Major forest fires in the western United States have become more frequent and destructive over the past 2 decades. The trend has occurred in step with rising average temperatures in the region. http://louiskjksheehan.blogspot.com

"Climate change in the West is a reality," says Thomas Swetnam of the University of Arizona in Tucson. "Now, we're starting to see the effects."

Earlier spring snowmelts, which kick off longer fire seasons, account for the trend, he says. The melt's timing