, for example, [[reforestation]] and preventing [[deforestation]].<ref name="autogenerated2007" /><ref name="2014 mitigation options"/>
A 2015 report by [[Citibank]] concluded that transitioning to a [[low carbon economy]] would yield positive return on investments.<ref>{{cite web|url=https://www.theguardian.com/environment/climate-consensus-97-per-cent/2015/aug/31/citi-report-slowing-global-warming-would-save-tens-of-trillions-of-dollars|title=Citi report: slowing global warming would save tens of trillions of dollars|year=2015|work=The Guardian}}</ref>
Near- and long-term trends in the global energy system are inconsistent with limiting global warming at below 1.5 or 2 °C, relative to pre-industrial levels.<ref>Clarke, L., ''et al''., Executive summary, in: [http://report.mitigation2014.org/report/ipcc_wg3_ar5_chapter6.pdf Chapter 6: Assessing Transformation Pathways] (archived [https://web.archive.org/web/20141230092610/http://report.mitigation2014.org/report/ipcc_wg3_ar5_chapter6.pdf 30 December 2014)], in: {{harvnb|IPCC AR5 WG3|2014|p=418}}
</ref><ref name="progress to 2 degrees C">SPM4.1: Long-term mitigation pathways, in: [http://report.mitigation2014.org/spm/ipcc_wg3_ar5_summary-for-policymakers.pdf Summary for Policymakers] (archived [https://web.archive.org/web/20141227021430/http://report.mitigation2014.org/spm/ipcc_wg3_ar5_summary-for-policymakers.pdf 27 December 2014)], in: {{harvnb|IPCC AR5 WG3|2014|pp=10–13}}
</ref> Pledges made as part of the [[2010 United Nations Climate Change Conference|Cancún agreements]] are broadly consistent with having a likely chance (66 to 100% probability) of limiting global warming (in the 21st century) at below 3 °C, relative to pre-industrial levels.<ref name="progress to 2 degrees C"/>
In limiting warming at below 2 °C, more stringent emission reductions in the near-term would allow for less rapid reductions after 2030.<ref>Edenhofer, O., ''et al''., TS.3.1.2: Short- and long-term requirements of mitigation pathways, in: [http://report.mitigation2014.org/report/ipcc_wg3_ar5_technical-summary.pdf Technical summary] (archived [https://web.archive.org/web/20141230092610/http://report.mitigation2014.org/report/ipcc_wg3_ar5_technical-summary.pdf 30 December 2014)], in: {{harvnb|IPCC AR5 WG3|2014|pp=55–56}}
: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>
</ref> Many integrated models are unable to meet the 2 °C target if pessimistic assumptions are made about the availability of mitigation technologies.<ref>Edenhofer, O., ''et al''., TS.3.1.3: Costs, investments and burden sharing, in: [http://report.mitigation2014.org/report/ipcc_wg3_ar5_technical-summary.pdf Technical summary] (archived [https://web.archive.org/web/20141230092610/http://report.mitigation2014.org/report/ipcc_wg3_ar5_technical-summary.pdf 30 December 2014)], in: {{harvnb|IPCC AR5 WG3|2014|p=58}}
</ref>
=== Adaptation ===
{{main article|Adaptation to global warming}}
Other policy responses include [[adaptation to global warming|adaptation]] to climate change. Adaptation to climate change may be planned, either in reaction to or anticipation of climate change, or spontaneous, i.e., without government intervention.<ref>Smit ''et al.'', [http://www.grida.no/climate/ipcc_tar/wg2/641.htm Chapter 18: Adaptation to Climate Change in the Context of Sustainable Development and Equity], [http://www.grida.no/climate/ipcc_tar/wg2/644.htm#1823 Section 18.2.3: Adaptation Types and Forms], in {{Harvnb|IPCC TAR WG2|2001}}.</ref> Planned adaptation is already occurring on a limited basis.<ref name="autogenerated2007"/> The barriers, limits, and costs of future adaptation are not fully understood.<ref name="autogenerated2007"/>
A concept related to adaptation is ''[[adaptive capacity]]'', which is the ability of a system (human, natural or managed) to adjust to climate change (including climate variability and extremes) to moderate potential damages, to take advantage of opportunities, or to cope with consequences.<ref>
{{Cite book
| url=http://www.ipcc.ch/publications_and_data/ar4/wg2/en/annexessglossary-a-d.html|title= Adaptive capacity
| chapter=Appendix I. Glossary
| ref=harv
}}, in {{harvnb|IPCC AR4 WG2|2007}}
</ref> Unmitigated climate change (i.e., future climate change without efforts to limit greenhouse gas emissions) would, in the long term, be likely to exceed the capacity of natural, managed and human systems to adapt.<ref>
{{Cite book
| url=http://www.ipcc.ch/publications_and_data/ar4/syr/en/mains6-3.html |title=Sec 6.3 Responses to climate change: Robust findings]
| chapter=Synthesis report
| ref=harv
}}, in {{harvnb|IPCC AR4 SYR|2007}}
</ref>
Environmental organizations and public figures have emphasized changes in the climate and the risks they entail, while promoting adaptation to changes in infrastructural needs and emissions reductions.<ref>{{Cite press release
| title = New Report Provides Authoritative Assessment of National, Regional Impacts of Global Climate Change
| publisher=[[U.S. Global Change Research Program]]
| date = 16 June 2009
| url = http://www.globalchange.gov/news/new-assessment-national-regional-impacts-climate-change
| accessdate =14 January 2016}}</ref>
=== Climate engineering ===
{{main article|Climate engineering}}
[[Climate engineering]] (sometimes called ''geoengineering'' or ''climate intervention'') is the deliberate modification of the climate. It has been investigated as a possible response to global warming, e.g. by NASA<ref>{{cite web|url=http://event.arc.nasa.gov/main/home/reports/SolarRadiationCP.pdf|title=Workshop on managing solar radiation|date=April 2007|publisher=NASA|accessdate=23 May 2009}}</ref> and the [[Royal Society]].<ref>{{cite press release
|title=Stop emitting CO2 or geoengineering could be our only hope
|url=http://royalsociety.org/Stop-emitting-CO2-or-geoengineering-could-be-our-only-hope/
|date=28 August 2009
|publisher=The Royal Society
|accessdate=14 June 2011}}</ref> Techniques under research fall generally into the categories [[solar radiation management]] and [[carbon dioxide removal]], although various other schemes have been suggested. A study from 2014 investigated the most common climate engineering methods and concluded they are either ineffective or have potentially severe side effects and cannot be stopped without causing rapid climate change.<ref>{{cite journal
| last = P. Keller
| first = David
| author2 = Feng, Ellias Y. |author3=Oschlies, Andreas
|date=January 2014
| title = Potential climate engineering effectiveness and side effects during a high carbon dioxide-emission scenario
| journal = Nature Communications
| volume = 5
| pages = 3304
| doi = 10.1038/ncomms4304
| url = http://www.nature.com/ncomms/2014/140225/ncomms4304/full/ncomms4304.html
| accessdate = 31 March 2014
| quote = We find that even when applied continuously and at scales as large as currently deemed possible, all methods are, individually, either relatively ineffective with limited (<8%) warming reductions, or they have potentially severe side effects and cannot be stopped without causing rapid climate change.
|bibcode = 2014NatCo...5E3304K }}</ref>
== Discourse about global warming ==
=== Political discussion ===
{{main article|Politics of global warming}}
{{hatnote|Further information: [[2011 United Nations Climate Change Conference|2011]], [[2012 United Nations Climate Change Conference|2012]], [[2013 United Nations Climate Change Conference|2013]], and [[2015 United Nations Climate Change Conference|2015]] sessions of [[United Nations Climate Change Conference]]}}
[[File:Stabilizing_the_atmospheric_concentration_of_carbon_dioxide_at_a_constant_level_would_require_emissions_to_be_effectively_eliminated_(vertical)_1.svg|thumb|alt=refer to caption|right|Article 2 of the UN Framework Convention refers explicitly to "stabilization of greenhouse gas concentrations."<ref>Quoted in {{Harvnb|IPCC SAR SYR|1996}}, "Synthesis of Scientific-Technical Information Relevant to Interpreting Article 2 of the UN Framework Convention on Climate Change", paragraph 4.1, p. 8 ([http://www.ipcc.ch/pdf/climate-changes-1995/ipcc-2nd-assessment/2nd-assessment-en.pdf pdf p. 18].) <!-- But would it not be better to quote the UNFCCC directly? --></ref> To stabilize the atmospheric concentration of {{chem|CO|2}}, emissions worldwide would need to be dramatically reduced from their present level.<ref>{{cite book
|year=2009
|chapter=Non-Technical Summary: BOX NT.1 Summary of Climate Change Basics
|title=Synthesis and Assessment Product 5.2: Best practice approaches for characterizing, communicating, and incorporating scientific uncertainty in decisionmaking. A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research
|publisher=National Oceanic and Atmospheric Administration
|location=Washington, D.C., USA.
