Climate models underestimate dynamic cloud feedbacks in the tropics
Abstract
Cloud feedbacks are the leading cause of uncertainty in climate sensitivity. The complex coupling between clouds and the large-scale circulation in the tropics contributes to this uncertainty. To address this problem, the coupling between clouds and circulation in the latest generation of climate models is compared to observations. Significant biases are identified in the models. The implications of these biases are assessed by combining observations of the present day with future changes predicted by models to calculate observationally constrained feedbacks. For the dynamic cloud feedback (i.e., due to changes in circulation), the observationally constrained values are consistently larger than the model-only values. This is due to models failing to capture a nonlinear minimum in cloud brightness for weakly descending regimes. Consequently, while the models consistently predict that these regimes increase in frequency in association with a weakening tropical circulation, they underestimate the positive cloud feedback associated with this increase.
Citation
Hill , P G , Holloway , C E , Byrne , M P , Lambert , F H & Webb , M J 2023 , ' Climate models underestimate dynamic cloud feedbacks in the tropics ' , Geophysical Research Letters , vol. 50 , no. 15 , e2023GL104573 . https://doi.org/10.1029/2023GL104573
Publication
Geophysical Research Letters
Status
Peer reviewed
ISSN
0094-8276Type
Journal article
Description
Funding: The authors acknowledge funding from the UK Natural Environment Research Council for the CIRCULATES project (Grant NE/T006315/1). Mark Webb was supported by the Met Office Hadley Centre Climate Programme funded by BEIS and Defra. The authors also acknowledge the World Climate Research Programme, which, through its Working Group on Coupled Modelling, coordinated and promoted CMIP6.Collections
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