Editing Greenhouse effect (section)

== Role in climate change ==
{{Main|Climate change|Earth's energy budget}}
[[File:Earth's heating rate since 2005.jpg|thumb|right|upright=1.2|[[Earth's Energy Imbalance|Earth's rate of heating]] (graph) is a result of factors which include the enhanced greenhouse effect.<ref>{{cite web |author=Joseph Atkinson |date=22 June 2021 |title=Earth Matters: Earth's Radiation Budget is Out of Balance |url=https://earthobservatory.nasa.gov/blogs/earthmatters/2021/06/22/earths-radiation-budget-is-out-of-balance/ |url-status=live |archive-url=https://web.archive.org/web/20220410085015/https://earthobservatory.nasa.gov/blogs/earthmatters/2021/06/22/earths-radiation-budget-is-out-of-balance/ |archive-date=10 April 2022 |access-date=1 March 2022 |publisher=NASA Earth Observatory}}</ref>]]
Strengthening of the greenhouse effect through additional greenhouse gases from human activities is known as the ''enhanced greenhouse effect''.<ref name="IPCC" />{{Rp|page=2232}} As well as being inferred from measurements by [[Argo (oceanography)|ARGO]], [[Clouds and the Earth's Radiant Energy System|CERES]] and other instruments throughout the 21st century,<ref>{{Cite web |title=IPCC AR6 WG1 |url=https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Full_Report.pdf |url-status=live |archive-url=https://web.archive.org/web/20210809080054/https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Full_Report.pdf |archive-date=9 August 2021}}</ref>{{Rp|page=7–17}} this increase in [[radiative forcing]] from human activity has been observed directly,<ref>{{cite web |author=Robert McSweeney |date=25 February 2015 |title=New study directly measures greenhouse effect at Earth's surface |url=https://www.carbonbrief.org/new-study-directly-measures-greenhouse-effect-at-earths-surface |url-status=live |archive-url=https://web.archive.org/web/20210418151415/https://www.carbonbrief.org/new-study-directly-measures-greenhouse-effect-at-earths-surface |archive-date=18 April 2021 |access-date=18 April 2021 |publisher=Carbon Brief}}</ref><ref>{{cite web |date=26 March 2021 |title=Direct observations confirm that humans are throwing Earth's energy budget off balance |url=https://phys.org/news/2021-03-humans-earth-energy.html |url-status=live |archive-url=https://web.archive.org/web/20210418072159/https://phys.org/news/2021-03-humans-earth-energy.html |archive-date=18 April 2021 |access-date=18 April 2021 |website=phys.org |publisher=Science X}}</ref> and is attributable mainly to increased atmospheric carbon dioxide levels.<ref>{{cite web |title=Enhanced Greenhouse Effect |url=http://www.ace.mmu.ac.uk/eae/Global_Warming/Older/Enhanced_Greenhouse_Effect.html |url-status=dead |archive-url=https://web.archive.org/web/20101024121935/http://www.ace.mmu.ac.uk/eae/global_warming/Older/Enhanced_Greenhouse_Effect.html |archive-date=24 October 2010 |access-date=15 October 2010 |publisher=Ace.mmu.ac.uk}}</ref>

