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New surprising results about the research on glaciers

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10.02.2005

In order to understand the dynamics of glaciers and ice sheets as well as their interactions with climate, we need fundamental detailed knowledge about the way in which glaciers and ice sheets move. The way water is routed through glaciers is highly significant for their movement since the water pressure at the base of the glacier directly influences its speed. The water pressure acts as a hydraulic jack and pushes that glacier forwards during high water pressure events. This may increase the velocity of the ice with a factor of two or even more.

Therefore, to understand how the speed of a glacier varies both in the long and the short term, it is important to have firm understanding of how water from rain and melting on the glacier’s surface reaches the glacier bed. Stockholm University runs a research station in Tarfala valley in the Kebnekaise mountains of northern Sweden.

Here on the 3 km2 glacier Storglaciären, a joint American-Swedish research team has investigated how water is transported within the glacier to better understand old established theories on water flow in glaciers. By drilling 48 vertical holes totaling 3.9 km into the glacier, mapping these with submersible video cameras and by imaging traces of cracks in the glacier by ground-penetrating radar surveys on the glacier surface, the team has established a detailed picture of how water circulates through the glacier.

The results are surprising since the old expectations that water should move in tubular conduits and that crevasses can not occur at great depths in the glacier are proven wrong. The new results show that the glacier is full of open cracks even at great depth and that these are interconnected to form an intricate system for water transport through Storglaciären which has an average thickness of 93 m with a maximum value of 250 m. The tubular conduits which have been predicted in earlier theories seem only to form in special cases. These new results will be of importance for our future knowledge on how dynamic processes act, not only in small glaciers but also for larger ice sheets such as the Greenland Ice Sheet.

Agneta Paulsson | Source: alphagalileo
Further information: www.eks.su.se

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