Mingyu Yan1, Jun Yang1*, Yixiao Zhang1, 2, Han Huang1, 3
1Laboratory for Climate and Ocean-Atmosphere Studies, Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, China
2Now at Department of Earth Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
3Now at Department of Atmospheric and Oceanic Sciences, McGill University, Montreal, QC, Canada
Correspondence to: junyang@pku.edu.cn
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−2 or 14% of the energy required to offset a 20% fainter Sun than today, or ≈10 W m−2 or 16% for a 30% fainter Sun. When insolation increases and meanwhile CO2 concentration decreases, low-level clouds increase, acting to stabilize the climate by raising planetary albedo, and vice versa.
Key Points
• A near-global cloud-permitting model with a resolution of 10 × 14 km is employed to test whether there is a long-term cloud feedback
• The cloud feedback does have a net cooling effect when the Sun becomes brighter and meanwhile the CO2 concentration decreases
• These results confirm that cloud feedback is a part of the solution to the faint young Sun problem but its magnitude is relatively small
Citation
Yan, M., Yang, J., Zhang, Y., & Huang, H. (2022). Cloud feedback on Earth's long-term climate simulated by a near-global cloud-permitting model. Geophysical Research Letters, 49, e2022GL100152. https://doi.org/10.1029/2022GL100152
