Surge development in the western sector of the Vavilov Ice Cap, Severnaya Zemlya, 1963–2017

Abstract

The glaciers and ice caps in the Arctic are experiencing noticeable changes which are manifested, in particular, in the intensification of their dynamic instability. In this paper we present data on a largescale surge in the Western basin of the Vavilov ice dome on the archipelago Severnaya Zemlya, derived from satellite images and supplemented by airborne RES-2014 and available publications. Analysis of 28 space images of 1963–2017 demonstrated that the surge developed over the whole period. In the fi st decade (1963–1973), the advance was very slow – from 2–5 to 12 m/year. Since the 1980-ies, the ice movement began to accelerate from tens to a hundred of meters per a year in the 2000-ies. The sudden change happened in the year 2012 when the surge front began to move already at speeds of about 0.5 km/year. In 2015, the volume of advanced part reached almost 4 km3. Maximal speed 9.2 km/year was recorded in 2016. From 1963 to 2017, the edge of the glacier advanced by 11.7 km, and its area increased by 134.1 km2 (by 47% relative to the basin area of 1963), that caused spreading of crevasse zone up the glacier. Surface speeds reached a maximum of 25.4 m/day in 2016 and decreased to 7.6 m/day in 2017. The authors suggest that the initial activation of the southern and western edges of the ice dome could be a reaction to the climate signal, possibly occurred several centuries ago. The ice crevassing and cryo-hydrological warming of ice, enhanced by positive feedback, resulted in instability of the glacier and the displacement of the edge of the ice belt containing moraine and frozen to the bed, which transformed into a catastrophic movement. The surge was facilitated by change of bedrock conditions as the ice lobe progressed offshore from permafrost coastal zone to the area of loose marine bottom sediments with low shear strength. The surge seems to be also stimulated by anomalously warm summer of 2012.

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

“…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).…”

“…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). 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).…”

“…Unlike many other surge-type glaciers, there are no historical records or morainal evidence of a glacier surge at Vavilov (Bushueva et al, 2018;Dowdeswell & Williams, 1997;Willis et al, 2018). The high rate of ice loss at Vavilov makes recovery to presurge conditions unlikely considering the polar desert climate (Moholdt et al, 2012;Willis et al, 2018) and the elevation loss that has moved 14% of the area of the ice cap to below the equilibrium line altitude (ELA).…”