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{{For|past [[climate change]]|Paleoclimatology|Geologic temperature record}}
{{Pp-semi-indef}}{{pp-move-indef}}
{{featured article}}

{{multiple image|align=right|direction=vertical|width=220|image1=Instrumental Temperature Record.png|caption1=Global mean surface temperature difference relative to the 1961–1990 average|image2=Satellite Temperatures.png|caption2=Comparison of ground based (blue) and satellite based (red: [[University of Alabama in Huntsville|UAH]]; green: [[Remote Sensing Systems|RSS]]) records of temperature variations since 1979. Trends plotted since January 1982.|image3=GISS temperature 2000-09 lrg.png|image4=GISS temperature palette.png|caption4=Mean surface temperature change for the period 2000 to 2009 relative to the average temperatures from 1951 to 1980.<ref>[http://earthobservatory.nasa.gov/IOTD/view.php?id=42392 2009 Ends Warmest Decade on Record]. [[NASA]] Earth Observatory Image of the Day, January 22, 2010.</ref>}}

'''Global warming''' is the increase in the [[Instrumental temperature record|average temperature]] of [[Earth]]'s near-surface air and oceans since the mid-[[20th century]] and its projected continuation. According to a report by the [[Intergovernmental Panel on Climate Change]] (IPCC) global surface temperature increased 0.74&nbsp;±&nbsp;0.18&nbsp;°[[Celsius|C]] (1.33&nbsp;±&nbsp;0.32&nbsp;°[[Fahrenheit|F]]) between the start and the end of the 20th century.<ref name="grida7"/>{{Cref2|A}} The climatology literature uniformly states that most of the observed temperature increase since the middle of the 20th century was [[attribution of recent climate change|caused]] by increasing concentrations of [[greenhouse gas]]es, which results from [[anthropogenic|human activity]] such as [[fossil fuel]] burning and [[deforestation]].<ref>{{cite web|title=Understanding and Responding to Climate Change|url=http://americasclimatechoices.org/climate_change_2008_final.pdf|publisher=[[United States National Academy of Sciences]]|accessdate=30 May 2010|date=2008|quote=Most scientists agree that the warming in recent decades has been caused primarily by human activities that have increased the amount of greenhouse gases in the atmosphere.}}</ref>

[[Climate model]] projections summarized in the latest IPCC report indicate that the global [[surface temperature]] is likely to rise a further {{nowrap|1.1 to 6.4&nbsp;°C}} {{nowrap|(2.0 to 11.5&nbsp;°F)}} during the 21st century.<ref name="grida7"/> The uncertainty in this estimate arises from the use of models with differing [[climate sensitivity|sensitivity to greenhouse gas concentrations]] and the use of differing [[Special Report on Emissions Scenarios|estimates of future greenhouse gas emissions]].
An increase in global temperature will cause [[sea level rise|sea levels to rise]] and will change the amount and pattern of [[precipitation (meteorology)|precipitation]], probably including expansion of [[Subtropics|subtropical]] [[desert]]s.<ref name="Lu-2007"/> Warming is expected to be [[Arctic shrinkage|strongest in the Arctic]] and would be associated with continuing [[retreat of glaciers since 1850|retreat of glaciers]], [[permafrost]] and [[sea ice]]. Other likely effects include changes in the frequency and intensity of [[extreme weather]] events, [[extinction risk from climate change|species extinctions]], and changes in [[agricultural yield]]s. Warming and related changes will vary from region to region around the globe, though the nature of these regional variations is uncertain.<ref name="IPCCSynthesisReport2007" />

The overwhelming scientific consensus is that human-made global warming is real.<ref>{{Citation| last = Oreskes| first = Naomi| author-link = Naomi Oreskes| title = BEYOND THE IVORY TOWER: The Scientific Consensus on Climate Change| journal = Science| volume = 306| pages = 1686| date = December 2004| url =http://www.sciencemag.org/cgi/content/full/306/5702/1686| year = 2004 | quote=Such statements suggest that there might be substantive disagreement in the scientific community about the reality of anthropogenic climate change. This is not the case. [...] Politicians, economists, journalists, and others may have the impression of confusion, disagreement, or discord among climate scientists, but that impression is incorrect. }}</ref><ref>Union of Concerned Scientists, 2009, [http://www.ucsusa.org/ssi/climate-change/scientific-consensus-on.html "Scientific Consensus on Global Warming"]</ref> Nevertheless, [[Politics of global warming|political]] and [[global warming controversy|public]] debate continues. Some fossil fuel companies have funded [[public relations]] campaigns intended to discredit the [[Scientific opinion on climate change|global scientific consensus]].<ref>{{Citation| last = Sanchez| first = Irene| title = Warming Study Draws Fire Harvard scientists accused of politicizing research| newspaper = The Harvard Crimson| location = Cambridge| date = 12 September 2003| url =http://www.thecrimson.com/article/2003/9/12/warming-study-draws-fire-a-study/}}</ref><ref>{{Citation| last = Vidal| first = John| title = US oil company donated millions to climate sceptic groups, says Greenpeace| newspaper = The Guardian| location = London| date = 30 March 2010| url =http://www.guardian.co.uk/environment/2010/mar/30/us-oil-donated-millions-climate-sceptics }}</ref><ref>{{Citation| last = Sample| first = Ian| title = Scientists offered cash to dispute climate study| newspaper = The Guardian| location = London| date = 2 February 2007| url= http://www.guardian.co.uk/environment/2007/feb/02/frontpagenews.climatechange}}</ref>

==Temperature changes==

{{Main|Temperature record}}

[[File:2000 Year Temperature Comparison.png|thumb|Two millennia of mean surface temperatures according to different reconstructions, each smoothed on a decadal scale. The instrumental record and the unsmoothed annual value for 2004 are shown in black.]]

Evidence for warming of the climate system includes observed increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.<ref>{{cite web
|year=2007
|month=May
|day=16
|title=Joint science academies’ statement: sustainability, energy efficiency and climate protection
|author=Joint science academies’ statement
|publisher=UK Royal Society website
|url=http://royalsociety.org/Joint-science-academies-statement-sustainability-energy-efficiency-and-climate-protection/
|accessdate=2010-04-17}}</ref><ref>{{cite web
|year=2008
|title=Understanding and Responding to Climate Change
|publisher=[http://dels.nas.edu/basc Board on Atmospheric Sciences and Climate], US National Academy of Sciences
|author=NRC
|page=4
|url=http://dels.nas.edu/dels/rpt_briefs/climate_change_2008_final.pdf
|accessdate=2009-05-20}}</ref><ref>{{cite web
|date=n.d.
|title=Explaining the evidence of climate change
|author=Slingo, J.
|url=http://www.metoffice.gov.uk/climatechange/science/controversy/facts.html
|publisher=UK Met Office website
|accessdate=2010-04-17}}</ref><ref>{{cite web
|date=n.d.
|title=Key Findings. On (website): Global Climate Change Impacts in the United States
|author=USGRCP
|publisher=U.S. Global Change Research Program website
|url=http://www.globalchange.gov/publications/reports/scientific-assessments/us-impacts/key-findings
|accessdate=2010-04-17}}</ref><ref name=spm1>{{cite web
|url=http://www.ipcc.ch/publications_and_data/ar4/syr/en/spms1.html
|title=1. Observed changes in climate and their effects. In (section): Summary for Policymakers. In (book): Climate Change 2007: Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (Core Writing Team, Pachauri, R.K and Reisinger, A. (eds.))
|author=IPCC
|year=2007
|publisher=Book publisher: IPCC, Geneva, Switzerland. This version: IPCC website
|accessdate=2010-04-17}}</ref> The most common measure of global warming is the trend in globally averaged temperature near the Earth's surface. Expressed as a [[linear]] trend, this temperature rose by 0.74&nbsp;±&nbsp;0.18&nbsp;°C over the period 1906–2005. The rate of warming over the last half of that period was almost double that for the period as a whole (0.13&nbsp;±&nbsp;0.03&nbsp;°C per decade, versus 0.07&nbsp;°C ± 0.02&nbsp;°C per decade). The [[urban heat island]] effect is estimated to account for about 0.002&nbsp;°C of warming per decade since 1900.<ref>{{Cite book|last=Trenberth|first=Kevin E.|coauthors=''et al.''|title=IPCC Fourth Assessment Report|url=http://www.ipcc.ch/pdf/assessment-report/ar4/syr/ar4_syr.pdf|format=PDF|year=2007|publisher=Cambridge University Press|location=Cambridge, United Kingdom and New York, NY, USA|page=244|chapter=Chapter 3: Observations: Surface and Atmospheric Climate Change|chapterurl=http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter3.pdf}}</ref> Temperatures in the lower [[troposphere]] have increased between 0.13 and 0.22&nbsp;°C (0.22 and 0.4&nbsre 1850, with regionally varying fluctuations such as the [[Medieval Warm Period]] and the [[Little Ice Age]].<ref>{{cite book |last1= Jansen |first1= E., J. Overpeck |first2= K.R. |last2= Briffa |first3= J.-C. |last3=Duplessy |first4= F. |last4=Joos|first5=V. |last5=Masson-Delmotte|first6=D. |last6=Olago|first7=B. |last7=Otto-Bliesner|first8=W.R. |last8=Peltier|first9=S. |last9=Rahmstorf|first10= R. |last10=Ramesh|first11=D. |last11=Raynaud |first12=D. |last12=Rind|first13=O. |last13=Solomina|first15=R. |last14=Villalba |first16=D. |last15=Zhang |editor1-last=Solomon |editor1-first= S. |editor2-first= D. |editor2-last= Qin |editor3-first=M. |editor3-last= Manning |editor3-first=Z. |editor4-last= Chen |editor4-first=M. |editor5-last= Marquis |editor6-first=K.B. |editor6-last= Averyt |editor7-first=M. |editor7-last= Tignor |editor8-first=H.L. |editor8-last= Miller |title= Climate Change 2007: The Physical Science Basis : contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change |url= http://www.worldcat.org/title/climate-change-2007-the-physical-science-basis-contribution-of-working-group-i-to-the-fourth-assessment-report-of-the-intergovernmental-panel-on-climate-change/oclc/132298563 |series= [[IPCC Fourth Assessment Report]] |date= 2007-02-11 |publisher= Cambridge University Press |location= Cambridge and New York |isbn= 978-0521705967 |oclc= 132298563 |pages= 466-478 |chapter= Palaeoclimate |chapterurl= http://www.ipcc-wg1.unibe.ch/publications/wg1-ar4/ar4-wg1-chapter6.pdf }} </ref>

