Model-Dependent Response of Low Clouds to Arctic Sea-Ice Loss

Clouds play a key role in the climate of the Arctic region. Observational evidence suggests that sea-ice loss fosters increased cloud cover due to enhanced surface turbulent fluxes. Yet, it is not clear whether this mechanism is (well) represented in climate models. In this study we analyze the simulated response of low clouds to sea-ice loss in a set of dedicated numerical model experiments prescribed with changes in sea ice only. We find large discrepancies between models regarding their representation of low cloud responses to identical sea-ice loss. We propose a physical explanation that links biases in simulated present-day surface temperature and stratification to the sign of the low cloud response to sea-ice loss. Our results suggest that mean-state temperature biases need to be reduced in order to narrow uncertainty in the simulated cloud response to sea-ice loss.