NSF PR 00-12 - March 22, 2000
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Massive Iceberg Peels Off from Antarctic Ice Shelf
A large iceberg was "born" early this week from the
Ross Ice Shelf in Antarctica near Roosevelt Island.
Scientists say the massive iceberg could drift to
sea within the next few days.
The iceberg has begun peeling away from the main ice
sheet only 200 miles east of the National Science
Foundation (NSF)'s McMurdo Station as measured from
the berg's western edge. Among the largest ever observed,
the iceberg is approximately 170 miles long x 25 miles
wide. Its 4,250 square-mile area is nearly as large
as the state of Connecticut.
The iceberg was formed from glacial ice moving off
the Antarctic continent and calved along pre-existing
cracks in the Ross Ice Shelf near Roosevelt Island.
The calving of the iceberg essentially moves the northern
boundary of the ice shelf about 25 miles to the south,
a loss that would normally take the ice shelf as long
as 50-100 years to replace.
Cracks in the Antarctic ice shelf have been closely
observed since the advent of remote sensing by satellite
and are of particular interest to scientists studying
the potential effects of global warming. The breakoff
of this iceberg is believed to be part of a normal
process in which the ice sheet maintains a balance
between constant growth and periodic losses.
Such a berg might bounce against the main ice shelf
for several days, sometimes breaking apart, before
drifting to sea. NSF supported researcher Doug MacAyeal
at the University of Chicago is already at work modeling
the potential path of the iceberg, based on the science
of iceberg drift dynamics. Polar scientists are concerned
that it could drift into McMurdo's shipping lanes,
which are used to supply the scientific research station
at McMurdo during the austral summer, which begins
in October. The rate and direction of drift and the
breakup of an iceberg depend primarily on the ocean
tides in the area.
NSF, through the United States Antarctic Program, coordinates
most U.S. scientific research in the Antarctic. McMurdo
Station is the largest of three U.S. Antarctic stations
and serves as a "gateway" for field teams studying
astronomy, atmospheric sciences, biology, earth science,
environmental science, geology, glaciology, marine
biology, oceanography and geophysics.
For satellite photos of the iceberg, see: http://uwamrc.ssec.wisc.edu/amrc/iceberg.html