A warmer world will make heatwaves more frequent: Study

From late June to early July 2021, an unprecedented heatwave swept across Western North America (WNA), causing considerable hazards to the regional society and economy. What is the likelihood of a similar heatwave under global warming?

Researchers led by Prof. Lin Wang from the Institute of Atmospheric Physics (IAP) of the Chinese Academy of Sciences, in collaboration with scientists from Yunnan University, have revealed that heatwaves similar to the unprecedented WNA one in summer 2021 are projected to become more frequent in a warmer world based on the multi-model simulations from the Coupled Model Intercomparison Project. The project began in 1995 under the auspices of the World Climate Research Programme (WCRP) and is now in its sixth phase (CMIP6).

The study was published in Earth's Future .

"Such a heatwave is projected to occur more frequently with increased extreme temperature and shortened return period, making a rare event in the current climate be a common event in a warmer climate," said Prof. Wang, corresponding author of the study, "especially under a high-emission scenario like the Shared Socioeconomic Pathways 585 (SSP5-8.5)."

Moreover, the researchers found a large expansion of areas over WNA that will break the 2021 record in the future with an increasing level of emission scenario. However, some heat records west of the Rocky Mountains are still difficult to break even at the end of the 21st century, highlighting the specific extremity of the observed 2021 WNA heatwave.

"We use multiple climate models that are involved in CMIP6 and consider different emission scenarios and warming levels for the future heatwave projections over WNA," said Dr. Zizhen Dong, first author of the study.