Skip to main content
U.S. flag

An official website of the United States government

Cascadia Burning: The historic, but not historically unprecedented, 2020 wildfires in the Pacific Northwest, USA

Author(s):

Joshua S. Halofsky
Alex W. Dye
Daniel C. Donato
Nathan Walker
Raymond J. Davis
Christopher J. Dunn
Matthew J. Gregory
James D. Johnston
Brian J. Harvey

Year:

2022

Publication type:

Scientific Journal (JRNL)

Primary Station(s):

Pacific Northwest Research Station

Source:

Ecosphere. 13(6): 6383-6403.

Description

Wildfires devastated communities in Oregon and Washington in September 2020, burning almost as much forest west of the Cascade Mountain crest (“the westside”) in 2 weeks (~340,000 ha) as in the previous five decades (~406,00 ha). Unlike dry forests of the interior western United States, temperate rain forests of the Pacific Northwest have experienced limited recent fire activity, and debates surrounding what drove the 2020 fires, and management strategies to adapt to similar future events, necessitate a scientific evaluation of the fires. We evaluate five questions regarding the 2020 Labor Day fires: (1) How do the 2020 fires compare with historical fires? (2) How did the roles of weather and antecedent climate differ geographically and from the recent past (1979–2019)? (3) How do fire size and severity compare to other recent fires (1985–2019), and how did forest management and prefire forest structure influence burn severity? (4) What impact will these fires have on westside landscapes? and (5) How can we adapt to similar fires in the future? Although 5 of the 2020 fires were much larger than any others in the recent past and burned ~10 times the area in high-severity patches >10,000 ha, the 2020 fires were remarkably consistent with historical fires. Reports from the early 1900s, along with paleo- and dendro-ecological records, indicate similar and potentially even larger wildfires over the past millennium, many of which shared similar seasonality (late August/early September), weather conditions, and even geographic locations. Consistent with the largest historical fires, strong east winds and anomalously dry conditions drove the rapid spread of high-severity wildfire in 2020. We found minimal difference in burn severity among stand structural types related to previous management in the 2020 fires. Adaptation strategies for similar fires in the future could benefit by focusing on ignition prevention, fire suppression, and community preparedness, as opposed to fuel treatments that are unlikely to mitigate fire severity during extreme weather. While scientific uncertainties remain regarding the nature of infrequent, high-severity fires in westside forests, particularly under climate change, adapting to their future occurrence will require different strategies than those in interior, dry forests.

Citation

Reilly, Matthew J.; Zuspan, Aaron; Halofsky, Joshua S.; Raymond, Crystal; McEvoy, Andy; Dye, Alex W.; Donato, Daniel C.; Kim, John B.; Potter, Brian E.; Walker, Nathan; Davis, Raymond J.; Dunn, Christopher J.; Bell, David M.; Gregory, Matthew J.; Johnston, James D.; Harvey, Brian J.; Halofsky, Jessica E.; Kerns, Becky K. 2022. Cascadia Burning: The historic, but not historically unprecedented, 2020 wildfires in the Pacific Northwest, USA. Ecosphere. 13(6): 6383-6403. https://doi.org/10.1002/ecs2.4070.

Cited

Publication Notes

  • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
  • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
https://www.fs.usda.gov/treesearch/pubs/64470