Estimates by [[NASA]]'s [[Goddard Institute for Space Studies]] and the [[National Climatic Data Center]] show that 2005 was the warmest year since reliable, widespread instrumental measurements became available in the late 1800s, exceeding the previous record set in 1998 by a few hundredths of a degree.<ref>{{Cite web|url=http://data.giss.nasa.gov/gistemp/2005/|last=Hansen|first=James E.|authorlink=James E. Hansen|coauthors=''et al.''|title=Goddard Institute for Space Studies, GISS Surface Temperature Analysis|accessdate=2007-01-17|date=2006-01-12|publisher=NASA Goddard Institute for Space Studies}}</ref><ref>{{Cite web|url=http://www.ncdc.noaa.gov/sotc/?report=global&year=2009&month=13|last=|first=|authorlink=|coauthors=|title=NOAA/NCDC 2009 climate|accessdate=2010-02-15|date=|publisher=}}</ref> Estimates prepared by the [[World Meteorological Organization]] and the [[Climatic Research Unit]] show 2005 as the second warmest year, behind 1998.<ref>{{Cite web|url=http://www.cru.uea.ac.uk/cru/press/2005-12-WMO.pdf|title=Global Temperature for 2005: second warmest year on record|accessdate=2007-04-13|date=2005-12-15|publisher=Climatic Research Unit, School of Environmental Sciences, University of East Anglia|format=PDF}}</ref><ref>{{Cite web|url=http://www.wmo.int/pages/prog/wcp/wcdmp/statement/documents/WMO998_E.pdf|format=PDF|title=WMO statement on the status of the global climate in 2005|accessdate=2009-04-24|date=2005-12-15|publisher=World Meteorological Organization}}</ref> Temperatures in 1998 were unusually warm because the strongest [[El Niño-Southern Oscillation|El Niño]] in the past century occurred during that year.<ref name="Changnon2000">{{Cite book|title=El Niño, 1997–1998: The Climate Event of the Century|last=Changnon|first=Stanley A.|coauthors=Bell, Gerald D.|year=2000|publisher=Oxford University Press|location=London|isbn=0195135520}}</ref> Global temperature is subject to short-term fluctuations that overlay long term trends and can temporarily mask them. The relative stability in temperature from 2002 to 2009 is consistent with such an episode.<ref>{{Cite journal|url=http://www.metoffice.gov.uk/corporate/pressoffice/2009/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=2009-09-08}}</ref><ref>{{Cite book|title=Global temperature slowdown&nbsp;— not an end to climate change|publisher=UK Met Office|url=http://www.metoffice.gov.uk/climatechange/policymakers/policy/slowdown.html|accessdate=2009-09-08}}</ref>

Temperature changes vary over the globe. Since 1979, land temperatures have increased about twice as fast as ocean temperatures (0.25&nbsp;°C per decade against 0.13&nbsp;°C per decade).<ref>{{Cite web|url=http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter3.pdf|format=PDF|title=IPCC Fourth Assessment Report, Chapter 3|accessdate=2009-03-14|date=2007-02-05|pages=237}}</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|author=Rowan T. Sutton, Buwen Dong, Jonathan M. Gregory|journal=Geophysical Research Letters|volume=34|url=http://www.agu.org/pubs/crossref/2007/2006GL028164.shtml|doi=10.1029/2006GL028164|year=2007|accessdate=2007-09-19|pages=L02701}}</ref> The [[Northern Hemisphere]] warms faster than the [[Southern Hemisphere]] because it has more land and because it has extensive areas of seasonal snow and sea-ice cover subject to [[ice-albedo feedback]]. 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>{{Cite book|chapterurl=http://www.grida.no/publications/other/ipcc_tar/?src=/CLIMATE/IPCC_TAR/WG1/127.htm|title=Climate Change 2001: The Scientific Basis|chapter=Atmospheric Chemistry and Greenhouse Gases|url=http://www.grida.no/publications/other/ipcc_tar/?src=/CLIMATE/IPCC_TAR/WG1/|author=Intergovernmental Panel on Climate Change|authorlink=Intergovernmental Panel on Climate Change|publisher=Cambridge University Press|location=Cambridge, UK|year=2001|isbn=0521014956}}</ref>

The [[Volumetric heat capacity|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. [[Climate commitment]] studies indicate that even if greenhouse gases were stabilized at 2000 levels, a further warming of about {{nowrap|0.5&nbsp;°C}} {{nowrap|(0.9&nbsp;°F)}} would still occur.<ref>{{Cite journal|last=Meehl|first=Gerald A.|coauthors=''et al.''|date=2005-03-18|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://www.sciencemag.org/cgi/reprint/307/5716/1769.pdf|format=PDF|accessdate=2007-02-11|pmid=15774757}}</ref>

{{Clear}}

==External forcings==

''External forcing'' refers to processes external to the climate system (though not necessarily external to Earth) that influence climate. Climate responds to several types of external forcing, such as [[radiative forcing]] due to changes in atmospheric composition (mainly [[greenhouse gases|greenhouse gas]] concentrations), changes in [[solar luminosity]], [[volcano|volcanic]] eruptions, and [[orbital forcing|variations in Earth's orbit]] around the Sun.<ref name=Hegerl-2001/> [[Attribution of recent climate change]] focuses on the first three types of forcing. Orbital cycles vary slowly over tens of thousands of years and thus are too gradual to have caused the temperature changes observed in the past century.

===Greenhouse gases===

{{Main|Greenhouse effect|Radiative forcing|Atmospheric CO2}}

{{Double image stack|right|Greenhouse Effect.svg|Mauna Loa Carbon Dioxide-en.svg|200|Greenhouse effect schematic showing energy flows between space, the atmosphere, and earth's surface. Energy exchanges are expressed in watts per square meter (W/m<sup>2</sup>).|Recent atmospheric [[carbon dioxide]] (CO<sub>2</sub>) increases. Monthly CO<sub>2</sub> measurements display seasonal oscillations in overall yearly uptrend; 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 greenhouse effect is the process by which [[Absorption (electromagnetic radiation)|absorption]] and [[Emission (electromagnetic radiation)|emission]] of [[infrared]] radiation by gases in the [[atmosphere]] are purported to warm a [[planet]]'s lower atmosphere and surface. It was proposed by [[Joseph Fourier]] in 1824 and 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://www.aip.org/history/climate/co2.htm|accessdate=21 April 2009|year=2008|publisher=American Institute of Physics|first=Spencer | last=Weart | authorlink=Spencer Weart}}</ref> The question in terms of global warming is how the strength of the presumed greenhouse effect changes when human activity increases the concentrations of greenhouse gases in the atmosphere.

Naturally occurring greenhouse gases have a mean warming effect of about 33&nbsp;°C (59&nbsp;°F).<ref name="IPCC_WG1_AR4_Ch1">{{Cite web|author=IPCC|work=Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change|title=Chapter 1: Historical Overview of Climate Change Science|url=http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch01.pdf|format=PDF|accessdate=21 April 2009|year=2007|publisher=IPCC|quote=To emit 240 W m–2, a surface would have to have a temperature of around −19&nbsp;°C. This is much colder than the conditions that actually exist at the Earth’s surface (the global mean surface temperature is about 14&nbsp;°C). Instead, the necessary −19&nbsp;°C is found at an altitude about 5 km above the surface.|pages=p97 (PDF page 5 of 36)|work=IPCC WG1 AR4 Report}}</ref>{{Cref2|C}} The major greenhouse gases are [[water vapor]], which causes about 36–70 percent of the greenhouse effect; [[carbon dioxide]] (CO<sub>2</sub>), which causes 9–26 percent; [[methane]] (CH<sub>4</sub>), which causes 4–9 percent; and [[ozone]] (O<sub>3</sub>), which causes 3–7 percent.<ref>{{Cite journal|url=http://www.atmo.arizona.edu/students/courselinks/spring04/atmo451b/pdf/RadiationBudget.pdf|title=Earth's Annual Global Mean Energy Budget|first=J.T. | last=Kiehl | first2=K.E. | last2=Trenberth | author2-link=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}}</ref><ref>{{Cite web|url=http://www.realclimate.org/index.php?p=142|year=6 Apr 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=May 16, 2007 | accessdate=Dec 27, 2009}}</ref> Clouds also affect the radiation balance, but they are composed of liquid water or ice and so have [[Cloud forcing|different effects on radiation]] from water vapor.

