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: Wiley 2007
• Subjects: Arctic; Holmströmbreen; Svalbard; glacier; Ice; permafrost
• Online Access: http://dx.doi.org/10.1111/j.1502-3885.2007.00014.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1502-3885.2007.00014.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1502-3885.2007.00014.x

An extensive dead‐ice area has developed at the stagnant snout of the Holmströmbreen 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.