  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.

Atmospheric and Oceanic Physics