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|CFC]]s and [[nitrous oxide]]. The [[Greenhouse gas#Anthropogenic greenhouse gases|concentrations]] of CO<sub>2</sub> and methane have increased by 36% and 148% respectively since 1750.<ref>{{Cite web|author=EPA|year=2008|title=Recent Climate Change: Atmosphere Changes|work=Climate Change Science Program|url=http://www.epa.gov/climatechange/science/recentac.html|accessdate=21 April 2009|year=2007|publisher=United States Environmental Protection Agency}}</ref> These levels are much higher than at any time during the last 650,000 years, the period for which reliable data has been extracted from [[ice core]]s.<ref>{{Cite journal|last=Spahni|first=Renato|coauthors=''et al.''|year=2005|month=November|title=Atmospheric Methane and Nitrous Oxide of the Late Pleistocene from Antarctic Ice Cores|journal=Science|volume=310|issue=5752|pages=1317–1321|url=http://www.sciencemag.org/cgi/content/abstract/310/5752/1317|doi=10.1126/science.1120132|accessdate=27 December 2009|pmid=16311333}}</ref><ref>{{Cite journal|last=Siegenthaler|first=Urs|coauthors=''et al.''|year=2005|month=November|title=Stable Carbon Cycle–Climate Relationship During the Late Pleistocene|journal=Science|volume=310|issue=5752|pages=1313–1317|url=http://ic.ucsc.edu/~acr/ocea285/articles/Siegenthaler.etal.2005.pdf|format=PDF|doi=10.1126/science.1120130|accessdate=27 December 2009|pmid=16311332}}</ref><ref>{{Cite journal|author=Petit, J. R.|coauthors=''et al.''|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}}</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|author=Pearson, P.N. and M.R. Palmer|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> [[Fossil fuel]] burning has produced about three-quarters of the increase in CO<sub>2</sub> from human activity over the past 20 years. Most of the rest is due to land-use change, particularly [[deforestation]].<ref name=spm-2001>{{Cite web|url=http://www.grida.no/climate/ipcc_tar/wg1/pdf/WG1_TAR-FRONT.pdf|format=PDF|title=Summary for Policymakers|author=IPCC|work=Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change|accessdate=21 April 2009|year=2001|publisher=IPCC}}</ref>

CO<sub>2</sub> concentrations are continuing to rise due to burning of fossil fuels and land-use change. The future rate of rise will depend on uncertain economic, [[sociology|sociological]], [[technology|technological]], and natural developments. Accordingly, the IPCC [[Special Report on Emissions Scenarios]] gives a wide range of future CO<sub>2</sub> scenarios, ranging from 541 to 970 ppm by the year 2100 (an increase by 90-250% since 1750).<ref>{{Cite web|url=http://www.grida.no/climate/ipcc_tar/wg1/123.htm|author=Prentice, I.C., ''et al.''|title=The Carbon Cycle and Atmospheric Carbon Dioxide: SRES scenarios and their implications for future CO2 concentration|work=Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change|accessdate=21 April 2009|year=2001|publisher=IPCC}}</ref> Fossil fuel reserves are sufficient to reach these levels and continue emissions past 2100 if [[coal]], [[tar sands]] or [[methane clathrate]]s are extensively exploited.<ref>{{Cite web|url=http://www.grida.no/climate/ipcc/emission/104.htm|author=Nakicenovic., N., ''et al.''|title=An Overview of Scenarios: Resource Availability|work=IPCC Special Report on Emissions Scenarios|accessdate=21 April 2009|publisher=IPCC|year=2001}}</ref>

The destruction of [[stratosphere|stratospheric]] ozone by [[chlorofluorocarbons]] is sometimes mentioned in relation to global warming. Although there are a few [[Ozone depletion#Ozone depletion and global warming|areas of linkage]], the relationship between the two is not strong. Reduction of stratospheric ozone has a cooling influence, but substantial ozone depletion did not occur until the late 1970s.<ref>{{Cite web|url=http://www.nas.nasa.gov/About/Education/Ozone/history.html|title=Ozone Depletion, History and politics|last=Sparling|first=Brien|date=May 30, 2001|publisher=NASA|accessdate=2009-02-15}}</ref> [[Tropospheric ozone|Ozone in the troposphere]] (the lowest part of the [[Atmosphere of Earth|Earth's atmosphere]]) does contribute to surface warming.<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|pages=D08302|last2=Faluvegi|first2=Greg|last3=Lacis|first3=Andrew|last4=Hansen|first4=James|last5=Ruedy|first5=Reto|last6=Aguilar|first6=Elliot}}</ref>

===Aerosols and soot===

[[File:ShipTracks MODIS 2005may11.jpg|thumb|left|[[Ship tracks]] over the [[Atlantic Ocean]] on the east coast of the United States. The climatic impacts from aerosol forcing could have a large effect on climate through the indirect effect.]]

[[Global dimming]], a gradual reduction in the amount of global direct [[irradiance]] at the Earth's surface, has partially counteracted global warming from 1960 to the present.<ref>{{Cite web|url=http://www.grida.no/climate/ipcc_tar/wg1/462.htm|author=Mitchell, J.F.B., ''et al.''|title=Detection of Climate Change and Attribution of Causes: Space-time studies|work=Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change|accessdate=21 April 2009|year=2001|publisher=IPCC}}</ref> The main cause of this dimming is [[aerosols]] produced by volcanoes and [[pollutant]]s. These aerosols exert a cooling effect by increasing the reflection of incoming sunlight. [[James E. Hansen]] and colleagues have proposed that the effects of the products of fossil fuel combustion—CO<sub>2</sub> and aerosols—have largely offset one another in recent decades, so that net warming has been driven mainly by non-CO<sub>2</sub> greenhouse gases.<ref name="pmid10944197">{{Cite journal|author=Hansen J., Sato M., Ruedy R., Lacis A., and Oinas V.|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|doi=10.1073/pnas.170278997|pmid=10944197|last1=Hansen|first1=J|last2=Sato|first2=M|last3=Ruedy|first3=R|last4=Lacis|first4=A|last5=Oinas|first5=V|pmc=27611}}</ref>

In addition to their direct effect by scattering and absorbing solar radiation, aerosols have indirect effects on the radiation budget.<ref>{{Cite journal|author=Lohmann, U. & J. Feichter|year=2005|title=Global indirect aerosol effects: a review|journal=Atmos. Chem. Phys.|volume=5|pages=715–737|url=http://www.atmos-chem-phys.net/5/715/2005/acp-5-715-2005.html}}</ref> Sulfate aerosols act as [[cloud condensation nuclei]] and thus lead to clouds that have more and smaller cloud droplets. These clouds [[Twomey effect|reflect solar radiation]] more efficiently than clouds with fewer and larger droplets.<ref>{{Cite journal|author=Twomey, S.|year=1977|title=Influence of pollution on shortwave albedo of clouds|journal=J. Atmos. Sci.|volume=34|pages=1149–1152|doi=10.1175/1520-0469(1977)034<1149:TIOPOT>2.0.CO;2}}</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.<ref>{{Cite journal|author=Albrecht, B.|year=1989|title=Aerosols, cloud microphysics, and fractional cloudiness|journal=Science|volume=245|pages=1227–1239|doi=10.1126/science.245.4923.1227|pmid=17747885|issue=4923}}</ref>

[[Soot]] may cool or warm, depending on whether it is airborne or deposited. Atmospheric [[soot]] aerosols directly absorb 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|last=Ramanathan|first=V.|coauthors=''et al.''|year=2005|url=http://www.pnas.org/content/102/15/5326.abstract|title=Atmospheric brown clouds: Impacts on South Asian climate and hydrological cycle|journal=Proc. Natl. Acad. Sci.|volume=102|pages=5326–5333|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=JT|last7=Washington|first7=WM|last8=Fu|first8=Q|last9=Sikka|first9=DR|issue=15|pmc=552786}}</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., ''et al.''|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|title=Report Summary}}</ref> The influences of aerosols, 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., ''et al.''|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|title=Part III: Global and Future Implications}}</ref>

===Solar variation===

{{Main|Solar variation}}

[[File:Solar-cycle-data.png|thumb|Solar variation over the last thirty years.]]

Variations in solar output have been the cause of past [[climate change]]s.<ref>{{Cite book|last=National Research Council|title=Solar Influences On Global Change|url=http://books.nap.edu/openbook.php?record_id=4778&page=R1|year=1994|publisher=National Academy Press|location=Washington, D.C.|isbn=0-309-05148-7|page=36}}</ref> The consensus among climate scientists is that changes in solar forcing probably had a slight cooling effect in recent decades. This result is less certain than some others, with a few papers suggesting a warming effect.<ref name=Hegerl-2001/><ref>Duffy, Santer and Wigley, "[http://www.clas.ufl.edu/users/prwaylen/GEO2200ARTICLES/Part1/Solar%20variability%20in%20late%2020th%20century.pdf Solar variability does not explain late-20th-century warming]" Physics Today, January, 2009, pp 48-49. The authors respond to recent assertions by Nicola Scafetta and Bruce West that solar forcing "might account" for up to about half of 20th-century warming.</ref><ref>{{Cite journal|title=Climate|year=2002|author=Hansen, J.|journal=Journal of Geophysical Research|volume=107|pages=4347|doi=10.1029/2001JD001143|unused_data=estimated by global circulation models isdoi=10.1029/2001JD001143}}</ref><ref>{{Cite journal|doi=10.1029/2005JD005776|title=Efficacy of climate forcings|year=2005|author=Hansen, J.|journal=Journal of Geophysical Research|volume=110|pages=D18104}}</ref>

Greenhouse gases and solar forcing affect temperatures in different ways. While both increased solar activity and increased greenhouse gases are expected to warm the [[troposphere]], an increase in solar activity should warm the [[stratosphere]] while an increase in greenhouse gases should cool the stratosphere.<ref name=Hegerl-2001/> Observations show that temperatures in the stratosphere have been cooling since 1979, when satellite measurements became available. [[Radiosonde]] (weather balloon) data from the pre-satellite era show cooling since 1958, though there is greater uncertainty in the early radiosonde record.<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|pages=D02107|last2=Shine|first2=Keith P.|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}}</ref>

