Climate commitment describes the fact that Earth's climate reacts with a delay to influencing factors ("climate forcings") such as the growth and the greater presence of greenhouse gases. Climate commitment studies attempt to assess the amount of future global warming that is "committed" under the assumption of some constant or some evolving level of forcing. The constant level often used for illustrative purposes is that due to CO2 doubling or quadrupling relative to the pre-industrial level; or the present level of forcing.
The ongoing buildup of long-lived greenhouse gases in Earth's atmosphere, whose warming influence has nearly doubled since 1979, shows mankind's influence on the global climate.[1][2][3]
Climate commitment is the "unavoidable future climate change resulting from inertia in the geophysical and socio-economic systems".[4] Different types of climate change commitment are discussed in the literature. These include the "constant composition commitment"; the "constant emissions commitment" and the "zero emissions commitment".[4]: 2222
Basic ideaedit
The accumulation of excess heat in the ocean, at ever greater depths, measures global warming that has already become "irreversible" in the near term[5]
As an analogue, consider the heating of a thin metal plate (by the sun or by a flame): the plate will warm relatively quickly. If a thick metal block is heated instead, it will take much longer for the entire block to reach equilibrium with the imposed heating because of its higher heat capacity.
Land only stores heat in the top few meters. Ocean water, by contrast, can move vertically and store heat within the ocean's depth (convection). This is why the land surface is observed to warm more than the oceans. It also explains the very large difference in response between
"equilibrium" climate prediction runs in which only a shallow ocean is used and it is assumed that the climate has come to equilibrium and
"transient" climate prediction runs in which a full ocean is used and the climate is out of balance.
The "commitment" can apply to variables other than temperature: because of the long mixing time for heat into the deep ocean, a given surface warming commits to centuries of sea level rise from thermal expansion of the ocean. Also once a certain threshold is crossed, it is likely that a slow melting of the Greenland ice sheet will commit us to a sea level rise of 5m over millennia.
Recent models forecast that even in the unlikely event of greenhouse gases stabilizing at present levels, the Earth would warm by an additional 0.5°C by 2100, a similar rise in temperature to that seen during the 20th century. In 2050, as much as 64% of that commitment would be due to past natural forcings. Over time, their contribution compared to the human influence will diminish. Overall, the warming commitment at 2005 greenhouse gas levels could exceed 1°C.[7] As ocean waters expand in response to this warming, global sea levels would mount by about 10 centimeters during that time. These models do not take into account ice cap and glacier melting; including those climate feedback effects would give a 1–1.5°C estimated temperature increase.[8]
Historyedit
The concept has been discussed as far back as 1995 in the IPCCTAR and in the SAR.
Wetherald, Richard T.; Stouffer, Ronald J.; Dixon, Keith W. (2001). "Committed warming and its implications for climate change" (PDF). Geophysical Research Letters. 28 (8): 1535–8. Bibcode:2001GeoRL..28.1535W. doi:10.1029/2000gl011786.
Meehl, Gerald A.; Washington, Warren M.; Collins, William D.; Arblaster, Julie M.; Hu, Aixue; Buja, Lawrence E.; Strand, Warren G.; Teng, Haiyan (17 March 2005). "How Much More Global Warming and Sea Level Rise?" (PDF). Science. 307 (5716): 1769–72. Bibcode:2005Sci...307.1769M. doi:10.1126/science.1106663. PMID 15774757.
^"The NOAA Annual Greenhouse Gas Index (AGGI)". NOAA.gov. National Oceanic and Atmospheric Administration (NOAA). Spring 2023. from the original on 24 May 2023.
^"Annual Greenhouse Gas Index". U.S. Global Change Research Program. from the original on 21 April 2021.
^"The NOAA Annual Greenhouse Gas Index (AGGI) - An Introduction". NOAA Global Monitoring Laboratory/Earth System Research Laboratories. Retrieved 2 March 2023.
^ abIPCC, 2021: Annex VII: Glossary [Matthews, J.B.R., V. Möller, R. van Diemen, J.S. Fuglestvedt, V. Masson-Delmotte, C. Méndez, S. Semenov, A. Reisinger (eds.)]. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 2215–2256, doi:10.1017/9781009157896.022.
^von Schuckmann, K.; Cheng, L.; Palmer, M. D.; Hansen, J.; et al. (7 September 2020). "Heat stored in the Earth system: where does the energy go?". Earth System Science Data. 12 (3): 2013-2041. Bibcode:2020ESSD...12.2013V. doi:10.5194/essd-12-2013-2020. hdl:20.500.11850/443809.
^Abraham, John; Cheng, Lijing; Mann, Michael E.; Trenberth, Kevin; von Schuckmann, Karina (1 July 2022). "The ocean response to climate change guides both adaptation and mitigation efforts". Atmospheric and Oceanic Science Letters. 15 (100221): 1–9. doi:10.1016/j.aosl.2022.100221.
^Wigley, T. M. L. (17 March 2005). "The Climate Change Commitment" (PDF). Science. 307 (5716): 1766–9. Bibcode:2005Sci...307.1766W. doi:10.1126/science.1103934. PMID 15774756.
