Anyone who has lived near an area susceptible to wildfires knows what an impact all that smoke can have on air quality – even when the fire is dozens of miles away. Turns out, the impact of those fires on the entire planet is significant as well, in terms of increased carbon emissions.
Now a new study published this week in the journal Environmental Science & Technology suggests sometimes-controversial prescribed burns in forests could significantly reduce the amount of CO2 emitted in the event of a wildfire.
The study, led by Christine Wiedinmyer of the National Center for Atmospheric Research (NCAR), shows that prescribed burns, which are often used by forest managers to protect larger trees from wildfires, could reduce emissions in the West by an average of 18 to 25 percent, and by as much as 60 percent in certain forest systems.
The burns clear out dry brush and other fuel close to the forest floor, preventing fires from building up the energy to consume larger trees, which contain much of the carbon stored in forests.
The NCAR study may add to pressure from environmentalists and conservationists to restrain development in and near national forests, since forest managers often cannot set prescribed burns when development is nearby. Property owners meanwhile want fires of any kind suppressed – leading to a dangerous buildup of fuel on the ground.
One enormous chimney stack
Using data collected from 2001 to 2008, Wiedinmyer and co-author Matthew Hurteau of Northern Arizona University estimated actual carbon emissions from wildfires in 11 Western states, based on the mass of vegetation burned in satellite photos.
The authors then modeled what emissions would have been, if prescribed burns had first taken place, using data on prescribed burns of different types of vegetation.
The conclusion? Prescribed burns would have reduced emissions in those fires from 37 to 63 percent, or 14 million metric tons of CO2, the equivalent of .25 percent of annual U.S. carbon emissions.
This may or may not seem like a lot, depending on whether you are aware that controlling carbon emissions, like controlling your waistline, is very much about losing a little here and a little there.
Actual results may vary
The scientists warned that actual results would probably be lower than their estimates, because many of the fires were either too remote or not remote enough for forest managers to light prescribed burns.
But this shouldn’t dissuade expanded adoption of the method. Wildfires emit about 290 million metric tons of carbon dioxide a year, according to one very rough estimate by Wiedinmyer. That’s a significant percentage of our national carbon output. In illustration, during one week in 2007, forest fires emitted the equivalent of one quarter of all fossil fuel emissions in the state of California.
While it can be costly to set controlled fires, there is also a cost in leaving forests vulnerable to larger fires. More research can help forest managers make better decisions about our forests and climate change.