On the Effect of Historical SST Patterns on Radiative Feedback

• Published in: Journal of Geophysical Research: Atmospheres
• Main Authors: Andrews, Timothy, Bodas-Salcedo, Alejandro, Gregory, Jonathan M., Dong, Yue, Armour, Kyle C., Paynter, David, Lin, Pu, Modak, Angshuman, Mauritsen, Thorsten, Cole, Jason N. S., Medeiros, Brian, Benedict, James J., Douville, Hervé, Roehrig, Romain, Koshiro, Tsuyoshi, Kawai, Hideaki, Ogura, Tomoo, Dufresne, Jean-Louis, Allan, Richard P., Liu, Chunlei
• Other Authors: Met Office Hadley Centre (MOHC), United Kingdom Met Office Exeter, NCAS-Climate Reading, Department of Meteorology Reading, University of Reading (UOR)-University of Reading (UOR), University of Washington Seattle, National Oceanic and Atmospheric Administration (NOAA), Princeton University, Stockholm University, Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL), Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), NERC National Centre for Earth Observation (NCEO), Natural Environment Research Council (NERC), Guangdong Ocean University
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: climate feedback; pattern effect; climate sensitivity; climate models; observations; historical record; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; Pacific; Southern Ocean; Sea ice
• Online Access: https://insu.hal.science/insu-03847095; https://insu.hal.science/insu-03847095/document; https://insu.hal.science/insu-03847095/file/Andrews.Gregory.ea-jgr-2022-smi-pattern.pdf; https://doi.org/10.1029/2022JD036675

International audience We investigate the dependence of radiative feedback on the pattern of sea-surface temperature (SST) change in 14 Atmospheric General Circulation Models (AGCMs) forced with observed variations in SST and sea-ice over the historical record from 1871 to near-present. We find that over 1871-1980, the Earth warmed with feedbacks largely consistent and strongly correlated with long-term climate sensitivity feedbacks (diagnosed from corresponding atmosphere-ocean GCM abrupt-4xCO2 simulations). Post 1980, however, the Earth warmed with unusual trends in tropical Pacific SSTs (enhanced warming in the west, cooling in the east) and cooling in the Southern Ocean that drove climate feedback to be uncorrelated with—and indicating much lower climate sensitivity than—that expected for long-term CO 2 increase. We show that these conclusions are not strongly dependent on the Atmospheric Model Intercomparison Project (AMIP) II SST data set used to force the AGCMs, though the magnitude of feedback post 1980 is generally smaller in nine AGCMs forced with alternative HadISST1 SST boundary conditions. We quantify a "pattern effect" (defined as the difference between historical and long-term CO 2 feedback) equal to 0.48 ± 0.47 [5%-95%] W m -2 K -1 for the time-period 1871-2010 when the AGCMs are forced with HadISST1 SSTs, or 0.70 ± 0.47 [5%-95%] W m -2 K -1 when forced with AMIP II SSTs. Assessed changes in the Earth's historical energy budget agree with the AGCM feedback estimates. Furthermore satellite observations of changes in top-of-atmosphere radiative fluxes since 1985 suggest that the pattern effect was particularly strong over recent decades but may be waning post 2014.