CEM - Abstract

Abstract Information :

Recent studies have shown significant rates of net uptake of atmospheric methane (CH4) in Arctic tundra soils. Oxidation of CH4 in these cold, dry soils in the Arctic region can counteract CH4 emissions from wetlands and play a potential important role for the net Arctic CH4 budget and its feedbacks to the global climate system. However, significant knowledge gaps exist on the overall magnitude of the net CH4 sink in these cold, dry systems as the spatial and environmental limits for CH4 oxidation has not been determined. In particular, the extent, magnitude and drivers of CH4 oxidation in mountains and alpine landforms, which occupy large land areas in the Arctic and High Arctic has not yet been investigated leaving a potential vast CH4 sink unquantified with major potential implications for our conceptual view of Arctic CH4 budget in a changing climate.

Here we present results from a newly developed fast deployable emission measurement system using state-of-the-art and highly-mobile cavity ringdowns spectrometers (e.g. Los Gatos Research Ultra Portable Greenhouse Gas Analyzer (UGGA) and Picarro G4301 GasScouter). The aim of our work is to determine the magnitude and spatial extent of net uptake of atmospheric CH4 across a variety of previously unexplored dry tundra and post-glacial landforms in the Arctic, i.e. marginal moraines and other glacial features at the Greenland ice sheet as well as mountain tops and outwash plains. Our results show a persistent net uptake of CH4 uptake in a wide variety of dry, extreme environments which have traditionally not been accounted for in the total CH4 exchange budget of the Arctic, indicating that our understanding of CH4 exchange from the terrestrial parts of certain Arctic landareas could be overestimated.

The study demonstrates how the high mobility and precision of the new generation of greenhouse gas analyzers, like the UGGA and the GasScouter, we can be utilized to expand our understanding of greenhouse gas emissions in areas where in situ measurements so far have been considered unfeasible, e.g. in harsh Arctic landscapes and mountain areas. The results highlight the wide-spread occurrence and importance of net CH4 uptake in tundra soils calling for a revised understanding for the Arctic CH4 exchange budget.