|page=11
|author=Granger Morgan, M. (Lead Author), H. Dowlatabadi, M. Henrion, D. Keith, R. Lempert, S. McBride, M. Small and T. Wilbanks (Contributing Authors)
|url=http://downloads.globalchange.gov/sap/sap5-2/sap5-2-final-report-all.pdf
|accessdate=June 1, 2011
}}</ref>]]
Most countries in the world are parties to the [[United Nations Framework Convention on Climate Change]] (UNFCCC).<ref>
{{cite web
| date = n.d.
| author=UNFCCC
| title = Essential Background
| url = http://unfccc.int/essential_background/items/2877.php
| publisher=UNFCCC website
| accessdate =18 May 2010
}}</ref>
The ultimate objective of the Convention is to prevent dangerous human interference of the climate system.<ref>
{{cite web
|date=n.d.
|author=UNFCCC
|title=Full text of the Convention, Article 2
|url=http://unfccc.int/essential_background/convention/background/items/1353.php
|publisher=UNFCCC website
|accessdate=18 May 2010
|deadurl=yes
|archiveurl=https://web.archive.org/web/20051028023600/http://unfccc.int:80/essential_background/convention/background/items/1353.php
|archivedate=28 October 2005
|df=dmy
}}</ref>
As stated in the Convention, this requires that GHG concentrations are stabilized in the atmosphere at a level where [[Climate change and ecosystems|ecosystems]] can adapt naturally to climate change, [[Climate change and agriculture|food production]] is not threatened, and [[Economics of global warming|economic development]] can proceed in a sustainable fashion.<ref>Rogner ''et al.'', [http://www.ipcc.ch/publications_and_data/ar4/wg3/en/ch1.html Chapter 1: Introduction], [http://www.ipcc.ch/publications_and_data/ar4/wg3/en/ch1s1-es.html Executive summary], in {{Harvnb|IPCC AR4 WG3|2007}}.</ref> The Framework Convention was agreed in 1992, but since then, global emissions have risen.<ref>{{cite journal| last3 = Ciais| last4 = Le Quere | first1 = R.| last2 = Marland | first2 = G. | first3 = P.| last6 = Klepper | first4 = C.| last7 = Field | first5 = G.| last5 = Canadell| last1 = Raupach | first6 = G. | first7 = B. | title = Global and regional drivers of accelerating CO2 emissions | url = http://www.pnas.org/cgi/pmidlookup?view=long&pmid=17519334 | format = Free full text | journal = Proceedings of the National Academy of Sciences | volume = 104 | issue = 24 | pages = 10288–10293 | date=Jun 2007 | issn = 0027-8424| pmid = 17519334| pmc = 1876160 | doi = 10.1073/pnas.0700609104 |bibcode = 2007PNAS..10410288R }}</ref>
During negotiations, the [[Group of 77|G77]] (a lobbying group in the United Nations representing 133 developing nations)<ref name=dessai>
==== Belief in global warming and political and religious views ====
{{cite web
| year=2001
| author=Dessai, S.
| title=The climate regime from The Hague to Marrakech: Saving or sinking the Kyoto Protocol?
| format=PDF
| work=Tyndall Centre Working Paper 12
| url=http://www.tyndall.ac.uk/sites/default/files/wp12.pdf
| publisher=Tyndall Centre website
| accessdate=5 May 2010
}}</ref>{{Rp|4|date=November 2012}} pushed for a mandate requiring developed countries to "[take] the lead" in reducing their emissions.<ref>{{cite journal
| title=The Economics of the Kyoto Protocol
| author=Grubb, M.
| date=July–September 2003
| journal=World Economics
| volume=4
| issue=3
| pages=144–145
| url=http://ynccf.net/pdf/CDM/The_economic_of_Kyoto_protocol.pdf
| format=PDF
| accessdate=25 March 2010
| ref=harv
}}</ref> This was justified on the basis that: the developed world's emissions had contributed most to the [[Greenhouse gas#Cumulative and historical emissions|cumulation]] of GHGs in the atmosphere; [[Greenhouse gas#Annual and per capita emissions|per-capita emissions]] (i.e., emissions per head of population) were still relatively low in developing countries; and the emissions of developing countries would grow to meet their development needs.<ref name=liverman>
{{cite journal
| year=2008
| title=Conventions of climate change: constructions of danger and the dispossession of the atmosphere
| doi=10.1016/j.jhg.2008.08.008
| author=Liverman, D.M.
| journal=Journal of Historical Geography
| url=http://www.sciencedirect.com/science/article/pii/S0305748808001023
| format=PDF
| accessdate=10 May 2011
| volume=35
| issue=2
| pages=279–296
| ref=harv
}}</ref>{{Rp|290|date=November 2012}}
This mandate was sustained in the [[Kyoto Protocol]] to the Framework Convention,<ref name=liverman/>{{Rp|290|date=November 2012}} which entered into legal effect in 2005.<ref name=kyoto>
{{cite web
| date = n.d.
| author=UNFCCC
| title = Kyoto Protocol
| url = http://unfccc.int/kyoto_protocol/items/2830.php
| publisher=UNFCCC website
| accessdate =21 May 2011
}}</ref> In ratifying the Kyoto Protocol, most developed countries accepted legally binding commitments to limit their emissions. These first-round commitments expired in 2012.<ref name=kyoto/>
United States President [[George W. Bush]] rejected the treaty on the basis that "it exempts 80% of the world, including major population centres such as China and India, from compliance, and would cause serious harm to the US economy."<ref name=dessai/>{{Rp|5|date=November 2012}}
At the [[2009 United Nations Climate Change Conference|15th UNFCCC Conference of the Parties]], held in 2009 at [[Copenhagen]], several UNFCCC Parties produced the [[Copenhagen Accord]].<ref>{{Cite book
| date = February 2010
| last = Müller | first = Benito
| title = Copenhagen 2009: Failure or final wake-up call for our leaders? EV 49
| page = i
| url = http://www.oxfordenergy.org/wpcms/wp-content/uploads/2011/03/EV49-Copenhagen2009Failureorfinalwake-upcallforourleaders-BenitoMuller-2010.pdf
| format=PDF
| publisher=[[Oxford Institute for Energy Studies]]
| isbn = 978-1-907555-04-6
| accessdate =18 May 2010
}}</ref><ref name="NYT-20150525">{{cite news |last=Rudd |first=Kevin |title=Paris Can't Be Another Copenhagen |url=http://www.nytimes.com/2015/05/26/opinion/kevin-rudd-paris-cant-be-another-copenhagen.html |date=25 May 2015 |work=[[The New York Times]] |accessdate=26 May 2015 }}</ref>
Parties associated with the Accord (140 countries, as of November 2010)<ref name=unep>
{{cite book
|date=November 2010| author=United Nations Environment Programme
|chapter=Technical summary
|title=The Emissions Gap Report: Are the Copenhagen Accord pledges sufficient to limit global warming to {{val|2|u=°C}} or {{val|1.5|u=°C}}? A preliminary assessment (advance copy)
|url= http://www.unep.org/publications/ebooks/emissionsgapreport/pdfs/The_EMISSIONS_GAP_REPORT.pdf
|format=PDF
|publisher=UNEP website
|accessdate=11 May 2011
}} This publication is also available in [http://www.unep.org/publications/ebooks/emissionsgapreport/ e-book format]</ref>{{Rp|9|date=November 2012}}
aim to limit the future increase in global mean temperature to below {{val|2|u=°C}}.<ref>{{cite web
| date = 30 March 2010
| author=UNFCCC
| title = Decision 2/CP. 15 Copenhagen Accord. In: Report of the Conference of the Parties on its fifteenth session, held in Copenhagen from 7 to 19 December 2009. Addendum. Part Two: Action taken by the Conference of the Parties at its fifteenth session
| page = 5
| format=PDF
| url = http://unfccc.int/documentation/documents/advanced_search/items/3594.php?rec=j&priref=600005735#beg
| publisher=United Nations Office at Geneva, Switzerland
| accessdate =17 May 2010
}}</ref> The 16th Conference of the Parties (COP16) was held at [[Cancún]] in 2010. It produced an agreement, not a binding treaty, that the Parties should take urgent action to reduce greenhouse gas emissions to meet a goal of limiting global warming to {{val|2|u=°C}} above pre-industrial temperatures. It also recognized the need to consider strengthening the goal to a global average rise of {{val|1.5|u=°C}}.<ref>{{cite web
| title = Outcome of the work of the Ad Hoc Working Group on long-term Cooperative Action under the Convention
| url = http://unfccc.int/files/meetings/cop_16/application/pdf/cop16_lca.pdf
| publisher=PRESIDENCIA DE LA REPÚBLICA, MÉXICO
| accessdate =12 January 2011
| page = 2
|date=11 December 2010
}}</ref>
===== Evangelicals =====
=== Scientific discussion ===
{{See also|Scientific opinion on climate change|Surveys of scientists' views on climate change}}
There is continuing discussion through published peer-reviewed scientific papers, which are assessed by scientists working in the relevant fields taking part in the [[Intergovernmental Panel on Climate Change]]. The [[scientific consensus]] as of 2013 stated in the [[IPCC Fifth Assessment Report]] is that it "is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century".<ref name="ipcc">{{citation
| author = IPCC
| title = Detection and Attribution of Climate Change
| chapter = Summary for Policymakers
| chapter-url = http://www.ipcc.ch/report/ar5/wg1/
| quote = «It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century» (page 15) and «In this Summary for Policymakers, the following terms have been used to indicate the assessed likelihood of an outcome or a result: (...) extremely likely: 95–100%» (page 2).
