Scientists found that the chances of the kind of extreme weather that triggered the blazes have increased by more than 30% since 1900, and that fire conditions like this are at least four times more likely than they were at the start of the 20th century.
However, the authors say that this is likely a conservative estimate, and that the risk of fires may have grown by far more than 30% due to the climate models’ underestimations of the actual increases in extreme temperatures and heatwaves.
“We found that climate models struggle to reproduce these extreme events and their trends realistically,” Dr. Geert Jan van Oldenborgh of the Royal Netherlands Meteorological Institute who contributed to this analysis said in a statement.
The analysis was conducted by World Weather Attribution (WWA), a coalition of academic and government scientists from around the globe that investigates how the climate crisis is influencing extreme weather events. Past WWA studies have looked at the role the climate crisis played in Europe’s sweltering June 2019 heatwave and the massive amounts of rain Tropical Storm Imelda dumped on Texas last year.
“Here for the first time, we have quantified how climate change has affected the risk of bushfires in the region of Southeastern Australia that has just experienced very severe fires,” said Dr. Friederike Otto, the acting director of the Environmental Change Institute at the University of Oxford and a co-investigator involved in this study.
The group found that human-caused climate change has loaded the dice in favor of these catastrophic fires, and that more fire seasons like this one are likely in the future.
If the world’s governments are unable to hold global warming to less than 2 degrees Celsius, then fire conditions like those experienced this summer could be four times more likely in the coming years.
However, the planet is currently on track to warm by more than 2 degrees Celsius, meaning future fire seasons could be even more extreme.
The scientists also explored the role that the climate crisis is playing in Australia’s heatwaves, like the one last December which shattered the continent’s all-time average temperature record.
Their analysis found that heatwaves are the primary driver behind the increasing fire risk, and that heatwaves in Australia are now about 1 to 2 degrees Celsius (1.8 to 3.6 degrees Fahrenheit) hotter and about 10 times more likely than they were in 1900.
The fires that burned in 2019 and 2020 were among the worst in Australia’s history.
Over several months, the infernos killed at least 28 people, destroyed thousands of homes and affected an estimated one billion animals across the country.
All told, an estimated 18 million hectares (44.5 million acres) were scorched, an area larger than the entire state of Florida.
On Tuesday, New South Wales – the hardest hit part of the country – announced that for the first time in 240 days, there were finally no fires burning in the state.
Australia is the world’s driest continent and one of its hottest, and it has long had a propensity for wild swings between weather extremes.
But its climate has gotten even hotter in recent decades.
On average, the country is more than 1 degree Celsius (2.8 degrees Fahrenheit) hotter than it was in 1910, and last year was the hottest and driest year in the country’s recorded history.
Those abnormally high temperatures and drought conditions converged to create an ideal environment for fires.
But scientists have warned for more than a decade that an extreme bushfire season was coming.
And if global efforts to reign in heat-trapping gas emissions continue to stall, more fire seasons like this one could be on the horizon.
CNN’s Brandon Miller, Helen Regan and Hannah Levy contributed to this report.