At the start of this year's wildfire season, some new research may prove unsettling for forest managers and property owners in Idaho, Oregon and Washington. Wildfires in the western U.S. have been growing larger and more frequent over the past 30 years. And a team of geophysical researchers fears that trend will continue as climate change pushes up temperatures and droughts become more severe in coming decades.
In a new study to be published in the journal of the American Geophysical Union, scientists found that the number of wildfires greater than a thousand acres in size increased by an average seven fires a year from 1984 to 2011. And the total area scorched by those fire jumped by nearly 90-thousand acres a year - an area roughly the size of Las Vegas.
The lead researcher, Doctor Philip Dennison of the University of Utah, said the increases are not random. His study team used satellite data to measure large fires since 1984, and then examined climate variables such as seasonal temperatures and rainfall during that time.
There was a clear link, Dennison said, between the increases in fire outbreaks and drought severity. He concluded that large-scale climate changes, rather than local factors, are probably driving the increase in fire activity. Further, climate models have projected that increased wildfires will occur as temperatures rise and droughts become more severe with global warming.
Dennison pointed out that one variable in the study may be fire suppression practices used for decades in western state forests. As he put it "It could be that our past fire suppression has caught up with us, and the increased area burned is a response of more continuous fuel sources".
This is the first wildfire study to use high-resolution satellite data to examine trends over a broad range of landscapes.