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Glacial Melt
09/24/2002
Listen in RealAudio 
Glacier scientists in Alaska monitor how much the giant ice sheets melt over time. And
they've found that in recent years, the rate has increased substantially. Amy Mayer
reports.
A glaciology team from the University of Alaska Geophysical Institute measured 67
glaciers in the early 1990s. Graduate student Anthony Arendt describes what they
found when they re-sampled almost 30 at the end of the decade.
AA: these glaciers were thinning at a rate that was about double what we had
measured in the earlier period. So there seems to be some kind of speed up in these
glaciers and we're not sure what's causing that.
Arendt says they ARE sure that increased glacier melt is related to climate change.
AA: Climate controls the rate of glacier thinning. And so the fact that glacier thinning
rates have doubled in the past five or seven years does indicate that the climate in
Alaska has changed somehow. It could be in the form of warmer summer
temperatures, or maybe less snowfall in the wintertime to nourish the glaciers.
The team's measurements come from a laser-altimetry system that involves flying over
a glacier with special equipment. This set-up has also been used to measure the
Greenland ice sheet. The modern data is compared to measurements derived from
aerial photographs taken in the 1950s.
AA: For our early period measurements, the mid-1950s to the mid 1990s we estimate
that Alaska glaciers contribute about the same amount of melt water to the ocean as
the Greenland ice sheet and almost double that for this recent period.
Arendt says that's significant because all Alaska glaciers equal only about five percent
of the area of Greenland's ice sheet. The next step for this glaciology team, Arendt
says, is to search for melting patterns.
Our Climate Change series is supported by The New England Science Center
Collaborative, and the Roy A. Hunt Foundation.
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More Information
http://www.nature.com/nsu/020715/020715-12.html
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