In a warming climate, climate extremes such as heatwaves and droughts pose increasing threats to human safety, economies, and ecosystems. However, their key drivers and future changes are still poorly understood.

Recently, researchers from the Institute of Atmospheric Physics of the Chinese Academy of Sciences revealed the spatiotemporal evolution of heatwaves both in China and globally, identified the dominant driving factors, and assessed the risks associated with compound heatwave and drought events. The findings were published in Climate Dynamics, Atmospheric Research and Quarterly Journal of the Royal Meteorological Society.

Using a gridded daily maximum and minimum temperature dataset from the China Meteorological Administration, researchers found that the frequency of both daytime and nighttime heatwaves increased significantly across most areas of China from 1961 to 2022. Using redundancy analysis and hierarchical partitioning, they identified surface air temperature as the dominant driver of the increase in heatwaves in China.

As compound heatwave and drought events have more severe impacts than individual extremes, researchers revealed that surface air temperature had a stronger impact on compound extremes than on heatwaves alone. Moreover, they revealed that population growth, together with intensifying compound extremes, led to moderate increases in exposure during 1991–2020.

At 1.5°C and 2.0°C global warming levels, multiple climate models from the sixth phase of the Coupled Model Intercomparison Project projected that the frequency and intensity of heatwaves will increase globally under the intermediate (SSP245) and very high (SSP585) emission scenarios. The Shapley additive explanation method showed that regional surface air temperature dominantly contributes to heatwave changes under the SSP245 scenario, while global sea surface temperature plays a more important role under the SSP585 scenario.

"Our results showed that heatwaves and compound heatwave and drought events will occur more frequently under a warming climate, which may lead to more severe climate risks," said Dr. QIN Peihua, the first author of these three studies. The studies call for targeted risk mitigation and adaptation strategies based on regional population exposure characteristics.

In Turpan's Flaming Mountains, Xinjiang, the temperature exceeds 50°C, and the ground is hot enough to cook eggs directly. (Image by QIN Peihua)