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|a Position Analysis |h [electronic resource] |b Changes to Antarctic Sea Ice- Impacts. |
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|a [S.l.] : |b The Antarctic Climate & Ecosystems Cooperative Resarch Centre, |c 2009. |
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|a Please contact the owning institution for licensing and permissions. It is the user's responsibility to ensure use does not violate any third party rights. |
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|a In Antarctica, the seasonal
growth and decay of sea ice is
one of the greatest changes on
the surface of the Earth, and
one that has an extraordinary
influence on ocean circulation,
global climate and Southern
Ocean ecosystems.
Sea ice is frozen seawater and is important
because it:
Plays a significant • role in driving
global ocean circulation;
• Is a key feature of Southern Ocean
marine ecosystems;
• Provides an insulating layer between
atmosphere and ocean; and
• Reflects a high percentage of
incoming solar radiation.
Two characteristics of sea ice – extent
and thickness – are important indicators
of the polar response to climate change.
Sea ice extent is a measure of the limit to
which sea ice extends from the poles and
has been monitored from satellites on a
daily basis in both hemispheres since
1979. This satellite data record shows
that sea ice in the two polar regions
has responded to climate change quite
differently over the past three decades.
The average annual sea ice extent in
the Arctic has declined by 2.9% per
decade since 1979 while summer extent
has decreased dramatically by 11% per
decade (Stroeve et al., 2007). In Antarctica
however, the changes have been much
more subtle and regionally variable, with
a net increase of 1% per decade (Comiso
and Nishio, 2008).
The different responses in sea ice extent
in the two polar regions appears to
be a paradox in the climate change
debate; however the changes are largely
consistent with known climate processes
(Overland, 2008). The small net increase
in Antarctica belies the much larger
regional differences that are linked to
changes in large-scale atmospheric
circulation, and in turn to CO2 increases
in the atmosphere and a reduction in
stratospheric ozone (Turner et al., 2009).
The western Antarctic Peninsula region
has shown a decrease in sea ice extent,
consistent with the recent change to
more northerly winds and the surface
warming observed there, while there
have been increases elsewhere including
the Weddell and Ross Seas.
While sea ice thickness is known to be
sensitive to climate change it remains
one of the most difficult of all climate
parameters to measure. Currently there
is no means to routinely measure and
monitor sea ice thickness over largescales,
although satellite radar and laser
altimeters show great potential in this
respect.
To date, most of our knowledge on
the changes in Arctic sea ice thickness
comes from de-classified sonar data from
military submarines. In the Antarctic,
however, no such data are available,
and equivalent instruments deployed
on deep-ocean moorings are highly
susceptible to destruction by drifting
icebergs.
Current climate models show large
discrepancies and uncertainties in
simulating the present-day extent and
thickness of sea ice, and in predicting
changes in both hemispheres. The
observed decrease in the Arctic has
occurred more rapidly than predicted
by climate models, while the observed
net increase and regional variability in
the Antarctic was not predicted at all.
Still, climate models predict that by 2100
Antarctic sea ice will reduce by 24% in
total extent and 34% in total volume, with
possible delays in observed reduction
until stratospheric ozone recovers (Turner
et al., 2009).
While field studies have yielded
extremely valuable information on sea
ice characteristics, and satellite data have
provided a detailed record of ice extent
and concentration since the late 1970s,
the Antarctic sea ice zone remains one of
the most data sparse region on Earth. |
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|a Electronic reproduction. |c Florida International University, |d 2015. |f (dpSobek) |n Mode of access: World Wide Web. |n System requirements: Internet connectivity; Web browser software. |
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|a Antarctic Climate & Ecosystems Cooperative Research Centre. |
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|a International Documents Collection. |
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|a dpSobek |c Sea Level Rise |
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|u http://dpanther.fiu.edu/dpService/dpPurlService/purl/FI15060960/00001 |y Click here for full text |
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|a http://dpanther.fiu.edu/sobek/content/FI/15/06/09/60/00001/The Antarctic Climate and Ecosystems Cooperative Research Center_2009_Changes to Antarctic Sea Iceth |
