The number and intensity of extreme forest fires, the most destructive and polluting, have more than doubled worldwide over the past 20 years, due to global warming due to human activity, according to a new study published Monday.
Using satellite data, researchers studied nearly 3,000 wildfires with enormous “radiative power” – the amount of energy emitted by radiation – between 2003 and 2023 and found that their frequency had increased by a factor of 2 .2 during this period.
Considering only the 20 most violent fires each year, their cumulative radiative power has also more than doubled, at a rate that “appears to be accelerating”, according to the study published in the journal Nature Ecology & Evolution.
Temperate coniferous forests
It is the temperate coniferous forests, particularly in the western United States, and the boreal forests, which cover Alaska, northern Canada and Russia, which are the most affected, with a frequency of such fires multiplied by 11 and 7 respectively.
“The effects of climate change are no longer a thing of the future and we are now seeing signs of a drying and warming atmosphere,” said study lead author Calum Cunningham of the Australian University of Tasmania, advocating for better preventative forest management.
2023, the most extreme year
The six most extreme years in wildfire intensity and frequency have occurred since 2017, the study found. Confirming the trend, it is the year 2023, the most recent, which experienced “the most extreme forest fire intensities” over the period studied.
During its growth, the forest cover absorbs CO2, but it returns en masse to the atmosphere when the vegetation burns, aggravating global warming caused by greenhouse gas emissions. This creates a “feedback effect”, Calum Cunningham said.
In addition, with these fires, “vast regions are crossed by the plume of smoke, which has significant effects on health and leads to many more premature deaths than the flames themselves”, underlined the researcher.
His study cites in particular work according to which air pollution due to megafires in 2015 in Indonesia led to an excess mortality of 100,000 people.
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