Andrew Fountain studies the movements, size, and melting
of Dry Valleys glaciers.
to Melt a Glacier p. 2
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.
is quick to point out that this years weather isnt
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.
years melting is a surprise, but its 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.
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 Andrews 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
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 Im aware that
this wall of ice is a dynamic and vital entity in this very
special place in Antarctica.