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Type: Journal Article
Author(s): Anthony Leroy Westerling; H. G. Hidalgo; Daniel R. Cayan; Thomas W. Swetnam
Publication Date: 2006

Western United States forest wildfire activity is widely thought to have increased in recent decades, but surprisingly, the extent of recent changes has never been systematically documented. Nor has it been established to what degree climate may be driving regional changes in wildfire. Much of the public and scientific discussion of changes in western United States wildfire has focused rather 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 to hydro-climatic and land-surface data. Here, we show that large wildfire activity increased suddenly and dramatically 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.

Online Links
Citation: Westerling, Anthony L.; Hidalgo, H.G.; Cayan, Daniel R.; Swetnam, Thomas W. 2006. Warming and earlier spring increase western U.S. forest wildfire activity. Science 313(5789):940-943.

Cataloging Information

Partner Sites:
  • area burned
  • Black Hills
  • coniferous forests
  • ENSO - El Nino Southern Oscillation
  • fire frequency
  • fire management
  • fire suppression
  • forest management
  • fuel management
  • histories
  • land surface
  • land use
  • logging
  • low intensity burns
  • Oregon
  • Pinus ponderosa
  • ponderosa pine
  • post-fire recovery
  • precipitation
  • season of fire
  • Sierra Nevada
  • surface fires
  • temperature
  • wildfires
Tall Timbers Record Number: 19945Location Status: In-fileCall Number: Fire FileAbstract Status: Fair use, Okay, Reproduced by permission
Record Last Modified:
Record Maintained By: FRAMES Staff (
FRAMES Record Number: 44561

This bibliographic record was either created or modified by Tall Timbers and is provided without charge to promote research and education in Fire Ecology. The E.V. Komarek Fire Ecology Database is the intellectual property of Tall Timbers.
This document is part of the Southwest FireCLIME Annotated Bibliography, which includes published research related to the interactions between climate change, wildfire, and subsequent ecosystem effects in the southwestern U.S. The publications contained in the Bibliography have each been summarized to distill the outcomes as they pertain to fire and climate. Go to this document's record in the Southwest FireCLIME Annotated Bibliography.