A related hypothesis, proposed by [[Henrik Svensmark]], is that magnetic activity of the sun deflects cosmic rays that may influence the generation of cloud condensation nuclei and thereby affect the climate.<ref>{{Cite journal|first=Nigel|last=Marsh|coauthors=Henrik, Svensmark|title=Cosmic Rays, Clouds, and Climate|journal=Space Science Reviews|volume=94|number=1–2|pages=215–230|year=2000|month=November|url=http://www.dsri.dk/~hsv/SSR_Paper.pdf|format=PDF|doi=10.1023/A:1026723423896|accessdate=2007-04-17}}</ref> Other research has found no relation between warming in recent decades and [[cosmic ray]]s.<ref>{{Cite journal|last=Lockwood|first=Mike|coauthors=Claus Fröhlich|title=Recent oppositely directed trends in solar climate forcings and the global mean surface air temperature|journal=Proceedings of the Royal Society A|volume=463|pages=2447|quote=Our results show that the observed rapid rise in global mean temperatures seen after 1985 cannot be ascribed to solar variability, whichever of the mechanisms is invoked and no matter how much the solar variation is amplified|url=http://www.pubs.royalsoc.ac.uk/media/proceedings_a/rspa20071880.pdf|doi=10.1098/rspa.2007.1880|accessdate=2007-07-21|format=PDF|year=2007}}</ref><ref>{{Cite journal|doi=10.1088/1748-9326/3/2/024001|title=Testing the proposed causal link between cosmic rays and cloud cover|author=T Sloan and A W Wolfendale|journal=Environ. Res. Lett.|volume=3|page=024001|year=2008|pages=024001|url=http://www.iop.org/EJ/abstract/1748-9326/3/2/024001/}}</ref> A recent study concluded that the influence of cosmic rays on cloud cover is about a factor of 100 lower than needed to explain the observed changes in clouds or to be a significant contributor to present-day climate change.<ref>{{Cite journal|journal=Geophysical Research Letters|author=Pierce, J.R. and P.J. Adams|year=2009|title=Can cosmic rays affect cloud condensation nuclei by altering new particle formation rates?|volume=36|pages=L09820|doi=10.1029/2009GL037946}}</ref>

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==Feedback==

{{Main|Climate change feedback}}

[[Feedback]] is a process in which changing one quantity changes a second quantity, and the change in the second quantity in turn changes the first. [[Positive feedback]] amplifies the change in the first quantity while [[negative feedback]] reduces it. Feedback is important in the study of global warming because it may amplify or diminish the effect of a particular process. The main positive feedback in global warming is the tendency of warming to increase the amount of [[Water vapor feedback|water vapor]] in the atmosphere, a significant [[greenhouse gas]]. The main negative feedback is [[radiative cooling]], which [[Stefan–Boltzmann law|increases as the fourth power of temperature]]; the amount of heat radiated from the Earth into space increases with the temperature of Earth's surface and atmosphere. Imperfect understanding of feedbacks is a major cause of uncertainty and concern about global warming.

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==Climate models==

{{Main|Global climate model}}

{{Double image stack|right|Global Warming Predictions.png|Global Warming Predictions Map.jpg|220|Calculations of global warming prepared in or before 2001 from a range of [[climate model]]s under the [[Special Report on Emissions Scenarios|SRES]] A2 emissions scenario, which [[Special_Report_on_Emissions_Scenarios#A2|assumes no action is taken to reduce emissions and regionally divided economic development]].|The geographic distribution of surface warming during the 21<sup>st</sup> century calculated by the [[HadCM3]] climate model if a business as usual scenario is assumed for economic growth and greenhouse gas emissions. In this figure, the globally averaged warming corresponds to 3.0&nbsp;°C (5.4&nbsp;°F).}}

The main tools for projecting future climate changes are [[mathematical models]] based on physical principles including [[fluid dynamics]], [[thermodynamics]] and [[radiative transfer]]. Although they 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. All modern climate models are in fact ''combinations'' of models for different parts of the Earth. These include an atmospheric model for air movement, temperature, clouds, and other atmospheric properties; an ocean model that predicts temperature, [[salinity|salt content]], and circulation of ocean waters; models for ice cover on land and sea; and a model of heat and moisture transfer from soil and vegetation to the atmosphere. Some models also include treatments of chemical and biological processes.<ref>{{Cite web|url=http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter7.pdf|author=Denman, K.L., ''et al.''|format=PDF|title=Chapter 7, Couplings Between Changes in the Climate System and Biogeochemistry|work=Fourth Assessment Report of the Intergovernmental Panel on Climate Change|accessdate=2008-02-21|year=2007|publisher=IPCC}}</ref> Warming due to increasing levels of greenhouse gases is not an assumption of the models; rather, it is an end result from the interaction of greenhouse gases with radiative transfer and other physical processes.<ref>{{Cite book|url=http://books.google.com/books?id=sx6DFr8rbpIC&dq=robert+lanza&printsec=frontcover&source=web&ots=S7MXYzoDqR&sig=jfUo33FtVZ3PSUS2fcc_EtawEnQ|last=Hansen|first=James|title=Climatic Change: Understanding Global Warming|work=One World: The Health & Survival of the Human Species in the 21st century|accessdate=2007-08-18|year=2000|publisher=Health Press}}</ref> Although much of the variation in model outcomes depends on the greenhouse gas emissions used as inputs, the temperature effect of a specific greenhouse gas concentration ([[climate sensitivity]]) varies depending on the model used. The representation of clouds is one of the main sources of uncertainty in present-generation models.<ref>{{Cite web|url=http://www.grida.no/climate/ipcc_tar/wg1/271.htm|last=Stocker|first=Thomas F.|coauthors=''et al.''|title=7.2.2 Cloud Processes and Feedbacks|work=Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change|accessdate=2007-03-04|year=2001|publisher=IPCC}}</ref>

Global climate model projections of future climate most often have used estimates of greenhouse gas emissions from the IPCC [[Special Report on Emissions Scenarios]] (SRES). In addition to human-caused emissions, some models also include a simulation of the [[carbon cycle]]; this generally shows a positive feedback, though this response is uncertain. Some observational studies also show a positive feedback.<ref>{{Cite journal|last=Torn|first=Margaret|coauthors=Harte, John|year=2006|title=Missing feedbacks, asymmetric uncertainties, and the underestimation of future warming|journal=Geophysical Research Letters|volume=33|issue=10|id=L10703|url=http://www.agu.org/pubs/crossref/2006/2005GL025540.shtml|accessdate=2007-03-04|doi=10.1029/2005GL025540|pages=L10703}}</ref><ref>{{Cite journal|last=Harte|first=John|coauthors=''et al.''|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|id=014001|url=http://www.iop.org/EJ/article/1748-9326/1/1/014001/erl6_1_014001.html|accessdate=2007-05-02|doi=10.1088/1748-9326/1/1/014001|pages=014001}}</ref><ref>{{Cite journal|last=Scheffer|first=Marten|coauthors=''et al.''|title=Positive feedback between global warming and atmospheric CO2 concentration inferred from past climate change.|journal=Geophysical Research Letters|volume=33|url=http://www.pik-potsdam.de/~victor/recent/scheffer_etal_T_CO2_GRL_in_press.pdf|doi=10.1029/2005gl025044|year=2006|accessdate=2007-05-04|pages=L10702|format=PDF}}</ref> Including uncertainties in future greenhouse gas concentrations and climate sensitivity, the IPCC anticipates a warming of {{nowrap|1.1&nbsp;°C to 6.4&nbsp;°C}} {{nowrap|(2.0&nbsp;°F to 11.5&nbsp;°F)}} by the end of the 21st century, relative to 1980–1999.<ref name="grida7"/>

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-derived 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 man-made greenhouse gas emissions.<ref name=Hegerl-2001/>

The physical realism of models is tested by examining their ability to simulate current or past climates.<ref>{{Cite web|url=http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter8.pdf|author=Randall, D.A., ''et al.''|format=PDF|title=Chapter 8, Climate Models and Their Evaluation|work=Fourth Assessment Report of the Intergovernmental Panel on Climate Change|accessdate=2009-03-21|year=2007|publisher=IPCC}}</ref> Current 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 name=spm-2001/> Not all [[effects of global warming]] are accurately predicted by the [[climate models]] used by the [[Intergovernmental Panel on Climate Change|IPCC]]. For example, observed [[Arctic shrinkage]] has been faster than that predicted.<ref>{{Cite journal|doi=10.1029/2007GL029703|title=Arctic sea ice decline: Faster than forecast|year=2007|author=Stroeve, J., ''et al.''|journal=Geophysical Research Letters|volume=34|pages=L09501}}</ref>

==Attributed and expected effects==

{{Main|Effects of global warming|Regional effects of global warming}}

Global warming may be detected in [[natural environment|natural]], [[ecology|ecological]] or [[social]] systems as a change having statistical significance.<ref>{{cite web
|url=http://www.ipcc.ch/publications_and_data/ar4/syr/en/mains1.html
|title=1.1 Observations of climate change. In (section): Synthesis Report. In (book): Climate Change 2007: Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (Core Writing Team, Pachauri, R.K and Reisinger, A. (eds.))
|author=IPCC
|year=2007d
|publisher=Book version: IPCC, Geneva, Switzerland. This version: IPCC website
|accessdate=2010-04-26}}</ref> Attribution of these changes e.g., to natural or human activities, is the next step following detection.<ref>{{cite web
|url=http://www.ipcc.ch/publications_and_data/ar4/syr/en/mains2-4.html
|title=2.4 Attribution of climate change. In (section): Synthesis Report. In (book): Climate Change 2007: Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (Core Writing Team, Pachauri, R.K and Reisinger, A. (eds.))
|author=IPCC
|year=2007d
|publisher=Book version: IPCC, Geneva, Switzerland. This version: IPCC website
|accessdate=2010-04-26}}</ref>

===Natural systems===

[[File:Glacier Mass Balance.png|thumb|left|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]].]]

Global warming has been detected in a number of systems. Some of these changes, e.g., based on the instrumental temperature record, have been described in the section on [[Global warming#Temperature changes|temperature changes]]. Rising sea levels and observed decreases in snow and ice extent are consistent with warming.<ref name=spm1/> Most of the increase in global average temperature since the mid-20<sup>th</sup> century is, with high probability,{{Cref2|D}} atttributable to human-induced changes in greenhouse gas concentrations.<ref>{{cite web
|url=http://www.ipcc.ch/publications_and_data/ar4/syr/en/spms2.html
|title=2. Causes of change. In (section): Summary for Policymakers. In (book): Climate Change 2007: Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (Core Writing Team, Pachauri, R.K and Reisinger, A. (eds.))
|author=IPCC
|year=2007d
|publisher=Book version: IPCC, Geneva, Switzerland. This version: IPCC website
|accessdate=2010-04-26}}</ref>

Even with current policies to reduce emissions, global emissions are still expected to continue to grow over the coming decades.<ref name=spm3>{{cite web
|url=http://www.ipcc.ch/publications_and_data/ar4/syr/en/spms3.html
|title=3. Projected climate change and its impacts. In (section): Summary for Policymakers. In (book): Climate Change 2007: Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (Core Writing Team, Pachauri, R.K and Reisinger, A. (eds.))
|author=IPCC
|year=2007d
|publisher=Book version: IPCC, Geneva, Switzerland. This version: IPCC website
|accessdate=2010-04-26}}</ref> Over the course of the 21<sup>st</sup> century, increases in emissions at or above their current rate would very likely induce changes in the climate system larger than those observed in the 20<sup>th</sup> century.

