Is human-caused climate change to blame for California’s record-breaking wildfires?

A figure from the new study shows changes in burned area. Credit: doi:10.1073/pnas.2213815120

Record-breaking forest fires during California’s summer months have become a regular occurrence. Wildfires not only cause catastrophic environmental and socioeconomic impacts, but also have negative consequences for human health. Environmental observations indicate that summer burned areas (BA) in northern and central California have increased fivefold during 1996 to 2021 compared to 1971 to 1995. While higher temperatures and increased dryness are thought to be the leading causes of increased BA, the extent to which BA changes due to natural variability or man-made climate change remains largely unresolved. With 10 of the largest California wildfires occurring in the last 20 years—five of which occurred in 2020 alone—scientists are asking if man-made climate change is to blame.