A new study from the University of Bristol in England has shown that the Greenland Ice Sheet emits tons of methane.

How? Apparently it’s all about the critters that live under the ice sheet. According to the study’s lead author, Guillaume Lamarche-Gagnon of the University of Bristol, the researchers “found unequivocal evidence of a widespread subglacial microbial system.”

“Whilst we knew that methane-producing microbes likely were important in subglacial environments, how important and widespread they were was debatable,” Lamarche-Gagnon added. “Now we clearly see that active microorganisms, living under kilometers of ice, are not only surviving, but likely impacting other parts of the Earth system. This subglacial methane is essentially a biomarker for life in these isolated habitats.”

How does the methane get from under the glaciers to the surface of the earth? Through meltwater that runs off from the glacier itself. “A key finding is that much of the methane produced beneath the ice likely escapes the Greenland Ice Sheet in large, fast-flowing rivers before it can be oxidized to CO2, a typical fate for methane gas which normally reduces its greenhouse warming potency,” said lead researcher Professor Jemma Wadham of the University of Bristol.

The researchers used newly developed sensors to measure methane in meltwater runoff in real time. In doing so, they discovered that methane was constantly being emitted from beneath the ice. They calculated that at least six tons of methane was transported to their measuring site. That’s about the same amount of methane released by up to 100 cows.

“The new sensor technologies that we used give us a window into this previously unseen part of the glacial environment,” stated co-researcher Dr. Elizabeth Bagshaw of Cardiff University. “Continuous measuring of meltwater enables us to improve our understanding of how these fascinating systems work and how they impact the rest of the planet.

Most studies on Arctic methane sources focus on permafrost because frozen soils tend to hold lots of organic carbon that could be converted into methane as the climate warms. But this study shows that ice sheet beds, which hold lots of carbon, liquid water, microorganisms, and very little oxygen (the ideal ingredients for methane gas) are also sources of methane released into the atmosphere.

With this new research comes a new focus on Antarctica, which holds the largest ice mass on the planet. “Several orders of magnitude more methane has been hypothesized to be capped beneath the Antarctic Ice Sheet than beneath Arctic ice-masses,” said Lamarche-Gagnon. “Like we did in Greenland, it’s time to put more robust numbers to that theory.”

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