2006/07/06 by A. L. Westerling, Hugo G. Hidalgo, Daniel R. Cayan +1 · 13 citations
Environmental Science · #Fire effects on ecosystems #Plant Water Relations and Carbon Dynamics #Landslides and related hazards
paper · doi:10.1126/science.1128834
openalex publication_date 2006/07/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Western United States forest wildfire activity is widely thought to have increased in recent decades, yet neither the extent of recent changes nor the degree to which climate may be driving regional changes in wildfire has been systematically documented. Much of the public and scientific discussion of changes in western United States wildfire has focused instead on the effects of 19th- and 20th-century land-use history. We compiled a comprehensive database of large wildfires in western United States forests since 1970 and compared it with hydroclimatic and land-surface data. Here, we show that large wildfire activity increased suddenly and markedly in the mid-1980s, with higher large-wildfire frequency, longer wildfire durations, and longer wildfire seasons. The greatest increases occurred in mid-elevation, Northern Rockies forests, where land-use histories have relatively little effect on fire risks and are strongly associated with increased spring and summer temperatures and an earlier spring snowmelt.