}}, in {{Harvnb|IPCC AR5 WG1|2013}}.</ref>
A 2008 report by the U.S. [[National Academy of Sciences]] stated that most scientists by then agreed that observed warming in recent decades was primarily caused by human activities increasing the amount of [[greenhouse gas]]es in the atmosphere.<ref name=nrc2008>
{{cite web
| year = 2008
| title = Understanding and Responding to Climate Change
| publisher=Board on Atmospheric Sciences and Climate, US National Academy of Sciences
| author=NRC
| page = 2
| url = http://dels.nas.edu/resources/static-assets/materials-based-on-reports/booklets/climate_change_2008_final.pdf
| accessdate =9 November 2010
}}</ref> In 2005 the [[Royal Society]] stated that while the overwhelming majority of scientists were in agreement on the main points, some individuals and organizations opposed to the consensus on urgent action needed to reduce greenhouse gas emissions have tried to undermine the science and work of the IPCC.<ref name="royal society misleading arguments">
{{cite book |date=13 April 2005 | author=Royal Society
| contribution=Letter from The Royal Society: A GUIDE TO FACTS AND FICTIONS ABOUT CLIMATE CHANGE: Misleading arguments: Many scientists do not think that climate change is a problem. Some scientists have signed petitions stating that climate change is not a problem. ... There are some individuals and organisations, some of which are funded by the US oil industry, that seek to undermine the science of climate change and the work of the IPCC. They appear motivated in their arguments by opposition to the United Nations Framework Convention on Climate Change and the Kyoto Protocol, which seek urgent action to tackle climate change through a reduction in greenhouse gas emissions.
| title=Economic Affairs – Written Evidence
| series=The Economics of Climate Change, the Second Report of the 2005–2006 session, produced by the UK Parliament House of Lords Economics Affairs Select Committee
|url=http://www.publications.parliament.uk/pa/ld200506/ldselect/ldeconaf/12/12we24.htm
|publisher=UK Parliament website
|accessdate=9 July 2011}} This document is also available in [http://royalsociety.org/Facts-and-fictions-about-climate-change/ PDF format]
</ref> National science academies have called on world leaders for policies to cut global emissions.<ref>{{cite web
| date = May 2009
| author=Academia Brasileira de Ciéncias (Brazil), Royal Society of Canada, Chinese Academy of Sciences, Académie des Sciences (France), Deutsche Akademie der Naturforscher Leopoldina (Germany), Indian National Science Academy, Accademia Nazionale dei Lincei (Italy), Science Council of Japan, Academia Mexicana de Ciencias, Russian Academy of Sciences, Academy of Science of South Africa, Royal Society (United Kingdom), National Academy of Sciences (United States of America)
| title = G8+5 Academies’ joint statement: Climate change and the transformation of energy technologies for a low carbon future| url = http://www.nationalacademies.org/includes/G8+5energy-climate09.pdf| publisher=US National Academies website| accessdate =5 May 2010}}</ref>
===The Bill Nye challenge===
In the scientific literature, there is a [[scientific opinion on climate change|strong consensus that global surface temperatures have increased]] in recent decades and that the trend is caused mainly by human-induced emissions of greenhouse gases.<ref>{{cite journal|author=John Cook et al|url=https://iopscience.iop.org/article/10.1088/1748-9326/11/4/048002/meta|title=Consensus on consensus: a synthesis of consensus estimates on human-caused global warming|accessdate=21 July 2016|date=13 April 2016|journal=Environmental Research Letters|volume=11|issue=4|doi=10.1088/1748-9326/11/4/048002|pages=048002}}</ref> No scientific body of national or international standing [[Scientific opinion on climate change#Opposing|disagrees with this view]].<ref name="The MIT Press"/><ref name=AQAonAAPG>{{cite journal|author=Julie Brigham-Grette|title=Petroleum Geologists' Award to Novelist Crichton Is Inappropriate|journal=[[Eos (journal)|Eos]]|volume=87|issue=36|quote=The AAPG stands alone among scientific societies in its denial of human-induced effects on global warming.|url=http://onlinelibrary.wiley.com/doi/10.1029/2006EO360008/abstract|date=September 2006|accessdate=23 January 2007|format=PDF|ref=harv|display-authors=etal|doi=10.1029/2006EO360008|bibcode=2006EOSTr..87..364B|pages=364}}</ref>
=== Discussion by the public and in popular media ===
{{Main article|Climate change denial|Global warming controversy|Media coverage of climate change}}
[[File:Ms. magazine Cover - Spring 2007.jpg|thumbnail|Global warming was the cover story in this 2007 issue of ''[[Ms. (magazine)|Ms.]]'' magazine]]
The [[global warming controversy]] refers to a variety of disputes, substantially more pronounced in the [[Media coverage of climate change|popular media]] than in the scientific literature,<ref>{{Cite journal| first1 = M.| first2 = J. | title = Balance as bias: global warming and the US prestige press| last1 = Boykoff | journal = Global Environmental Change Part A | volume = 14| issue = 2 | pages = 125–136 | date = July 2004 | doi = 10.1016/j.gloenvcha.2003.10.001| last2 = Boykoff}}</ref><ref name="merchants_doubt">{{cite book | title=Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming | first1=Naomi | last1=Oreskes | author1-link = Naomi Oreskes| first2=Erik | last2=Conway | publisher=Bloomsbury Press | edition=first | isbn=978-1-59691-610-4}}</ref> regarding the nature, causes, and consequences of global warming. The disputed issues include the causes of increased [[instrumental temperature record|global average air temperature]], especially since the mid-20th century, whether this warming trend is unprecedented or within normal climatic variations, whether humankind has contributed significantly to it, and whether the increase is completely or partially an artefact of poor measurements. Additional disputes concern estimates of climate sensitivity, predictions of additional warming, and what the consequences of global warming will be.
By 1990, [[Conservatism in the United States|American conservative]] think tanks had begun challenging the legitimacy of global warming as a social problem. They [[climate change denial|challenged the scientific evidence]], argued that [[benefits of global warming|global warming will have benefits]], and asserted that proposed solutions would do more harm than good.<ref>Aaron M. McCright and Riley E. Dunlap, "Challenging Global Warming as a Social Problem: An Analysis of the Conservative Movement's Counter-Claims", ''Social Problems'', November 2000, Vol. 47 Issue 4, pp 499–522 [http://www.jstor.org/pss/3097132 in JSTOR]</ref> Some people dispute aspects of climate change science.<ref name="royal society misleading arguments"/><ref>{{cite web
===Climate "science" fraud===
| date = July 2009
{{main|Climategate}}
| author=Weart, S.
| title = The Public and Climate Change (cont. – since 1980). Section: After 1988
| url = http://www.aip.org/history/climate/public2.htm
| publisher=American Institute of Physics website
| accessdate =5 May 2010
}}
* {{cite web
| date = n.d.
