Microbes in arctic soil could worsen global warming

Study: Permafrost thaw accelerates release of carbon from soil into the atmosphere


An experimental warming plot.

A new study warns of increased greenhouse gas emissions from permafrost thaw because of rapid changes in the microbes buried beneath the arctic soil, creating another challenge to curbing global warming.

Scientists have long known that permafrost – perennially frozen ground that covers a quarter of the land in the Northern Hemisphere, primarily in the Arctic – contains enormous amounts of carbon. As the Arctic warms, the thawing permafrost releases two major greenhouse gases – carbon dioxide and methane – into the atmosphere.

Now a new study finds that as permafrost thaws, rapid changes in the way soil microbes function will increase emissions of carbon dioxide and methane into the Earth’s atmosphere. The findings appear in an article published in the Feb. 22 edition of Nature Climate Change.

The conclusions are based on an ecosystem warming experiment that researchers began in Alaska in 2008. To conduct the experiment, scientists warmed plots of frozen tundra to thaw the permafrost. After 18 months of warming, researchers found numerous changes in the soil microbes, including significant increases in the genes that control the decomposition of soil carbon.

“This study highlights the critical role that microbes play in mediating carbon losses from Arctic soils,” said Susan Natali, an associate scientist at Woods Hole Research Center and co-author of the Nature Climate Change paper. “The rapid response of the microbial community to warming suggests that the large store of soil carbon currently contained in permafrost will be highly susceptible to decomposition once it is thawed.”

Previous studies suggest that permafrost could decline by 30 to 70 percent by the end of the 21st Century. Thawing permafrost, coupled with the rapid changes in the microbial community, could lead to more carbon emissions into the atmosphere, further accelerating the warming of the Earth.

“Altogether, our results demonstrate the vulnerability of active-layer soil carbon in this permafrost-based tundra ecosystem to climate warming and the importance of microbial communities in mediating such vulnerability,” the scientists said.

Link to abstract » Tundra soil carbon is vulnerable to rapid microbial decomposition under climate warming

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