'Catastrophic wildfires in the West are indicators of a fire deficit '

KVAL via the University of Oregon: 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."

...Wildfires have been debated for years as either a destructive force of nature that should be eradicated or natural disturbance that keep ecosystems healthy. For nearly 100 years, national policy, as administered by the U.S. Forest Service, had been to respond rapidly to suppress all wildfires, but in recent years, local forest managers have been given more latitude to evaluate which fires to suppress, while ensuring public safety.

...Their key findings:....Climate and humans acted synergistically -- by the end of the 18th century and early 19th century -- to increase fire events that were often sparked by agricultural practices, clearing of forests, logging activity and railroading....

Photo of a forest fire by the US Department of Agriculture