More than 20 million Australians in Melbourne, Sydney and Adelaide could swelter through deadly heatwaves of more than 44 degrees stretching across 1.72 million square kilometres if temperatures rise by 3 degrees.
Australia’s National Climate Risk Assessment 2025 predicts catastrophic outcomes for Australian health, society and the economy if global temperatures continue to climb.
The landmark report, released on Monday, predicts that if Australia hits 3 degrees of warming above pre-industrial temperatures, heat-related deaths will increase by 444 per cent in Sydney (with western Sydney residents most at risk), 423 per cent in Darwin, 335 per cent in Townsville, 312 per cent in Perth, 259 per cent in Melbourne and 146 per cent in Launceston.
Heatwaves are already the main climate-related cause of death in Australia, causing 909 deaths nationally between 1990 and 2022. They kill more people than bushfires and floods combined.
The assessment of life under projected temperature increases of 1.5 degrees, 2 degrees and 3 degrees above pre-industrial levels is underpinned by the fact Australia is already ahead of the curve on warming.
As a global average, temperatures have risen by 1.2 degrees. In Australia, average temperatures have already risen by 1.5 degrees, making the higher temperature predictions more compelling.
Erwin Jackson, head of Australian programs at Monash University’s Climateworks Centre, said 70 per cent of existing Australian homes were not climate-ready.
“Renovating existing homes to be energy efficient and all-electric is essential to both reduce emissions and make communities climate resilient,” he said.
The problem is forecast to be particularly acute in northern Australia, where some regions could become uninhabitable.
Environs Kimberley executive director Martin Pritchard said First Nations people in northern parts of Australia risked becoming climate change refugees. He called on the government to stop approving new gas and coal projects.
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“Places like the Kimberley’s Fitzroy Crossing, which already has 67 days a year over 40 degrees, will be like a place from a Mad Max movie if it gets to the projected seven and a half months over 40 by century’s end.”
The report said regional Australians, children, the elderly, and First Nations people would be disproportionately affected.
A coalition of environmental and climate groups said much of northern Australia could experience “near unliveable” conditions if warming hit 3 degrees, producing extreme temperatures akin to the Sahara desert.
“It’s hard to hear that the places we call home will no longer exist,” said the NT Environment Centre’s Kirsty Howey.
“We’re talking about whole communities being wiped out because politicians and gas companies see the north as a sacrifice zone.”
The report, released by Climate Change Minister Chris Bowen, said no less than the “values and knowledge of Aboriginal and Torres Strait Island people [would be] at risk” as extreme temperatures placed regional and communities under critical pressure.
“Public health risks will become more pronounced with significant potential for loss of life and strain on health systems,” Bowen said. “That’s what the report says ... Again, that’s confronting. It means that the national climate health strategy is important.”
The report was released ahead of the federal government unveiling its 2035 emissions reductions targets this week, and after criticism from the Greens and crossbench about the delays in releasing the report.
Urban heat expert Professor Sebastian Pfautsch from the University of Western Sydney said heatwaves already killed an average 190 people every year in Greater Sydney.
Dr Sebastian Pfautsch has been studying the effects and costs of urban heat for years.Credit: Brook Mitchell
“We know that heat across the continent already costs more lives than all the other natural disasters combined,” he said.
“Fifty-five per cent of natural hazard-related deaths in Australia are because of heat, and only 45 per cent are because of landslides, earthquakes, floods, hurricanes and bush fires ... And we accept that.
“I struggle with that. I really struggle with that.”
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Pfautsch said the warnings contained within the report should be taken seriously, although he questioned why it mentioned the root cause of fossil fuels only once, in passing.
“The three-degree scenario is still relatively optimistic because when you read the science, some people are starting to talk about 5 degrees, which [would have] catastrophic impacts,” he said.
“I don’t want to fall into this doom and gloom scenario too much because people just turn away; they don’t listen because it’s too scary. But we need to listen.”
According to the national risk assessment, in the wheat belt and food production regions of the Mallee and Sunraysia, in northwest Victoria and southern NSW, the time spent in drought would increase to 7 per cent of the year at 1.5 degrees of warming.
At 3 degrees, the time spent in drought would increase to 33 per cent – about three years per decade.
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