In the IPCC Fourth Assessment Report, across a range of future emission scenarios, model-based estimates of sea level rise for the end of the 21<sup>st</sup> century (the year 2090-2099, relative to 1980-1999) range from 0.18 to 0.59&nbsp;m. These estimates, however, were not given a likelihood due to a lack of scientific understanding, nor was an upper bound given for sea level rise. Over the course of centuries to millennia, the melting of ice sheets could result in sea level rise of 4–6&nbsp;m or more.<ref>{{cite web
|url=http://www.ipcc.ch/publications_and_data/ar4/wg2/en/spmsspm-c-15-magnitudes-of.html
|title=Magnitudes of impact. In (section): Summary for Policymakers. In (book): Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson, Eds.)
|author=IPCC
|year=2007b
|publisher=Book version: Cambridge University Press, Cambridge, UK. This version: IPCC website
|accessdate=2010-04-26}}</ref>

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=spm3/> Snow cover area and sea ice extent are expected to decrease. The frequency of hot extremes, heat waves and heavy precipitation will very likely increase.

===Ecological systems===

In terrestrial [[ecosystem]]s, the earlier timing of [[spring (season)|spring]] events, and poleward and upward shifts in plant and animal ranges, have been linked with high confidence to recent warming.<ref name=spm1/> Future climate change is expected to particularly affect certain ecosystems, including [[tundra]], [[mangrove]]s, and [[coral reef]]s.<ref name=spm3/> It is expected that most ecosystems will be affected by higher atmospheric CO<sub>2</sub> levels, combined with higher global temperatures.<ref>{{cite web
|url=http://www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-chapter4.pdf
|title=Executive Summary. In (book chapter): Ecosystems, their properties, goods and services. In: Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson, Eds.)
|author=Fischlin, A., G.F. Midgley, J.T. Price, R. Leemans, B. Gopal, C. Turley, M.D.A. Rounsevell, O.P. Dube, J. Tarazona, A.A. Velichko
|year=2007
|page=213
|publisher=Book version: Cambridge University Press, Cambridge, UK. This version: IPCC website
|accessdate=2010-04-26}}</ref> Overall, it is expected that climate change will result in the [[extinction]] of many species and reduced diversity of ecosystems.<ref>{{cite web
|url=http://www.ipcc.ch/publications_and_data/ar4/wg2/en/ch19s19-3-4.html
|title=19.3.4 Ecosystems and biodiversity. In (book chapter): Assessing Key Vulnerabilities and the Risk from Climate Change. In: Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson, Eds.)
|author=Schneider, S.H., S. Semenov, A. Patwardhan, I. Burton, C.H.D. Magadza, M. Oppenheimer, A.B. Pittock, A. Rahman, J.B. Smith, A. Suarez and F. Yamin
|year=2007
|publisher=Book version: Cambridge University Press, Cambridge, UK. This version: IPCC website
|accessdate=2010-04-26}}</ref>

===Social systems===

There is some evidence of regional climate change affecting systems related to human activities, including agricultural and [[forestry]] management activities at higher latitudes in the Northern Hemisphere.<ref name=spm1/> Future climate change is expected to particularly affect some sectors and systems related to human activities.<ref name=spm3/> These include:
*[[Water resources]] in some dry regions at mid-latitudes, the dry [[tropics]], and areas that depend on [[snow melt|snow]] and ice melt
*Agriculture in low latitudes
*Low-lying [[coast]]al systems
*Human [[health]] in populations with limited capacity to adapt to climate change
It is expected that some regions will be particularly affected by climate change, including the [[Arctic]], [[Africa]], small [[island]]s, and [[Asia]]n and African [[mega delta|megadeltas]]. Some people, such as the poor, young children, and the elderly, are particularly at risk, even in high-income areas.

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==Responses to global warming==

[[File:Carbon sequestration-2009-10-07.svg|thumb|[[Carbon capture and storage]] (CCS) is an approach to mitigation. Emissions may be [[Carbon sequestration|sequestered]] from fossil fuel power plants, or removed during processing in hydrogen production. When used on plants, it is known as [[bio-energy with carbon capture and storage]].]]

Reducing the amount of future climate change is called [[climate change mitigation|mitigation]] of climate change. The IPCC defines mitigation as activities that reduce greenhouse gas (GHG) emissions, or enhance the capacity of [[carbon sink]]s to absorb GHGs from the atmosphere.<ref>{{cite book
|year=2007
|title=Glossary J-P. In (book section): Annex I. In: Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds.))
|publisher=Print version: Cambridge University Press, Cambridge, U.K., and New York, N.Y., U.S.A.. This version: IPCC website
|isbn=9780521880114
|author=Verbruggen, A. (ed.)
|url=http://www.ipcc.ch/publications_and_data/ar4/wg3/en/annex1sglossary-j-p.html
|accessdate=2010-04-23}}</ref> Many countries, both [[developing country|developing]] and [[developed country|developed]], are aiming to use cleaner, less polluting, technologies.<ref>{{cite book
|year=2010
|author=World Bank
|title=Chapter 4: Energizing Development without Compromising the Climate. In: World Development Report 2010: Development and Climate Change
|publisher=The International Bank for Reconstruction and Development / The World Bank, 1818 H Street NW, Washington DC 20433
|page=192
|url=http://go.worldbank.org/BKLQ9DSDU0
|isbn=9780821379875
|doi=10.1596/978-0-8213-7987-5
|accessdate=2010-04-06}}</ref> Use of these technologies aids mitigation and could result in substantial reductions in CO<sub>2</sub> emissions. Policies include targets for emissions reductions, increased use of [[renewable energy]], and increased [[energy efficiency]]. Studies indicate substantial potential for future reductions in emissions.<ref name=spm4>{{cite book
|url=http://www.ipcc.ch/publications_and_data/ar4/syr/en/spms4.html
|title=4. Adaptation and mitigation options. In (book section): Summary for Policymakers. In: Climate Change 2007: Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (Core Writing Team, Pachauri, R.K and Reisinger, A. (eds.))
|author=IPCC
|year=2007
|publisher=Print version: IPCC, Geneva, Switzerland. This version: IPCC website
|isbn=9291691224
|accessdate=2010-04-26}}</ref>

Other policy responses include [[adaptation to global warming|adaptation]] to climate change. Adaptation to climate change may be planned, e.g., by local or national government, or spontaneous, i.e., done privately without government intervention.<ref>{{cite book
|date=2001
|title=18.2.3. Adaptation Types and Forms. In (book chapter): Adaptation to Climate Change in the Context of Sustainable Development and Equity. In: Climate Change 2001: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Third Assessment Report of the Intergovernmental Panel on Climate Change (J.J. McCarthy, O.F. Canziani, N.A. Leary, D.J. Dokken, K.S. White (eds.))
|publisher=Print version: Cambridge University Press, Cambridge, U.K., and New York, N.Y., U.S.A.. This version: GRID-Arendal website
|isbn=0521807689
|author=Smit, B. and O. Pilifosova. Lead Authors: I. Burton, B. Challenger, S. Huq, R.J.T. Klein, G. Yohe. Contributing Authors: N. Adger, T. Downing, E. Harvey, S. Kane, M. Parry, M. Skinner, J. Smith, J. Wandel. Review Editors: A. Patwardhan and J.-F. Soussana
|url=http://www.grida.no/climate/ipcc_tar/wg2/644.htm#1823
|accessdate=2010-01-10}}</ref> The ability to adapt (called "[[adaptive capacity]]") is closely linked to [[social development|social]] and [[economic development]].<ref name=spm4/> Even societies with high capacities to adapt are still vulnerable to climate change. Planned adaptation is already occurring on a limited basis. The barriers, limits, and costs of future adaptation are not fully understood.

Another policy response is engineering of the climate ([[geoengineering]]). This policy response is sometimes grouped together with mitigation.<ref>{{cite book
|year=2007
|title=11.2.2 Ocean fertilization and other geo-engineering options. In (book chapter): Mitigation from a cross-sectoral perspective. In: Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds))
|publisher=Print version: Cambridge University Press, Cambridge, U.K., and New York, N.Y., U.S.A.. This version: IPCC website
|isbn=9780521880114
|author=Barker, T., I. Bashmakov, A. Alharthi, M. Amann, L. Cifuentes, J. Drexhage, M. Duan, O. Edenhofer, B. Flannery, M. Grubb, M. Hoogwijk, F. I. Ibitoye, C. J. Jepma, W.A. Pizer, K. Yamaji
|url=http://www.ipcc.ch/publications_and_data/ar4/wg3/en/ch11s11-2-2.html
|accessdate=2010-04-05}}</ref> Geoengineering is largely unproven, and reliable cost estimates for it have not yet been published.<ref>{{cite book
|year=2007
|title=C. Mitigation in the short and medium term (until 2030). In (book section): Summary for Policymakers. In: Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds))
|publisher=Print version: Cambridge University Press, Cambridge, U.K., and New York, N.Y., U.S.A.. This version: IPCC website
|isbn=9780521880114
|author=IPCC
|url=http://www.ipcc.ch/publications_and_data/ar4/wg3/en/spmsspm-c.html
|accessdate=2010-05-15}}</ref>

=== UNFCCC ===

Most countries 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=2010-05-18}}</ref> The ultimate objective of Convention is the 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=2010-05-18}}</ref> As is stated in the Convention, this requires that GHGs are stabilized in the atmosphere at a level where:
*ecosystems can adapt naturally to climate change;
*[[food industry|food production]] is not threatened;
*economic development can proceed in a sustainable fashion.

