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Gordon Hamilton, Research Assistant Professor, UMaine Climate Change
Institute:
The study took place in East Greenland, along the coast between latitude
74 north and 66 degrees north. We set sail from northwest iceland, sailing
for 4 days across the Denmark straits and then started our work on one
of the large fjord systems. The purpose of our work was to understand the
flow dynamics of large outlet glaciers that drain the ice sheet. These
outlet glaciers are the main corridors that transport ice from the interior
of the ice sheet to the ocean. We studied 5 glaciers in total and we had
some extremely interesting results. The 3 northernmost glaciers seem to
be in the same flow configuration as they were when they were first studied
by our Danish colleagues back in the 1960's. Then when we moved farther
south, we noticed very quickly that things changed dramatically since the
last satellite images were acquired 2 years ago. The fronts had retreated
about 5 kilometers and after we had a chance to study the velocity over
the course of a few days, we discovered that they had accelerated about
3 times faster than their normal speed.
Leigh Stearns, PhD. Candidate- Earth Sciences:
We were very surprised to see all those changes. We had an idea where
the front of the glacier would be and when we got there it was 3 1/2 miles
farther back. We were sort of floored.
Gordon Hamilton:
These glaciers were already moving fast- about 5 kilometers a year but
one of them has accelerated to about 14 kilometers a year so its about
a 3-fold increase in speed. that translates into about half a football
field of motion per day- so its a lot of ice that's being transported off
the ice sheet faster than it was just a summer or two ago.
Leigh Stearns:
We often think of glaciers moving very slowly and changing very slowly
to climate systems or conditions of the bed but to see these changes happening
in a year or 2 or 3, that's pretty dramatic and it sort of adjusts our
sense of how to model and how to predict and how to make hypotheses if
we have to shorten our time scale.
Gordon Hamilton:
We studied 5 glaciers and we're always sort of nervous about extrapolating
to other places but when we see, especially in the south, 2 glaciers exhibiting
the same kind of behavior, then that gives us a basis to make predictions
for other parts of the Greenland ice sheet. The most likely scenario is
that there has been a regional warming in this part of Greenland and the
generation of more meltwater is allowing the glaciers to slide faster over
their beds. Of course that doesn't tell us anything about what the cause
of the regional warming is but the scientific consensus is that its a human
induced event.
Leigh Stearns:
If it is from warming and this warming trend is continuing to progress
north then its possible that similar events will happen to other glaciers
in Greenland. That has huge implication for sea level rise and the status
and stability of the Greenland ice sheet.
