In the wake of Australia’s most severe heatwave since the devastating Black Summer of 2019-20, a new analysis has revealed that human-caused global heating has made such extreme heat events five times more likely to occur. The heatwave earlier this month saw temperatures soar past 40°C in major cities like Melbourne and Sydney, with even hotter conditions in regional Victoria and New South Wales. The extreme heat also impacted Western Australia, South Australia and Tasmania.
The report by the World Weather Attribution (WWA) group suggests that the effects of greenhouse gas emissions have outweighed the cooling influence of a weak La Niña weather pattern, which typically brings milder temperatures across most of mainland Australia. The researchers estimate that the climate crisis has made the extreme heat around 1.6°C hotter, while the La Niña likely lowered maximum temperatures by 0.3 to 0.5°C.
“There was definitely a signal of human-induced climate change behind this event,” said Professor Sarah Perkins-Kirkpatrick, one of the report’s co-authors and a climate scientist at the Australian National University. Heatwaves, defined as three or more consecutive days of temperatures higher than average, are now the deadliest natural hazard in Australia, surpassing all other threats combined.
“When people are affected by extreme heat, it is very insidious,” Perkins-Kirkpatrick explained. “It’s not something that happens straight away… it’s something that comes to light in a number of days after the event, and may also be due to the exacerbation of underlying diseases.”
The analysis suggests that in the current climate, Australians should expect heatwaves similar to the January event about once every five years. However, the researchers warn that such heat events could become an annual occurrence if global temperatures rise 2.6°C above pre-industrial levels, a scenario projected to be reached by the end of the century based on current carbon emissions.
“As extreme heat is one of the deadliest extreme weather events that is changing very fast with global warming, it is important to highlight these rapid changes, even if the results are not surprising at all,” said Friederike Otto, a professor of climate science at Imperial College London and a co-founder of WWA.
While the techniques used by the group are well-established, Otto noted that the heatwave study itself is not yet peer-reviewed. Nevertheless, the findings serve as a stark reminder of the escalating climate crisis and the urgent need for robust action to mitigate its most severe impacts on Australia and beyond.
