TWO LARGE ICEBERGS BREAK OFF ROSS ICE SHELF
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Posted on May 12, 2002
The National Ice Center reports two new icebergs (C-18 and C-19)
have broken off of the Ross Ice Shelf in Antarctica. The iceberg C-19 is 108
nautical miles long and 17 nautical miles wide and is located 77.23 South
173.30 East. C-18 is 41 nautical miles long by 4 nautical miles wide and is
located at 77.78 South 178.78 East.
The iceberg C-18 was spotted by NIC analyst Judy Shaffer on May
5 using satellite images from the Defense Meteorological Satellite Program.
The iceberg C-19 was discovered on May 11. The icebergs are named for the
Antarctic quadrant in which they were discovered. Yahoo News says the
icebergs are floating close to the ice shelf and are not considered
hazardous to navigation.
The National Ice Center is an agency represented by the United
States Navy, the National Oceanic and Atmospheric Administration and the
United States Coast Guard. - National Ice Center, Yahoo News, Image credit -
National Ice Center
SIMILAR ANTARCTIC MELTING IDENTIFIED IN THE PAST
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Posted on Apr 8, 2002
Researchers from the University of Oregon published a study that
determined that a very large and unusually abrupt rise in sea levels 14,200
years ago was caused by the partial collapse of ice sheets in Antarctica.
The period exhibited conditions similar to today with increased
temperatures, sea levels and atmospheric carbon dioxide. Using shoreline
fossil deposits scientists were able to develop a method of identifying each
possible melting scenario from ice sheets that existed at that time.
According to Peter Clark, professor of geosciences at OSU, "We
can't say at this point whether the recent breakup of part of an ice shelf
in Antarctica has any relevance to this type of huge meltwater event that
originated from Antarctica thousands of years ago. We don't know yet how
important these ice shelves are to stabilizing the larger ice sheets of the
continent. This event happened near the end of the last Ice Age, a period of
de-glaciation that lasted from about 21,000 years ago to 12,000 years ago.
The average sea level rise during that period was about eight millimeters
per year. But during this meltwater pulse there was an extremely rapid
disintegration of an ice sheet and sea levels rose much faster than
average."
The OSU report states, "What is very clear, however, is the
importance of Antarctica's huge ice sheets remaining stable. The West
Antarctic ice sheet is thought to be potentially unstable, and if it
collapsed sea levels around the world would rise almost 20 feet. The melting
of the larger and more stable East Antarctic ice sheet would raise Earth's
sea levels another 200 feet. In less than 500 years at the end of the last
Ice Age, this event caused the Earth's sea level to rise about 70 feet. The
cause of this event, called the "global meltwater pulse 1A" since it was
first identified in 1989, has until now been unknown. This study not only
pinpoints the source of the meltwater pulse, but it also makes clear that
significant climatic events can occur very rapidly and unpredictably. Prior
to the partial collapse of the Antarctic ice sheets 14,200 years ago, carbon
dioxide levels had risen about 50 parts-per-million in the atmosphere. In
the past 150 years, since the beginning of the Industrial Revolution, carbon
dioxide levels in Earth's atmosphere have risen 85 parts-per-million." The
research was published in the journal Science. - University of Oregon,
Graphic credit: www.cia.gov
