Global warming may burn down Arctic tundra

March 5th, 2008 - 12:50 pm ICT by admin  

New York, March 5 (IANS) An ecological disaster sparked by global warming - and eventually contributing to it - is waiting to strike the remote Arctic tundra, warns a new study. The high latitude tundra and boreal forest ecosystems comprise a significant 30 percent of the planet’s total soil carbon, much of which is locked in permafrost - or soil that has been at below freezing temperatures for two years or more.

A warming climate could cause the permafrost to melt and release its carbon stores into the atmosphere where it would contribute greatly to the greenhouse effect, the study contends.

Findings of the study have been published online in PloS ONE.

Research on ancient sediment cores indicates that a warming climate could make the world’s Arctic tundra far more susceptible to fires than previously thought.

Montana State University researcher Philip Higuera has co-authored the paper, which summarises a portion of a four-year study funded by the National Science Foundation.

Higuera examined ancient sediments from four lakes in a remote region of Alaska to determine what kind of vegetation existed in the area after the last ice age, 14,000 to 9,000 years ago.

And it was very different from what it is now. Instead of being covered with grasses, herbs, and short shrubs, it was covered with vast expanses of tall birch shrubs.

Charcoal preserved in the sediment cores also showed evidence that those shrub expanses burned - frequently.

“This was a surprise,” Higuera said. “Modern tundra burns so infrequently that we don’t really have a good idea of how often tundra can burn. Best estimates for the most flammable tundra regions are that it burns once every 250-plus years.”

The ancient sediment cores showed the shrub tundra burned as frequently as modern boreal forests in Alaska - every 140 years on average, but with some fires spaced only 30 years apart.

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