The Global Dynamics of Arctic Ice Caps

Thu, Mar 6, 4:30 pm
243 Gaines Hall MSU
Speaker Name: 
Martin Sharp
University of Alberta
Earth and Atmospheric Sciences

Professor Martin Sharp is visiting Montana State University March 6th. His seminar is at 4.30pm in Gaines Hall 243 in the Earth Sciences seminar series.

Martin is an internationally recognized glaciologist and is currently part of the IPCC Working Group on the Cryosphere. He has recent publications in Science and Nature on his research, see details at


Martin Sharp
Earth and Atmospheric Sciences
University of Alberta

Like the large ice sheets in Antarctica and Greenland, the larger ice caps in the Arctic are dynamically complex. They consist of a mixture of fast-flowing outlet glaciers, many of which
reach the ocean, and slower flowing interior regions that tend to terminate on land in cases where they extend all the way to the ice cap margin. Studies of individual outlet glaciers suggest that
they may contain up to 4 distinct “flow regimes”, that are characterized by differences in ice temperature, flow mechanics, hydrology, bed properties, and surface morphology. Multi-year
measurements of surface velocity made with continuously recording GPS demonstrate that different flow regimes are characterized by distinct patterns of seasonal velocity variability that
can be explained in terms of differences in the extent to which surface meltwater penetrates to the glacier bed, and the processes by which penetration occurs. Depending upon which flow regime occurs in the terminus region of the glacier, outlet glaciers can differ enormously in terms of the sensitivity of their dynamics and geometry to external forcing. In some cases this may
allow large changes in geometry and dynamics to occur in response to forcings that are essentially undetectable while, in other cases, larger forcings may have no obvious effect. This
suggests that efforts to explain long-term changes in the behaviour of some outlet glaciers and in the rate at which they deliver ice to the oceans by “dynamic discharge” in terms of discernable variability in external forcing factors may prove to be fruitless.



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