A look back suggests a sobering future of wildfire dangers in US west

EurekAlert: The American West has seen a recent increase in large wildfires due to droughts, the build-up of combustible fuel, or biomass, in forests, a spread of fire-prone species and increased tree mortality from insects and heat. In a paper appearing online Feb. 14 in the Proceedings of the National Academy of Sciences, a 12-member research team warns that these conditions may be "a perfect storm" for more fires.

While grazing and fire suppression have kept incidents of wildfires unusually low for most of the last century, the amounts of combustible biomass, temperatures and drought are all rising. "Consequently, a fire deficit now exists and has been growing throughout the 20th century, pushing fire regimes into disequilibrium with climate," the team concludes.

"The last two centuries have seen dramatic changes in wildfire across the American West, with a peak in wildfires in the 1800s giving way to much less burning over the past 100 years," said lead author Jennifer R. Marlon, now a National Science Foundation Earth Science Postdoctoral Fellow at the University of Wisconsin, Madison. "The decline was mostly caused by the influx of explorers and settlers and by their subsequent suppression of wildfires, both intentionally and accidentally."

...In their analysis, Marlon and colleagues used existing records on charcoal deposits in lakebed sediments to establish a baseline of fire activity for the past 3,000 years. They compared that with independent fire-history data drawn from historical records and fire scars on the landscape.

..."We can use the relationship between climate and fire," Marlon said, "to answer the question: What would the natural level of fire be like today if we didn't work so hard to suppress or eliminate fires? The answer is that because of climate change and the buildup of fuels across the western U.S., levels of burning would be higher than at any time over the past 3,000 years, including the peak in burning during the Medieval Climate Anomaly."...

July - Sep 2000 -- Air Force Reserve firefighting aircraft and aircrews quenched wildfires in California, Idaho and Montana, flying C-130s equipped with Modular Airborne Fire Fighting Systems. Here, an Air Force Reserve C-130 Hercules MAFFS aircraft assigned to the 302nd Airlift Wing, Peterson Air Force Base, Colo., drops fire retardant chemicals on the "Big Crow" wildfire in southwestern Idaho