High-resolution simulations reveal positive global warming feedback from Pacific low clouds.

Authors

Sheide Chammas, Qing Wang, Tapio Schneider, Rob Carver, Zhaoyi Shen, Jeffrey B Parker, Cenk Gazen, Matthias Ihme, Yi-Fan Chen, John Anderson

Published in

Science advances. Volume 12. Issue 30. Pages eaec8488. Jul 24, 2026. Epub Jul 24, 2026.

Abstract

Uncertainty in marine low-level cloud feedbacks limits accurate climate projections. Using 7083 high-resolution simulations of tropical Pacific low clouds, we separated the impacts of sea surface warming from direct carbon dioxide (CO₂) effects. Surface warming alone drives a positive low-cloud feedback of [Formula: see text]. While this changes little with doubled CO₂, the total cloud radiative response strengthens markedly to [Formula: see text] under quadrupled CO₂, revealing a strong nonlinear interaction. Surface warming alone modifies the boundary layer through increased inversion strength and weakened subsidence, which buffers clouds by promoting higher liquid water content while cloud fraction decreases. Rapid adjustments to high CO₂ concentrations counteract this protective cloud thickening. Consequently, a pronounced reduction in cloud fraction is no longer offset by an increase in cloud brightness, markedly strengthening the total radiative response under quadrupled CO₂. Ultimately, our results suggest that climate sensitivity is more state-dependent than often assumed.

PMID:
42497251
Bibliographic data and abstract were imported from PubMed on 25 Jul 2026.

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