Faculty Research - Jennifer Burnham

Quantification and Spatial Assessment of High Arctic Organic Carbon Storage in Northwest Greenland

Research Summary
As anthropogenically-emitted greenhouse gases continue to warm the global climate of the 21st century, one terrestrial feedback will be the release or storage of carbon in vegetation and soils. To evaluate the potential release of greenhouse gases (e.g. carbon dioxide and methane) from terrestrial systems, it is imperative to have accurate estimates of the quantity and quality of soil organic carbon (SOC). Because of its generally labile nature, SOC may be quickly released as CO2 and CH4 in the short term under conditions of forecasted global climate change.

The Arctic is one of the most climatically sensitive terrestrial ecosystems in the world, and due its short growing season, seasonal sea ice and snow cover, and the presence of near-surface permafrost, it is expected to have one of the strongest responses to global climate change. The amount of carbon stored in arctic and boreal soils is equivalent to over half of the carbon currently in the atmosphere, making the Arctic a significant carbon store. With the Arctic already showing dramatic signs of, it is imperative that we understand the impact of these changes on the storage of Arctic SOC and the repercussions of these changes on global climate.

Field research for my dissertation was conducted in Pituffik (Thule), Greenland on the northwest coast of Greenland (76°N, 68°W, UTM Zone 19N) near Thule Air Base (United States Air Force installation). The region is an 800 km2 dry, sparsely vegetated, ice-free peninsula bounded to the west by the Store Landgletscher (a segment of the Greenland Ice Sheet) and Baffin Bay to the south and east. It is approximately 1118 km north of the Arctic Circle and 1529 km south of the geographic North Pole.

The primary objectives of this research were to assess the quantity and state of subsurface organic carbon in the High Arctic soils of northwest Greenland and to investigate correlations of soil organic carbon (SOC) with surface characteristics for the purposes of predicting carbon stores over larger regions.

One key finding of this research is that previous studies of SOC in the High Arctic appear to have been substantially underestimated, particularly for the most sparsely vegetated landscapes primarily due to unaccounted SOC stored at depth. Compared to the most cited study of High Arctic SOC, an estimated 127 times more SOC is stored in polar desert regions and nearly 8 times more in polar semidesert regions [Bliss and Matveyeva, 1992].  Based on the field observations and mapping of disturbed soil horizons, it appears that most of the unaccounted SOC is brought to depth primarily by cryoturbation. Although the polar desert is most underestimated region of the High Arctic, the largest portion of the High Arctic SOC pool is located in the polar semidesert regions. The amounts of SOC below 25 cm vary with vegetation community (and corresponding NDVI class) with 57% of total pit SOC content stored below 25 cm in sparsely vegetated polar desert landscapes compared to 31% and 16% in more densely vegetated polar semideserts and mires, respectively.