December 6, 2010
Forest Fires Add To Growing Global Warming Problem
According to a study released on Sunday, global warming is driving forest fires in northern latitudes to burn more frequently and fiercely.
The study found that increased intensity of fires in Alaska over the last decade has changed the region from a sink to a source of carbon dioxide, which is the greenhouse gas most responsible for global warming.
Boreal forests in the northern hemisphere may now soak up less of the heat-trapping gas than they give off now.
The majority of the CO2 comes from what is on the ground and not from the burning trees.
"Most of what fuels a boreal fire is plant litter, moss and organic matter in surface soils," Merritt Turetsky, a professor at the University of Guelph in Ontario, Canada and lead author of the study, wrote in a perss release.
He said that the findings were something to worry about because about half of the world's soil carbon is trapped in northern permafrost and peatlands.
"This is carbon that has accumulated in ecosystems a little bit at a time for thousands of years, but is being released very rapidly."
The study focused on Alaska's 45 million acres of forest, but it could be applied to wilderness in Siberia, Canada and northern Europe as well.
Wildfires have taken over 2.5 million acres in Russia earlier this year, destroying whole villages and leaving over 50 people dead.
The study said that the shift of subarctic forests and peatlands from a CO2-absorbing sponge to a net source of the gas means that these regions could help trigger accelerated global warming.
"Essentially, it represents a runaway climate change scenario in which warming is leading to larger and more intense fires, releasing more greenhouse gases and resulting in more warming," Turetsky told the AFP new agency.
The same vicious-circle effect is true of the shrinking Arctic ice cap, which has likewise become both symptom and cause of climate change
More of the Sun's radioactive force is absorbed by dark-blue ocean water rather than bounced back into space by reflective ice and snow as ice cover recedes decade-by-decade.
The Arctic and subarctic regions have been hit particularly hard by global warming, with temperatures rising two to three times faster than the global average.
Turetsky and colleagues examined nearly 200 forest and peatland sites in Alaska shortly after blazes were extinguished to measure how much biomass had burnt.
They found that the amount of earth that has been set on fire has doubled in interior Alaska over the last 10 years, mostly because of increased burning late in the fire season.
"We have demonstrated for the first time that increases in burned area are clearly linked to increases in fire severity," co-author Eric Kasische, a professor at the University of Maryland, told AFP.
"This not only impacts carbon storage, but also will accelerate permafrost loss and changes in forest cover."
Tens of billions of tons of methane gas, which is another greenhouse gas, are also trapped inside permafrost.
The study comes out as leaders from about 200 countries gather in Cancun, Mexico in an attempt to hammer out an agreement on how to keep down emissions.
The U.N. forum could announce measures to slow tropical deforestation, which releases CO2 and also shrinks the biomass that soaks it up.
According to recent calculations, the destruction of equatorial forests in Latin America, Asia and Africa accounts for 12 to 15 percent of the carbon pollution released into the atmosphere each year.
However, boreal forests have received little attention during the talks.
Image Caption: This is an image of wildfires in the Alaskan Interior. A new study reveals that climate change is causing these fires to burn more fiercely over the last decade which has resulted in an increase in greenhouse gases being pumped into the atmosphere. Credit: Roger Ottmar, US Forest Service
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