The UNFCCC recognizes differences among countries in their responsibility to act on climate change.<ref>{{cite web
|date=n.d.
|author=UNFCCC
|title=Full text of the Convention, start
|url=http://unfccc.int/essential_background/convention/background/items/1350.php
|publisher=UNFCCC website
|accessdate=2010-05-18}}</ref> In the [[Kyoto Protocol]] to the UNFCCC, most developed countries (listed in Annex I of the treaty) took on legally binding commitments to reduce their emissions.<ref name=liverman/> Policy measures taken in response to these commitments have reduced emissions.<ref>{{cite web
|year=2007
|month=November
|day=19
|author=UNFCCC
|title=Compilation and synthesis of fourth national communications. Executive summary. Note by the secretariat. Document code: FCCC/SBI/2007/INF.6
|url=http://unfccc.int/documentation/documents/advanced_search/items/3594.php?rec=j&priref=600004368#beg
|page=11
|publisher=United Nations Office at Geneva, Switzerland
|accessdate=2010-05-17}}</ref> For many developing (non-Annex I) countries, reducing [[poverty reduction|poverty]] is their overriding aim.<ref>{{cite web
|year=2005
|month=October
|day=25
|author=UNFCCC
|title=Sixth compilation and synthesis of initial national communications from Parties not included in Annex I to the Convention. Note by the secretariat. Executive summary. Document code: FCCC/SBI/2005/18
|url=http://unfccc.int/documentation/documents/advanced_search/items/3594.php?rec=j&priref=600003578#beg
|page=6
|publisher=United Nations Office at Geneva, Switzerland
|accessdate=2010-05-17}}</ref>

At the [[2009 United Nations Climate Change Conference|15<sup>th</sup> UNFCCC Conference of the Parties]], held in 2009 at [[Copenhagen]], several UNFCCC Parties produced the [[Copenhagen Accord]].<ref>{{cite book
|year=2010
|month=February
|author=Müller, B.
|title=Copenhagen 2009: Failure or final wake-up call for our leaders? EV 49
|page=i
|url=http://www.oxfordenergy.org/pdfs/EV49.pdf
|format=PDF
|publisher=Dr Benito Müller's web page on the Oxford Institute for Energy Studies website
|isbn=978190755046
|accessdate=2010-05-18}}</ref> Parties agreeing with the Accord aim to limit the future increase in global mean temperature to below 2&nbsp;°C.<ref>{{cite web
|year=2010
|month=March
|day=30
|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=2010-05-17}}</ref>

==Views on global warming==

{{Main|Global warming controversy|Politics of global warming}}
{{See also|Scientific opinion on climate change|Climate change consensus|Climate change denial}}

{{Double image stack|right|GHG per capita 2000.svg|GHG by country 2000.svg|220|[[List of countries by greenhouse gas emissions per capita|Per capita greenhouse gas emissions]] in 2000, including [[Land use, land-use change and forestry|land-use change]].|Total greenhouse gas emissions in 2000, including land-use change.}}

There are different views over what the appropriate policy response to climate change should be.<ref>{{cite web
|year=2007
|author=Rogner, H.-H., D. Zhou, R. Bradley. P. Crabbé, O. Edenhofer, B.Hare, L. Kuijpers, M. Yamaguchi
|title=Executive Summary. In (book chapter): Introduction. In: Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds))
|url=http://www.ipcc.ch/publications_and_data/ar4/wg3/en/ch1s1-es.html
|publisher=Print version: Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Web version: IPCC website
|accessdate=2010-05-05}}</ref><ref>{{cite book
|year=1996
|author=Banuri, T., K. Göran-Mäler, M. Grubb, H.K. Jacobson and F. Yamin
|title=Equity and Social Considerations. In: Climate Change 1995: Economic and Social Dimensions of Climate Change. Contribution of Working Group III to the Second Assessment Report of the Intergovernmental Panel on Climate Change (J.P. Bruce, H. Lee and E.F. Haites, (eds.))
|page=87
|publisher=This version: Printed by Cambridge University Press, Cambridge, U.K., and New York, N.Y., U.S.A.. PDF version: IPCC website
|format=PDF
|url=http://www.ipcc.ch/ipccreports/sar/wg_III/ipcc_sar_wg_III_full_report.pdf
|isbn=9780521568548
|doi=10.2277/0521568544}}</ref> These competing views weigh the benefits of limiting emissions of greenhouse gases against the costs. In general, it seems likely that climate change will impose greater damages and risks in poorer regions.<ref>Banuri ''et al.'', 1996, p.&nbsp;83</ref>

=== Politics ===

Developing and developed countries have made different arguments over who should bear the burden of costs for cutting emissions. Developing countries often concentrate on per capita emissions, that is, the total emissions of a country divided by its population.<ref name=banuri>Banuri ''et al''., 1996, pp.&nbsp;94-95</ref> Per capita emissions in the industrialized countries are typically as much as ten times the average in developing countries.<ref>{{cite journal
|title=The Economics of the Kyoto Protocol
|author=Grubb, M.
|date=July-September 2003
|journal=World Economics
|volume=4
|issue=3
|page=144
|url=http://www.econ.cam.ac.uk/rstaff/grubb/publications/J36.pdf
|accessdate=2010-03-25}}</ref> This is used to make the argument that the real problem of climate change is due to the profligate and unsustainable lifestyles of those living in rich countries.<ref name=banuri/> On the other hand, commentators from developed countries more often point out that it is total emissions that matter.<ref name=banuri/> In 2008, developing countries made up around half of the world's total emissions of CO<sub>2</sub> from cement production and fossil fuel use.<ref>{{cite web
|year=2009
|month=June
|day=25
|author=PBL
|title=Global CO<sub>2</sub> emissions: annual increase halves in 2008
|url=http://www.pbl.nl/en/publications/2009/Global-CO2-emissions-annual-increase-halves-in-2008.html
|publisher=Netherlands Environmental Assessment Agency (PBL) website
|accessdate=2010-05-05}}</ref>

The Kyoto Protocol, which came into force in 2005, sets legally binding emission limitations for most developed countries.<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.eci.ox.ac.uk/~dliverma/CV/JHGE07-17.pdf
|accessdate=2009-08-08
|volume=35
|pages=12–14}}</ref> Developing countries are not subject to limitations. This exemption led the U.S. (under President [[George W. Bush]]) and a previous Australian Government to decide not to ratify the treaty.<ref>{{cite web
|year=2005
|author=IEA
|title=Energy Policies of IEA Countries - Australia- 2005 Review
|page=51
|url=http://www.iea.org/publications/free_new_Desc.asp?PUBS_ID=1565
|publisher=International Energy Agency (IEA), Head of Publications Service,
9 rue de la Fédération, 75739 Paris Cedex 15, France
|accessdate=2010-04-29}}</ref><ref name=dessai/> At the time, almost all world leaders expressed their disappointment over President Bush's decision.<ref name=dessai>{{cite web
|year=2001
|author=Dessai, S.
|title=The climate regime from The Hague to Marrakech: Saving or sinking the Kyoto Protocol? Tyndall Centre Working Paper 12
|pages=5–6
|url=http://www.tyndall.ac.uk/content/climate-regime-hague-marrakech-saving-or-sinking-kyoto-protocol
|publisher=Tyndall Centre website
|accessdate=2010-05-05}}</ref> Australia has since ratified the Kyoto protocol.<ref>{{cite web
|year=2009
|month=January
|day=20
|author=UNFCCC
|title=Report of the in-depth review of the fourth national assessment communication of Australia
|page=3
|url=http://unfccc.int/documentation/documents/advanced_search/items/3594.php?rec=j&priref=600004916#beg
|publisher=United Nations Office at Geneva, Switzerland
|accessdate=2010-05-05}}</ref>

=== Public opinion ===

In 2007–2008 [[Gallup Poll]]s surveyed 127 countries. Over a third of the world's population was unaware of global warming, with people in developing countries less aware than those in [[Developed country|developed]], and those in Africa the least aware. Of those aware, Latin America leads in belief that temperature changes are a result of human activities while Africa, parts of Asia and the Middle East, and a few countries from the Former Soviet Union lead in the opposite belief.<ref>{{Cite web
|first=Brett
|last=Pelham
|title=Awareness, Opinions About Global Warming Vary Worldwide
|url=http://www.gallup.com/poll/117772/Awareness-Opinions-Global-Warming-Vary-Worldwide.aspx
|publisher=Gallup
|date=2009-04-22
|accessdate=2009-07-14}}</ref> In the Western world, opinions over the concept and the appropriate responses are divided. Nick Pidgeon of [[Cardiff University]] finds that "results show the different stages of engagement{{Clarify|date=May 2010|reason=what does "engagement" mean?}} about global warming on each side of the Atlantic"; where Europe debates the appropriate responses while the United States debates whether climate change is happening.<ref name="pewpoll">{{Cite web
|title=Summary of Findings
|work=Little Consensus on Global Warming. Partisanship Drives Opinion
|publisher=Pew Research Center
|date=2006-07-12
|accessdate=2007-04-14
|url=http://people-press.org/reports/display.php3?ReportID=280}}</ref><ref>[http://www.nytimes.com/2007/01/04/health/04iht-poll.4102536.html More in Europe worry about climate than in U.S., poll shows - Health & Science - International Herald Tribune]</ref>{{Vague|what questions were asked in these polls, and what were the percentage responses to these questions?|date=May 2010}}{{Dubious|"Debate and skepticism" section|date=May 2010}}

