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Polar Amplification as an Inherent Response of a Circulating Atmosphere: Results From the TRACMIP Aquaplanets
Author(s) -
Russotto Rick D.,
Biasutti Michela
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 - 10.1029/2019gl086771
Subject(s) - polar , climatology , environmental science , atmosphere (unit) , atmospheric sciences , forcing (mathematics) , cloud feedback , radiative forcing , water vapor , climate model , extratropical cyclone , radiative transfer , climate change , meteorology , climate sensitivity , geology , physics , oceanography , quantum mechanics , astronomy
In the Tropical Rain belts with an Annual cycle and Continent Model Intercomparison Project (TRACMIP) ensemble of aquaplanet climate model experiments, CO 2 ‐induced warming is amplified in the poles in 10 out of 12 models, despite the lack of sea ice. We attribute causes of this amplification by perturbing individual radiative forcing and feedback components in a moist energy balance model. We find a strikingly linear pattern of tropical versus polar warming contributions across models and processes, implying that polar amplification is an inherent consequence of diffusion of moist static energy by the atmosphere. The largest contributor to polar amplification is the instantaneous CO 2 forcing, followed by the water vapor feedback and, for some models, cloud feedbacks. Extratropical feedbacks affect polar amplification more strongly, but even feedbacks confined to the tropics can cause polar amplification. Our results contradict studies inferring warming contributions directly from the meridional gradient of radiative perturbations, highlighting the importance of interactions between feedbacks and moisture transport for polar amplification.