Microbial gourmands prefer millennial-aged carbon in arctic waters

Falmouth, Mass. – Global warming continues to thaw permafrost soils that have been frozen in the Arctic for millennia.  As these soils thaw, ancient carbon is released into streams and rivers, where it can either flow to the ocean or be consumed or transformed in the rivers.  A new study, published in Nature Communications and co-authored by Woods Hole Research Center scientist R. Max Holmes, examined the carbon signature in arctic river samples to determine the fate of ancient permafrost carbon once it enters river systems.

Hundreds of water samples were collected from the Kolyma River watershed in northeastern Siberia, Earth’s largest watershed that is completely underlain by permafrost.  The team measured the quantity, age, and source of the organic carbon in the samples, and found that ancient permafrost carbon is the preferred snack for microbes and as such is highly vulnerable to being respired into the atmosphere as CO2, further amplifying global warming.

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Thawing permafrost in Duvannyi Yar, a riverbank on the Kolyma River. Photo by Chris Linder.

“It’s really remarkable that ancient organic matter that had been frozen away for so long in permafrost is so quickly consumed once it enters the river system”, said R. Max Holmes.  According to Paul Mann of Northumbria University, Newcastle, the lead author of this study, “This research will help us to develop more accurate future predictions of climate change. We know that the earth is continuing to warm from our activities, so we must try to understand how additional factors like thawing permafrost may alter the rate and speed of change.

For him, “Although the Arctic seems a distance place, it is important to realize that changes happening there can and will affect all of us.”

The National Science Foundation (NSF) Arctic Natural Science program funded the study.

Link to abstract »


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