150,000+ people died in three decades to 2019 due to heatwaves according to first global mapping of heat-triggered mortality

A Monash-led study - the first to globally map heatwave-related mortality over a three-decade period from 1990 to 2019 – has found that an additional 153,000+ deaths per warm season were associated with heatwaves, with nearly half of those deaths in Asia.

In comparison to 1850–1990, the global surface temperature has increased by 1.14℃ in 2013–2022 and is expected to increase by another 0.41-3.41℃ by 2081–2100. With the increasing impacts of climate change, heatwaves are increasing not only in frequency but also in severity and magnitude.

The study, published today in PLOS Medicine and led by Monash University’s Professor Yuming Guo, looked at data on daily deaths and temperature from 750 locations in 43 countries or regions.

The study – done in collaboration with Shandong University in China, London School of Hygiene & Tropical Medicine in UK, and universities/research institutes from other countries- found that, during 1990–2019, heatwaves led to an increase in deaths of 236 deaths per ten million residents per warm season of a year. The regions with the highest heatwave-related deaths were in:

• Southern and Eastern Europe
• in areas had polar and alpine climates
• where residents had high incomes

Locations with tropical climate or low incomes were observed with the greatest decline in heatwave-related mortality burden from 1990 to 2019.

According to Professor Guo, studies so far looking at increased deaths related to exposure to heatwaves has been studied, “the evidence mainly comes from limited locations,” he said.

“Our findings that heatwaves are associated with substantial mortality burden that varies spatiotemporally over the globe in the past 30 years suggest that there should be localised adaptation planning and risk management across all government levels.”

According to the study’s authors heatwaves cause an increased risk of death due to overwhelming thermal stress on human body and triggering dysfunction of multiple organs as well as heat exhaustion, heat cramps, and heatstroke. The heat stress can also aggravate pre-existing chronic conditions, leading to premature death, psychiatric disorders and other outcomes.