| author=SEPP
| title = Frequently Asked Questions About Climate Change
| url = http://www.sepp.org/FAQ/faq.html
| archiveurl = https://web.archive.org/web/20080511011611/http://www.sepp.org/FAQ/faq.html
| archivedate = 11 May 2008
| publisher=Science & Environmental Policy Project (SEPP) website
| accessdate =5 May 2010}}</ref> Organizations such as the [[Libertarianism|libertarian]] [[Competitive Enterprise Institute]], conservative commentators, and some companies such as [[ExxonMobil]] have challenged IPCC climate change scenarios, funded scientists who disagree with the scientific consensus, and provided their own projections of the economic cost of stricter controls.<ref>{{Cite news
| last = Begley
| first = Sharon
| title = The Truth About Denial
|work=Newsweek
| date = 13 August 2007
| url = http://www.newsweek.com/id/32482|accessdate =13 August 2007
}}</ref><ref>{{cite web
| title = Royal Society tells Exxon: stop funding climate change denial
| url = https://www.theguardian.com/environment/2006/sep/20/oilandpetrol.business
| first = David
| last = Adams
| work= The Guardian |location=London | date = 20 September 2006
| accessdate =9 August 2007
}}</ref><ref name="MSNBC 01-12">{{Cite news
| title = Exxon cuts ties to global warming skeptics
| url = http://www.msnbc.msn.com/id/16593606
| publisher=MSNBC
| date = 12 January 2007
| accessdate =2 May 2007
}}</ref><ref>{{Cite news
| title = Report: Big Money Confusing Public on Global Warming
| url = http://abcnews.go.com/Technology/Business/story?id=2767979&page=1
| last = Sandell
| first = Clayton
| publisher=ABC
| date = 3 January 2007
| accessdate =27 April 2007}}
</ref> On the other hand, some fossil fuel companies have scaled back their efforts in recent years,<ref>{{Cite news
| url = http://www.usatoday.com/weather/climate/globalwarming/2007-05-18-greenpeace-exxon_N.htm
| title = Greenpeace: Exxon still funding climate skeptics
| date = 18 May 2007
|work=USA Today
| agency=[[Reuters]]
| accessdate =21 January 2010}}</ref> or even called for policies to reduce global warming.<ref>{{Cite press release
| url = http://www.csrwire.com/press/press_release/23395-Global-Warming-Resolutions-at-U-S-Oil-Companies-Bring-Policy-Commitments-from-Leaders-and-Record-High-Votes-at-Laggards
| title = Global Warming Resolutions at U.S. Oil Companies Bring Policy Commitments from Leaders, and Record High Votes at Laggards
| date = 13 May 2004
| publisher=Ceres
| accessdate =4 March 2010}}</ref> Global oil companies have begun to acknowledge climate change exists and is caused by human activities and the burning of fossil fuels.<ref>{{cite web|title=Oil Company Positions on the Reality and Risk of Climate Change|url=http://www.uwosh.edu/es/climate-change/oil-company-positions-on-the-reality-and-risk-of-climate-change|website=Environmental Studies|publisher=University of Oshkosh - Wisconsin|accessdate=27 March 2016}}</ref>
==== Surveys of public opinion ====
{{main article|Public opinion on climate change}}
The world public, or at least people in economically advanced regions, became broadly aware of the global warming problem in the late 1980s. Polling groups began to track opinions on the subject, at first mainly in the United States.<ref>{{cite web| date = February 2015| author=Weart, S.| title = The Public and Climate Change (cont. – since 1980). Section: after 1988| url = http://www.aip.org/history/climate/public2.htm| publisher=American Institute of Physics website| accessdate =18 August 2015}}</ref> The longest consistent polling, by [[Gallup (company)|Gallup]] in the US, found relatively small deviations of 10% or so from 1998 to 2015 in opinion on the seriousness of global warming, but with increasing polarization between those concerned and those unconcerned.<ref>{{cite web | url=http://www.gallup.com/poll/1615/environment.aspx |title=Environment| publisher=Gallup |year=2015 | accessdate=18 August 2015}}</ref>
The first major worldwide poll, conducted by Gallup in 2008-2009 in 127 countries, found that some 62% of people worldwide said they knew about global warming. In the advanced countries of North America, Europe and Japan, 90% or more knew about it (97% in the U.S., 99% in Japan); in less developed countries, especially in Africa, fewer than a quarter knew about it, although many had noticed local weather changes. Among those who knew about global warming, there was a wide variation between nations in belief that the warming was a result of human activities.<ref>{{cite web | url=http://www.gallup.com/poll/117772/Awareness-Opinions-Global-Warming-Vary-Worldwide.aspx|title=Awareness, Opinions about Global Warming Vary Worldwide| last=Pelham | first=Brett | publisher=Gallup |year=2009 | accessdate=18 August 2015}}</ref>
By 2010, with 111 countries surveyed, Gallup determined that there was a substantial decrease since 2007–08 in the number of Americans and Europeans who viewed global warming as a serious threat. In the US, just a little over half the population (53%) now viewed it as a serious concern for either themselves or their families; this was 10 points below the 2008 poll (63%). Latin America had the biggest rise in concern: 73% said global warming is a serious threat to their families.<ref>{{cite web | url=http://www.gallup.com/poll/147203/Fewer-Americans-Europeans-View-Global-Warming-Threat.aspx |title=Fewer Americans, Europeans View Global Warming as a Threat| last=Pugliese | first=Anita | publisher=Gallup | date=20 April 2011 | accessdate=22 April 2011}}</ref> This global poll also found that people are more likely to attribute global warming to human activities than to natural causes, except in the US where nearly half (47%) of the population attributed global warming to natural causes.<ref>
{{cite web
| last = Ray
| first = Julie
|author2=Anita Pugliese
| title = Worldwide, Blame for Climate Change Falls on Humans
| work=Gallup.Com
| date = 22 April 2011
| accessdate =3 May 2011
| url = http://www.gallup.com/poll/147242/Worldwide-Blame-Climate-Change-Falls-Humans.aspx
| quote = People nearly everywhere, including majorities in developed Asia and Latin America, are more likely to attribute global warming to human activities rather than natural causes. The U.S. is the exception, with nearly half (47%) – and the largest percentage in the world – attributing global warming to natural causes.
}}
</ref>
[[File:ad.jpg|center]]
A March–May 2013 survey by [[Pew Research Center for the People & the Press]] polled 39 countries about global threats. According to 54% of those questioned, global warming featured top of the perceived global threats.<ref>{{cite web|publisher=Pew Research Center for the People & the Press|title= Climate Change and Financial Instability Seen as Top Global Threats|url=http://www.pewglobal.org/2013/06/24/climate-change-and-financial-instability-seen-as-top-global-threats/}}</ref> In a January 2013 survey, Pew found that 69% of Americans say there is solid evidence that the Earth's average temperature has gotten warmer over the past few decades, up six points since November 2011 and 12 points since 2009.<ref>[https://web.archive.org/web/20130515145510/http://www.pewresearch.org/2013/04/02/climate-change-key-data-points-from-pew-research/ Climate Change: Key Data Points from Pew Research | Pew Research Center]</ref>
===Past speculation===
A 2010 survey of 14 industrialized countries found that [[Climate change skeptics|skepticism]] about the danger of global warming was highest in Australia, Norway, New Zealand and the United States, in that order, correlating positively with [[List of countries by carbon dioxide emissions|per capita emissions of carbon dioxide]].<ref>{{cite journal|last1=Tranter|first1=Bruce|last2=Booth|first2=Kate|title=Scepticism in a Changing Climate: A Cross-national Study|journal=Global Environmental Change|date=July 2015|volume=33|pages=54–164|doi=10.1016/j.gloenvcha.2015.05.003}}</ref>
== Etymology ==
In the 1950s, research suggested increasing temperatures, and a 1952 newspaper reported "climate change". This phrase next appeared in a November 1957 report in ''[[The Times of Northwest Indiana|The Hammond Times]]'' which described [[Roger Revelle]]'s research into the effects of increasing human-caused {{co2}} emissions on the [[greenhouse effect]], "a large scale global warming, with radical climate changes may result". Both phrases were only used occasionally until 1975, when [[Wallace Smith Broecker]] published a scientific paper on the topic, "Climatic Change: Are We on the Brink of a Pronounced Global Warming?" The phrase began to come into common use, and in 1976 [[Mikhail Budyko]]'s statement that "a global warming up has started" was widely reported.<ref name="Weart 27">{{cite web |first=Spencer R.|last= Weart|authorlink=Spencer R. Weart| title= The Discovery of Global Warming; The Public and Climate Change: Suspicions of a Human-Caused Greenhouse (1956-1969) | website=American Institute of Physics | date=February 2014 | url=http://history.aip.org/climate/public.htm#S2 | accessdate=12 May 2015}}, and [http://www.aip.org/history/climate/public.htm#M_27_ footnote 27]</ref> Other studies, such as a 1971 [[Massachusetts Institute of Technology|MIT]] report, referred to the human impact as "inadvertent climate modification", but an influential 1979 [[National Academy of Sciences]] study headed by [[Jule Gregory Charney|Jule Charney]] followed Broecker in using ''global warming'' for rising surface temperatures, while describing the wider effects of increased {{co2}} as ''climate change''.<ref name=nasacbaon>[[Erik M. Conway|Erik Conway]]. [http://www.nasa.gov/topics/earth/features/climate_by_any_other_name.html "What's in a Name? Global Warming vs. Climate Change"], NASA, 5 December 2008</ref>
[[Richard Lindzen]] wrote in 1992 on the doubtfulness of man-caused warming on Earth.
