Human-caused climate change made Spanish, French fires much more likely, scientists calculate

Climate change’s fingerprints are all over the extreme fire weather that sparked this week’s devastating wildfires in Spain and France and has spiked Southern Europe’s burning the past eight years, two new studies conclude.

Human-caused climate change made the hot and dry conditions responsible for Spain’s record-sized inferno 20 times more likely to happen, and it doubled the chances of extreme fire conditions for the flames in France, scientists at World Weather Attribution calculated in a rapid analysis Thursday, conducted while fires were still burning. Warming in the past 26 years has tripled the odds of the severe fire risk conditions in Spain and increased the chances in France 40%, the same report found.

At the same time, researchers published a separate study on Thursday — written and edited long before this week’s fires began — that found the number of days that Southern Europe’s weather reached extreme fire-prone levels has more than doubled compared to decades ago.

Both studies examined changes in the weather that creates fire-prone conditions. The measurements factor in air temperature, drought conditions, humidity and wind.

“The change in these fire weather conditions in Spain is really extremely strong and is, I think, one of the largest changes that I’ve seen,” said Friederike Otto, an Imperial College of London climate scientist who coordinates World Weather Attribution. Spain is having its hottest summer on record, after an incredibly wet January that allowed plants to grow before a severe drought hit, a combination that increased wildfire fuel, the report said.

Spain also had the added problem of land abandonment, which left unmanaged plants and trees to dry out, Otto said. France’s Bordeaux region, meanwhile, had thick groves of pines that also burn well when a fire starts, she said.

World Weather Attribution — an international collaboration of scientists who examine extreme events to determine climate change’s role, if any — did that study so quickly, the report didn’t get peer reviewed, which is the scientific gold standard. But Otto and her colleagues used techniques that are scientifically accepted, and many of their reports are published in peer-reviewed journals later.

Warming world means fires ignite ‘more explosively’

Otto’s team calculated how much climate change — from the burning of coal, oil and gas — increased the chances for fires of this intensity to happen. They did so by comparing fire weather severity levels to past measurements for the region and to what they would be if the world was 2.5 degrees (1.4 degrees Celsius) cooler. That is how much Earth has warmed since pre-industrial times.

“This study makes sense and provides numbers to confirm what fire scientists already knew,” said Syracuse University fire scientist Jacob Bendix, who wasn’t part of either research. “We have always known that fires ignite more easily and spread more explosively under conditions of extreme heat and drought. And we’ve known for decades that extreme heat and drought are becoming more common due to anthropogenic climate change. So the general outline of these events, if not all the details, was tragically predictable.”

Thursday’s other study, in the journal Scientific Reports, finds that there were about 10 extreme fire weather days a year in Southern Europe in earlier decades, but it is now up to around 25 a year, said study author Raúl Cordero, a climate scientist at the University of Groningen in the Netherlands. And it is not just more frequent bad fire weather days. Those days are about 50% more intense than they were from 1981 to 2010, his study said.

Fires were decreasing until climate change overwhelmed gains

The number of Southern European fires and amount of land burned had decreased quite a bit from the 1980s to 2018, mostly because of better fire suppression and management techniques, Cordero said. But then things quickly got worse fast because climate change overwhelmed that improvement, he said.

“It doesn’t matter how many resources or how much money you have, you just cannot stop the propagation of a fire when the weather is so extreme,” Cordero said. “The climate forcing is so extreme nowadays that it’s just amazing.”

University of California Merced fire scientist John Abatzaglou, who also wasn’t part of either research, said, “these findings make clear that climate change is not just a future problem, it’s already here.”

“We need to stop burning fossil fuels,” Otto said. “Because as long as we keep burning fossil fuels, temperatures will increase globally. And that will mean that these fire weather conditions will get worse and worse and worse. And there are hard limits to what we can adapt to.”

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