199 research outputs found
Biocryomorphology:Integrating Microbial Processes with Ice Surface Hydrology, Topography, and Roughness
Published version. Also available at http://dx.doi.org/10.3389/feart.2015.00078</a
Structural glaciology of Isunguata Sermia, West Greenland
We present a 1:42,000 scale map of Isunguata Sermia, a land-terminating outlet glacier draining the western-sector of the Greenland Ice Sheet. Structure-from-Motion software applied to âź3,600 aerial images collected by a fixed-wing unmanned aerial vehicle in July 2015 allowed us to produce a high resolution (0.3â
m ground sampling distance (GSD)) orthomosaic and digital elevation model (DEM; 1.5â
m GSD).These products were used to map and describe the structural, geomorphological and hydrological features of the lower 16â
km terminus of Isunguata Sermia and include many thousands of crevasses, crevasse traces and supraglacial channels. Additionally, several geomorphological features and pro-glacial hydrological features were identified, including debris-covered ice, lateral moraines and ice-marginal lakes. The map has potential for informing and reconstructing the long-term dynamic history of the glacier, including its response to variable environmental forcing
Ice-sheet-driven methane storage and release in the Arctic
It is established that late-twentieth and twenty-ďŹrst century ocean warming has forced
dissociation of gas hydrates with concomitant seabed methane release. However, recent dating of
methane expulsion sites suggests that gas release has been ongoing over many millennia. Here we
synthesize observations of B1,900 ďŹuid escape featuresâpockmarks and active gas ďŹaresâacross a
previously glaciated Arctic margin with ice-sheet thermomechanical and gas hydrate stability zone
modelling. Our results indicate that even under conservative estimates of ice thickness with
temperate subglacial conditions, a 500-m thick gas hydrate stability zoneâwhich could serve as a
methane sinkâexisted beneath the ice sheet. Moreover, we reveal that in water depths 150â520 m
methane release also per- sisted through a 20-km-wide window between the subsea and subglacial gas
hydrate stability zone. This window expanded in response to post-glacial climate warming and
deglaciation
thereby opening the Arctic shelf for methane release
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