In 1986 and November 1987, NASA climate scientist [[James Hansen]] gave testimony to Congress on global warming. There were increasing heatwaves and drought problems in the summer of 1988, and when Hansen testified in the Senate on 23 June he sparked worldwide interest.<ref name="Weart Hansen">{{cite web |first=Spencer R.|last= Weart | title= The Discovery of Global Warming; The Public and Climate Change: The Summer of 1988 | website=American Institute of Physics | date=February 2014 | url=http://history.aip.org/climate/public2.htm#L_0575 | accessdate=12 May 2015}}</ref> He said: "global warming has reached a level such that we can ascribe with a high degree of confidence a cause and effect relationship between the greenhouse effect and the observed warming."<ref>U.S. Senate, Committee on Energy and Natural Resources, "Greenhouse Effect and Global Climate Change, part 2" 100th Cong., 1st sess., 23 June 1988, p. 44.</ref> Public attention increased over the summer, and ''global warming'' became the dominant popular term, commonly used both by the press and in public discourse.<ref name=nasacbaon/>
{{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"/>}}
In a 2008 NASA article on usage, [[Erik M. Conway]] defined ''global warming'' as "the increase in Earth’s average surface temperature due to rising levels of greenhouse gases", while ''climate change'' was "a long-term change in the Earth’s climate, or of a region on Earth." As effects such as changing patterns of rainfall and rising sea levels would probably have more impact than temperatures alone, he considered ''global climate change'' a more scientifically accurate term, and like the [[Intergovernmental Panel on Climate Change]], the NASA website would emphasize this wider context.<ref name=nasacbaon/>
== See also ==
{{portal|Global warming|Science}}
{{Wikipedia books}}
* [[Anthropocene]]
* [[Climate change and agriculture]]
* [[Effects of global warming on oceans]]
[[Image:Teller_Card_100dpi.jpg|600px|center|thumb| Global Warming Petition]]
* [[Environmental impact of the coal industry]]
* [[Geologic temperature record]]
* [[Global cooling]]
* [[Glossary of climate change]]
* [[Greenhouse gas emissions accounting]]
* [[History of climate change science]]
* [[Holocene extinction]]
* [[Index of climate change articles]]
* [[Scientific opinion on climate change]]
*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>
[[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>
===Al Gore's claims===
== Notes ==
{{notelist}}
== Citations ==
<!-- ** NOTE TO EDITORS: don't add <ref>s to reflist; there's no point for them. -->
{{Reflist|30em}}
*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.
== References ==
<!-- NOTE TO EDITORS:
* please add new entries in alphabetical order of author's last name.
* These are the 'general references' to the source; do not incorporate quotes, etc. here.
* 'citation' works better than 'cite xxx'.
-->
{{refbegin|30em}}
*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.
* {{citation
| title=An updated review of developments in climate science research since IPCC AR4. A report by the AVOID consortium
| author=Good, P.
| ref=CITEREFGoodothers2010
| year=2010
| url=http://archive.theccc.org.uk/aws2/4th%20Budget/fourthbudget_supporting_research_reviewofclimatescience_developements_since_IPPC_AR4.pdf
| publisher=Committee on Climate Change
| location=London, UK
|display-authors=etal}}, p. 14. [http://www.theccc.org.uk/publication/the-fourth-carbon-budget-reducing-emissions-through-the-2020s-2/ Report website.]
*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.
* {{citation
| author=IAP
| title=Interacademy Panel (IAP) Member Academies Statement on Ocean Acidification
| date=June 2009
| url=http://www.interacademies.net/10878/13951.aspx
}}, Secretariat: TWAS (the Academy of Sciences for the Developing World), Trieste, Italy.
*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.
* {{Cite book
|year=2009
|title=World Energy Outlook 2009
|publisher=International Energy Agency (IEA)
|location=Paris, France
|author=IEA
|isbn=978-92-64-06130-9
|url=http://www.worldenergyoutlook.org/media/weowebsite/2009/WEO2009.pdf
|ref=harv
}}
*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.
* {{Cite book
| year = 2007
| author = IPCC AR4 SYR
| author-link = Intergovernmental Panel on Climate Change
| title = Climate Change 2007: Synthesis Report
| series = Contribution of Working Groups I, II and III to the [[IPCC Fourth Assessment Report|Fourth Assessment Report]] of the Intergovernmental Panel on Climate Change
| editor = Core Writing Team |editor2=Pachauri, R.K |editor3=Reisinger, A.
| publisher = IPCC
| url= http://www.ipcc.ch/publications_and_data/ar4/syr/en/contents.html
| isbn = 92-9169-122-4
| ref = harv
}}
*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.
* {{Cite book
| year = 2007
| author = IPCC AR4 WG1
| title = Climate Change 2007: The Physical Science Basis
| series = Contribution of Working Group I to the [[IPCC Fourth Assessment Report|Fourth Assessment Report]] of the Intergovernmental Panel on Climate Change
| editor = Solomon, S. |editor2=Qin, D. |editor3=Manning, M. |editor4=Chen, Z. |editor5=Marquis, M. |editor6=Averyt, K.B. |editor7=Tignor, M. |editor8=Miller, H.L.
| publisher = Cambridge University Press
| url = http://www.ipcc.ch/publications_and_data/ar4/wg1/en/contents.html
| isbn = 978-0-521-88009-1
| ref = harv
}} (pb: {{ISBNT|978-0-521-70596-7}})
*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.
* {{Cite book
| year = 2007
| author = IPCC AR4 WG2
| title = Climate Change 2007: Impacts, Adaptation and Vulnerability
| series = Contribution of Working Group II to the [[IPCC Fourth Assessment Report|Fourth Assessment Report]] of the Intergovernmental Panel on Climate Change
| editor = Parry, M.L. |editor2=Canziani, O.F. |editor3=Palutikof, J.P. |editor4=van der Linden, P.J. |editor5=Hanson, C.E.
| publisher = Cambridge University Press
| url = http://www.ipcc.ch/publications_and_data/ar4/wg2/en/contents.html
| isbn = 978-0-521-88010-7
| ref = harv
}} (pb: {{ISBNT|978-0-521-70597-4}})
*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.
* {{Cite book
| year = 2007
| author = IPCC AR4 WG3
| title = Climate Change 2007: Mitigation of Climate Change
| series = Contribution of Working Group III to the [[IPCC Fourth Assessment Report|Fourth Assessment Report]] of the Intergovernmental Panel on Climate Change
| editor = Metz, B. |editor2=Davidson, O.R. |editor3=Bosch, P.R. |editor4=Dave, R. |editor5=Meyer, L.A.
| publisher = Cambridge University Press
| url = http://www.ipcc.ch/publications_and_data/ar4/wg3/en/contents.html
| isbn = 978-0-521-88011-4
| ref = harv
}} (pb: {{ISBNT|978-0-521-70598-1}})
*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.
* {{citation
| year=2013
| author=IPCC AR5 WG1
| editor=Stocker, T.F.| title=Climate Change 2013: The Physical Science Basis. Working Group 1 (WG1) Contribution to the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report (AR5)
| url=http://www.ipcc.ch/report/ar5/wg1/
| publisher=Cambridge University Press
| ref=harv
|display-editors=etal}}. [http://www.climatechange2013.org/ Climate Change 2013 Working Group 1 website.]
* {{citation
| year=2014
| author=IPCC AR5 WG2 A
| editor=Field, C.B.| title=Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects (GSA). Contribution of Working Group II (WG2) to the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC)
| url=http://www.ipcc.ch/report/ar5/wg2/
| publisher=Cambridge University Press
| ref=harv
|display-editors=etal}}. Archived [https://web.archive.org/web/20140625062244/http://ipcc.ch/report/ar5/wg2/ 25 June 2014.]
* {{citation
|year=2014
|author=IPCC AR5 WG3
|editor=Edenhofer, O.
|title=Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III (WG3) to the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC)
|url=http://www.ipcc.ch/report/ar5/wg3/
|publisher=Cambridge University Press
|ref=harv
|display-editors=etal
|deadurl=yes
|archiveurl=https://web.archive.org/web/20141127222605/http://www.ipcc.ch/report/ar5/wg3/
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|df=dmy
}}. Also available at [https://web.archive.org/web/20141230092610/http://mitigation2014.org/report/publication/ mitigation2014.org].
* {{Cite journal
| year = 1996
| author = IPCC SAR SYR
| title = Climate Change 1995: A report of the Intergovernmental Panel on Climate Change
| series = [[IPCC Second Assessment Report|Second Assessment Report]] of the Intergovernmental Panel on Climate Change
| publisher = IPCC
| ref = harv
}} [http://www.ipcc.ch/pdf/climate-changes-1995/ipcc-2nd-assessment/2nd-assessment-en.pdf pdf]. <small>The "Full Report", consisting of "The IPCC Second Assessment Synthesis of Scientific-Technical Information Relevant to Interpreting Article 2 of the UN Framework Convention on Climate Change" and the Summaries for Policymakers of the three Working Groups.</small>
*1. The Film is a political work and promotes only one side of the argument.
* {{Cite book
| year = 1996
| author = IPCC SAR WG3
| title = Climate Change 1995: Economic and Social Dimensions of Climate Change
| series = Contribution of Working Group III to the [[IPCC Second Assessment Report|Second Assessment Report]] of the Intergovernmental Panel on Climate Change
| editor = Bruce, J.P. |editor2=Lee, H. |editor3=Haites, E.F.
| publisher = Cambridge University Press
| url =
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| ref = harv
}} (pb: {{ISBNT|0-521-56854-4}}) [http://www.ipcc.ch/ipccreports/sar/wg_III/ipcc_sar_wg_III_full_report.pdf pdf].
*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.
