Scientists Say
Greenland Glaciers Retreating
December 08, 2005 — By Alicia Chang, Associated Press
SAN FRANCISCO — Two of Greenland's
largest glaciers are retreating at an alarming pace, most likely because
of climate warming, scientists said Wednesday.
But researchers at the annual meeting of the American Geophysical Union
also presented studies of the retreat of Alaska's Columbia Glacier that
suggest more complexity in the processes of glacial melt.
One of the Greenland glaciers, Kangerdlugssuaq, is currently moving at
about nine miles a year compared to three miles a year in 2001, said
Gordon Hamilton of the University of Maine's Climate Change Institute.
The other glacier, Helheim, is speeding at about seven miles a year --
up from four miles a year during the same period.
"It's quite a staggering rate of increase," Hamilton said during the AGU
meeting.
Glaciers worldwide play a major role in discharging flowing water into
oceans.
Sea levels have swelled globally an estimated 4 inches to 8 inches over
the past century due to melting glaciers and polar ice -- enough to
cause some low-lying places to be awash at high tide or during severe
storms.
Melting of Greenland ice and calving of icebergs from glaciers is
responsible for about 7 percent of the annual rise in global sea level.
Global warming is frequently blamed for retreating glaciers around the
world. The rapid retreat of Greenland glaciers suggest that climate
change is a factor, Hamilton said.
Meanwhile, one of the fastest melting glaciers in North America has
reached the halfway point of disintegration and will continue retreat
for another two decades.
Alaska's Columbia Glacier -- about the size of Los Angeles -- has shrunk
nine miles since the 1980s. It is expected to lose an additional nine
miles in the next 15 to 20 years before the bed of the glacier rises
above sea level.
The glacier, which moves about 80 feet a day, currently releases about 2
cubic miles of ice every year into the Prince William Sound on the south
coast of Alaska.
Understanding what happens during Alaskan glacier retreat could help
explain the phenomenon in Greenland, said Tad Pfeffer, associate
director of the University of Colorado's Institute of Arctic and Alpine.
Pfeffer said climate change warming trends do not directly explain the
shrinking Columbia Glacier and other tidewater glaciers. Instead,
scientists think the retreat is triggered by a slow warming trend that
began five centuries ago.
Significant thinning of the Columbia Glacier is thought to be caused by
huge chunks of iceberg that break off into the sound as a result of
seawater pressure rather than climate change, Pfeffer said.
The glacier, which is up to 3,000 feet thick, has thinned up to 1,300
feet in some places over the last two decades.
Since the 1970s, scientists have monitored the Columbia Glacier with
satellites, lasers and aerial photography and found that the increase of
its so-called calving rate might be dangerous to shipping lanes in the
sound.
Source: Associated Press
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