Human-caused global heating made the intense heatwave that affected much of Australia in early January five times more likely, according to a new analysis. The heatwave was the most severe since the 2019-20 black summer, with temperatures exceeding 40°C in Melbourne and Sydney, and extreme heat also hitting regional Victoria, New South Wales, Western Australia, South Australia and Tasmania.
In Victoria, the heat preceded bushfires that burned through 400,000 hectares and destroyed almost 900 buildings. A report by World Weather Attribution (WWA) suggests that the effect of greenhouse gas emissions outweighed the cooling influence of a weak La Niña, which usually brings milder temperatures across most of mainland Australia.
The report’s authors estimate that the climate crisis made the extreme heat about 1.6°C hotter, while La Niña likely lowered maximum temperatures by between 0.3 and 0.5°C. Co-author Prof Sarah Perkins-Kirkpatrick, a climate scientist at the Australian National University, said there was “a signal of human-induced climate change behind this event”.
Heatwaves cause more deaths in Australia than all other natural hazards combined. “When people are affected by extreme heat, it is very insidious,” Perkins-Kirkpatrick said. “The mentality here of ‘suck it up, she’ll be right’ does not fly any more. The heat is getting worse and there’s ultimately a limit to what we can actually physically cope with.”
In the current climate, Australians should expect similar heat events about once every five years, the analysis suggests. The authors warn that such heatwaves could occur every second year if the world warms 2.6°C above preindustrial levels, which is projected by the end of the century under current emissions. WWA co-founder Friederike Otto noted that while the study is not yet peer reviewed, it highlights rapid changes in one of the deadliest extreme weather events.
