A Shorter, Sharper Rainy Season Amplifies California Wildfire Risk

• Published in: Geophysical research letters 2021-03, Vol.48 (5), p.n/a
• Main Author: Swain, Daniel L.
• Format: Article
• Language: English
• Subjects: california; climate change; downslope winds; precipitation seasonality; wildfire risk
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2021GL092843

California has experienced increasingly severe autumn wildfires over the past several decades, which have exacted a rising human and environmental toll. Recent fire and climate science research has demonstrated a clear link between worsening California wildfires and climate change, mainly though the vegetation‐drying effect of rising temperatures and shifting precipitation seasonality. New work by Luković et al. (2021) explores observed changes in California's autumn precipitation in greater detail, finding that the rainy season has indeed become progressively delayed and that the “sharpness” of California precipitation seasonality has increased. These precipitation shifts have important implications for the region's ecology and wildfire risk, as they increase the degree of temporal overlap between extremely dry vegetation conditions and fire‐promoting downslope winds in late autumn. Both of these observed shifts are consistent with climate model projections for the region's future, suggesting that recent trends may offer an early preview of larger changes to come. Key Points California autumn precipitation of outsized importance from ecological and wildfire risk perspectives An observed decrease in autumn precipitation and delay in rainy season onset have contributed to an increase in peak seasonal wildfire risk Sharpening precipitation seasonality reported by Luković et al. (2021) is consistent with climate model projections in a warming climate