Historically, the response of marine boundary layer clouds to planetary warming has been among the most uncertain of all climate feedbacks. Recent advances in observational methods have substantially reduced this uncertainty and revealed previously unrecognized climate model biases in cloud feedback simulation. These advances stem from the framework of cloud-controlling factor analysis, which posits that large-scale meteorological conditions set the boundary conditions to which clouds respond. We highlight recent studies that use satellite observations to estimate the sensitivity of low clouds to meteorological perturbations, and that exploit model simulations of meteorological changes under greenhouse warming, to predict cloud feedbacks over the global oceans. These studies predict that shallow cumulus in the tropics will exert a negligible feedback to planetary heating, whereas eastern ocean stratocumulus and midlatitude low clouds will exert positive feedbacks. This suggests a moderate global cloud feedback and climate sensitivity. These observational results motivate critical research questions that should be further investigated, including: Why are shallow cumulus apparently insensitive to greenhouse warming? Why do climate models tend to produce large positive shallow cumulus feedbacks? How are mesoscale organization patterns related to the predicted cloud feedbacks?

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-825375.