Tuesday, February 28, 2012

As Arctic temperatures rise, tundra fires increase

Research.gov: Scientists have found evidence of unprecedented tundra burning on the North Slope of Alaska. Their research indicates that tundra burning increases dramatically when temperatures rise above a mean threshold.

Within the global carbon cycle, what is the fate of the enormous amount of organic carbon stored in tundra ecosystems? Scientists just aren't sure. But results from this study shed new light, indicating that tundra burning is sensitive to climate warming. Increased burning could cause sudden releases of carbon dioxide and accelerate climate warming, while also diminishing subsistence resources for Arctic indigenous people.

In September 2007, the Anaktuvuk River Fire burned more than 1,000 square kilometers of tundra on Alaska's North Slope. This burn area was twice the size of any measured since recordkeeping began in 1950. A team of scientists from multiple universities, led by Feng Sheng Hu at the University of Illinois, sought to answer a simple question: Was this seemingly historic fire an anomaly, or were large fires regular occurrences in the region? They analyzed the distribution of charcoal particles in lake-sediment cores and found no evidence of a fire of similar scale or intensity in the region over the past 5,000 years.

The researchers then developed a model relating the tundra area burned in Alaska each year to the mean temperature and precipitation in the warmest period of the year--June through September. They found a dramatic, nonlinear relationship between climate conditions and tundra fires. That is, once the temperature rises above a mean threshold--or what one may call a tipping point--of 10 degrees Celsius (50 degrees Fahrenheit), tundra burning increases dramatically...

A tundra fire in Northern Alaska, shot by the US National Park Service

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