In the western United States, land managers for more than a century have focused on suppressing fires, which has led to comparatively dense forests that store large amounts of carbon. But these forests have become overgrown and vulnerable to large fires. Changes in climate, including hotter and drier weather in summer, are expected to spur increasingly large fires in the future.
This could complicate U.S. efforts to comply with agreements on reducing carbon emissions. Such agreements rely, in part, on forest carbon accounting methodologies that call for trees to store carbon for long periods of time. Large carbon releases from wildland fires over the next several decades could influence global climate as well as agreements to reduce emissions.
To determine whether prescribed burns would likely affect the carbon balance, the scientists first estimated actual carbon emissions from fires for 11 Western states from 2001 to 2008. They used satellite observations of fires and a sophisticated computer model, developed by Wiedinmyer, that estimates carbon dioxide emissions based on the mass of vegetation burned.
Their next step was to estimate the extent of carbon emissions if Western forests, during the same time period, had been subjected to a comprehensive program of prescribed burns. The scientists used maps of vegetation types, focusing on the forest types that are subject to frequent natural fires and, therefore, would be top candidates for prescribed burns. Emissions in the model were based on observations of emissions from prescribed burns of specific types of forests.
The results showed that carbon emissions were reduced by anywhere from 37 to 63 percent for the fore
|Contact: David Hosansky|
National Center for Atmospheric Research/University Corporation for Atmospheric Research