Cloud source and sink process as a path toward constraining climate sensitivity
Abstract
The leading contributor to GCM diversity in equilibrium climate sensitivity (ECS) is spread in shortwave (SW) cloud feedback. This is because clouds exist on finer temporal and spatial scales than even the most computationally expensive GCMs can resolve and they must be parameterized. In the last decade, confidence has grown in a positive subtropical SW cloud feedback, with progress on quantifying the feedback magnitude and underlying mechanisms. On the other hand, GCMs continue to simulate a diversity of both negative and positive extratropical SW cloud feedbacks. Between CMIP5 and CMIP6, the multimodel mean extratropical SW cloud feedback has become more positive. The multimodel mean in CMIP6 is nearly one standard deviation above the CMIP5 models. This has resulted in a dramatic increase in the climate sensitivity in CMIP6. It is critical to investigate the extratropical SW cloud feedback in order to understand and interpret results emerging from the GCMs participating in CMIP6.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMA193...03M
- Keywords:
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- 3310 Clouds and cloud feedbacks;
- ATMOSPHERIC PROCESSES;
- 3311 Clouds and aerosols;
- ATMOSPHERIC PROCESSES;
- 3333 Model calibration;
- ATMOSPHERIC PROCESSES;
- 3354 Precipitation;
- ATMOSPHERIC PROCESSES