[[File:Mauna Loa CO2 monthly mean concentration.svg|thumb|left|upright=0.7|The [[Keeling Curve]] of atmospheric CO<sub>2</sub> abundance.]]
{{CO2}} is produced by [[fossil fuel burning]] and other activities such as [[cement]] production and [[tropical deforestation]].<ref name="IPCC deforestation">IPCC [http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter7.pdf Fourth Assessment Report, Working Group I Report "The Physical Science Basis"] {{Webarchive|url=https://web.archive.org/web/20110315005004/http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter7.pdf|date=15 March 2011}} Chapter 7</ref>  Measurements of {{CO2}} from the [[Mauna Loa Observatory]] show that concentrations have increased from about 313 parts per million (ppm)<ref>{{cite web |title=Atmospheric Carbon Dioxide – Mauna Loa |url=http://www.esrl.noaa.gov/gmd/ccgg/trends/co2_data_mlo.html |url-status=live |archive-url=https://web.archive.org/web/20190520204843/https://www.esrl.noaa.gov/gmd/ccgg/trends/co2_data_mlo.html |archive-date=20 May 2019 |access-date=8 December 2008 |publisher=[[NOAA]]}}</ref> in 1960, passing the 400 ppm milestone in 2013.<ref>{{cite magazine |date=12 May 2013 |title=Climate Milestone: Earth's {{CO2}} Level Passes 400 ppm |url=http://news.nationalgeographic.com/news/energy/2013/05/130510-earth-co2-milestone-400-ppm/ |url-status=live |magazine=National Geographic |archive-url=https://web.archive.org/web/20131215081625/http://news.nationalgeographic.com/news/energy/2013/05/130510-earth-co2-milestone-400-ppm/ |archive-date=15 December 2013 |access-date=10 December 2017}}</ref>  The current observed amount of {{CO2}} exceeds the geological record maxima (≈300 ppm) from ice core data.<ref>{{cite journal |author=Hansen J. |date=February 2005 |title=A slippery slope: How much global warming constitutes "dangerous anthropogenic interference"? |url=https://zenodo.org/record/1232798 |url-status=live |journal=Climatic Change |volume=68 |issue=333 |pages=269–279 |bibcode=2005ClCh...68..269H |doi=10.1007/s10584-005-4135-0 |s2cid=153165132 |archive-url=https://web.archive.org/web/20200801065245/https://zenodo.org/record/1232798 |archive-date=1 August 2020 |access-date=8 June 2020}}</ref>

Over the past 800,000 years,<ref>{{cite news |date=4 September 2006 |title=Deep ice tells long climate story |work=BBC News |url=http://news.bbc.co.uk/2/hi/science/nature/5314592.stm |url-status=live |access-date=4 May 2010 |archive-url=https://web.archive.org/web/20130123202651/http://news.bbc.co.uk/2/hi/science/nature/5314592.stm |archive-date=23 January 2013}}</ref> [[ice core]] data shows that carbon dioxide has varied from values as low as 180 ppm to the pre-industrial level of 270 ppm.<ref>{{cite journal |author=Hileman B |date=28 November 2005 |title=Ice Core Record Extended |url=http://pubs.acs.org/cen/news/83/i48/8348notw1.html |url-status=live |journal=Chemical & Engineering News |volume=83 |issue=48 |page=7 |doi=10.1021/cen-v083n048.p007 |archive-url=https://web.archive.org/web/20190515033556/http://pubs.acs.org/cen/news/83/i48/8348notw1.html |archive-date=15 May 2019 |access-date=6 September 2006|url-access=subscription }}</ref> [[Paleoclimatologists]] consider variations in carbon dioxide concentration to be a fundamental factor influencing climate variations over this time scale.<ref name="Bowen (2005), Thin Ice">{{cite book |last=Bowen |first=Mark |url=https://books.google.com/books?id=HGIcabCZHVUC |title=Thin Ice: Unlocking the Secrets of Climate in the World's Highest Mountains |publisher=Owl Books |year=2006 |isbn=978-1429932707 |access-date=1 June 2018 |archive-url=https://web.archive.org/web/20200802192430/https://books.google.com/books?id=HGIcabCZHVUC |archive-date=2 August 2020 |url-status=live}}</ref><ref>{{Cite web |date=20 August 2008 |title=Temperature change and carbon dioxide change |url=http://www.ncdc.noaa.gov/paleo/globalwarming/temperature-change.html |url-status=dead |archive-url=https://web.archive.org/web/20170118144841/https://www.ncdc.noaa.gov/paleo/globalwarming/temperature-change.html |archive-date=18 January 2017 |website=U.S. National Oceanic and Atmospheric Administration Paleoclimatology}}</ref>