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Arctic, Antarctic: Poles Apart in Climate Response
 While
the Arctic and the Antarctic experience similar greenhouse
gas levels and solar radiation, each region responds in a
dramatically different way, especially in temperature and
loss of sea ice, says an international team of scientists
that includes a NOAA oceanographer. While the Arctic is warming,
most of Antarctica is not, largely because of the ozone hole,
but projections indicate that is likely to change.
"While
some people would say this is a paradox, these different responses
are mostly consistent with what we know about how the climate
system works," said James Overland, lead author and an oceanographer
at NOAA's Pacific Marine Environmental Laboratory in Seattle.
The
findings, based on an October 2007 polar climate workshop,
will be published in the May 6 issue of EOS, a publication
of the American Geophysical Union. Co-authors are John Turner
and Gareth Marshall of the British Antarctic Survey, Jennifer
Francis of Rutgers University, Nathan Gillett of the University
of East Anglia, and Michael Tjernstrom of Stockholm University.
Thirty
scientists attended the Seattle workshop that looked at the
Polar Regions from 1987 to 2007. The scientists concluded,
based on new research since the 2007 Intergovernmental Panel
on Climate Change Report, that a combination of factors is
responsible for the recent dramatic sea ice loss in the Arctic
as well as masking some of the effects in the Antarctic.
Warmth
Arctic:
Experienced seasonal temperatures that at times
were more than four degrees Fahrenheit warmer than usual.
Antarctic:
For most of the Antarctic, temperatures were not unusual,
except on the Antarctic Peninsula, a finger of land and
ice about 1,000 miles south of the tip of South America,
which had the largest increase in temperatures of any location
in the Southern Hemisphere. Temperatures warmed by three
degrees Fahrenheit. Warming temperatures and exposure to
ocean waves were cited by the National Snow and Ice Data
Center as the cause of the collapse of a 160-square-mile
segment of the Wilkins Ice Shelf on the Antarctic Peninsula,
which began collapsing in late February.
Sea Frost
Arctic:
Summer sea ice loss was greater and declining more
rapidly than climate models projected..
Antarctic:
The amount and stability of the sea ice was not unusual.
Human Influenced Change
Arctic:
"In the Arctic, there is a combination of factors,
such as warming of the air because of more greenhouse gases,
an unusual wind pattern, and warming of the ocean water
in regions with reduced sea ice."
Antarctic:
The depletion of ozone has strengthened the atmospheric
circulation, called the Southern Annual Mode, or SAM. As
the ozone hole recovers, the winds that currently whiz around
Antarctica and block air masses from crossing into the continent's
interior would weaken, and Antarctica would no longer be
so isolated from global warming patterns.
In The Future
Arctic:
Sea ice losses will continue. The study says that
a combination of factors has sent the Arctic into a new
state of sea ice loss, which is occurring much earlier than
projected by climate models subject to greenhouse gases
alone.
Antarctic:
Scientists project that the ozone hole should fully recover
by 2070. "As the ozone hole recovers, we expect that warming
will appear on the central plateau of Antarctica and we
will see a reduction in sea ice area," said Turner.
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