Abstract
Abstract. The climate sensitivity of Abrahamsenbreen, a 20 km long surge-type glacier in northern Spitsbergen, is studied with a simple glacier model. A scheme to describe the surges is included, which makes it possible to account for the effect of surges on the total mass budget of the glacier. A climate reconstruction back to AD 1300, based on ice-core data from Lomonosovfonna and climate records from Longyearbyen, is used to drive the model. The model is calibrated by requesting that it produce the correct Little Ice Age maximum glacier length and simulate the observed magnitude of the 1978 surge. Abrahamsenbreen is strongly out of balance with the current climate. If climatic conditions remain as they were for the period 1989–2010, the glacier will ultimately shrink to a length of about 4 km (but this will take hundreds of years). For a climate change scenario involving a 2 m year−1 rise of the equilibrium line from now onwards, we predict that in the year 2100 Abrahamsenbreen will be about 12 km long. The main effect of a surge is to lower the mean surface elevation and thereby to increase the ablation area, causing a negative perturbation of the mass budget. We found that the occurrence of surges leads to a faster retreat of the glacier in a warming climate. Because of the very small bed slope, Abrahamsenbreen is sensitive to small perturbations in the equilibrium-line altitude. If the equilibrium line were lowered by only 160 m, the glacier would steadily grow into Woodfjorddalen until, after 2000 years, it would reach Woodfjord and calving would slow down the advance. The bed topography of Abrahamsenbreen is not known and was therefore inferred from the slope and length of the glacier. The value of the plasticity parameter needed to do this was varied by +20 and −20%. After recalibration the same climate change experiments were performed, showing that a thinner glacier (higher bedrock in this case) in a warming climate retreats somewhat faster.
Highlights
Abrahamsenbreen is a valley glacier in the north-western part of Svalbard (79.10◦ N, 14.25◦ E), originating at the ice field Holtedahlfonna
The glacier snout terminates on land and is only a few tens of m a.s.l
We considered using a linear bed profile, but this generates problems for glacier stands that are significantly larger than today
Summary
Abrahamsenbreen is a valley glacier in the north-western part of Svalbard (79.10◦ N, 14.25◦ E), originating at the ice field Holtedahlfonna (for more topographic information, see the interactive map: http://www.npolar.no/en/services/maps/). We note that with a significantly different (smaller) value, it is impossible to explain the glacier advance during the surge in terms of mass conservation (which implies a direct relation between change in glacier length and change in mean ice thickness). The value main glacier is modelled as a flow band with a constant width of h cannot be taken directly as a measure of the change of 2000 m It has its own surface mass budget, which is defin mean ice thickness Hm, because the mean bed elevation initely negative because it is almost entirely in the ablation is different before and after the surge The calculation of a simBtot is described
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
