Colder Oregon, Washington forests likely to see 'rapid acceleration' of fires

PORTLAND, Ore. (KOIN) – Forests in the coldest and wettest parts of the western Pacific Northwest are likely to see more wildfires, and an increase in fire size, amid a warming climate, according to an Oregon State University study.

Lead researcher, Alex Dye of OSU's College of Forestry, and the U.S. Forest Service conducted novel wildfire simulations for over 23 million acres of forest land west of the Cascade Range in Oregon and Washington.

During a 30-year period starting in 2035, the simulations showed Washington’s North Cascades region, the Olympic Mountains, the Puget Lowlands, and the western Oregon Cascades could see at least twice as much fire activity compared to the last 30 years, according to the study published Feb. 22 in JGR Biogeosciences.

That trend also remains, to a lesser degree, for the western Washington Cascades, and the Oregon Coast Range, researchers said.

Forests in these areas are “linchpins” of several socio-ecological systems in the region, Dye said – adding more fire will put pressure on drinking water, timber resources, biodiversity, and carbon stocks.

“The moist, highly productive forests of the Northwest don’t get fire as often as other parts of the West, like California or eastern Oregon,” Dye said. “But fire does naturally occur in the PNW ‘Westside’ as we call it – the fire regimes are actually quite complex in this region. It can be challenging to assess fire probability in an environment where there isn’t a lot of empirical information about the fire history to build models.”

The infrequency of fire can also lead the public to believe the westside is not a high-risk area, and also means the region is generally not included in studies, Dye noted.

The researcher says studies are critical to prepare for a "rapid acceleration of fire over the next few decades," in the westside, pointing to the severity of the Labor Day fires of 2020.

“And what if fires like that were to start happening more frequently in the near future?” Dye said. “What if that once every 200 years became once every 50 years, or once every 25 years as climate change brings hotter and drier conditions to the region?”

“Describing the possibilities of how, when and where climate change could affect fire regimes helps bracket everyone’s expectations,” he said. “Particularly important among our findings are new insights into the possibility of shifts towards more frequent and large fires, especially those greater than 40,000 hectares [just under 99,000 acres] as well as shifts toward more fires burning at the beginning of fall when extreme weather has the potential to increase fire spread.”