Quantification of dead-ice melting in ice-cored moraines at the high-Arctic glacier Holmströmbreen, Svalbard

• Published in: Boreas
• Main Authors: Schomacker, Anders, Kjær, Kurt H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: John Wiley & Sons Inc. 2008
• Subjects: Geology; Arctic; Holmströmbreen; Svalbard; glacier; Ice; permafrost
• Online Access: https://lup.lub.lu.se/record/634300; https://doi.org/10.1111/j.1502-3885.2007.00014.x

Abstract in UndeterminedAn extensive dead-ice area has developed at the stagnant snout of the Holmstrombreen glacier, Svalbard, following its last advance during the Little Ice Age (LIA). The most common landform is ice-cored slopes hosting sediment gravity flows. Dead-ice melting is described and quantified through field studies and analyses of high-resolution, multi-temporal aerial photographs and QuickBird 2 satellite imagery. Field measurements of backwasting of ice-cored slopes indicate melting rates of 9.2 cm/day. Downwasting rates reveal a dead-ice surface lowering of 0.9 m/yr from 1984 to 2004. The volume of melted dead-ice in the marginal zone since the LIA is estimated at 2.72 km(3). Most prominently, dead-ice melting causes the growth of an ice-walled lake with an area increasing near-exponentially over the last 40 years. Despite the high-Arctic setting, dead-ice melting progresses with similar rates as in humid sub-polar climates, stressing that melt rates are governed by processes and topography rather than climate. We suggest that the permafrost and lack of glacier karst prevent meltwater percolation, thus maintaining a liquefied debris-cover where new dead-ice is continuously exposed to melting. As long as backwasting and mass movement processes prevent build-up of an insulating debris-cover, the de-icing continues despite the continuous permafrost.