Contributions of Global Warming and Urbanization to the Intensification of Human-Perceived Heatwaves Over China

Abstract

Urbanization and global warming are the two major drivers of the warming environment in cities. The contributions of urbanization and global warming to the past occurrence of human-perceived heatwaves (HWs) over China are evaluated in this study. Both observations and model simulations show HWs have become more intensive, longer-lasting, and more frequent in recent decades. Urbanization and greenhouse gases contribute to 21.9% and 72.9% of the intensification of HWs, respectively. The occurrence probability of observed human-perceived HWs has doubled over 1961–2012 and is projected to be about 4.36/5.92 times under the 1.5/2°C warming relative to the preindustrial level. At the 3.5°C warming, the average duration of HWs is projected to increase to 43.63 days/year, and the occurrence probability is expected to increase by 11.95 times, 91% of which is attributable to human-induced warming. The highest sensitivity of the increases in HWs due to human-induced warming is in Southern China.

Plain Language Summary

Both in situ observations and model simulations show that the occurrence probability of human-perceived heatwaves (HWs) nearly doubled in China over recent decades, of which urbanization and greenhouse gases contribute to 21.9% and 72.9% of the intensification of HWs. When the China warming level reaches 3.5°C respective to the preindustrial period, the occurrence probability of HWs is expected to be 11.95-fold than that in the preindustrial period. The contribution of human-induced warming to the increase in occurrence probability of HWs would be 91%. Southern China is the region where the intensification of HWs is most prominent due to human-induced warming. Increased adaptation and mitigation efforts are needed in China specifically Southern China to offset the increasing HWs due to urban expansion and anthropogenic activities.