Origins ANTARCTICA, Scientific Journeys from McMurdo to the Pole
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  Andrew Fountain  
Glaciologist Andrew Fountain studies the movements, size, and melting of Dry Valleys glaciers.

How to Melt a Glacier p. 2

by Mary Miller

This year turns out to be a banner year for water production from the glaciers. Since a spell of warm weather that started on Christmas Day, the Canada Glacier has been melting at a rate that Andrew has never seen. As we walked along the face of the glacier, we counted a half dozen ephemeral waterfalls rushing off Canada Glacier and feeding the raging streams along its base. It was a rare sight and sound in Antarctica that I felt privileged to witness.

Andrew is quick to point out that this year’s weather isn’t necessarily a result of global warming; in fact the trend in the Dry Valleys has been for cooler-than-normal temperatures. This is just another blip in a climate system that is naturally variable. But it still provides a unique opportunity to study what will happen to the lake biology when all this water and fresh nutrients from the soil flow into the ecosystem.

This year’s melting is a surprise, but it’s not the only one I learned about on my walk. One of the things that Andrew has been studying is the movement of the glaciers in Antarctica compared with other warmer places on the globe. In much of the temperate world, glaciers have generally been retreating, presumably under the influence of warmer temperatures. But here in the Dry Valleys, the glaciers are advancing. Why should polar glaciers be different? Andrew and a colleague have been working on this puzzle, and some preliminary climate modeling may provide an answer.

Polar glaciers are different from temperate glaciers because the colder temperatures here freeze the base of the glaciers to their rock base. Under the force of gravity, the only way for these glaciers to move is to flow from their tops and sides. The cold temperatures also stiffen the glacier, making the ice stick together rather than squeeze out like toothpaste from a tube. But Andrew’s computer model shows that when you increase the temperature of ice from -19 degrees Centigrade to -17 degrees, the ice loses some of its stiffness and flows more easily. So, these glaciers may be responding to a gradual increase in temperature, but in an opposite way than scientists would expect.

But such movements are too slow for us to measure during our short stay in the Dry Valleys. We do occasionally hear creaking and groaning from the Canada Glacier and I’m aware that this wall of ice is a dynamic and vital entity in this very special place in Antarctica.

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