Extreme heat is no longer rare it is becoming the norm, according to a new analysis by World Weather Attribution.
Human-induced climate change made the intense early January heatwave in Australia five times more likely.
The study also found that the heatwave happened against the backdrop of a weak La Niña, which usually brings mild temperatures to much of the region.
However, the influence of fossil fuel emissions on temperatures far outweighed this effect. Across southeastern Australia, maximum temperatures were widely above 40ºC between January 7-9 as the area sweltered through the hottest temperatures since the ‘Black Summer’ of 2019/2020.
In Melbourne, where temperatures topped out at 44.4ºC at its airport on January 9, one hospital reported that emergency admissions were up by 25 per cent.
The heat was followed by devastating bushfires in Victoria leading to a state of disaster being declared. Across the world, climate change has made heatwaves more common, longer and hotter.
To quantify the effect of climate change on the Australian heatwave, scientists used peer-reviewed methods to analyse weather data and computer model simulations to compare the climate as it is today, after about 1.3°C of global warming since the late 1800s, with the climate of the past.
The analysis shows that, in today’s climate, Australians can now expect to experience similar heatwaves about once every five years.
The scientists also found that if carbon emissions continue on the trajectory predicted under current policies, heatwaves like this are expected every other year by the end of the century.
These findings underline not just the urgent need to cut emissions, but the need for Australians to better prepare for the dangers of extreme heat.
Dr Ben Clarke, Researcher at the Centre for Environmental Policy, Imperial College London said the evidence is clear.
“Extreme heatwaves are in the fast lane to becoming the norm rather than the exception during the Australian summer,” he said.
“We see it time and time again that climate change is making heatwaves all across the world both more frequent and more severe.
“One of our most striking findings is that the impact of climate change far outweighed natural climate variability - including a weak La Niña, which typically signals cooler temperatures.”
Dr Sarah Perkins-Kirkpatrick, Professor of Climate Science, Fenner School of Environment and Society at the Australian National University said this isn't just a minor shift in the statistics; it is a total transformation of the Australian summer.
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