Climate study reveals rising risk of hourly heat extremes

A study published in Nature Climate Change suggests that heatwave risks should be measured on an hourly basis rather than daily to capture previously invisible thermal exposures. Researchers led by Weilin Liao from Sun Yat-sen University analyzed global hourly heat extremes (HHE) using historical data from 1981 to 2023 alongside projections through 2099.

The research indicates that under high-emission scenarios, the global frequency of these hourly heat extremes could quadruple by the end of the century, with population exposure potentially increasing sixfold. Notably, even days currently classified as normal by traditional metrics are expected to see an additional three to four hours of extreme heat. Statistical analysis attributes the vast majority of this increase—between 92% and 96% depending on the scenario—directly to climate change rather than population growth.