Almost everywhere on the planet where combustible green cover exists, wildfires are becoming a bigger risk, new research has found. Fire seasons on an average are almost 20 percent longer today than they were 35 years ago, a study published in Nature Communications says. Areas where combustible vegetation grows that are at risk from wildfires have doubled in this time period.

“Conditions across the U.S. are becoming more conducive to fires,” said Matt Jolly, the lead author of the study, who is a scientist with the U.S. Forest Service. “We may be moving into a new normal. If these trends persist, we are on track to see more fire activity and more burned area.”

The study, which looked at data from five continents, was a collaboration among scientists from the Forest Service, South Dakota State University, the Desert Research Institute and the University of Tasmania, Australia. All continents with green cover except Australia have longer wildfire seasons, their data showed.

“This study adds to a growing body of knowledge about the increases in wildfire risk and climate change,” said Chris Field, director of the Department of Global Ecology at the Carnegie Institution for Science. “There are multiple factors that can cause wildfires. What the study shows is that weather opens the door to fire risk,” he explained: The number of fires may not necessarily increase, but the risk goes up.

The result comes at a time when the United States is battling a severe fire season. Though the number of fires has been fewer than the 10-year average of wildfires, until this date, the extent of acreage that has been affected by the fires is significantly greater. It crossed the 5-million-acre mark by about mid-July, which is vastly more that the average of 2.9 million acres from 2005 to 2014).

Blazes over 865M acres
A majority of this area, about 4.4 million acres, is in the state of Alaska, said Jennifer Jones, a spokeswoman at the Forest Service. In May, the agency issued a release saying that it anticipated another “active fire year, as above normal wildland fire potential exists across the north central United States and above normal wildland fire potential will threaten many parts of the West this summer.” The prediction has rung true so far.

The Nature Communications study echoes what the Forest Service has been saying for many years now. Forest Service Chief Tom Tidwell in a Senate hearing in 2013 cited a lengthening fire season as one of the challenges for suppression efforts. The press release this year reiterated that at the national and global levels, we are witnessing “heightened levels of wildfire activity.”

The new study noted that every year from 1979 to 2013, on average, about 865 million acres of land all over the world was affected by wildfires.

There are many factors that lead to wildfires, the major ones being the presence of fuels, a source of ignition and conducive weather conditions. “Of the three factors, weather is the most variable and largest driver of regional burned area,” Jolly said. “So we separated weather from the other driving factors in order to isolate the impacts of climate change on wildland fire potential.”

Field said he was surprised by the magnitude of the change captured by the study. “An average 18 percent increase in the fire season, that is a big effect,” he said. “It is a reminder that many parts of the Earth’s system are extremely sensitive to modest changes in the environmental conditions.”

Growing fire activity means growing costs
There is no fixed definition for fire season, but what scientists can estimate is how many days in a year conditions exist that are favorable for a wildfire to break out. Field explained that in mountainous areas, it could be the time between when the snow melts and when the snow cover comes back. Warmer temperatures leads to earlier melting of the snow, he said, and that is a well-documented phenomenon throughout the western United States.

The current study does not elaborate on the ways in which climate change could be leading to a protracted fire season, and Jolly said this would be an area for further research.

But one reason to be worried, Field pointed out, is that the forests hold a large amount of carbon. There is concern in the scientific community that forest fires may set in motion a vicious cycle, where the burning of forests releases more carbon into the atmosphere, thus aggravating the effects of climate change.

Over the past decade, the United States has spent $1.7 billion on wildfire suppression, the study noted. In 2014, the Forest Service exceeded the budget for wildfire suppression by approximately $200 million. The total suppression costs for this year are likely to be around $1.225 billion.

“Over the past few decades, wildfire suppression costs have increased as fire seasons have grown longer and the frequency, size, and severity of wildfires has increased,” Jones said. “Funding has not kept pace with the cost of fighting fire.”

Every fiscal year since 2002, barring two, the agency has exceeded its budget, and on seven occasions, it has been forced to transfer funds from its other programs.

“Transferring funds to cover the cost of wildfire suppression is disruptive and harmful to other critical Forest Service programs and services,” Jones said. But even as the United States musters resources to fight its fiery battles, it is reaching out to Canada, which is experiencing an even more strenuous fire season. Five crews and 30 personnel have already been dispatched across the border to assist with fire suppression efforts there.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC., 202-628-6500