Thawing permafrost soils in the Arctic contribute to the greenhouse effect by releasing methane gas close to the surface and deeply below it, according to a new study.
Rising temperatures cause more microbial methane production near the surface of permafrost, while thawing subsurface opens pathways for old geologic methane to escape, according to the study by scientists from the German Research Centre for Geosciences, the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research and partners in the U.S.
Researchers studied an area in Northern Canada 10,000 square kilometers wide using aircraft to conduct airborne measurements of gas concentrations in 2012 and 2013.
“We found strong emissions solely where the permafrost is discontinuous, meaning parts where the permafrost contains areas that are thawed permanently”, said Katrin Kohnert of GFZ. “We think that the methane comes predominantly from deeper geologic sources and not from recent microbial activity close to the surface.”
Arctic permafrost behaves as a massive cap of frozen material over mineral resources and fossil fuels. Thawing permafrost could lead to rising methane emissions, the researchers said.
The warming climate triggers not only the natural production of biogenic methane, but can also lead to stronger emissions of fossil gas, which contributes significantly to the permafrost-carbon-climate feedback.
“Therefore permafrost areas vulnerable to thawing warrant much more attention,” Kohnert said.
The study was published in the journal Scientific Reports.