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Observational constraints on decadal low cloud feedbacks associated with varying sea surface temperature patterns

Presentation Date
Friday, December 11, 2020 at 4:00am



Decadal variations in low-level clouds produce changes in Earth’s energy budget that can act as a positive or negative feedback to planetary warming. These changes are tied to varying patterns of sea surface temperature (SST) that differ from the long-term pattern of warming expected from increasing carbon dioxide. Model evidence for this “pattern effect” assumes that climate models faithfully simulate how marine low clouds respond to varying SST anomaly patterns and the associated meteorological perturbations. Here we exploit satellite-based estimates of the sensitivity of distinct marine low cloud types to meteorological perturbations to constrain and quantify how these clouds respond to varying historical SST patterns. We find that decadal variations in the near-global low cloud feedback observationally constrained in this way are largely consistent with variations in simulated low cloud feedbacks produced by CMIP6 models forced by historical SST patterns. Observations show that increasing estimated inversion strength in recent decades has produced increasingly negative stratocumulus and trade cumulus feedbacks. These observation-based results corroborate model evidence that estimates of climate sensitivity inferred from observations of Earth’s energy budget during the satellite era are biased low.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. It is supported by the Regional and Global Model Analysis Program of the Office of Science at the DOE. IM Release #LLNL-ABS- 812886.

Funding Program Area(s)