Full citation: Safford, H. D., et al. (2022). The 2020 California Fire Season: A year like no other, a return to the past or a harbinger of the future? Global Ecology and Biogeography, 31(10), 2005–2025. https://doi.org/10.1111/geb.13498

Abstract: Aim: Wildfire burned area, fire size, fire severity and the ecological and socio-economicimpacts of fire have been increasing rapidly in California in recent decades. We summarize the record-breaking 2020 wildfire season in California statistically, evaluate the drivers of high-severity burning in the 2020 fires and consider implications for fire and resource management.

Location: California, USA.

Time period: 2020, with consideration of long-term trends in many variables.

Major taxa studied: Humans, vegetation and wildlife.

Methods: We statistically summarize the record-breaking 2020 fire year in California and outline the salient ecological and socio-economic impacts. Then we fit two statistical models to determine how a suite of weather- and fuel-related variables influenced high-severity burning in different vegetation types and in different fire events during the 2020 fire season.

Results: In 2020, 1.74 million ha burned in California, 2.2 times more than the previous historical record but only average when compared with pre-Euroamerican conditions. Economic losses exceeded $19 billion, and 33 people were killed directly by fire. Vegetation type and recent fire history had important effects on burning. Variability in high-severity burning among vegetation types was driven principally by vapour pressure deficit and wind speed; variability among fire events was related principally to time since the last fire (a surrogate for fuel loading).

Main conclusions: The 2020 fires were part of an accelerating decades-long trend of increasing burned area, fire size, fire severity and socio-ecological costs in California. In fire-prone forests, the management emphasis on reducing burned area should be replaced by a focus on reducing the severity of burning and restoring key ecosystem functions after fire. There have been positive developments in California vis-à-vis collaborative action and increased pace and scale of fuel management and pre- and postfire restoration, but the warming climate and other factors are rapidly constraining our options.

Keywords: 2020 fires, burned area, California, fire management, fire severity, fire weather, fuels