Sea‐Surface Temperature Patterns, Radiative Cooling, and Hydrological Sensitivity

Abstract Global climate models project an increase in global‐mean precipitation in response to increases in global‐mean surface temperature; that is, a positive “hydrological sensitivity.” However, there are hints in the literature that global‐mean precipitation is sensitive to the pattern of warming in addition to global‐mean warming. Here we leverage previous theoretical insights into tropical dynamics and radiative cooling to connect clear‐sky longwave radiative cooling, a key component of hydrological sensitivity, to sea‐surface temperature (SST) patterns in the tropics. We use this theory to explain why hydrological sensitivity is about 25% larger in uniform warming scenarios compared to abrupt‐ runs. This discrepancy is driven by different changes in clear‐sky longwave radiative cooling in the tropics, which we quantitatively attribute to differences in the rate of SST warming in regions of tropical convection.