Abstract
Low-cloud based emergent constraints have the potential to substantially
reduce uncertainty in Earth’s Equilibrium Climate Sensitivity, but
recent work has shown that previously-developed constraints fail in the
latest generation of climate models, suggesting that new approaches are
needed. Here, we investigate the potential for emergent constraints to
reduce uncertainty in regional cloud feedbacks, rather than the
global-mean cloud feedback. Strong relationships are found between the
monthly/interannual variability of tropical clouds and the tropical net
cloud feedback. These relationships are combined with observations to
substantially narrow the uncertainty in the tropical cloud feedback and
demonstrate that the tropical cloud feedback is likely $>
0$. Promising relationships are also found in the
90$^\circ$-60$^\circ$S and
30$^\circ$-60$^\circ$N regions,
though these relationships are not robust across model generations and
we have not identified the associated physical mechanisms.