Extratropical Shortwave Cloud Feedbacks in the Context of the Global Circulation and Hydrological Cycle

Shortwave (SW) cloud feedback (SWFB) is the primary driver of uncertainty in effective climate sensitivity (ECS) predicted by global models (GCMs). ECS for several GCMs participating sixth assessment report exceed 5K, above fifth “likely” maximum (4.5K) due to extratropical SWFB's that are more positive than those simulated previous generation GCMs. Here we show across 57 Southern Ocean SWFB can be from column-integrated liquid water mass (LWP) moisture convergence and surface temperature. The response LWP albedo anti-correlate This because simulate a larger tend have higher mean-state LWPs, which reduces impact additional on albedo. Observational constraints suggest modestly negative SWFB— inconsistent with extreme ECS.