# Compensation between Model Feedbacks and Curtailment of Climate Sensitivity

 dc.contributor.author Huybers, Peter John dc.date.accessioned 2012-11-28T19:47:00Z dc.date.issued 2010 dc.identifier.citation Huybers, Peter. 2010. Compensation between model feedbacks and curtailment of climate sensitivity. Journal of Climate 23(11): 3009-3018. en_US dc.identifier.issn 0894-8755 en_US dc.identifier.uri http://nrs.harvard.edu/urn-3:HUL.InstRepos:9962007 dc.description.abstract The spread in climate sensitivity obtained from 12 general circulation model runs used in the Fourth Assessment of the Intergovernmental Panel on Climate Change indicates a 95% confidence interval of $$2.1^{\circ}-5.5^{\circ}C$$, but this reflects compensation between model feedbacks. In particular, cloud feedback strength negatively covaries with the albedo feedback as well as with the combined water vapor plus lapse rate feedback. If the compensation between feedbacks is removed, the 95% confidence interval for climate sen- sitivity expands to $$1.9^{\circ}-8.0^{\circ}C$$,. Neither of the quoted 95% intervals adequately reflects the understanding of climate sensitivity, but their differences illustrate that model interdependencies must be understood before model spread can be correctly interpreted. en_US The degree of negative covariance between feedbacks is unlikely to result from chance alone. It may, however, result from the method by which the feedbacks were estimated, physical relationships represented in the models, or from conditioning the models upon some combination of observations and expectations. This compensation between model feedbacks when taken together with indications that variations in radiative forcing and the rate of ocean heat uptake play a similar compensatory role in models suggests that conditioning of the models acts to curtail the intermodel spread in climate sensitivity. Observations used to condition the models ought to be explicitly stated, or there is the risk of doubly calling on data for purposes of both calibration and evaluation. Conditioning the models upon individual expectation (e.g., anchoring to the Charney range of $$3^{\circ} \pm 1.5^{\circ} C$$, to the extent that it exists, greatly complicates statistical interpretation of the intermodel spread. dc.description.sponsorship Earth and Planetary Sciences en_US dc.language.iso en_US en_US dc.publisher American Meteorological Society en_US dc.relation.isversionof doi:10.1175/2010JCLI3380.1 en_US dc.relation.hasversion http://www.people.fas.harvard.edu/~phuybers/Doc/compensation_jclimate2010.pdf en_US dash.license LAA dc.title Compensation between Model Feedbacks and Curtailment of Climate Sensitivity en_US dc.type Journal Article en_US dc.description.version Version of Record en_US dc.relation.journal Journal of Climate en_US dash.depositing.author Huybers, Peter John dc.date.available 2012-11-28T19:47:00Z

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Peer reviewed scholarly articles from the Faculty of Arts and Sciences of Harvard University