July 30th, 2011
Econintersect: Research has shown that wildfires in the Arctic tundra pose an environmental threat from several standpoints. An article in RD Magazine summarizes a paper published in the scientific journal Nature that says significant amounts of carbon are released to the atmosphere when tundra burns, much more than when an equivalent area of temperate forest or brush land fires. A 2007 tundra fire studied released 2.1 million metric tons of carbon, roughly twice the annual amount emitted by the city of Miami. Follow up:
Follow up:The research by a University of Florida team was led by Michele Mack, an ecologist. From RDMg:
The fire also consumed up to 30% of the insulating layer of organic matter that protects the permafrost beneath the tundra's shrub- and moss-covered landscape.
In a pine forest, fire would burn up leaf litter on the ground, but not the soil beneath. Because the Arctic tundra has a carbon-rich, peaty soil, however, the ground itself is combustible, and when the fire recedes, some of the soil is gone. In a double whammy, the vulnerable permafrost is not only more exposed, but also covered by blackened ground, which absorbs more of the sun's heat and could accelerate thawing.
"When the permafrost warms, microbes will begin to decompose that organic matter and could release even more carbon that’s been stored in the permafrost for hundreds or thousands of years into the atmosphere," Mack says. "If that huge stock of carbon is released, it could increase atmospheric carbon dioxide drastically."
The problem of burning tundra is a very new development, at least for the last 9,000 years or so. A research report in 2008 covered by Science Daily described the nature of the vegetation in the tundra 9,000 to 14,000 years ago to be much more susceptible to fires than has been the case since. In those early years the vegetation was comprised substantially of brushy birch which was extremely flammable. In recent millennia the vegetation has been largely grass, herbs and short brush, which was much less flammable and has been protected by high moisture levels. The soil has been incorporating carbon over the centuries and has become much like a thin layer of peat. When the changing climate has resulted in drier and warmer summer conditions, wild fires have become more common and, when they start, are sustained by burning the soil more than by burning living plant material.