* {{Cite journal
| author=IPCC SREX
| year=2012
| title=Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX)
| editors=Field, C.B.| url=http://ipcc-wg2.gov/SREX/report/full-report/
| publisher=Cambridge University Press
| ref=harv
| display-editors=etal}}. Summary for Policymakers [http://www.ipcc.ch/publications_and_data/publications_and_data_reports.shtml Summary for Policymakers].
*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>
* {{Cite book
| year = 2001
| author = IPCC TAR WG1
| title = Climate Change 2001: The Scientific Basis
| series = Contribution of Working Group I to the [[IPCC Third Assessment Report|Third Assessment Report]] of the Intergovernmental Panel on Climate Change
| editor = Houghton, J.T. |editor2=Ding, Y. |editor3=Griggs, D.J. |editor4=Noguer, M. |editor5=van der Linden, P.J. |editor6=Dai, X. |editor7=Maskell, K. |editor8=Johnson, C.A.
| publisher = Cambridge University Press
| url = http://www.grida.no/publications/other/ipcc%5Ftar/?src=/climate/ipcc_tar/wg1/index.htm
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* {{Cite book
| year = 2001
| author = IPCC TAR WG2
| title = Climate Change 2001: Impacts, Adaptation and Vulnerability
| series = Contribution of Working Group II to the [[IPCC Third Assessment Report|Third Assessment Report]] of the Intergovernmental Panel on Climate Change
| editor = McCarthy, J. J. |editor2=Canziani, O. F. |editor3=Leary, N. A. |editor4=Dokken, D. J. |editor5=White, K. S.
| publisher = Cambridge University Press
| url = http://www.grida.no/publications/other/ipcc%5Ftar/?src=/climate/ipcc_tar/wg2/index.htm
| isbn = 0-521-80768-9
| ref = harv
}} (pb: {{ISBNT|0-521-01500-6}})
* {{Cite book
| year = 2001
| author = IPCC TAR WG3
| title = Climate Change 2001: Mitigation
| series = Contribution of Working Group III to the [[IPCC Third Assessment Report|Third Assessment Report]] of the Intergovernmental Panel on Climate Change
| editor = Metz, B. |editor2=Davidson, O. |editor3=Swart, R. |editor4=Pan, J.
| publisher = Cambridge University Press
| url = http://www.grida.no/publications/other/ipcc%5Ftar/?src=/climate/ipcc_tar/wg3/index.htm
| isbn = 0-521-80769-7
| ref = harv
}} (pb: {{ISBNT|0-521-01502-2}})
* {{Include-USGov
| agency=US Global Change Research Program ([[USGCRP]])
| source={{citation
| author=NCADAC
| date=11 January 2013
| title=Federal Advisory Committee Draft Climate Assessment. A report by the National Climate Assessment Development Advisory Committee (NCADAC)
| url=http://ncadac.globalchange.gov/
| location=Washington, D.C., USA
}}
}}
: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."
* {{citation
| author=USGCRP
| ref=CITEREFUSGCRP2015
| year=2015
| title=Glossary
| publisher=U.S. Global Change Research Program (USGCRP)
| location=Washington, DC, USA
| url=http://www.globalchange.gov/climate-change/glossary
| accessdate=20 January 2014
}}. [https://web.archive.org/web/*/http://www.globalchange.gov/climate-change/glossary Archived url].
* {{citation
|author=National Research Council
|year=2011
|title=Climate Stabilization Targets: Emissions, Concentrations, and Impacts over Decades to Millennia
|url=http://www.nap.edu/catalog.php?record_id=12877
|publisher=National Academies Press
|location=Washington, D.C., USA
|deadurl=yes
|archiveurl=https://web.archive.org/web/20140327000317/http://www.nap.edu/catalog.php?record_id=12877
|archivedate=27 March 2014
|df=dmy
}}
===Scientists===
* {{Cite book
| publisher= The National Academies Press
| isbn = 0-309-14588-0
| title = America's Climate Choices: Panel on Advancing the Science of Climate Change;
| author = National Research Council
| location = Washington, D.C.
| year = 2010
| url = http://www.nap.edu/catalog.php?record_id=12782
| ref= harv
}}
* {{citation
| author=Parris, A.
| ref=CITEREFParrisothers2012
| date=6 December 2012
| title=Global Sea Level Rise Scenarios for the US National Climate Assessment. NOAA Tech Memo OAR CPO-1
| url=http://cpo.noaa.gov/sites/cpo/Reports/2012/NOAA_SLR_r3.pdf
| publisher=NOAA Climate Program Office
|display-authors=etal}}. Report [http://cpo.noaa.gov/AllNews/TabId/315/ArtMID/668/ArticleID/80/Global-Sea-Level-Rise-Scenarios-for-the-United-States-National-Climate-Assessment.aspx website.]
{|
* {{citation
| valign="top" width="35%"|
| title=UNEP Emerging Issues: Environmental Consequences of Ocean Acidification: A Threat to Food Security
| author=UNEP
| year=2010
| url=http://www.unep.org/dewa/Portals/67/pdf/Ocean_Acidification.pdf
* [[Richard Lindzen]]
| publisher=United Nations Environment Programme (UNEP)
| location=Nairobi, Kenya
}}. [http://www.unepmap.org/index.php?module=news&action=detail&id=109 Report summary.]
| valign="top" width="33%"|
* {{Include-USGov
| agency=US Global Change Research Program ([[USGCRP]])
| source={{Cite book
| author=USGCRP
| year=2009
| title=Global Climate Change Impacts in the United States
|editor1=Karl, T.R. |editor2=Melillo. J. |editor3=Peterson, T. |editor4=Hassol, S.J. | publisher=Cambridge University Press
| isbn=978-0-521-14407-0
| url= http://www.globalchange.gov/publications/reports/scientific-assessments/us-impacts
| ref=harv
}}. Public-domain status of this report can be found on p.4 of [http://library.globalchange.gov/downloads/download.php?id=102 PDF]
}}
====Hal Lewis====
* {{Cite journal
| year=2008
| title=Understanding and responding to climate change: Highlights of National Academies Reports, 2008 edition, produced by the US National Research Council (US NRC)
| publisher=National Academy of Sciences
| location=Washington, D.C., USA
| author=US NRC
| url=http://dels.nas.edu/Materials/Booklets/Lines-of-Evidence
| ref=harv
}}
===Critique of the "Hockey Stick" reconstruction===
* {{Cite journal
| author=US NRC
| year=2012
| title=Climate Change: Evidence, Impacts, and Choices
| url=http://www.scribd.com/doc/98458016/Climate-Change-Lines-of-Evidence
| publisher=US National Research Council (US NRC)
| ref=harv
}} Also available as [http://nas-sites.org/americasclimatechoices/files/2012/06/19014_cvtx_R1.pdf PDF]
*Dalmia, Shikha (December 2, 2009). [http://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.
* {{citation
| author=Zeebe, R.E.
| ref=CITEREFZeebe2012
| date=May 2012
| title= History of Seawater Carbonate Chemistry, Atmospheric CO<sub>2</sub>, and Ocean Acidification
| url=http://www.soest.hawaii.edu/oceanography/faculty/zeebe_files/Publications/ZeebeAR12.pdf
| work= Annual Review of Earth and Planetary Sciences
| volume=40
| doi=10.1146/annurev-earth-042711-105521
|bibcode = 2012AREPS..40..141Z
| pages=141–165}}.
