How Responsible Is Climate Change for Increased Wildfires?

With much of the East Coast recently shrouded in wood smoke due to Canadian wildfires, as with many extreme weather events, there has been debate about how much to blame climate change for the unhealthy conditions. To be clear, a new study from the Lawrence Livermore National Laboratory (LLNL) is focused solely on California, so the findings do not necessarily apply to the Canadian wildfires.

Summer wildfire-burned acreage in central and northern California has “increased fivefold between 1996 and 2021 compared to between 1971 and 1995,” writes Anne M. Stark, an LLNL public information officer on June 12.

Although the drivers of increased temperature and dryness are known, the contribution of human-caused climate change to wildfire activity, relative to natural climate variation, is unclear.

However, a new study by a Lawrence Livermore National Laboratory (LLNL) scientist and collaborators shows that nearly all the recent increase in summer wildfire burned area is attributable to human-caused (anthropogenic) climate change. Anthropogenic simulations yielded burn areas an average of 172% higher than natural variation simulations. 

Non-climate factors, including forest and woodland management that has “facilitated fuel buildup, which favors increased burn severity,” continue to play a role, adds Stark.

“Beneath these ‘external’ factors, natural climate variability also influences the occurrence and severity of forest wildfires, creating a noise that can mask the signal of human-caused impacts on wildfire changes,” said LLNL scientist Don Lucas, a co-author of the study.

Canada wildfires

In fact, climate variability may be why wildfire expert Mark Cochrane at the University of Maryland, when asked by Voice of America if climate change was “responsible for the wildfires burning in eastern Canada that supplied the smoke,” responded, a ‘definite maybe.’

“This could have happened without climate change,” Cochrane said. “On the other hand, because of climate change, more and more often the conditions are there for this sort of event.”

Additional reading on the LLNL study in Common Dreams: "Study Shows Climate Crisis Driving Increase in California Summer Wildfire Damage," June 13, 2023

Related in Planetizen: Wildfires Prompt Forestry Debate on Climate Change, Nov. 29, 2017