Microbial communities in thawing permafrost contribute a significant amount to atmospheric methane, a greenhouse gas many times more potent than carbon dioxide. A new paper published in Nature on 23 October describes how a newly discovered microbe—Methanoflorens stordalenmirensis—adds another layer to the complicated relationship between the world’s permafrost fields and greenhouse gas (GHG) emissions.

Lead author Carmody McCalley, postdoctoral research associate at the University of New Hampshire, explained that the question has always been whether these microbes matter for models of GHG emissions to the overall role of thawing wetlands in climate change.

After Methanoflorens was discovered in northern Sweden, McCalley and her colleagues found that microbes trapped in permafrost do have a significant role.

Scientists must think about which microbes are “making the methane [and] what does that say about the isotopic signature of the methane in the atmosphere,” McCalley told Eos.

Researchers use the isotopic signature of methane to figure out its source. Methane produced by these microbial communities tends to have a lighter isotopic signature than that produced by other means, such as fossil fuel burning. What McCalley and her team found was that models have been overestimating the amount of methane originating from thawing permafrost and underestimating the methane coming from burning of fossil fuels.

“Now when people are looking at where the methane is coming from, it’s such an important contributor to global warming and climate change, the ways that the source of that methane is calculated might change as a result of these findings,” said John Leigh, professor of microbiology at the University of Washington, who was not involved in the study.

“If you don’t take [microbes] into consideration in reconstructing where the methane came from, you can get the wrong answer,” said McCalley, “and you end up assuming that more methane came from thawing permafrost than actually did.”

—JoAnna Wendel, Staff Writer

© 2014. American Geophysical Union. All rights reserved.

© 2014. American Geophysical Union. All rights reserved.