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Snow and ice are pervasive
elements of high latitude environmental systems and have an active
role in the global environment. Glaciologists in Antarctica are
concerned with the study of the history and dynamics of all naturally
occurring forms of snow and ice, including floating ice, seasonal
snow, glaciers, and continental and marine ice sheets.
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The Essence
of Antarctica
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Antarctic ice has accumulated over millions
of years.
The ice is up to 3 miles deep and covers
about 5.3 million square miles, or about 97.6 percent of the
continent.
This volume of ice amounts to about 6
million cubic miles - if it were returned to the oceans, it
would raise global sea level about 200 feet.
The average thickness of ice makes Antarctica
the highest continent.
Antarctic ice represents 90 percent of
all the world's ice and 70 percent of all the world's fresh
water.
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One priority for scientists
is to determine the origins of the polar ice sheet, along with the
fundamental behavior of the ice sheet during worldwide glaciations.
Data has shown that the East Antarctic ice sheet has remained relatively
static during worldwide glaciation whereas the marine-based West
Antarctic Ice sheet has expanded to the eastern edges of the Ross
and Weddell continental shelves, nearly tripling in size in the
process.
About one-third of the Antarctic coastline
is comprised of ice shelves-floating ice fed by glaciers emanating
from the vast polar plateau and by snowfall upon their surfaces.
The ice shelves are as much as 300 meters
thick at their seaward edges and they thicken toward the land.
Ross Ice Shelf is the largest, covering
about 520,000 square kilometers and measuring about 650 kilometers
across.
It moves northward to the Ross Sea, flowing
about 1.4 kilometers a year, where it calves tabular icebergs,
some small and some covering more than 200 square kilometers
or more.
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Of critical importance
to glaciological research is the examination of deep ice cores.
Ice cores are unique in that they continuously record and preserve
annual precipitation, atmospheric temperature and components of
the atmosphere, including gases, soluble and insoluble aerosol particles
from a wide variety of sources.
Another focus for scientists
is to improve our understanding of the growth and movement of Antarctic
sea ice, not only to aid in navigation but to give insight into future
changes. Sea ice
originates on or at the edge of the polar land mass and is dispersed
by strong winds blowing northward into the surrounding oceans.  Annually
the ice pack grows from an average minimum of 2.9 million square kilometers
in March to about 18.8 square kilometers in September. The average
thickness of the sea ice is about 1.5 meters and 85 percent of the
ice pack melts each year. This ice is characterized by undulating
ridges and troughs and crevassed areas which have created route-finding
problems for those traveling across these marginal areas of the ice
shelf. The pack moves
quickly with the winds--as much as 65 kilometers in a single day--and
ships can easily be caught in some of the thicker, more complex multiyear
ice that is trapped within indentations on the Ross Sea coastline.
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Floating
Ice Shelves
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Glaciologists monitor not only when a
giant berg breaks off one of Antarctica's ice shelves, but
also measure its slow progress away from the continent.
Other research on the ice shelves concentrates
on determining flow rates to see how quickly ice is moving
off the continent, and how rapidly the shelf ice thins from
the melting of its underside.
The long-term objective is to provide
researchers with a computer model that will allow the loss
of ice to the Southern Ocean to be accurately predicted.
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