Divergent trends of Tmax-based and Tw-based heat extremes across Asia's climatic divide

Abstract

This study investigates the contrasting trends in extreme Tmax events and extreme wet-bulb temperature (Tw) events across the monsoon and arid regions of Asia using the ERA5 reanalysis dataset. Our analysis reveals a substantial shift in the monsoon region, where extreme Tw events have risen by 1.95 days, outpacing the increase in extreme Tmax events. In the arid region, extreme Tmax events have increased more significantly, exceeding extreme Tw by an average of 2.05 days in recent years, reflecting the limited moisture availability in this area. Spatiotemporal analyses also reveal the widespread prevalence of humid-heat extremes in monsoon Asia and the intensification of primarily dry heat extremes in arid regions. These divergent trajectories highlight the pivotal role of climatological differences, with the change in monsoonal circulations amplifying humid extremes, while the inherent aridity constrains humidity increases. Our findings emphasize the need for regional adaptation strategies and mitigation efforts to address the escalating impacts on human society and ecosystems across Asia's climatic divide.