On the Controlling Factors for Globally Extreme Humid Heat

Humid heat presents a major societal challenge through its impacts on human health, energy demand, and economic productivity, underlined by the projected emergence of conditions beyond tolerance. However, systematic assessment what drives most extreme humid worldwide has been lacking. Here, we investigate factors determining location magnitude humid-heat extremes, framing our analysis around four regions with highest values: southern Persian Gulf, north-central Pakistan, eastern South Asia, western Amazon. We find that strong boundary-layer moisture fluxes, together stability inhibits moist convection, explain well timing near-surface extremes. These favorable are achieved regionally distinct factors, including shallow sea breezes in Gulf large-scale subsidence Asia. Our results demonstrate some principal controls intense heat, both globally for particular events.