The thawing permafrost soils in the Arctic regions might contribute to the greenhouse effect in two respects: On the one hand, rising temperatures lead to higher microbial methane production close to the surface. On the other hand, the thawing subsurface opens pathways for old, geologic methane. This is shown in a study in the Mackenzie Delta (Canada), conducted by scientists from the German Research Centre for Geosciences GFZ, the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) and partners in the U.S. The study is published in the journal Scientific Reports.