Variation in climate sensitivity and feedback parameters during the historical period

Gregory, J. M. ORCID: https://orcid.org/0000-0003-1296-8644 and Andrews, T. (2016) Variation in climate sensitivity and feedback parameters during the historical period. Geophysical Research Letters, 43 (8). pp. 3911-3920. ISSN 0094-8276 doi: 10.1002/2016GL068406

Abstract/Summary

We investigate the climate feedback parameter α (W m−2 K−1) during the historical period (since 1871) in experiments using the HadGEM2 and HadCM3 atmosphere general circulation models (AGCMs) with constant preindustrial atmospheric composition and time-dependent observational sea surface temperature (SST) and sea ice boundary conditions. In both AGCMs, for the historical period as a whole, the effective climate sensitivity is ∼2 K (α≃1.7 W m−2 K−1), and α shows substantial decadal variation caused by the patterns of SST change. Both models agree with the AGCMs of the latest Coupled Model Intercomparison Project in showing a considerably smaller effective climate sensitivity of ∼1.5 K (α = 2.3 ± 0.7 W m−2 K−1), given the time-dependent changes in sea surface conditions observed during 1979–2008, than the corresponding coupled atmosphere-ocean general circulation models (AOGCMs) give under constant quadrupled CO2 concentration. These findings help to relieve the apparent contradiction between the larger values of effective climate sensitivity diagnosed from AOGCMs and the smaller values inferred from historical climate change.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/61849
Item Type	Article
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > NCAS
Publisher	American Geophysical Union
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