=== Other views ===

Most scientists accept that humans are contributing to observed climate change.<ref name=nrc2008>NRC, 2008, p.&nbsp;2</ref><ref>{{cite web
|year=2005
|month=March
|author=Wallace, D. and J. Houghton
|title=A guide to facts and fictions about climate change
|pages=3–4
|url=http://royalsociety.org/Facts-and-fictions-about-climate-change/
|publisher=UK Royal Society website
|accessdate=2010-05-05}}</ref> National science academies have called on world leaders for policies to cut global emissions.<ref>{{cite web
|year=2009
|month=May
|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=2010-05-05}}</ref> There are, however, some scientists and non-scientists who question aspects of climate change science.<ref>{{cite web
|year=2009
|month=July
|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=2010-05-05}}</ref><ref>{{cite web
|date=n.d.
|author=SEPP
|title=Frequently Asked Questions About Climate Change
|url=http://www.sepp.org/FAQ/faq.html
|publisher=Science & Environmental Policy Project (SEPP) website
|accessdate=2010-05-05}}</ref>

Organizations such as the libertarian [[Competitive Enterprise Institute]], conservative commentators, and companies such as [[ExxonMobil]] have challenged IPCC climate change scenarios, funded scientists who disagree with the [[Scientific opinion on climate change|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
|publisher=Newsweek
|date=2007-08-13
|url=http://www.newsweek.com/id/32482|accessdate=2007-08-13}}</ref><ref>{{Cite web
|title=Royal Society tells Exxon: stop funding climate change denial
|url=http://www.guardian.co.uk/environment/2006/sep/20/oilandpetrol.business
|first=David
|last=Adams
|publisher=The Guardian
|date=2006-09-20
|accessdate=2007-08-09}}</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=2007-01-12
|accessdate=2007-05-02}}</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=2007-01-03
|accessdate=2007-04-27}}</ref> Environmental organizations and public figures have emphasized changes in the current 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=June 6, 2009 |format=PDF
|url=http://www.globalchange.gov/images/cir/pdf/Climate-Impacts-PR_june-6-2009.pdf
|accessdate=2009-06-27}}</ref> 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=May 18, 2007
|publisher=[[USA Today]]
|author=[[Reuters]]
|accessdate=Jan 21, 2010}}</ref> or 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=May 13, 2004
|publisher=Ceres
|accessdate=2010-03-04}}</ref>

Many studies link [[population growth]] with emissions and the effect of climate change.<ref>[[John T. Houghton]] (2004)."''[http://books.google.com/books?id=jE9mwoLXdwYC&pg=PA326&dq&hl=en#v=onepage&q=&f=false Global warming: the complete briefing]''". [[Cambridge University Press]]. p.326. ISBN 0521528747</ref><ref>{{cite news | url=http://www.independent.co.uk/environment/once-taboo-population-enters-climate-debate-1834789.html | title=Once taboo, population enters climate debate| publisher=[[The Independent]] | date=December 5, 2009 | accessdate=Jan 21, 2010}}</ref>

{{Clear}}

==See also==

{{Portal|Global warming|Global Warming Map.jpg}}

* [[Glossary of climate change]]
* [[Index of climate change articles]]
* [[History of climate change science]]

==Notes==

{{Cnote2 Begin|list-style=upper-alpha|colwidth=40em}}

{{Cnote2|A|Increase is for years 1905 to 2005. Global surface temperature is defined in the [[AR4|IPCC Fourth Assessment Report]] as the average of near-surface air temperature over land and sea surface temperature. These error bounds are constructed with a 90% [[confidence interval]].}}

{{Cnote2|B|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]]. 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]].}}

{{Cnote2|C|Note that the greenhouse effect produces an average worldwide temperature '''increase''' of about 33&nbsp;°C (59&nbsp;°F) compared to black body predictions without the greenhouse effect, not an average '''surface temperature''' of 33&nbsp;°C (91&nbsp;°F). The average worldwide surface temperature is about 14&nbsp;°C (57&nbsp;°F).}}

{{Cnote2|D|2=In the IPCC Fourth Assessment Report, published in 2007, this attribution is given a probability of greater than 90%, based on expert judgement.<ref>{{cite web
|url=http://www.ipcc.ch/publications_and_data/ar4/syr/en/mainssyr-introduction.html
|title=Introduction. In (section): Synthesis Report. In (book): Climate Change 2007: Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (Core Writing Team, Pachauri, R.K and Reisinger, A. (eds.))
|author=IPCC
|year=2007d
|publisher=Book version: IPCC, Geneva, Switzerland. This version: IPCC website
|accessdate=2010-04-26}}</ref> According to the US National Research Council Report – ''Understanding and Responding to Climate Change'' - published in 2008, "[most] scientists agree that the warming in recent decades has been caused primarily by human activities that have increased the amount of greenhouse gases in the atmosphere."<ref name=nrc2008/>}}

{{Cnote2 End}}

==References==

{{Reflist|colwidth=30em|refs=

<ref name="grida7">
{{Cite web
|url=http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-spm.pdf
|author=IPCC
|format=PDF
|title=Summary for Policymakers
|work=Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change
|date=2007-05-04
|accessdate=2009-07-03}}</ref>

<ref name=Hegerl-2001>
{{Cite web
|url=http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch09.pdf
|format=PDF
|title=Understanding and Attributing Climate Change
|work=Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change
|year=2007
|publisher=IPCC
|last=Hegerl
|first=Gabriele C.
|coauthors=''et al.''
|quote=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.}}</ref>

<ref name="IPCCSynthesisReport2007">
{{Cite book
|author=IPCC
|others=[Core Writing Team, Pachauri, R.K and Reisinger, A. (eds.)]
|title=Climate Change 2007: Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change
|url=http://www.ipcc.ch/publications_and_data/publications_ipcc_fourth_assessment_report_synthesis_report.htm
|format=Full free text
|year=2007
|publisher=IPCC
|location=Geneva, Switzerland
}}</ref>

<ref name="Lu-2007">
{{Cite journal
|last=Lu
|first=Jian
|coauthors=Vecchi, Gabriel A.; Reichler, Thomas
|title=Expansion of the Hadley cell under global warming
|journal=Geophysical Research Letters
|volume=34
|year=2007
|url=http://www.atmos.berkeley.edu/~jchiang/Class/Spr07/Geog257/Week10/Lu_Hadley06.pdf
|format=PDF
|doi=10.1029/2006GL028443
|pages=L06805
|authorlink=Jian Lu}}</ref>

}}

==Further reading==
{{refbegin|colwidth=40em}}
*{{Cite book|title=Financial Risks of Climate Change|author=Association of British Insurers|year=2005–06|url=http://www.climatewise.org.uk/storage/610/financial_risks_of_climate_change.pdf|format=PDF}}
*{{Cite journal|last=Ammann|first=Caspar|coauthors=''et al.''|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 ≈0.2&nbsp;°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}}
*{{Cite journal|last=Barnett|first=Tim P.|coauthors=Adam, J. C.; Lettenmaier, D. P.|date=2005-11-17|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|last1=Barnett|first1=TP|last2=Adam|first2=JC|last3=Lettenmaier|first3=DP}}
*{{Cite journal|last=Behrenfeld|first=Michael J.|coauthors=''et al.''|date=2006-12-07|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}}
*{{Cite journal|first=Onelack|last=Choi|coauthors=Fisher, Ann|month=May|year=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|url=http://www.springerlink.com/content/m6308777613702q0/}}
*{{Cite book|last=Dyurgerov|first=Mark B.|coauthors=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|id={{ISSN|0069-6145}}}}
*{{Cite journal|last=Emanuel|first=Kerry A.|date=2005-08-04|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=K}}
*{{Cite journal|last=Hansen|first=James|authorlink=James E. Hansen|coauthors=''et al.''|date=2005-06-03|title=Earth's Energy Imbalance: Confirmation and Implications|journal=Science|volume=308|issue=5727|pages=1431–1435|url=http://pangea.stanford.edu/research/Oceans/GES205/Hansen_Science_Earth's%20Energy%20Balance.pdf|format=PDF|doi=10.1126/science.1110252|pmid=15860591}}
*{{Cite journal|last=Hinrichs|first=Kai-Uwe|coauthors=Hmelo, Laura R.; Sylva, Sean P.|date=2003-02-21|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}}
*{{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=2006-01-11}}
*{{Cite journal|last=Hoyt|first=Douglas V.|coauthors=Schatten, Kenneth H.|year=1993–11|title=A discussion of plausible solar irradiance variations, 1700–1992|journal=Journal of Geophysical Research|volume=98|issue=A11|pages=18,895–18,906|url=http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1993JGR....9818895H&amp;db_key=AST&amp;data_type=HTML&amp;format=&amp;high=448f267ff303582|doi=10.1029/93JA01944}}
*{{Cite web|author=|url=http://www.imeche.org/NR/rdonlyres/FA401F02-3193-4A19-826A-3FEEFB89DEDE/0/ClimateChangeAdaptationReportIMechE.pdf|format=PDF|title=Climate Change: Adapting to the inevitable|publisher=Institution of Mechanical Engineers|accessdate=2009-03-07}}
*{{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.|coauthors=''et al.''|date=2003-02-14|title=Methane Hydrates in Quaternary Climate Change: The Clathrate Gun Hypothesis|publisher=American Geophysical Union|url=https://www.agu.org/cgi-bin/agubooks?book=ASSP0542960}}
*{{Cite news|last=Keppler|first=Frank|coauthors=''et al.''|title=Global Warming&nbsp;– 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=2006-01-18}}
*{{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.|coauthors=Wang, Y.M.; Sheeley, N.R.|date=2002–12|journal=Geophysical Research Letters|volume=29|issue=24|url=http://adsabs.harvard.edu/abs/2002GeoRL..29x..77L|doi=10.1029/2002GL015880|pages=2224|format=abstract}}
*{{Cite book|last=Lerner|first=K. Lee|coauthors=Lerner, K. Lee; Wilmoth, Brenda|title=Environmental issues: essential primary sources|publisher=Thomson Gale|date=2006-07-26|isbn=1414406258}}
*{{Cite journal|last=Muscheler, Raimund|coauthors=''et al.''|date=2005-07-28|title=Climate: How unusual is today's solar activity?|journal=Nature|volume=436|issue=7012|pages=1084–1087|url=http://www.cgd.ucar.edu/ccr/raimund/publications/Muscheler_et_al_Nature2005.pdf|format=PDF|doi=10.1038/nature04045|pmid=16049429|last1=Muscheler|first1=R|last2=Joos|first2=F|last3=Müller|first3=SA|last4=Snowball|first4=I}}
*{{Cite journal|last=Oerlemans|first=J.|date=2005-04-29|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}}
*{{Cite journal|last=Purse|first=Bethan V.|coauthors=''et al.''|title=Climate change and the recent emergence of bluetongue in Europe|journal=Nature Reviews Microbiology|volume=3|issue=2|pages=171–181|month=February|year=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=2005-11-05|title=Rise in Gases Unmatched by a History in Ancient Ice|publisher=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 book|last=Ruddiman|first=William F.|authorlink=William Ruddiman|date=2005-12-15|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.|authorlink=William Ruddiman|date=2005-08-01|title=Plows, Plagues, and Petroleum: How Humans Took Control of Climate|location=New Jersey|publisher=Princeton University Press|isbn=0-691-12164-8}}
*{{Cite journal|last=Solanki|first=Sami K.|authorlink=Sami Solanki|coauthors=''et al.''|date=2004-10-23|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|last1=Solanki|first1=SK|last2=Usoskin|first2=IG|last3=Kromer|first3=B|last4=Schüssler|first4=M|last5=Beer|first5=J|issue=7012}}
*{{Cite journal|last=Solanki|first=Sami K.|authorlink=Sami Solanki|coauthors=''et al.''|date=2005-07-28|title=Climate: How unusual is today's solar activity? (Reply)|journal=Nature|volume=436|pages=E4–E5|url=http://cc.oulu.fi/%7Eusoskin/personal/sola_nature05.pdf|format=PDF|doi=10.1038/nature04046}}
*{{Cite journal|last=Sowers|first=Todd|date=2006-02-10|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}}
*{{Cite journal|last=Svensmark|first=Henrik|coauthors=''et al.''|date=2007-02-08|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}}''(online version requires registration)''
*{{Cite journal|last=Walter|first=K. M.|coauthors=''et al.''|date=2006-09-07|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|last1=Walter|first1=KM|last2=Zimov|first2=SA|last3=Chanton|first3=JP|last4=Verbyla|first4=D|last5=Chapin Fs|first5=3rd}}
*{{Cite journal|last=Wang|first=Y.-M.|coauthors=Lean, J.L.; Sheeley, N.R.|date=2005-05-20|title=Modeling the sun's magnetic field and irradiance since 1713|journal=Astrophysical Journal|volume=625|pages=522–538|url=http://climatesci.colorado.edu/publications/pdf/Wang_2005.pdf|format=PDF|doi=10.1086/429689}}
*{{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}}
{{refend}}

