Today, the largest uncertainty when it comes to the consequences of Arctic warming and wetting, revolves around whether ancient C stored in the form of permafrost will thaw and then be transferred to the atmosphere or the rivers and ocean adding to even more warming and ocean acidification-a positive feedback loop.
By over-wintering in Longyearbyen, Svalbard and working with the University Center on Svalbard (UNIS), I was able to undertake a first-ever study of ancient C emissions into the winter atmosphere in the High Arctic. The study was a collaborative effort with colleagues from the University of Tromso (Dr. Liz Cooper), and from the University of California Irvine (Drs. Claudia Czimczik and Massamo Lupascu) were we used a long-term snow manipulation study and winter-long access to the High Arctic to measure the 14C of CO2 emitted from areas with ambient and deep snow from October to May. The 14C of CO2 allows us to date the carbon diffusing from the soil into the atmosphere and to determine whether the sources of the CO2 were some proportions of modern, permafrost or bedrock shale.
During winter, emissions were significantly older and likely sourced from microorganisms decomposing aged SOM formed during the Holocene (permafrost C) mixed with biotic or abiotic mineralization of the carbonaceous, fossil parent material. Our findings imply that snow cover duration and depth is a key control on soil temperatures and thus control the magnitude of ecosystem respiration in winter. We also discovered that in shallow Arctic soils, mineralization of carbonaceous parent materials can contribute significant proportions of fossil C to winter CO2 emissions. Therefore, permafrost-C inventories informing C emission projections must carefully distinguish between more vulnerable SOM from recently fixed biomass and more recalcitrant ancient sedimentary C sources.
The full article can be found with the next credentials:
Lupascu, M., Czimczik, C. I., Welker, M. C., Ziolkowski, L. A., Cooper, E. J., & Welker, M. (2018). Winter ecosystem respiration and sources of CO2 from the High Arctic tundra of Svalbard: Response to a deeper snow experiment. Journal of Geophysical Research: Biogeosciences, 123. https://doi.org/10.1029/2018JG004396