The study led by Oregon State University’s Linnia Hawkins, which covered 2017 and 2018, looked at the role climate change may have played in extreme fire weather conditions that accompanied recent large September, October and November fires in those states.
The collaboration that included David Rupp of the Oregon Climate Change Research Institute examined the weather conditions during big fires driven by strong offshore winds such as California’s Santa Ana and Diablo winds and western Oregon’s East wind.
The modeling found that human influences on climate actually reduced the frequency of those winds in the two years studied. But higher temperatures and dryer fuels mean the four study areas were nevertheless much more likely to have extreme autumn fire weather than they would have had without human-caused increases in atmospheric aerosols and carbon dioxide.
“Over the last handful of years, California and western Oregon have experienced their largest and most destructive wildfires ever recorded,” said Hawkins, a postdoctoral researcher in the OSU College of Forestry. “The rapid and extensive growth of many of the fires was driven by strong, dry, offshore, downslope autumn winds blowing across fuels that had become very parched over the summer and stayed that way into fall.”
For this research, the scientists focused on conditions like those seen during recent catastrophic fires, including Northern California’s Wine Country fires in October 2017, the Camp Fire in November 2018 and the North Complex Glass fires in September 2020; Southern California’s Woolsey Fire in November 2018; and western Oregon’s Lionshead Fire in September 2020.