The first study to map mortality from heat waves worldwide shows that there are more than 153,000 deaths caused by heat waves

A Monash-led study – the first to map mortality from heat waves worldwide over a three-decade period from 1990 to 2019 – found that more than 153,000 additional deaths were linked to heat waves per warm season, with almost half of these deaths occurring in Asia.

Compared to 1850–1990, global surface temperature increased by 1.1°C during 2013–2022 and is expected to increase by a further 0.41–3.41°C during 2081–2100. With the increasing impacts of climate change, heat waves are not only increasing in frequency, but also in severity and magnitude.

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

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

• Southern and Eastern Europe
• Areas with polar and alpine climates
• Areas where residents had high incomes

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

According to Professor Guo, in previous studies on the increased number of deaths due to exposure to heat waves, “the evidence is mainly from limited locations.”

“Our findings that heat waves are associated with a substantial mortality burden that varies spatially and temporally across the globe over the past three decades suggest the need for local adaptation planning and risk management at all levels of government.”

According to the study authors, heat waves cause an increased risk of death due to overwhelming thermal stress on the human body and causing multi-organ dysfunction, as well as heat exhaustion, heat cramps and heatstroke. The heat stress can also worsen pre-existing chronic conditions, leading to premature death, psychiatric disorders and other consequences.