Hansbreen is a tidewater glacier in the northern archipelago of Svalbard, it is around 16 km in length and 2.5 km wide where it calves icebergs into the fjord. In recent years, Hansbreen has been retreating – in other words, its terminus has been losing icebergs faster than the movement of the glacier delivers new ice. This is a pattern that has been repeated in tidewater glaciers across many near-polar glacier systems (for example; Alaska, the Antarctic Peninsula and Greenland).

The Polish science facility, Hornsund, is close to the terminus of Hansbreen and is ideally situated to allow study of the processes of iceberg calving that have led to the recent retreat. Ice2sea researchers working at Hornsund have gathered data about the seasonal variations in the flow of Hansbreen, its present and former geometry, and recent rates of retreat.  These data have been used collaboratively by a group at the Universidad Politécnica de Madrid to drive and test a model of the retreat of the glacier since 1938. The processes governing the production of icebergs were based on a particular hypothesis of the interaction of crevasses in the glacier surface and melt-water produced on the surface of the glacier water which fills them. The model is a significant break-through in that it reproduces rather well the broad-scale pattern of retreat. The study gives confidence that a “calving law” based on this process can be developed for use in the large-scale models required within the predictive parts of ice2sea. The data from Hansbreen are unparalleled in their detail and length, and it is hoped that this will become a benchmark against which the improvements and refinement of calving laws will be measured, and form a lasting legacy of the ice2sea programme.

Publication: Otero, J., F. J. Navarro, J. J. Lapazaran, M. Grabiec, D. Puczko, C. Molina, and A. Vieli (2011), Modelling the seasonal and long-term variations of the calving front position of Hansbreen, Journal of Glaciology.