Don McKenzie and Dave Peterson
Tuesday, October 5
3:30 to 5:00
Climatic change and wildfire: past, present, and future
Climatic variability is a dominant factor affecting large wildfires in the western United States, an observation supported by paleoecological data on charcoal in lake sediments and reconstructions from fire-scarred trees. At the regional scale, severe extreme fire weather is still the dominant influence on area burned and fire severity, although this varies among ecosystem types. In some forests and rangelands, bringing fuel loadings back to their historical ranges may partially restore historical fire regimes, but in a rapidly changing climate we can expect that historical conditions are of limited value for establishing target conditions for the future.
Methods for reconstructing historical fires are of two types: those that use sediment records and those that use fire-scarred trees or stand-level reconstructions. Each has its strengths and limitations. Fire history for much of the 20th century is available from a variety of local and national databases, and records provide not only time and place of individual fires, but also explicit fire perimeters and thus fire areas. These fire records, along with instrumental climate records, allow us to develop statistical models of fire-climate interactions that enable predictions of future wildfire.
Increased temperature in the future will likely extend fire seasons throughout the western United States, with more fires earlier and later than is currently typical, and increase the total area burned in some regions. We present predictive models on a state-by-state basis as a first step in developing predictive models of area burned by wildfire under future climate. The effects of climatic change will partially depend, however, on the extent to which resource management modifies vegetation structure and fuels. Improved predictive models will depend on better spatial resolution of input data, a combination of statistical and process-based modeling, and incorporation of climate-derived variables that are more directly associated with wildfire than seasonal or annual averages of precipitation and temperature.
Don McKenzie is a researcher with Fire and Environmental Research Applications Team at the U.S. Forest Service Pacific Northwest Research Station. Don is also an Affiliate Assistant Professor at the UW's College of Forest Resources and has been involved in numerous research projects at the Climate Impacts Group. (bio)
Dave Peterson is a researcher with Fire and Environmental Research Applications Team at the U.S. Forest Service Pacific Northwest Research Station. Dave is also a Professor at the UW's College of Forest Resources and a Principal for the Climate Impacts Group. (bio)