Climate commitment: Difference between revisions

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{{refimprove|date=December 2012}}

'''Climate commitment''' describes the fact that [[climate]] reacts with a delay to influencing factors ("[[climate forcing]]s") such as the presence of [[greenhouse gas]]es. Climate commitment studies attempt to assess the amount of future [[global warming]] that is "committed" under the assumption of some constant level of forcings. The constant level often used for illustrative purposes is [[carbon dioxide|CO₂{{CO2}}]] doubling or quadrupling; or the present level of forcing.

== Basic idea ==

If a [[wiktionary:perturbation|perturbation]] -— such as an increase in greenhouse gases or [[solar variation|solar activity]] -— is applied to the [[climate system]] the response will not be immediate, principally because of the large [[heat capacity]] (i.e., [[Volumetric heat capacity#Thermal inertia|thermal inertia]]) of the [[ocean]]s.

:''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 [[Thermodynamic equilibrium|equilibrium]] with the imposed heating because of its higher heat capacity.''

Land only stores [[heat]] in the top few meters.

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== Models ==

{{main|global climate model}}

Recent [[model (abstract)|model]]s 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.(<ref>{{cite journal |last=Wigley |first=T. M. L. |title=The Climate Change Commitment |journal=Science |volume=307 |issue=5716 |pages=1766–9 |date=17 March 2005) |doi=10.1126/science.1103934 |pmid=15774756 |url=ftp://ftp.soest.hawaii.edu/coastal/Climate%20Articles/Wigley_2005%20Sea%20level%20commitment.pdf |format=PDF}}</ref> As ocean waters expand in response to this warming, global [[sea level]]s 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°C - 11–1.5°C estimated temperature increase.<ref>{{cite web |url= http://www.nature.com/news/2005/050314/full/050314-13.html |title= Oceans extend effects of climate change |authorfirst= Deirdre |last=Lockwood |date= 2005-05-17 |work=Nature News |publisher= [[Nature Publishing Group]] |accessdatedoi=201010.1038/news050314-05-0713}} </ref>

==History==

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== References ==

{{refbegin}}

* Meehl G. A., et al. Sciencexpress, 10.1126/science.1106663 (2005)[http://www.geo.utexas.edu/courses/387h/PAPERS/meehl2005.pdf].

*{{cite journal |last=Wetherald |first=Richard T. |first2=Ronald J. |last2=Stouffer |first3=Keith W. |last3=Dixon |title=Committed warming and its implications for climate change. |journal=Geophysical Research Letters |volume=28 |issue=8 |pages=1535-8 |year=2001 |doi= |url=https://www.gfdl.noaa.gov/bibliography/related_files/rw0101.pdf |format=PDF}}

* Wigley T. M. L., et al. Sciencexpress, 110.1126/science.1103934 (2005)[ftp://ftp.soest.hawaii.edu/coastal/Climate%20Articles/Wigley_2005%20Sea%20level%20commitment.pdf].

*{{cite journal |last=Meehl |first=Gerald A. |last2=Washington |first2=Warren M. |last3=Collins |first3=William D. |last4=Arblaster |first4=Julie M. |last5=Hu |first5=Aixue |last6=Buja |first6=Lawrence E. |last7=Strand |first7=Warren G. |last8=Teng |first8=Haiyan |title=How Much More Global Warming and Sea Level Rise? |journal=Science |volume=307 |issue=5716 |pages=1769–72 |date=17 March 2005 |pmid=15774757 |doi=10.1126/science.1106663 |url=http://www.geo.utexas.edu/courses/387h/PAPERS/meehl2005.pdf |format=PDF}}

<references/>

{{refend}}

{{reflist}}

== External links ==

* http://www.nature.com/news/2005/050314/full/050314-13.html

* [http://www.agu.org/pubs/crossref/2001/2000GL011786.shtml GRL, VOL. 28, NO. 8, PAGES 1535–1538, 2001, ''Committed warming and its implications for climate change'', Richard T. Wetherald et al.]

{{Global warming}}