How a warming climate is paving the way for fast-spreading, devastating wildfires

By | March 3, 2024

Texas is no stranger to winter wildfires, but the ferocity of the Smokehouse Creek fire — the state’s largest ever after burning more than 1 million acres — caught even experts off guard.

Its severity was due to a perfect storm of environmental factors: highly flammable grasses and high winds, combined with record high temperatures and dry conditions – the kind of extreme weather often worsened by climate change.

This fire adds to a growing list of fast-spreading, devastating wildfires in the US and elsewhere. As humans continue to warm the world with fossil fuel pollution, scientists warn that these types of fires will only become more common.

Recent years have seen some of the most devastating fires in the United States. The fire that swept through Maui in August, fueled by a combination of heat, drought and high winds, killed at least 100 people and was the deadliest U.S. wildfire in more than a century.

California has seen 80% of the state’s largest wildfires over the past decade, including the 2018 Camp Fire, which killed 85 people and destroyed the town of Paradise.

But it’s not just the US that’s grappling with alarming new fire behavior. Canada experienced its worst wildfire season on record in 2023, with flames scorching more than 18 million hectares (44.5 million acres) – more than double the previous record.

In Greece, winds and record temperatures led to deadly fires last summer, the largest ever recorded in the European Union. And in early February, forest fires swept through parts of Chile, killing more than 130 people.

Flames spread through the forest near Mistissini, Quebec, Canada in June 2023.  - Cpl Marc-Andre Leclerc/Canadian Forces via Reuters

Flames spread through the forest near Mistissini, Quebec, Canada in June 2023. – Cpl Marc-Andre Leclerc/Canadian Forces via Reuters

“We’ve certainly seen a lot of extreme and catastrophic fires and fire seasons around the world in the last decade,” said John Abatzoglou, a climate professor at the University of California, Merced.

What ties many of these fires together, he told CNN, is “the rapid fire spread and a sense of surprise at how quickly individual fires grew – or in the case of Canada, their entire fire season.”

In many cases, climate change plays a role, he added, “enabling more active fire seasons and very large fire events.”

Why did the fires in Texas grow so explosively?

To understand why fires in Texas have been so intense, look to last spring, said Luke Kanclerz, a fire analyst with the Texas A&M Forest Service. Parts of the Texas Panhandle were drenched in rain, about 300% to 400% above average, which allowed grasses to grow very quickly, he told CNN.

Then a hard frost late in the fall caused all that grass to go dormant. They had been stripped of moisture and were highly flammable. It only took a short period of warm, dry weather for them to dry out further, creating a carpet for the fire to spread.

Temperatures were unusually high the day the fires started, rising to more than 85 degrees Fahrenheit in some parts of the panhandle, Kanclerz said.

Strong winds helped fan the fire, and the passage of a breezy cold front whipped it further, causing the fire to change direction and spread.

The geography of the region exacerbated the situation. The fire was able to spread across open countryside without any response, making firefighting efforts extremely challenging. The fire grew explosively and engulfed 150 football fields every minute in the first few days.

Kanclerz said that before the fires broke out, it was clear that wind, temperature and humidity indicators were combining to create critical fire conditions.

“But the size of the fire exceeded our expectations,” he said.

It’s hard to witness, he added. Massive fires in these parts of Texas are “not unheard of,” he said, “but we hate to see the frequency of them.”

A changing climate

Wildfires are fueled by a range of factors, both natural and man-made, but scientists say global warming is raising the odds in favor of more intense and fierce fires.

Higher temperatures are the clearest cause of forest fires caused by climate change. Heat sucks the moisture out of the vegetation, making it much more flammable. “Dryer fuels are a crucial part of fire; the drier the fuel, the easier it is to start a fire,” said Mike Flannigan, a wildfire professor at the University of Alberta.

In addition to drying out vegetation, heat can also change vegetation. In Hawaii, hotter summers have made it easier for fast-growing and more flammable invasive species to become established, crowding out native vegetation such as shady forests.

Periods of drought, which become longer and more intense as the world warms, also dry out vegetation and increase the chance that fires will spread quickly. The Maui fires occurred when a third of the island was in drought.

But drought isn’t always necessary for fires to spread explosively, Abatzoglou said — something evidenced by the fact that there was no drought earlier this week where the Smokehouse Creek fire originated and spread.

In West Texas, shorter periods of drought could be enough to spark major fires when there is both a bumper crop of grasses and high winds, he said.

And these dry conditions are more common in the state, as they are elsewhere in the US. “There is an overall decrease in relative humidity,” Texas state climatologist John Nielsen-Gammon told CNN.

A volunteer assesses damage at a charred apartment complex in the aftermath of the Lahaina fire in August 2023. - Yuki Iwamura/AFP/Getty ImagesA volunteer assesses damage at a charred apartment complex in the aftermath of the Lahaina fire in August 2023. - Yuki Iwamura/AFP/Getty Images

A volunteer assesses damage at a charred apartment complex in the aftermath of the Lahaina fire in August 2023. – Yuki Iwamura/AFP/Getty Images

Scientists are still trying to understand what impact global warming has on the winds that cause wildfires.

Research has found that climate change is fueling the rapid intensification of hurricanes, causing storms to explode at a deadly rate. Hurricane Dora, a Category 4 storm that passed about 700 miles south of Hawaii’s Big Island, amplified strong winds that helped fuel the fires in Maui.

But it’s difficult to attribute climate change to the winds that fueled the Texas fires, Abatzoglou said: “any link is most likely weak at this point.”

Overall, however, the climate projections paint “a future of more extreme fire conditions for the overall region,” he added.

It’s a picture that extends across the U.S., according to a recent report from Climate Central, a nonprofit research group, which found that wildfire seasons are getting longer and more intense as climate change increases the likelihood of the kind of extreme weather events that fuel fires. works in hand.

West Texas is one of the hardest-hit states, said Kaitlyn Trudeau, senior researcher at Climate Central. For example, the Texas High Plains region is experiencing 32 additional days of warm, dry and windy conditions compared to the 70s, she said.

Devastating wildfires are increasingly part of life in the US and elsewhere, Trudeau told CNN.

“As long as the climate continues to warm and fires become more common, the risks will only increase.”

CNN’s Rachel Ramirez contributed to this report.

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