We compare the radiative feedbacks resulting from a uniform warming and
cooling of sea surface temperatures by 4 K in an ensemble of global
climate models. The global-mean net feedback is less stabilising in
response to warming in all nine models. This is primarily due to a
stronger tropical water vapour feedback, with a smaller contribution
from the shortwave cloud feedback. The zonal-mean feedbacks are
similarly robust across the ensemble. In the extra-tropics, more
positive shortwave cloud feedback under warming is associated with
further poleward migration of the mean Southern Hemisphere jet latitude
in some models. However, additional experiments with an aquaplanet
version of the HadGEM3 model suggest that the asymmetry of the jet shift
is not driving that in the cloud feedbacks at these latitudes. In the
tropics, stronger water vapour feedback under warming is offset by a
weaker shortwave cloud feedback. The result is that the ensemble spread
in the differences between the global feedbacks under warming and
cooling is mainly determined by their differences in the tropics. The
spatial distribution of the feedbacks largely reflects the zonal mean
behaviour, although there is considerable intermodel variation in the
regional cloud feedbacks, particularly in the tropical shortwave cloud
feedback. Comparison with CO2- and solar-forced coupled experiments
suggests that the global-mean longwave cloud feedback is nearly
invariant to warming and cooling, regardless of the nature of the
forcing. The shortwave cloud feedback is generally more positive under
warming in the coupled models, consistent with the uniform SST
perturbation experiments.