Climate change ‘unequivocal’ in driving wildfires — report

Source: By Thomas Frank, E&E News reporter • Posted: Sunday, September 27, 2020

Climate change has played an “unequivocal and pervasive role” in the increase and intensification of wildfires and must be addressed directly, according to a new report that questions the effectiveness of forest management strategies championed by President Trump.

The report, released this morning on the ScienceBrief platform, summarizes recent studies on climate change and wildfire, and it casts doubts on efforts to reduce wildfire risk by thinning out forests. It says “land management can ameliorate or compound climate-driven changes in wildfire risk.”

The authors reviewed 116 papers on climate change and wildfire, and they said the publications “strengthen the evidence” that climate change has increased and intensified “fire weather” in the United States and elsewhere through high temperatures, low humidity and limited precipitation.

“Climate change is bringing hotter, drier weather to the western U.S., and the region is fundamentally more exposed to fire risks than it was before humans began to alter the global climate,” the four-page report says.

“We know that climate change is promoting the conditions on which fires depend and leading to increased wildfire risk,” co-author Matthew Jones, a researcher at the Tyndall Centre for Climate Change Research at the University of East Anglia, said in an interview. “It’s so well supported in scientific literature, there’s not really any doubt involved.”

The report tacitly rebukes Trump, who said in a recent visit to California that the surge in wildfires on the West Coast “is more of a management situation.” It also raises questions about bipartisan legislation in Congress — opposed by some environmental groups — that would promote increased forest management.

At a House Agriculture Committee hearing yesterday, an official with the Trump administration blamed forest management for the “unprecedented” wildfire this year.

“If we want to maintain forests, we need to safely return fire to the landscape,” said John Phipps, deputy chief for state and private forestry with the Forest Service.

Forests in California currently have an average of 320 trees per acre — a huge increase from 64 trees per acre before people settled the state, Phipps said.

“It happened because we’ve been trying for over 110 years to put out every fire we can,” Phipps told the Conservation and Forestry Subcommittee during testimony in Washington. “It’s just really a bad trajectory that we’re on. It’s going to take a paradigm shift in thinking.”

Recent wildfires have caused massive evacuations and pollution across the West Coast. Blazes in California have burned a record 3.6 million acres this year, destroyed 8,000 buildings and killed 26 people. Wildfires burned 7.7 million acres in California in the 2010s — more than double the 3.5 million acres burned in the 1990s, according to state figures.

The report cites a study projecting a 25% increase in the number of fire days in California by the late 21st century.

The report acknowledges that “a legacy of fire suppression” in the western United States has contributed to the increase and intensification of wildfire by leaving forests dense with vegetation. But it says that the buildup of fuel in forests and grasslands “cannot alone explain the magnitude of the observed increase in wildfires” in the West in recent decades.

Jones, the author, said that forest management “is a delicate balance.”

Thinning forests through controlled burns can reduce the number of wildfires in the short term and protect populated areas by creating firebreaks, Jones said. But in the long term, removing leaves and twigs from a forest floor can enable trees to grow larger, which fuels more powerful wildfires.

“What prescribed fire does is remove the loose material that’s dead and lying on the forest floor,” Jones said. “The canopy and the trees are not affected. You start to modify cycle in the forest, so trees and flammable fuels are allowed to grow to a size that’s essentially beyond their natural state.”

The report also acknowledges that wildfires are triggered by weather patterns, such as short spells of heat and dryness, but says that such “natural variability is superimposed on the increasingly warm and dry background conditions resulting from climate change.”