Fire-Climate Interactions in the Mediterranean Climate Areas of the Pacific Coast

Valerie Trouet

Climate strongly influences the occurrence and extent of fires at the US West Coast and fire managers desire the ability to predict problematic fire seasons in advance> Currently, they must wait until the climatic pattern for the current year is well in place before the potential severtity of the coming fire season becomes apparent. Hemispheric-scale atmospheric circulation patterns (such as ENSO, PDO, and PNA), however, are predictable weeks to years in advance. The predictability of these patterns can thus potentially be used to predict fire season severity. In order to develop and evaluate this approach to predicting fire season severity, we identify the functional links between atmospheric circulation patterns, fire weather, and fire regimes over a range of spatial and temporal scales. The goal of this project is to identify the relationships of inter-annual and intra-decadal variation and multi-decadal and multi-century climate change on sub-regional variation in montane forest fire regimes in the Mediterranean Climate Area (MCA) of the Pacific Coast. Specific objectives are to:

  • Determine how ENSO, PDO, and PNA are related to surface fire weather, secondary circulateion features , and spatial and temporal variation in 20th century fire extent.
  • Determine how multi-century records of fire extent, climate variability, climate change, dominant circulation modes, and fire danger rating indices vary within MCA.
  • Identify the key variables associated with circulation modes that can be used for spatially explicit prediction of problematic fire seasons in different parts of MCA months to years in advance.

    • The strength of this project are the wide range of spatial and temporal scales that are being covered. We investigate contemporary (1920-2000) fire-climate interactions using observational fire records from California, Oregon, Washington, and Nevada. Contemporary fire weather conditions (1960-2000) are studied on atmospheric scales as well as from local station data. Long-term (1700-1900) tree ring records of fire come from over 50 sites collected for this study extending from Baja California to Grants Pass, Oregon (see map). Over 1000 tree ring samples are analysed for this study.

    Photo of forest pines Map of fires in study area Photo of collecting tree ring samples Photo of Alan by tree stump

    This project was supported with funding from the National Forest Service and the Joint Fire Science Program

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