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CLIMATE
CHANGE & ENVIRONMENT
Melting of ice sheet can lead to rapid rise in sea
level
Washington: A new research by
a team of scientistshas shown that sea level rise
as a result of ice sheet melt can happen very rapidly,
with a prominent example being the increased Greenland
ice melt and sea level rise. The research came about
because of the fact that scientists still have to
reach a consensus on how much and how quickly melting
of the Greenland Ice Sheet will contribute to sea
level rise. To shed light on this question, scientists
at the University of Wisconsin and Columbia University's
Center for Climate Systems Research analyzed the disappearance
of the Laurentide Ice Sheet, the last ice sheet to
melt completely in the Northern Hemisphere and the
closest example of what can be expected to happen
to the Greenland Ice Sheet in the next century. "We
have never seen an ice sheet retreat significantly
or even disappear before, yet this may happen for
the Greenland Ice Sheet in the coming centuries to
millennia," said Anders Carlson, the study's
lead author and assistant professor of geology and
geophysics at the University of
Wisconsin-Madison. "What we don't know is the
rate of melting of the Greenland Ice Sheet. The geologic
data we compiled on the retreat history of the Laurentide
Ice Sheet, however, gives us a window into how fast
these large blocks
of ice can melt and raise sea level," he added.
Analyzing geologic data and computer models, the team
of researchers used terrestrial and marine records
to reconstruct the demise of the Laurentide Ice Sheet,
a land-based ice mass that covered much of North America,
until its ultimate disappearance at around 6,500 years
ago. The ice sheet, which once covered most of Canada
and the upper reaches of the United States, had two
intervals of rapid melting, the first around 9,000
years ago, and the second 7,500 years ago. The researchers
estimate that around the time of the first melting
phase, the retreating ice sheet led to about approximately
7 meters of sea level rise at about 1.3 cm a year.
The second phase accounts for around 5 meters of sea
level rise at about 1.0 cm a year. These rates are
comparable to evidence for global sea level rise for
this interval derived from coral records. "I
was surprised to see that the model-in agreement with
Anders' data-showed the Laurentide Ice Sheet disappearing
at 2.7 m/year," said Allegra LeGrande, who led
the computer modeling portion of this study and is
a postdoctoral research scientist at the NASA Goddard
Institute for Space Studies and the Center for Climate
Systems Research at Columbia University. "This
finding shows the potential for ice to disappear quickly,
given the right push," she added.
-Sept
1, 2008
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