Observational constraint on a feedback from supercooled clouds reduces projected warming uncertainty

Autor: Grégory V. Cesana, Andrew S. Ackerman, Ann M. Fridlind, Israel Silber, Anthony D. Del Genio, Mark D. Zelinka, Hélène Chepfer, Théodore Khadir, Romain Roehrig
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: Communications Earth & Environment, Vol 5, Iss 1, Pp 1-14 (2024)
Druh dokumentu: article
ISSN: 2662-4435
DOI: 10.1038/s43247-024-01339-1
Popis: Abstract The increase of carbon-dioxide-doubling-induced warming (climate sensitivity) in the latest climate models is primarily attributed to a larger extratropical cloud feedback. This is thought to be partly driven by a greater ratio of supercooled liquid-phase clouds to all clouds, termed liquid phase ratio. We use an instrument simulator approach to show that this ratio has increased in the latest climate models and is overestimated rather than underestimated as previously thought. In our analysis of multiple models, a greater ratio corresponds to stronger negative cloud feedback, in contradiction with single-model-based studies. We trace this unexpected result to a cloud feedback involving a shift from supercooled to warm clouds as climate warms, which corresponds to greater cloud amount and optical depth and weakens the extratropical cloud feedback. Better constraining this ratio in climate models – and thus this supercooled cloud feedback – impacts their climate sensitivities by up to 1 ˚C and reduces inter-model spread.
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