{{refend}}
== Further reading ==
{{Refbegin|30em}}
* {{Cite book | title = Financial Risks of Climate Change|author=Association of British Insurers|date=June 2005| url = http://www.climatewise.org.uk/storage/610/financial_risks_of_climate_change.pdf|format=PDF}}
* {{Cite journal|last=Ammann|first=Caspar|year=2007 | title = Solar influence on climate during the past millennium: Results from transient simulations with the NCAR Climate Simulation Model|journal=Proceedings of the National Academy of Sciences of the United States of America|volume=104|issue=10| pages =3713–3718| url = http://www.pnas.org/cgi/reprint/104/10/3713.pdf|format=PDF|quote=Simulations with only natural forcing components included yield an early 20th century peak warming of {{val|p=≈|0.2|u=°C}} (≈1950 AD), which is reduced to about half by the end of the century because of increased volcanism|doi=10.1073/pnas.0605064103|pmid=17360418|pmc=1810336| bibcode=2007PNAS..104.3713A|display-authors=etal}}
* {{Cite journal|last1=Barnett|first1=TP|last2=Adam|first2=JC|last3=Lettenmaier|first3=DP|date = 17 November 2005 | title = Potential impacts of a warming climate on water availability in snow-dominated regions|journal=Nature|volume=438|issue=7066| pages =303–309| url = http://www.nature.com/nature/journal/v438/n7066/abs/nature04141.html|doi=10.1038/nature04141|format=abstract|pmid=16292301| bibcode=2005Natur.438..303B}}
* {{Cite journal|date = 7 December 2006 | title = Climate-driven trends in contemporary ocean productivity|journal=Nature|volume=444|issue=7120| pages =752–755| url = http://www.icess.ucsb.edu/~davey/MyPapers/Behrenfeld_etal_2006_Nature.pdf|format=PDF|doi=10.1038/nature05317|pmid=17151666|last1=Behrenfeld|first1=MJ|last2=O'malley|first2=RT|last3=Siegel|first3=DA|last4=Mcclain|first4=CR|last5=Sarmiento|first5=JL|last6=Feldman|first6=GC|last7=Milligan|first7=AJ|last8=Falkowski|first8=PG|last9=Letelier|first9=RM|displayauthors=3| bibcode=2006Natur.444..752B}}
* {{Cite journal|first=Onelack|last=Choi|author2=Fisher, Ann|date = May 2005| title = The Impacts of Socioeconomic Development and Climate Change on Severe Weather Catastrophe Losses: Mid-Atlantic Region (MAR) and the U.S|journal=Climate Change|volume=58|issue=1–2| pages =149–170|doi=10.1023/A:1023459216609}}
* {{Cite book|last=Dyurgerov|first=Mark B.|author2=Meier, Mark F.|year=2005 | title = Glaciers and the Changing Earth System: a 2004 Snapshot|publisher=Institute of Arctic and Alpine Research Occasional Paper #58| url = http://instaar.colorado.edu/other/download/OP58_dyurgerov_meier.pdf|format=PDF|issn=0069-6145}}
* {{Cite journal|date = 4 August 2005 | title = Increasing destructiveness of tropical cyclones over the past 30 years|journal=Nature|volume=436|issue=7051| pages =686–688|url=ftp://texmex.mit.edu/pub/emanuel/PAPERS/NATURE03906.pdf|format=PDF|doi=10.1038/nature03906|pmid=16056221|last1=Emanuel|first1=KA|bibcode=2005Natur.436..686E}}
* {{Cite journal|author1=[[James E. Hansen]]|author2=Larissa Nazarenko|author3=Reto Ruedy|author4=Makiko Sato|author5=Josh Willis|author6=Anthony Del Genio|author7=Dorothy Koch|author8=Andrew Lacis|author9=Ken Lo|author10=Surabi Menon|author11=Tica Novakov|author12=Judith Perlwitz|author13=Gary Russell|author14=Gavin A. Schmidt|author15=Nicholas Tausnev|date = 3 June 2005 | title = Earth's Energy Imbalance: Confirmation and Implications|journal=Science|volume=308|issue=5727| pages =1431–1435| url = http://science.sciencemag.org/content/308/5727/1431.abstract|format=PDF|doi=10.1126/science.1110252|pmid=15860591| bibcode=2005Sci...308.1431H}}
* {{Cite journal|last=Hinrichs|first=Kai-Uwe|author2=Hmelo, Laura R.|author3=Sylva, Sean P.|date = 21 February 2003 | title = Molecular Fossil Record of Elevated Methane Levels in Late Pleistocene Coastal Waters|journal=Science|volume=299|issue=5610| pages =1214–1217|doi=10.1126/science.1079601|pmid=12595688|bibcode=2003Sci...299.1214H}}
* {{Cite news|last=Hirsch|first=Tim|publisher=BBC | url = http://news.bbc.co.uk/2/hi/science/nature/4604332.stm | title = Plants revealed as methane source|date = 11 January 2006}}
* {{Cite journal|last=Hoyt|first=Douglas V.|author2=Schatten, Kenneth H.|date=November 1993 | title = A discussion of plausible solar irradiance variations, 1700–1992|journal=Journal of Geophysical Research|volume=98|issue=A11| pages =18,895–18,906| bibcode = 1993JGR....9818895H|doi=10.1029/93JA01944}}
* {{Cite book
| year = 2001
| author = IPCC TAR SYR
| title = Climate Change 2001: Synthesis Report
| series = Contribution of Working Groups I, II, and III to the [[IPCC Third Assessment Report|Third Assessment Report]] of the Intergovernmental Panel on Climate Change
|editor1=Watson, R. T. |editor2=the Core Writing Team | publisher = Cambridge University Press
| url = http://www.ipcc.ch/ipccreports/tar/vol4/english/index.htm
| isbn = 0-521-80770-0
}} (pb: {{ISBNT|0-521-01507-3}})
*{{Cite journal|last1=Ivanova |first1=Diana |last2= Stadler|first2= Konstantin|last3= Steen-Olsen|first3= Kjartan |last4= Wood |first4= Richard|last5= Vita|first5= Gibran |last6= Tukker|first6= Arnold|last7= Hertwich|first7=Edgar G. |date = 18 December 2015 | title = Environmental Impact Assessment of Household Consumption |journal=[[Journal of Industrial Ecology]] |volume= 20 |issue=3| pages =526–536 | url = |doi=10.1111/jiec.12371|format=|pmid=| bibcode=}}
* {{cite journal
|author1=Jamet, S. |author2=J. Corfee-Morlot
| date=7 April 2009
| title=Assessing the Impacts of Climate Change: A Literature Review
| work=OECD Economics Department Working Papers
| issue=691
| publisher=OECD
| doi=10.1787/224864018517
| url=http://www.oecd-ilibrary.org/economics/assessing-the-impacts-of-climate-change_224864018517
}}. Paper at [https://ideas.repec.org/p/oec/ecoaaa/691-en.html IDEAS].
* {{Cite journal|last=Karnaukhov|first=A. V.|year=2001 | title = Role of the Biosphere in the Formation of the Earth's Climate: The Greenhouse Catastrophe|journal=Biophysics|volume=46|issue=6| url = http://avturchin.narod.ru/Green.pdf|format=PDF}}
* {{Cite book|last=Kenneth|first=James P.|date = 14 February 2003 | title = Methane Hydrates in Quaternary Climate Change: The Clathrate Gun Hypothesis|publisher=American Geophysical Union| url = http://onlinelibrary.wiley.com/doi/10.1002/9781118665138.ch0/summary}}
* {{Cite news|last=Keppler|first=Frank| title = Global Warming – The Blame Is not with the Plants| url = http://www.mpg.de/english/illustrationsDocumentation/documentation/pressReleases/2006/pressRelease200601131/index.html|publisher=Max Planck Society|date = 18 January 2006|display-authors=etal}}
* {{Cite journal | title = The effect of increasing solar activity on the Sun's total and open magnetic flux during multiple cycles: Implications for solar forcing of climate|last=Lean|first=Judith L.|author2=Wang, Y.M.|author3=Sheeley, N.R.|date = December 2002|journal=Geophysical Research Letters|volume=29|issue=24| bibcode = 2002GeoRL..29x..77L|doi=10.1029/2002GL015880|page =2224}}
* {{Cite book|last=Lerner|first=K. Lee|author2=Lerner, K. Lee |author3=Wilmoth, Brenda | title = Environmental issues: essential primary sources|publisher=Thomson Gale|date = 26 July 2006|isbn = 1-4144-0625-8}}
* {{Cite book|last=McKibben|first=Bill | title = The Global Warming Reader |url=http://www.orbooks.com/our-books/gwr/ |publisher=[[OR Books]]|year = 2011|isbn = 978-1-935928-36-2}}
* {{Cite journal|date = 28 July 2005 | title = Climate: How unusual is today's solar activity?|journal=Nature|volume=436|issue=7012| pages =1084–1087| url =http://www.nature.com/nature/journal/v436/n7050/abs/nature04045.html|format=PDF|doi=10.1038/nature04045|pmid=16049429|last1=Muscheler|first1=R|last2=Joos|first2=F|last3=Müller|first3=SA|last4=Snowball|first4=I| bibcode=2005Natur.436E...3M}}
* {{Cite journal|last=Oerlemans|first=J.|date = 29 April 2005 | title = Extracting a Climate Signal from 169 Glacier Records|journal=Science|volume=308|issue=5722| pages =675–677| url = http://www.cosis.net/abstracts/EGU05/04572/EGU05-J-04572.pdf|format=PDF|doi=10.1126/science.1107046|pmid=15746388| bibcode=2005Sci...308..675O}}
* {{Cite journal| title = Climate change and the recent emergence of bluetongue in Europe|journal=Nature Reviews Microbiology|volume=3|issue=2| pages =171–181|date=February 2005|doi=10.1038/nrmicro1090| url = http://www.nature.com/nrmicro/journal/v3/n2/abs/nrmicro1090_fs.html|format=abstract|pmid=15685226|last1=Purse|first1=BV|last2=Mellor|first2=PS|last3=Rogers|first3=DJ|last4=Samuel|first4=AR|last5=Mertens|first5=PP|last6=Baylis|first6=M}}
