Wildfire deficit creating growing problem for Western United States.

A paper in the Proceedings of the National Academy of Sciences is warning that the American West is seeing increased wildfires as a result of drought. The dry conditions cause a build up of combustible biomass, a spread of more vulnerable species and higher tree mortality.

The team behind the research consider the situation as a delicate balance. Increased combustible material causes more fires, which lessens the risk of future fires. The problem lies in the increasing temperatures and drought, which is increasing the normal amount of combustible biomass and creating a fire deficit. This is also confounded by fire suppression, which prevents fires, but not the build up of dry biomass.

Jennifer Marlon, report lead author and a National Science Foundation Earth Science Postdoctoral Fellow at the University of Wisconsin, Madison says, "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. The decline was mostly caused by the influx of explorers and settlers and by their subsequent suppression of wildfires, both intentionally and accidentally.”

The problem of how to manage wildfires is brought up regularly. Some insist they should be prevented in order to protect homes and farmland, however others say they should be allowed to occur in a controlled manor, in order to all the natural removal of combustible biomass and preventing larger scale fires.

The problem is that as the wildfire deficit increases, there is greater likelihood of larger scale fires and greater destruction. The factoring in of climate change alters this slightly however. The study finds that if the natural level of fire existed today (without human influence), “because of climate change and the build-up 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."

The report gives a great deal of support for limiting the control of wildfires. Given this knowledge, it would at least make sense to allow wildfires in places where humanity is least affected.