Short Warm Distribution Tails Accelerate the Increase of Humid‐Heat Extremes Under Global Warming

Abstract

Humid‐heat extremes threaten human health and are increasing in frequency with global warming, so elucidating factors affecting their rate of change is critical. We investigate the role of wet‐bulb temperature (TW) frequency distribution tail shape on the rate of increase in extreme TW threshold exceedances under 2°C global warming. Results indicate that non‐Gaussian TW distribution tails are common worldwide across extensive, spatially coherent regions. More rapid increases in the number of days exceeding the historical 95th percentile are projected in locations with shorter‐than‐Gaussian warm side tails. Asymmetry in the specific humidity distribution, one component of TW, is more closely correlated with TW tail shape than temperature, suggesting that humidity climatology strongly influences the rate of future changes in TW extremes. Short non‐Gaussian TW warm tails have notable implications for dangerous humid‐heat in regions where current‐climate TW extremes approach human safety limits.