Climate change made heatwave five times more likely
Australia’s summer is undergoing a “total transformation” as scientists warn climate change has increased the likelihood of an imminent severe heatwave fivefold.
Australia’s southern states were overwhelmed in early January by the worst heatwave conditions since the summer of 2018, which was scarred by devastating bushfires.
High temperatures in the 40s across much of southeastern Australia constitute the kind of extreme event that would occur only four times a century before human-caused global warming.
Now, the World Weather Attribute says similarly intense three-day heatwaves can be expected every five years.
If the world warms by 2.6 degrees above pre-industrial averages, as predicted under current policy, such extreme heat events could occur every two years by the end of the century.
Australian National University climate science professor Sarah Perkins-Kirkpatrick said the huge shift in the incidence of heatwaves underlined the urgency of reducing emissions and adapting to the warming that was already occurring.
“This is a complete transformation of the Australian summer,” Dr Perkins-Kirkpatrick said.
“What we once considered an extraordinary heat event has today become something an elementary school student will likely experience several times before graduating high school.”
During a heatwave in early January, healthcare resources were strained as southern states recorded temperatures above 40C for several days and one hospital reported a 25 per cent increase in emergency admissions.
Victoria was hit hard, with a maximum temperature of 44°C recorded at Melbourne Airport, and a state of disaster was declared as strong winds fueled out-of-control fires on land left bone dry after days of brutal heat.
One person lost his life in the fire, which caused more than 900 structures to burn and tens of thousands of sheep and cattle to perish.
Ben Clarke, a researcher at the Center for Environmental Policy at Imperial College London, said extreme heatwaves were on track to become “the norm rather than the exception” in Australia.
“One of our most striking findings is that the impact of climate change far outweighs natural climate variability, including weak La Nina, which generally indicates cooler temperatures,” he said.
Australia’s weather is heavily influenced from year to year by the natural cycle known as the El Niño-Southern Oscillation.
La Nina is associated with wetter conditions and cooler daytime temperatures; El Niño, on the other hand, is associated with drier conditions and higher maximums throughout the day.
Extreme heat is known as a “silent killer” in Australia, causing more deaths than floods, bushfires, cyclones and storms combined.
Australia’s own national climate risk assessment It suggests heatwave deaths could rise by more than 400 per cent in Sydney and more than 250 per cent in Melbourne.
Researchers are increasingly linking higher temperatures to a range of worse health outcomes, including mental health problems. more common and severe sleep apnea.
Emmanuel Raju, director of the Copenhagen Disaster Research Center at the University of Copenhagen, said the most vulnerable are the ones bearing the brunt of extreme heat.
“The elderly, those living in poor quality housing or without refrigeration, and people with pre-existing health conditions,” he said.
“We urgently need to adapt our cities and health systems to this new reality.”
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