The Fires in California, Portugal and Spain Share One Thing in Common

As wildfires raged in the Western United States this month, southern Europe was experiencing an intense wildfire season of its own.

Last week, one tore through Portugal and northern Spain, killing at least 40 people and threatening cities. Thousands of firefighters, and even local residents, mobilized to fight hundreds of blazes. Air pollution from the fires tinged the sky red as far north as the UK.

These fires, like those in California, are a sample of the sort of disaster that is becoming, and will continue to become, more common as the planet warms. The flames that threatened the Iberian Peninsula last week were made worse by two weather events that were, in turn, likely made worth by climate change.

The first culprit was a former hurricane, Ophelia, that trundled its way from the Azores into the Northern Atlantic, traveling further north and east than any hurricane in decades. The storm crossed over the top of Ireland last Monday, battering the country with hundred-mile-an-hour winds, killing three people and leaving hundreds of thousands without power, then continued through the UK and into Scandinavia.

Further south, the winds fanned the flames of fires on the Iberian peninsula. Many of the fires were set by arsonists, according to local officials, but the weather conditions kept them burning.

Which brings us to the second culprit behind such severe fires: A summer heatwave, called “Lucifer,” that left European countries around the Mediterranean particularly parched.

In both these weather events — the rogue hurricane and the heat wave — climate change was a factor.

Several studies have examined how climate change will worsen storms in Europe, and one 2013 study published in Geophysical Research Letters specifically predicted more and stronger hurricanes in Western Europe. “The rise in Atlantic tropical sea surface temperatures extends eastward the breeding ground of tropical cyclones, yielding more frequent and intense hurricanes following pathways directed toward Europe,” the study’s authors wrote.

And scientists with World Weather Attribution found that the Lucifer heatwave’s high temperatures were made at least 10 times more likely by climate change.

As climate change advances, so to is “attribution science,” allowing researchers to understand climate change’s role in worsening particular weather events, and allowing world leaders to better understand how climate change is affecting their people in the present.

“Summers keep getting hotter,” climate scientist Friederike Otto at the University of Oxford, part of the World Weather Attribution project, told The Guardian’s Damian Carrington last month. “Heatwaves are far more intense than when my parents were growing up in the 1950s. If we do nothing to reduce our greenhouse gas emissions, the kind of extreme heat we saw this past summer will be the norm when my young son is a grown man.”

Europe’s fire season is also getting worse, and longer, researchers have found. In the last fifty years, the fire season has more than doubled in length, from two to five months.

When it comes to driving climate change, wildfires are a particularly ferocious problem. Not only are they themselves a symptom of climate change, they are a cause. The fires release carbon dioxide and destroy forests, making it harder for the planet to take those greenhouse gases back out of the atmosphere. These fires are a deadly phenomenon that climate scientists call a “positive feedback mechanism” — a vicious cycle that becomes more powerful as climate change advances.

These factors — storms, heatwaves, floods and fires — add up to play off of each other in unpredictable ways, as was the case with the Lucifer heat wave and Hurricane Ophelia. These new, unusual and deadly weather events, and the way they interact, create natural disasters of the sort that have made climate change a reality for millions around the world — from South Asia to Eastern Africa to the Caribbean — in 2017.