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Equilibrium Climate Sensitivity Estimated by Equilibrating Climate Models
Author(s) -
Rugenstein Maria,
BlochJohnson Jonah,
Gregory Jonathan,
Andrews Timothy,
Mauritsen Thorsten,
Li Chao,
Frölicher Thomas L.,
Paynter David,
Danabasoglu Gokhan,
Yang Shuting,
Dufresne JeanLouis,
Cao Long,
Schmidt Gavin A.,
AbeOuchi Ayako,
Geoffroy Olivier,
Knutti Reto
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2019gl083898
Subject(s) - climate sensitivity , climatology , environmental science , climate model , extrapolation , climate change , global warming , sensitivity (control systems) , latitude , range (aeronautics) , atmospheric sciences , coupled model intercomparison project , geology , mathematics , statistics , oceanography , materials science , geodesy , electronic engineering , engineering , composite material
The methods to quantify equilibrium climate sensitivity are still debated. We collect millennial‐length simulations of coupled climate models and show that the global mean equilibrium warming is higher than those obtained using extrapolation methods from shorter simulations. Specifically, 27 simulations with 15 climate models forced with a range of CO 2 concentrations show a median 17% larger equilibrium warming than estimated from the first 150 years of the simulations. The spatial patterns of radiative feedbacks change continuously, in most regions reducing their tendency to stabilizing the climate. In the equatorial Pacific, however, feedbacks become more stabilizing with time. The global feedback evolution is initially dominated by the tropics, with eventual substantial contributions from the mid‐latitudes. Time‐dependent feedbacks underscore the need of a measure of climate sensitivity that accounts for the degree of equilibration, so that models, observations, and paleo proxies can be adequately compared and aggregated to estimate future warming.