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This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Climate commitment news newspapers books scholar JSTOR December 2012 Learn how and when to remove this template message Climate commitment describes the fact that Earth s climate reacts with a delay to influencing factors climate forcings such as the growth and the greater presence of greenhouse gases Climate commitment studies attempt to assess the amount of future global warming that is committed under the assumption of some constant or some evolving level of forcing The constant level often used for illustrative purposes is that due to CO2 doubling or quadrupling relative to the pre industrial level or the present level of forcing The ongoing buildup of long lived greenhouse gases in Earth s atmosphere whose warming influence has nearly doubled since 1979 shows mankind s influence on the global climate 1 2 3 Contents 1 Definition 2 Basic idea 3 Models 4 History 5 See also 6 References 7 External linksDefinition editClimate commitment is the unavoidable future climate change resulting from inertia in the geophysical and socio economic systems 4 Different types of climate change commitment are discussed in the literature These include the constant composition commitment the constant emissions commitment and the zero emissions commitment 4 2222 Basic idea edit nbsp The accumulation of excess heat in the ocean at ever greater depths measures global warming that has already become irreversible in the near term 5 If a perturbation such as an increase in greenhouse gases or solar activity is applied to Earth s climate system the response will not be immediate principally because of the large heat capacity i e thermal inertia of the oceans 6 As an analogue consider the heating of a thin metal plate by the sun or by a flame the plate will warm relatively quickly If a thick metal block is heated instead it will take much longer for the entire block to reach equilibrium with the imposed heating because of its higher heat capacity Land only stores heat in the top few meters Ocean water by contrast can move vertically and store heat within the ocean s depth convection This is why the land surface is observed to warm more than the oceans It also explains the very large difference in response between equilibrium climate prediction runs in which only a shallow ocean is used and it is assumed that the climate has come to equilibrium and transient climate prediction runs in which a full ocean is used and the climate is out of balance The commitment can apply to variables other than temperature because of the long mixing time for heat into the deep ocean a given surface warming commits to centuries of sea level rise from thermal expansion of the ocean Also once a certain threshold is crossed it is likely that a slow melting of the Greenland ice sheet will commit us to a sea level rise of 5m over millennia Models editMain article global climate model Recent models forecast that even in the unlikely event of greenhouse gases stabilizing at present levels the Earth would warm by an additional 0 5 C by 2100 a similar rise in temperature to that seen during the 20th century In 2050 as much as 64 of that commitment would be due to past natural forcings Over time their contribution compared to the human influence will diminish Overall the warming commitment at 2005 greenhouse gas levels could exceed 1 C 7 As ocean waters expand in response to this warming global sea levels would mount by about 10 centimeters during that time These models do not take into account ice cap and glacier melting including those climate feedback effects would give a 1 1 5 C estimated temperature increase 8 History editThe concept has been discussed as far back as 1995 in the IPCC TAR 1 and in the SAR See also editClimate inertia Climate sensitivityReferences editWetherald Richard T Stouffer Ronald J Dixon Keith W 2001 Committed warming and its implications for climate change PDF Geophysical Research Letters 28 8 1535 8 Bibcode 2001GeoRL 28 1535W doi 10 1029 2000gl011786 Meehl Gerald A Washington Warren M Collins William D Arblaster Julie M Hu Aixue Buja Lawrence E Strand Warren G Teng Haiyan 17 March 2005 How Much More Global Warming and Sea Level Rise PDF Science 307 5716 1769 72 Bibcode 2005Sci 307 1769M doi 10 1126 science 1106663 PMID 15774757 The NOAA Annual Greenhouse Gas Index AGGI NOAA gov National Oceanic and Atmospheric Administration NOAA Spring 2023 Archived from the original on 24 May 2023 Annual Greenhouse Gas Index U S Global Change Research Program Archived from the original on 21 April 2021 The NOAA Annual Greenhouse Gas Index AGGI An Introduction NOAA Global Monitoring Laboratory Earth System Research Laboratories Retrieved 2 March 2023 a b IPCC 2021 Annex VII Glossary Matthews J B R V Moller R van Diemen J S Fuglestvedt V Masson Delmotte C Mendez S Semenov A Reisinger eds In Climate Change 2021 The Physical Science Basis Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change Masson Delmotte V P Zhai A Pirani S L Connors C Pean S Berger N Caud Y Chen L Goldfarb M I Gomis M Huang K Leitzell E Lonnoy J B R Matthews T K Maycock T Waterfield O Yelekci R Yu and B Zhou eds Cambridge University Press Cambridge United Kingdom and New York NY USA pp 2215 2256 doi 10 1017 9781009157896 022 von Schuckmann K Cheng L Palmer M D Hansen J et al 7 September 2020 Heat stored in the Earth system where does the energy go Earth System Science Data 12 3 2013 2041 Bibcode 2020ESSD 12 2013V doi 10 5194 essd 12 2013 2020 hdl 20 500 11850 443809 Abraham John Cheng Lijing Mann Michael E Trenberth Kevin von Schuckmann Karina 1 July 2022 The ocean response to climate change guides both adaptation and mitigation efforts Atmospheric and Oceanic Science Letters 15 100221 1 9 doi 10 1016 j aosl 2022 100221 Wigley T M L 17 March 2005 The Climate Change Commitment PDF Science 307 5716 1766 9 Bibcode 2005Sci 307 1766W doi 10 1126 science 1103934 PMID 15774756 Lockwood Deirdre 2005 05 17 Oceans extend effects of climate change Nature News doi 10 1038 news050314 13 External links edit Retrieved from https en wikipedia org w index php title Climate commitment amp oldid 1193764693, wikipedia, wiki, book, books, library,
