New knowledge about surging glaciers
Top image: Camera monitoring the tidewater glacier Kronebreen in Svalbard. Photo: Monica Sund/UNIS.
New research by PhD candidate Monica Sund show that the dynamics of both surge- and tidewater glaciers must be taken into consideration when assessing the glaciers’ response to climate change. Sund will defend her PhD on 15 December at the University of Oslo.
13 December 2011
Press release from UNIS and the University of Oslo
Fieldwork and analysis of satellite- and aerial photos have been used to study the dynamics of surge- and tidewater glaciers in Svalbard. Monica Sund’s study show that care should therefore be taken when evaluating the mass balance of Svalbard glaciers and surge and tidewater dynamics needs to be addressed in future climate models.
Largest surge in Svalbard since 1936
In her PhD work, Sund studied the biggest surge recorded in Svalbard since 1936 before the surge fully developed, and thus the surge could be monitored before its final stage. In the last three years the Nathorstbreen has surged more than 11 kilometers into the sea and has increased its surface area with more than 60 km2 about 16 per cent.
More than 50 new glaciers were identified as surge-type glaciers. Large internal mass displacements, not visible as surface crevassing, were also identified, which is important in the evaluation of glaciers’ response to climate change. Sund has identified common factors in the surge dynamics of different types of glaciers and proposed a common surge model.
Many of the Svalbard glaciers are surge- and tidewater glaciers. Their special dynamics makes changes in the glacier fronts unsuitable as climate indicators.
On Kronebreen in Kongsfjorden, Spitsbergen, daily velocities close to the calving front were directly related to temperature increase in spring, while this correlation was reduced later in season, possibly due to a more developed drainage system. The retreat of the terminus through several decades was attributed to a widening of the front as a result of interaction with quiescent phase dynamics, combined with the sea bed topography.
Surge dynamics, especially in combination with tidewater glaciers, has a potential to accentuate mass loss in a warmer climate. Studies of glacier volume changes in Svalbard must be combined with information about the dynamics in order to be used as an indicator of climate change.
Surge-type glaciers alternate between short, active surge phases (10 years) with up to a 100 times higher velocities than normal and longer, quiescent phases (30-500 years) with very low velocities. In the quiescent phase, the glacier front retreats as a normal part of the surge cycle. Glacier surges is a phenomenon which is not caused by climate change, but caused by internal factors in the glacier and are common in Svalbard.
Monica Sund will defend her dissertation entitled “On the dynamics of surge-type and tidewater glaciers in Svalbard” at the University of Oslo on 15 December 2011. The candidate will give a trial lecture entitled “Models of glacier sliding” on the same day.
Usually UNIS PhD candidates will defend their dissertation in Longyearbyen, but in this case it was not possible due to logistical reasons.
About the candidate
Monica Sund was born in 1971 in Oslo, Norway. She has a Cand.scient (MSc) degree in glaciology from University of Oslo and UNIS.
Sund worked, among other things, several years as a hydrologist before starting her PhD at UNIS and University of Oslo in 2007.