A study finds that emissions of the greenhouse gas nitrous oxide from subarctic peatlands increase upon permafrost thaw. Arctic permafrost thaw exposes trapped carbon and nitrogen stocks to decomposition, and Arctic soil thaw could be a source of nitrous oxide, a greenhouse gas with almost 300 times the global warming potential of carbon dioxide. Carolina Voigt and colleagues used 16 subarctic permafrost peatland mesocosms from Finnish Lapland to directly measure nitrous oxide emissions from thawing permafrost during a 33-week experiment. The highest post-thaw emissions occurred in bare peat surfaces, which are commonly found in permafrost peatlands. For these surfaces, permafrost thaw resulted in a five-fold increase in emissions. These emission rates are similar to those found in tropical forest soils, a major natural terrestrial nitrous oxide source. The presence of vegetation cover in the mesocosms lowered thaw-induced nitrous oxide emissions by approximately 90%, and emissions from water-saturated soils were negligible. A vulnerability assessment indicated that areas with high probability of nitrous oxide emissions cover approximately one quarter of the Arctic. According to the authors, the Arctic nitrous oxide budget may depend on future changes in moisture and that the Arctic might become a substantial source of nitrous oxide upon permafrost thaw. - Read at PNAS
Article #17-02902: “Increased nitrous oxide emissions from Arctic peatlands after permafrost thaw,” by Carolina Voigt et al.