Symmetric and Antisymmetric Components of Polar-Amplified Warming

• Published in: Journal of Climate
• Main Authors: Hill, Spencer, Burls, Natalie, Fedorov, Alexey, Merlis, Timothy M.
• Other Authors: Lamont-Doherty Earth Observatory (LDEO), Columbia University New York, George Mason University Fairfax, Océan et variabilité du climat (VARCLIM), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), 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)-École normale supérieure - Paris (ENS-PSL), 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)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-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)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Department of Earth and Planetary Sciences New Haven, Yale University New Haven, Department of Atmospheric and Oceanic Sciences Montréal, McGill University = Université McGill Montréal, Canada, ANR-18-MPGA-0001,ARCHANGE,Changement climatique et Arctique et circulation océanique globale(2018)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: [SDU]Sciences of the Universe [physics]; Antarc*; Antarctic; Arctic
• Online Access: https://hal.science/hal-03952637; https://doi.org/10.1175/jcli-d-20-0972.1

International audience Abstract CO 2 -forced surface warming in general circulation models (GCMs) is initially polar amplified in the Arctic but not in the Antarctic—a largely hemispherically antisymmetric signal. Nevertheless, we show in CESM1 and 11 LongRunMIP GCMs that the hemispherically symmetric component of global-mean-normalized, zonal-mean warming ( ) under 4 × CO 2 changes weakly or becomes modestly more polar amplified from the first decade to near-equilibrium. Conversely, the antisymmetric warming component ( ) weakens with time in all models, modestly in some including FAMOUS, but effectively vanishing in others including CESM1. We explore mechanisms underlying the robust behavior with a diffusive moist energy balance model (MEBM), which given radiative feedback parameter ( λ ) and ocean heat uptake ( ) fields diagnosed from CESM1 adequately reproduces the CESM1 and fields. In further MEBM simulations perturbing λ and , is sensitive to their symmetric components only, and more to that of λ . A three-box, two-time-scale model fitted to FAMOUS and CESM1 reveals a curiously short Antarctic fast-response time scale in FAMOUS. In additional CESM1 simulations spanning a broader range of forcings, changes modestly across 2–16 × CO 2 , and in a Pliocene-like simulation is more polar amplified but likewise approximately time invariant. Determining the real-world relevance of these behaviors—which imply that a surprising amount of information about near-equilibrium polar amplification emerges within decades—merits further study.