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Northeast Greenland Soils – Net Regional Methane Sink in the High Arctic

According to Juncher Jørgensen et al. tundra soils of the Arctic serve as potentially important sinks of atmospheric methane, a powerful greenhouse gas, though they are not well understood (Whalen & Reeburgh, 1990; Bácena, Finster & Yde, 2011; Curry, 2009; Emmerton et al., 2014; Flessa et al., 2008). A net increase in the consumption of methane in soils in the high northern latitudes as a consequence of warming in the past few decades is projected by numerical simulations (Curry, 2009; Zhuang et al., 2013). Advances have been made in the quantifying of hotspots of methane emissions in wetlands of the Arctic (Mastepanov et al., 2008; Ström, Tagesson, Mastepanov & Christensen, 2012; Van Huissteden et al., 2011; Whalen, 2005; Torn & Chapin, 1993; O’Connor et al., 2010; Olefeldt, Turetsky, Crill & McGuire, 2013), though the drivers, magnitude, timing and location of methane consumption rates are not clear for the high Arctic. In this paper Juncher Jørgensen et al. present measurements of methane consumption rates in various vegetation types within the Zackenberg Valley in northeast Greenland over a full growing season. Methane uptake in all landforms that are not water-saturated are shown by field measurements to be seasonal averages of -8.3 ± 3.7 μmol CH₄ m^-2h^-1 in dry tundra and -3.1 ± 1.6 μmol CH₄ m^-2h^-1 in moist tundra. Methane uptake increased with temperature, the fluxes being sensitive to temperature. They extrapolated their measurements and published measurements from wetlands with the help of remote sensing classification of land-cover by the use of 9 Landsat scenes. They concluded that for northeast Greenland the ice-free area acts as a net sink of atmospheric methane, suggesting that this sink will probably be enhanced by warmer conditions in the future.

Sources & Further reading

Juncher Jorgensen, C., K. M. Lund Johansen, A. Westergaard-Nielsen and B. Elberling (2015). "Net regional methane sink in High Arctic soils of northeast Greenland." Nature Geosci 8(1): 20-23.