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Three Flavors of Radiative Feedbacks and Their Implications for Estimating Equilibrium Climate Sensitivity
Author(s) -
Rugenstein Maria A. A.,
Armour Kyle C.
Publication year - 2021
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 - 10.1029/2021gl092983
Subject(s) - climate sensitivity , sensitivity (control systems) , radiative transfer , realization (probability) , radiative forcing , climate change , climate model , environmental science , climatology , differential (mechanical device) , econometrics , interpretation (philosophy) , cloud feedback , atmospheric sciences , computer science , mathematics , geology , statistics , physics , thermodynamics , oceanography , quantum mechanics , electronic engineering , engineering , programming language
Abstract The realization that atmospheric radiative feedbacks depend on the underlying patterns of surface warming and global temperature, and thus, change over time has lead to a proliferation of feedback definitions and methods to estimate equilibrium climate sensitivity (ECS). We contrast three flavors of radiative feedbacks – equilibrium, effective, and differential feedback – and discuss their physical interpretations and applications. We show that their values at any given time can differ more than 1 W m − 2K − 1and their implied equilibrium or effective climate sensitivity can differ several degrees. With ten (quasi) equilibrated climate models, we show that 400 years might be enough to estimate the true ECS within a 5% error using a simple regression method utilizing the differential feedback parameter. We argue that a community‐wide agreement on the interpretation of the different feedback definitions would advance the quest to narrow the estimate of climate sensitivity.