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arXiv · 2209.02519

Cloud Feedback on Earth's Long-term Climate Simulated by a Near-global Cloud-permitting Model

Mingyu Yan·Jun Yang·Yixiao Zhang·Han Huang
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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 $\approx$6 W m$^{-2}$ or 14% of the energy required to offset a 20% fainter Sun than today, or $\approx$10 W m$^{-2}$ or 16% for a 30% fainter Sun. When insolation increases and meanwhile CO$_2$ concentration decreases, low-level clouds increase, acting to stabilize the climate by raising planetary albedo, and vice versa.

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Mingyu Yan, Jun Yang, Yixiao Zhang, Han Huang. 2022-09-06. Cloud Feedback on Earth's Long-term Climate Simulated by a Near-global Cloud-permitting Model. https://doi.org/10.1029/2022gl100152

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