Rapid rises in the magnitude and risk of extreme regional heat wave events in China

Increasing occurrence of extreme heat waves poses serious risks to human society and ecosystems. Past studies generally examined the changes in heat wave characteristics at individual stations or grid points; however, a heat wave typically appears as a regional event being continuous in time and space. Using an objective identification technique for distinguishing regional extreme events and a metric for measuring regional heat wave magnitude (i.e., an integrated index that accounts for heat wave intensity, duration, and spatial extent), this study revealed an approximate doubling in both the frequency and the magnitude of regional heat wave events observed over 1960-2018 in China. The identified top three regional heat wave events occurred in the summers of 2013, 2017, and 2003, respectively. Fine-resolution multimodel climate projections suggest that China will experience regional heat wave events with magnitude exceeding the 2013 heat event on a regular basis by 2030 under a business-as-usual scenario (RCP8.5). Compared to a 2 degrees C warming level, 1.5 degrees C warming could halve the expected occurrence of future severe regional heat wave events with magnitude similar to or slightly greater than the record-breaking one in 2013.

Automated summary

This study used an objective identification technique to reveal a significant increase in both the frequency and magnitude of regional heat wave events in China, with projections indicating a continued rise in severe heat waves by 2030. Additionally, it was found that limiting global warming to 1.5 degrees Celsius could halve the occurrence of future severe regional heat wave events compared to a 2-degree Celsius warming scenario.