MULTI-SCALE SYNCHRONY IN WILDFIRE AND CLIMATE IN WESTERN NORTH AMERICA OVER THE PAST 5 CENTURIES

KITZBERGER, T. (1), BROWN, P.M. (2), HEYERDAHL, E.K. (3), SWETNAM, T.W. (4) AND VEBLEN, T.T. (5)

(1)Laboratorio Ecotono, Universidad Nacional del Comahue, Quintral 1250, 8400, Bariloche, Argentina, (2) Rocky Mountain Tree-Ring Research, Inc., 2901 Moore Ln, Ft. Collins, CO 80526, USA, (3) USDA Forest Service, Rocky Mountain Research Station, P.O. Box 8089, Missoula, MT 59807, USA, (4) Laboratory of Tree-Ring Research, University of Arizona, Tucson, AZ 85721, USA, (5) Department of Geography, University of Colorado, Boulder, 80301, USA.

Recent advances in our understanding of ocean-atmosphere patterns and their effects on climate in western North America suggest that contingent states of sea-surface temperature and atmospheric pressure in both the Pacific and Atlantic may be important controls of drought and fire in western North America. We used fire occurrence, reconstructed from over 4,700 fire-scarred trees across western North America to show that drought and widespread forest fires co-varied significantly over the past 5 centuries, but in a manner contingent on the states of the El Niño-Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), and the Atlantic Multidecadal Oscillation (AMO).

Based on our current analyses we suggest that both ENSO and decadal-scale states of the major ocean basins (Pacific and Atlantic) can be useful as partial guides to anticipated fire hazards. The current state of the AMO, which is trending positive offers a warning of increased burning and extensive fire synchrony in the western US during the current decade. Knowledge of the contingent states of oscillatory ocean-atmosphere patterns could be of predictive value, enabling land managers and fire fighters to prepare for and carry out appropriate responses at both national and regional levels.