The first study of the health impacts of increasing heatwaves predicts that almost 6000 Australians will die from heatwaves in the year 2100 under climate change, compared to around 250 deaths per year during 2016–19.

In some of Australia’s hottest regions, such as the Northern Territory, the increase in mortality due to heatwaves will increase by 4412 per cent and, in the least heat-affected region, the West Coast of South Australia, the impact will still be significant at 356 per cent.

The study, led by Monash University researchers and published in The Lancet Planetary Health, reveals that average annual excess mortality rates are likely to be highest in Northern Territory during 2090–99, at 33.9 deaths per 100 000 population, followed by Queensland, at 18.4 deaths per 100 000 population, and New South Wales, at 12.8 deaths per 100,000 population.

According to lead researcher, Professor Shandy Li, projected percentage changes in excess mortality rate compared to 2020–29 ranged from 356 per cent (in West Coast, South Australia) to 4412 per cent (in Thamarrurr, Northern Territory).

“These projections underscore the urgent need for integrated mitigation and locally tailored adaptation strategies to address climate-related health inequities,” Professor Li said.

The study looked at climate data for more than 2200 communities across Australia. Heatwaves are defined as prolonged periods of excessively hot weather and are significantly associated with increased morbidity and mortality from cardiovascular, respiratory, renal, and heat-related illnesses, contributing substantially to the global burden of disease.

According to Professor Guo, a co-lead author, increased heatwave deaths will impact the most vulnerable Australians. 

“Northern and inland regions, where Indigenous populations account for a larger share of residents compared with other regions and access to cooling and medical resources is inadequate, are especially vulnerable to the effects of heatwaves,” Professor Guo said. 

He added that rural and socioeconomically disadvantaged areas often have high exposure to heatwaves; such areas generally also have insufficient adaptive capacity, while metropolitan centres face intensifying urban heat-island effects. 

“Without coordinated action, climate change will substantially exacerbate the health impacts of extreme heat and strain public health resilience across Australia,” Professor Guo said.

Read full paper Projected heatwave-related excess mortality under climate change scenarios across 2288 communities in Australia: a nationwide ecological projection modelling study in The Lancet Planetary Health: https://www.doi.org/10.1016/j.lanplh.2026.101446

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