FROM THE FIELD
Arctic Thaw

The shrinking face of Jacobshavn Isbrae (Glacier)

by |May 19, 2010

Flying over Jacobshavn Isbrae

Flying over Jacobshavn Isbrae

Jacobshavn Isbrae is one of the fastest moving and most productive glaciers in the world. Scientists estimate that close to the snout (front) its movement has accelerated in recent years from 20 to 40 meters a day. At the same time that the front has accelerated the glacier  has been rapidly retreating through ‘calving’ (large sections breaking off ). From the first time I heard we would be flying over this magnificent glacier I have been waiting; this is the high point of the project for me!

As we moved our operation back from Kangerlussuaq to Thule we would finally be flying over the Jacobshavn Isbrae. The science survey plan involved completing a large grid over the most rapidly reducing section of the glacier, an area scientists refer to as the ‘ablation zone’. I don’t think anything I say on this forum will do justice to the magnificence of the third of the ‘Big Three’ glaciers I have talked about in the previous posts (http://blogs.ei.columbia.edu/blog/2010/05/10/greenlands-big-three-glaciers/). ‘Wow’ was what I felt when I finally looked down and saw it from the P3 window.

A portion of the calving front of Jacobshavn

A portion of the calving front of Jacobshavn

The grid we flew was designed to cover the ablation zone, so we kept returning to the calving front from different angles. From every angle of visbility I was equally speechless at its awesome beauty, troubled by how much mass it had lost by the tremendous amount of calving it had undergone, and troubled by the thought of how it may one day disappear. ‘Its scary’ observed NASA’s Michael Studinger who had flown over it a number of times, referring to the speed of its change.

ATM laser instrument used to study the surface of the Jacobshavn glacier

ATM laser instrument used to study the surface of the Jacobshavn glacier

Looking down I could see that the entire fjord was strewn with icebergs, making a pretty picture, but it hurt me to see that they had broken from my favorite glacier, a sign of its declining state. There is a town called Ilulissat near the glacier and my colleagues have shown me pictures of icebergs floating in the sea near this town; they are comparable to the size of the town itself! Although melting on the glacier surface is not the main way this glacier is losing mass, I saw many melt ponds on top which can explain the rapid acceleration of the glacier. The melt water makes it way to the base of the glacier adding lubrication, causing basal sliding.

Chunk of glacier ice floating near Rink Glacier fjord

Chunk of glacier ice floating near Rink Glacier fjord

As we flew further north up the western coast of Greenland we passed over Rink glacier, and although the landscape was breathtakingly beautiful, here again the glacier health was a concern. The topography is rugged and steep with several icefalls and smaller glaciers gracefully draining into the ocean. But the Rink glacier fjord that was frozen up when Tim flew over it in the DC8 almost exactly one month ago, was beginning to open. The icebergs I saw floating in portions of the glacier were so massive I would prefer to call them portions of glacier.  As we flew over the calving front, it looked as though another piece of the glacier was getting ready to separate from the main trunk further reducing Rink’s size.

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