California has experienced a rapid increase in burned area over the past several decades. This study uses a standardized database of wildfire behavior, including daily fire rate-of-spread and fire radiative power for large wildfires in California (2012–2018), to show that human-ignited fires start at locations with lower tree cover and during periods with more extreme fire weather, leading to more explosive growth and larger ecosystem impact (tree mortality more than three times higher for fast-moving fires) compared to lightning-caused fires. Limiting human-caused fires during extreme fire weather is crucial for forest conservation.

Stijn Hantson, Niels Andela, Michael L. Goulden, James T. Randerson