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Record‐setting climate enabled the extraordinary 2020 fire season in the western United States

Author(s): Philip E. Higuera, John T. Abatzoglou
Year Published: 2021

The 2020 fire season in the western United States (the West) has been staggering: over 2.5 million ha have burned as of 30 September, including over 1.5 million ha in California (3.7% of the state), in part from five of the six largest fires in state history; over 760,000 ha have burned in Oregon and Washington, most occurring within a few‐day period (www.nifc.gov; Figure 1a). The human impacts are unprecedented: millions have endured hazardous air, with estimates of thousands of smoke‐related deaths; over 10,000 structures have been damaged or destroyed, and dozens of lives have been lost. While fire is a fundamental natural process in most western ecosystems, these events have distinct human fingerprints—human‐caused ignitions, increased human exposure from expansion into flammable landscapes, increased fuel loads due to fire suppression, and increased fuel aridity due to climate change.

This year's widespread burning was clearly enabled by record‐setting atmospheric aridity across much of the West, reflected by vapor pressure deficit (VPD; Figure 1b). A dry atmosphere directly increases fuel aridity, and dry fuels facilitate ignitions and catalyze rapid fire spread and fire behavior that resists suppression efforts. Dozens of studies highlight fuel aridity as a dominant control of burned area, particularly where fuel is non‐limiting, over interannual, decadal, and millennial timescales (Marlon et al., 2012). Here we show that VPD explains 56% of the variability in burned area since 1984, with 2020 ranking second highest in VPD and burned area (Figure 1c,d).

Citation: Higuera PE and Abatzoglou JT. 2021. Record‐setting climate enabled the extraordinary 2020 fire season in the western United States. Global Change Biology V27(1), p1-2. https://doi.org/10.1111/gcb.15388
Topic(s): Fire Behavior, Weather, Fire & Climate
Ecosystem(s): None
Document Type: Book or Chapter or Journal Article
NRFSN number: 22631
Record updated: Feb 3, 2021