Svalbard-Polar Night-Permafrost Feedbacks and Deeper Winter Snow

Tue, Oct 16, 2018

According to new research of the UArctic Chair Jeffrey Welker and co-authors, the High Arctic has the most extreme conditions of the Northern Hemisphere, with areas such as Svalbard, having total darkness, “Polar Night” lasting for over 60 days each winter, reaching temperatures as low as -40C/-40F. These extreme winter conditions have limited scientific studies in winter and have thus, minimized our full understanding of the way the Arctic functions during the dominant Arctic season-winter. And, we have even a lower understanding of what the consequences of changes in winter climate will do to the High Arctic landscape as snow becomes, deeper or whether winters turn from snow to a rain dominated season.

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

Svalbard-Polar Night-Permafrost Feedbacks and Deeper Winter Snow

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