Dr Peter Douglas - Mud, moss, and microbial metabolisms: Deciphering the processes controlling greenhouse gas fluxes in complex permafrost peatland landscapes

There is concern that high latitude warming and permafrost thaw will greatly enhance natural greenhouse gas emissions, especially of methane, from subarctic and Arctic permafrost landscapes, creating a feedback to global climate change. However, the processes driving this feedback are not well understood, and there are important knowledge gaps regarding the role of old permafrost carbon, the relative importance of lake vs soil emissions, and how much methane oxidation limits emissions.  I will present research using 14C and 13C isotope geochemistry, as well as high-resolution flux chamber measurements, to better understand these processes at sites in the subarctic (Nunavik) and High Arctic (Nunavut). Key findings include that: 1) mobilized old permafrost carbon is relatively inefficient at driving methane emissions; 2) riparian areas surrounding ponds could be more important for methane emissions than ponds themselves; and 3) aerobic methane oxidation is an especially critical process controlling emissions in the High Arctic.