Cloud Feedback on Earth's Long-term Climate Simulated by a Near-global Cloud-permitting Model
arXiv:2209.02519 · doi:10.1029/2022GL100152
Abstract
The Sun becomes brighter with time, but Earth's climate is roughly temperate for life during its long-term history; for early Earth, this is known as the Faint Young Sun Problem (FYSP). Besides the carbonate-silicate feedback, recent researches suggest that a long-term cloud feedback may partially solve the FYSP. However, the general circulation models they used cannot resolve convection and clouds explicitly. This study re-investigates the clouds using a near-global cloud-permitting model without cumulus convection parameterization. Our results confirm that a stabilizing shortwave cloud feedback does exist, and its magnitude is 6 W m or 14% of the energy required to offset a 20% fainter Sun than today, or 10 W m or 16% for a 30% fainter Sun. When insolation increases and meanwhile CO concentration decreases, low-level clouds increase, acting to stabilize the climate by raising planetary albedo, and vice versa.