The latest installment in a series of behind-the-scenes stories on how fire affects people, places, and wildlife.
By Tim Mayer/USFWS Hydrologist
Photo: Residents evacuating Pateros in Central Washington in mid-July of this year as the Carlton Complex Fire threatens the town. Credit: Garson Shortt Photography
Every summer, forests around the Pacific Northwest ignite in a string of forest fires. This summer has been no exception with record-setting fires burning in central Washington and Central and Eastern Oregon. It’s like an endless series of sequels to a Hollywood disaster movie, where the plot never changes.
Since 2000, the average area burned in wildfires every year has more than doubled from the 1985 to 1999 yearly average. The fire season has grown from an average of five months in the 1970s to seven months today. Costs associated with fighting these fires have soared, with much of the financial burden falling on American taxpayers.
Why are we seeing these changes? For years, the public and scientific discussion has focused on fire suppression; the theory being that we have done such an excellent job of preventing fires that underbrush, dead wood and other fuels have accumulated, increasing the flammability of our forests. This is true to a certain extent but recently, the role of climate and climate change is also being acknowledged.
Strong scientific evidence shows that climate change has resulted in hotter, drier conditions in our region. Average annual air temperatures have increased and snowpacks have decreased over the last century (see figure). Low precipitation and high temperatures in summer dry out fuels over a larger than normal area, increasing the number and extent of fires. Earlier snowmelt from warm spring temperatures leads to an earlier, longer fire season with drier soils and vegetation and more opportunities for ignition. High-elevation forests that were previously protected from wildfire by late snowpacks are becoming more vulnerable to fire as well.
Figure credit: Climate Impacts Group, University of Washington cses.washington.edu
Climate warming has affected forests and fuels in another way too. Warm winters have allowed bark beetles to survive longer and reproduce more, resulting in record pine beetle outbreaks. From 2000 to 2013, bark beetles killed 47.6 million acres of forests in the western U.S., an area the size of Nebraska. I personally have observed steadily expanding patches of dead pine trees on the hillsides surrounding my home town of Hood River, OR. All these dead trees potentially make more fuel wood available for wildfires. It’s quite frightening to think about.