==External links==
{{Wikipedia-Books}}

{{Sisterlinks|wikt=Global warming|b=Climate Change|q=Global warming|s=Global warming|commons=Category:Global warming|n=Category:Climate change|v=Global warming}}

;Research
{{refbegin}}
*[http://www.ipcc.ch Intergovernmental Panel on Climate Change]&nbsp;— collection of IPCC reports
*[http://www.nas.edu/climatechange Climate Change at the National Academies]&nbsp;— repository for reports, workshops, and meetings
*[http://www.nature.com/climate/index.html Nature Reports Climate Change]&nbsp;— free-access web resource
*[http://www.metoffice.gov.uk/climatechange/ Met Office: Climate change]&nbsp;— UK National Weather Service
*[http://www.istl.org/01-fall/internet.html Global Science and Technology Sources on the Internet]&nbsp;— extensive commented list of internet resources
*[http://edgcm.columbia.edu/ Educational Global Climate Modelling] (EdGCM)&nbsp;— research-quality climate change simulator
*[http://discover.itsc.uah.edu/ DISCOVER]&nbsp;— satellite-based ocean and climate data since 1979 from NASA
*[http://www.globalwarmingart.com/ Global Warming Art]&nbsp;— collection of figures and images
{{refend}}

;Educational
{{refbegin}}
*[http://green.nationalgeographic.com/environment/global-warming/gw-overview.html What Is Global Warming?]&nbsp;— by National Geographic
*[http://www.ncdc.noaa.gov/oa/climate/globalwarming.html Global Warming Frequently Asked Questions]&nbsp;— from NOAA
*[http://www.ucar.edu/news/features/climatechange/faqs.jsp Understanding Climate Change&nbsp;– Frequently Asked Questions]&nbsp;— from UCAR
*[http://climate.jpl.nasa.gov/ Global Climate Change: NASA's Eyes on the Earth]&nbsp;— from NASA's JPL and Caltech
*[http://ourworld.unu.edu/en/series/climate/ OurWorld 2.0]&nbsp;— from the United Nations University
*[http://www.pewclimate.org/ Pew Center on Global Climate Change]&nbsp;— business and politics
*[http://demonstrations.wolfram.com/BestEffortGlobalWarmingTrajectories/ Best Effort Global Warming Trajectories&nbsp;– Wolfram Demonstrations Project]&nbsp;— by Harvey Lam
*[http://www.koshland-science-museum.org/exhibitgcc/ Koshland Science Museum&nbsp;– Global Warming Facts and Our Future]&nbsp;— graphical introduction from National Academy of Sciences
*[http://www.aip.org/history/climate The Discovery of Global Warming&nbsp;– A History]&nbsp;— by Spencer R. Weart from The American Institute of Physics
*[http://site.videoproject.com/coralreefs/ Climate Change: Coral Reefs on the Edge]&nbsp;— A video presentation by Prof. Ove Hoegh-Guldberg, University of Auckland
*[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.whrc.org/resources/online_publications/warming_earth/index.htm Global Warming (The Warming of the Earth)]—A beginner's guide to understanding the issue of global warming—by the [[Woods Hole Research Center]]
*[http://chemistry.beloit.edu/Warming/index.html Global Warming]
{{refend}}

{{Global warming|state=expanded}}

{{DEFAULTSORT:Global Warming}}
[[Category:Global warming| ]]
[[Category:Carbon finance]]
[[Category:Climate change]]
[[Category:Economic problems]]
[[Category:History of climate]]
[[Category:19th century]]
[[Category:20th century]]
[[Category:21st century]]

{{Link GA|fr}}
{{Link GA|lt}}
{{Link GA|zh}}
{{Link GA|zh-classical}}

{{Link FA|de}}
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{{Link FA|pl}}
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[[af:Aardverwarming]]
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[[ar:احترار عالمي]]
[[an:Escalfamiento global]]
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[[be:Глабальнае пацяпленне]]
[[be-x-old:Глябальнае пацяпленьне]]
[[bs:Globalno zatopljenje]]
[[br:Tommadur ar blanedenn]]
[[bg:Глобално затопляне]]
[[ca:Escalfament global]]
[[ceb:Kalibotanong pagpanginit]]
[[cs:Globální oteplování]]
[[cy:Cynhesu byd eang]]
[[da:Global opvarmning]]
[[de:Globale Erwärmung]]
[[et:Globaalne soojenemine]]
[[el:Παγκόσμια θέρμανση]]
[[es:Calentamiento global]]
[[eo:Tutmonda varmiĝo]]
[[eu:Berotze globala]]
[[fa:گرم‌شدن زمین]]
[[fr:Réchauffement climatique]]
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[[ga:Téamh domhanda]]
[[gd:Blàthachadh na cruinne]]
[[gl:Quentamento global]]
[[ko:지구 온난화]]
[[hy:Գլոբալ տաքացում]]
[[hi:भूमंडलीय ऊष्मीकरण]]
[[hr:Globalno zatopljenje]]
[[id:Pemanasan global]]
[[ia:Calefaction global]]
[[is:Heimshlýnun]]
[[it:Riscaldamento globale]]
[[he:התחממות עולמית]]
[[jv:Pamanasan global]]
[[kn:ಜಾಗತಿಕ ತಾಪಮಾನ ಏರಿಕೆ]]
[[ka:გლობალური დათბობა]]
[[sw:Kupanda kwa halijoto duniani]]
[[la:Calefactio globalis]]
[[lv:Globālā sasilšana]]
[[lt:Visuotinis atšilimas]]
[[hu:Globális felmelegedés]]
[[mk:Глобално затоплување]]
[[ml:ആഗോളതാപനം]]
[[mr:जागतिक तापमानवाढ]]
[[arz:دفا عالمى]]
[[ms:Pemanasan global]]
[[mn:Дэлхийн дулаарал]]
[[nl:Opwarming van de Aarde]]
[[ja:地球温暖化]]
[[no:Global oppvarming]]
[[nn:Global oppvarming]]
[[oc:Escalfament global]]
[[pl:Globalne ocieplenie]]
[[pt:Aquecimento global]]
[[ro:Încălzirea globală]]
[[rm:Stgaudament global]]
[[ru:Глобальное потепление]]
[[sah:Аан дойду сылыйыыта]]
[[si:පෘථිවිය උණුසුම් වීම]]
[[simple:Global warming]]
[[sk:Globálne otepľovanie]]
[[sl:Globalno segrevanje]]
[[sr:Глобално загревање]]
[[sh:Globalno zatopljenje]]
[[su:Jagat nyongkab]]
[[fi:Ilmaston lämpeneminen]]
[[sv:Global uppvärmning]]
[[tl:Pag-init ng daigdig]]
[[ta:புவி சூடாதல்]]
[[te:భూగోళం యొక్క వేడిమి]]
[[th:ปรากฏการณ์โลกร้อน]]
[[tg:Гармшавии глобалӣ]]
[[tr:Küresel ısınma]]
[[uk:Глобальне потепління]]
[[vi:Ấm lên toàn cầu]]
[[fiu-vro:Ilma lämmämbäsminek üle ilma]]
[[zh-classical:全球暖化]]
[[war:Pagpaso han kalibutan]]
[[wuu:全球暖化]]
[[yi:גלאבאלע אנווארימונג]]
[[zh-yue:全球變暖]]
[[bat-smg:Gluobalėnis atšėlėms]]
[[zh:全球变暖]]

Revision as of 21:00, 5 June 2010

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