Cloud feedback uncertainty in the equatorial Pacific across CMIP6 models

Hill, P. G. ORCID: https://orcid.org/0000-0002-9745-2120, Finney, D. L. ORCID: https://orcid.org/0000-0002-3334-6935 and Zelinka, M. D. ORCID: https://orcid.org/0000-0002-6570-5445 (2025) Cloud feedback uncertainty in the equatorial Pacific across CMIP6 models. Geophysical Research Letters, 52 (19). e2025GL117183. ISSN 1944-8007 doi: 10.1029/2025gl117183

Abstract/Summary

Cloud feedback is the largest uncertainty in estimating Equilibrium Climate Sensitivity. In this study we focus on the equatorial Pacific, where CMIP6 model cloud feedback spread is notably large. Cloud radiative effects in this region are relevant for the global climate. Our findings show that models predict a consistent shift towards the ascent regime in response to El Nino‐like sea surface warming. Models diverge in terms of the radiative impact due to differences in cloud characteristics in ascent and subsidence regimes. Using the observed relationship between circulation regime and cloud radiative effect, we find a reduction in the regional mean cloud feedback estimate from 0.77 to 0.22 W m− 2 K− 1, though this does not substantially lessen the model spread in total feedback. Pathways to reduce this spread include: improving confidence in the regional ocean warming pattern, and using observations and models to understand cloud type and circulation interactions.

Item Type	Article
URI	https://centaur.reading.ac.uk/id/eprint/125321
Identification Number/DOI	10.1029/2025gl117183
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Publisher	American Geophysical Union
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