* {{Cite news|last=Revkin|first=Andrew C|date = 5 November 2005 | title = Rise in Gases Unmatched by a History in Ancient Ice|work=The New York Times| url = http://www.nytimes.com/2005/11/25/science/earth/25core.html?ei=5090&en=d5078e33050b2b0c&ex=1290574800&adxnnl=1&partner=rssuserland&emc=rss}}
* {{cite web | title = Joint science academies' statement: Global response to climate change|author=[[Royal Society]]| url = http://royalsociety.org/Joint-science-academies-statement-Global-response-to-climate-change/|accessdate=19 April 2009|year=2005}}
* {{cite book |author1=Roulstone, Ian |author2=Norbury, John |title=Invisible in the Storm: the role of mathematics in understanding weather |url=https://books.google.com/books/about/Invisible_in_the_Storm.html?id=qnMrFEHMrWwC&redir_esc=y|year=2013 |publisher=Princeton University Press}} (see Chapter 8)
* {{Cite book|last=Ruddiman|first=William F.|authorlink=William Ruddiman|date = 15 December 2005 | title = Earth's Climate Past and Future|location=New York|publisher=Princeton University Press|isbn = 0-7167-3741-8| url = http://www.whfreeman.com/ruddiman/}}
* {{Cite book|last=Ruddiman|first=William F.|date = 1 August 2005 | title = Plows, Plagues, and Petroleum: How Humans Took Control of Climate|location=New Jersey|publisher=Princeton University Press|isbn = 0-691-12164-8}}
* {{cite encyclopedia |last1=Schelling |first1=Thomas C. |authorlink= Thomas Schelling |editor= [[David R. Henderson]] (ed.) |encyclopedia=[[Concise Encyclopedia of Economics]] |title=Greenhouse Effect |url=http://www.econlib.org/library/Enc1/GreenhouseEffect.html |year=2002 |edition= 1st |publisher=[[Library of Economics and Liberty]] }} {{OCLC|317650570|50016270|163149563}}
* {{Cite journal|authorlink=Sami Solanki|last1=Solanki|first1=SK|last2=Usoskin|first2=IG|last3=Kromer|first3=B|last4=Schüssler|first4=M|last5=Beer|first5=J|date = 23 October 2004 | title = Unusual activity of the Sun during recent decades compared to the previous 11,000 years|journal=Nature|volume=431| pages =1084–1087| url = http://cc.oulu.fi/%7Eusoskin/personal/nature02995.pdf|format=PDF|doi=10.1038/nature02995|pmid=15510145|issue=7012| bibcode=2004Natur.431.1084S}}
* {{Cite journal|author=Solanki, Sami K.|date = 28 July 2005 | title = Climate: How unusual is today's solar activity? (Reply)|journal=Nature|volume=436|issue=7050| pages =E4–E5| url = http://cc.oulu.fi/%7Eusoskin/personal/sola_nature05.pdf|format=PDF|doi=10.1038/nature04046| bibcode=2005Natur.436E...4S|display-authors=etal}}
* {{Cite journal|last=Sowers|first=Todd|date = 10 February 2006|journal=Science|volume=311|issue=5762| pages =838–840 | title = Late Quaternary Atmospheric CH<sub>4</sub> Isotope Record Suggests Marine Clathrates Are Stable|doi=10.1126/science.1121235|pmid=16469923|bibcode=2006Sci...311..838S}}
* {{Cite journal|author=Svensmark, Henrik|date = 8 February 2007 | title = Experimental evidence for the role of ions in particle nucleation under atmospheric conditions|journal=Proceedings of the Royal Society A|volume=463|issue=2078| pages =385–396|publisher=FirstCite Early Online Publishing|doi=10.1098/rspa.2006.1773|bibcode=2007RSPSA.463..385S|display-authors=etal}}''(online version requires registration)''
* {{Cite journal|last1=Walter|first1=KM|last2=Zimov|first2=SA|last3=Chanton|first3=JP|authorlink3=Jeff Chanton|last4=Verbyla|first4=D|last5=Chapin|first5=F. S., 3rd|date = 7 September 2006 | title = Methane bubbling from Siberian thaw lakes as a positive feedback to climate warming|journal=Nature|volume=443|issue=7107| pages =71–75|doi=10.1038/nature05040|pmid=16957728|bibcode=2006Natur.443...71W}}
* {{Cite journal|last=Wang|first=Y.-M.|last2=Lean |first2=J.L.|first3=N. R.|last3=Sheeley|date = 20 May 2005 | title = Modeling the sun's magnetic field and irradiance since 1713|journal=Astrophysical Journal|volume=625|issue=1| pages =522–538| url = http://climatesci.colorado.edu/publications/pdf/Wang_2005.pdf|format=PDF|doi=10.1086/429689| bibcode=2005ApJ...625..522W}}
* {{Cite journal|last=Wiens|first=John J. |date = 8 December 2016 | title =Climate-Related Local Extinctions Are Already Widespread among Plant and Animal Species |journal=[[PLOS Biology]]|volume=14 |issue=12| pages =e2001104| url =http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.2001104 |doi=10.1371/journal.pbio.2001104| bibcode=}}
*Hausfather, Zeke. [http://therealnews.com/t2/story:18075:No-%27Pause%27-in-Global-Warming%3A-Oceans-Heating-Up-and-Sea-Levels-Rising-at-%0D%0AAlarming-Pace No 'Pause' in Global Warming: Oceans Heating Up and Sea Levels Rising at Alarming Pace] (January 2017). "[[UC-Berkeley]] climate scientist Zeke Hausfather details the findings of a new report that confirms [[NOAA]] data about climate change."
{{Refend}}
== External links ==
{{Sister project links|wikt=Global warming|b=Climate Change|q=Global warming|s=Global warming|commons=Global warming|n=Category:Climate change|v=Global warming}}
{{sister project|project=Wikiversity
|text=[[v:How things work college course/Global warming quizzes|Wikiversity hosts a testbank of quizzes to assess students' understanding of this article]]}}
{{Library resources box
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;Research
* [http://www.giss.nasa.gov/ NASA Goddard Institute for Space Studies] – Global change research
* [http://www.ncdc.noaa.gov/sotc NOAA State of the Climate Report] – U.S. and global monthly state of the climate reports
* [http://dels.nas.edu/Climate/Climate-Change/Reports-Academies-Findings Climate Change at the National Academies] – repository for reports
* [http://www.nature.com/nclimate/index.html Nature Reports Climate Change] – free-access web resource
* [http://www.metoffice.gov.uk/climatechange/ Met Office: Climate change] – UK National Weather Service
* [http://edgcm.columbia.edu/ Educational Global Climate Modelling] (EdGCM) – research-quality climate change simulator
* [http://www-pcmdi.llnl.gov/projects/pcmdi/index.php Program for Climate Model Diagnosis and Intercomparison] – develops and releases standardized models such as CMIP3 (AR4) and CMIP5 (AR5)
;Educational
[http://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>[http://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>
* [http://climate.nasa.gov/evidence/ NASA: Climate change: How do we know?]
* [http://green.nationalgeographic.com/environment/global-warming/gw-overview.html What Is Global Warming?] – National Geographic
* [http://www.ncdc.noaa.gov/indicators/ Global Climate Change Indicators] – NOAA
* [http://www.climate.gov/#understandingClimate NOAA Climate Services] – NOAA
* [http://www.skepticalscience.com/ Skeptical Science: Getting skeptical about global warming skepticism]
* [http://www.globalwarmingart.com/ Global Warming Art, a collection of figures and images]
* [http://www.ncdc.noaa.gov/oa/climate/globalwarming.html Global Warming Frequently Asked Questions] – NOAA
* [http://www.ucar.edu/news/features/climatechange/faqs.jsp Understanding Climate Change – Frequently Asked Questions] – UCAR
* [http://cgs.illinois.edu/content/global-warming-resources Global Warming: Center for Global Studies at the University of Illinois]
* [http://climate.jpl.nasa.gov/ Global Climate Change: NASA's Eyes on the Earth] – NASA, JPL, Caltech
* [http://www.jpl.nasa.gov/news/news.php?feature=6701 Global Carbon Dioxide Circulation] ([[NASA]]; December 13, 2016)
* [http://ourworld.unu.edu/en/series/climate/ OurWorld 2.0] – United Nations University
* [http://www.c2es.org/ Center for Climate and Energy Solutions] – business and politics
* [http://www.eaa-phev.org/wiki/Climate_change Climate change - EAA-PHEV Wiki] – electric vehicles fuelled with electricity from wind or solar power will reduce greenhouse gas pollution from the transportation sector
* [http://www.epa.gov/climatechange/indicators.html Climate Change Indicators in the United States] – report by United States Environmental Protection Agency, 80 pp.
* [http://www.worldbank.org/en/news/feature/2012/11/18/Climate-change-report-warns-dramatically-warmer-world-this-century The World Bank - Climate Change - A 4 Degree Warmer World - We must and can avoid it]
* [https://www.youtube.com/watch?v=lft4OHt0-gE A world with this much CO²: lessons from 4 million years ago]
* [http://geology.com/sea-level-rise/ Global Sea Level Rise Map]
* [http://www.emdat.be/ International Disaster Database]
* [http://www.cop21paris.org/ Paris Climate Conference]
==External links==
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