Australia Weather News

The onset of autumn has done little to break Australia's recent spate of heatwaves, with temperatures soaring up to 15 degrees above average across south-east states on Saturday.

It followed the warmest spring and summer on record, with national mean temperatures exceeding pre-industrial levels by more than 2 degrees Celsius.

Already, these extreme heat trends are responsible for 7.3 per cent of Australia's heart disease burden, according to new research.

And if the current trend of greenhouse gas emissions continues, that figure could double, or even triple, by the middle of the century.

Impacts of heat on the heart

Cardiovascular disease is the leading cause of death globally and in Australia.

Ischaemic heart disease, a type of cardiovascular disease, accounted for 9.2 per cent of deaths in 2023, according to the data from the Australian Bureau of Statistics.

It was listed as the factor for more than 35,000 deaths.

A peer-reviewed study by a group of Australian universities, published in the European Heart Journal, found that the risk of heart disease increased with higher temperatures.

During the 15-year period from 2003 to 2018, the study found there were more than 48,000 years of life lost each year to cardiovascular disease due to hot weather.

Most of those years were lost due to death, rather than illness.

Lead researcher Peng Bi, professor of public health and environmental medicine at the University of Adelaide, explained how heat placed stress on the heart.

"When the weather is hot, our hearts have to work harder to help us cool down," he said.

"This added pressure can be dangerous, especially for people with cardiovascular disease."

The picture across Australia

To calculate the current impact of high temperatures, the researchers examined data from the Australian Burden of Disease Database on illness or death caused by cardiovascular disease between 2003 and 2018.

The study also looked into how the burden of cardiovascular disease could evolve under future climate scenarios.

It painted a picture of varying impacts across the country, based on population growth, demographics and how Australians adapt to heat.

"This study combines several key factors — climate change, population shifts and adaptation strategies — to give a full picture of the disease burden across Australia," Professor Bi said.

South Australia had the highest rate of cardiovascular disease attributable to high temperatures, followed by Victoria.

The study said the southern regions had higher relative risks and less adaptation to high-temperature exposures.

South Australia was projected to continue having the highest rate and proportion of heart disease linked to warmer weather by the 2030s.

The Northern Territory had the lowest rate of cardiovascular disease attributable to increased temperatures.

But, with its already warm climate, the territory was expected to face the most significant percentage increase in the future.

Depending on the extent of human adaption, the NT was expected to have the highest rate of and proportion of cardiovascular disease associated with higher temperatures by the 2050s.

The study noted that a high proportion of the Northern Territory's population had socio-economic and health challenges, suggesting that climate mitigation and human adaption strategies were "urgently needed".

Different future climate scenarios

Last year was the hottest on record, according to the Copernicus Climate Change Service (C3S).

And 2024 also became the first calendar year in which the Earth was more than 1.5C warmer than pre-industrial times.

Climate scientists have attributed the increase of 1.5C on a global scale to many more extremely hot days.

The study looked at two different climate scenarios, as outlined by the Intergovernmental Panel on Climate Change, to project the future burden of cardiovascular disease in the face of climate change.

It used a measure called disability-adjusted life years, which quantifies the number of years of healthy life lost through either illness or death.

In a scenario where emissions stabilise, the number of disability-adjusted life years lost due to heart disease could increase by 83.5 per cent by 2030.

If emissions continue to rise, it could increase by up to 92.7 per cent in the next five years.

In a "severe scenario" there could be a 182.6 per cent increase by 2050.

Adapting to a hotter climate

The researchers said predicting future disease burden always came with some uncertainty.

Models rely on assumptions that might not capture every real-life detail.

However, the study showed that it would be possible to "drastically lower" the impact of high temperatures on cardiovascular disease with strategies that helped people adapt to hotter weather.

The research calls for urgent investment in adaptation and mitigation strategies, with tailored solutions for different jurisdictions in Australia.

These include urban cooling plans, public health campaigns and improved emergency responses during hot weather.

"Our research shows that as climate change brings more frequent and intense heat, the risks associated with higher temperatures are likely to increase, especially for vulnerable groups," Professor Bi said.

"It highlights the importance of taking precautions during hot weather, such as staying hydrated, finding cool environments and seeking medical help when needed."

Researchers from the University of Adelaide, The University of Sydney, the Australian Institute of Health and Welfare (AIHW) and Monash University were all involved in the report.

And it was funded as part of an Australian Research Council Discovery Program project.

The researchers said that although the research focused on Australia, the findings were relevant to people around the world.