Massive destabilization of an Arctic ice cap

Willis, M. J.; Zheng, Whyjay; Durkin, William J.; Pritchard, M. E.; Ramage, J. M.; Dowdeswell, Julian A.; Benham, Toby; Bassford, R. P.; Stearns, L. A.; Glazovsky, A. F.; Macheret, Yu. Ya.; Porter, Claire

doi:10.1016/j.epsl.2018.08.049

Cited by 56 publications

(67 citation statements)

References 44 publications

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“…In order to estimate the ELA, we identify the snow line location from Landsat 8 late-summer images around the entire ice cap and read the corresponding elevations from the DSMs. Other elevation products used include a digitized cartographic map from 1984 and an ASTER DSM from 2005 as reference elevations before the collapse (Figure 1g; Willis et al, 2018). We also estimate the total ice mass of the collapsed basin using the glacier outline from Randolf Glacier Inventory version-6 (Pfeffer et al, 2014) and the density assumed here.…”

Section: Methodsmentioning

confidence: 99%

“…The annual ice volume change and annual ice mass change above sea level are derived from the elevation change, assuming a fixed ice density of 850 ± 60 kg/m 3 (2 sigma; Huss, 2013;Zheng et al, 2018). We also use bedrock depths from an airborne radar sounding survey in 2007 (Bassford et al, 2006;Willis et al, 2018;Figure 2i) to calculate ice thickness. Other elevation products used include a digitized cartographic map from 1984 and an ASTER DSM from 2005 as reference elevations before the collapse (Figure 1g; Willis et al, 2018).…”

Section: Methodsmentioning

confidence: 99%

“…During 2015-2016 the glacier reached the maximum thinning rate at ∼100 m/yr (Figure 2j; Willis et al, 2018) in the region of the ELA (330-530 m). During 2015-2016 the glacier reached the maximum thinning rate at ∼100 m/yr (Figure 2j; Willis et al, 2018) in the region of the ELA (330-530 m).…”

Section: Elevation Changementioning

confidence: 99%

“…However, recent surges in Svalbard and the Russian Arctic challenge this hypothesis; these Arctic surges have undergone irreversible ice mass loss in a short period, which is likely triggered by different factors (Dunse et al, 2015;Murray et al, 2012; frontal support when one of its marine-terminating glaciers advanced and overran weak marine sediment ; Figure 1). Between 2015 and 2016, the glacier speed reached a maximum number of 26 m/day (9.5 km/yr; Bushueva et al, 2018;Willis et al, 2018) with a negative mass balance of −4.5 Gt/yr (0.9% of the mass of the entire ice cap; Willis et al, 2018). During this time, the glacier terminus advanced ∼10 km from the precollapse terminus position ( Figure 1g) and subsequently formed a mostly grounded piedmont fan Figures 1c-1f).…”

Section: Introductionmentioning

confidence: 97%

“…Glacier dynamic instabilities can be triggered in several different ways, such as by changes in basal conditions (Dunse et al, 2015;McMillan et al, 2014;Murray et al, 2002), frontal ice advance or retreat (Nuth et al, 2019;Willis et al, 2018), or loss of buttress support from either an ice shelf or moraine sediment (Benn et al, 2007;De Angelis & Skvarca, 2003;Goldberg, 2017;Willis et al, 2018). A glacier surge, defined as a sudden and short-lived fast glacier acceleration (Clarke et al, 1986;Dowdeswell et al, 1991;Meier & Post, 1969), is a common expression of glacier instability and has been observed in all major glacierized areas of the world except for Antarctica (Sevestre & Benn, 2015).…”

Section: Introductionmentioning

confidence: 99%

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The Possible Transition From Glacial Surge to Ice Stream on Vavilov Ice Cap

Zheng

Pritchard

Willis

et al. 2019

Geophysical Research Letters

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Surge-type glaciers typically undergo cyclical flow instability due to mass accumulation; however, some recent glacier surges have caused irreversible ice loss in a short period. At Vavilov Ice Cap, Russia, surge-like behavior initiated in 2013 and by spring 2019 the ice cap had lost 9.5 Gt of ice (11% mass of the entire basin). Using time series of surface elevation and glacier velocity derived from satellite optical and synthetic-aperture radar imagery, we identify a shift of flow pattern starting in 2017 when shear margins formed within the grounded marine piedmont fan. Multiple summer speedups correlate with warmer summers during 2015-2019 and suggest that surface melt may access the subglacial environment. Force balance analysis and examination of the Péclet number show that glacier thinning propagated upstream in 2016-2017, and diffusion became a significant dynamic response to thinning perturbations. Our results suggest that the glacier has entered a new ice stream-like regime. Plain Language SummaryA glacier surge is a sudden speedup of glacier flow coinciding with a large advance of the ice front. Some glaciers surge periodically every 10-100 years, and so surge mechanism is thought to be independent of climate change. However, some recent surges have evacuated so much ice that another surge is unlikely to occur in the same place again. A glacier surge at the Vavilov Ice Cap, Russia, is one of these cases. Since 2013, the glacier has drained more than 11% of the ice basin (9.5 Gt) into the ocean. After the initial surge in 2013, the glacier still retains fast flow at around 1.8 km/year, an unusually high and long-lasting speed for a glacier surge. To understand the future of the surge, we use satellite images to calculate surface elevations and ice speeds, and analyze their change over time for the glacier. The results reveal that the glacier now physically behaves more like an "ice stream," a stream of fast-flowing ice within an ice sheet, which can probably flow at high speed for a long time and drain ice efficiently. This is the first documented case of an ice stream-like feature ever being formed.

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Section: Methodsmentioning

confidence: 99%