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Author Topic: New paper explains the recent growth of Antarctic sea ice.  (Read 3117 times)

Jim Pettit

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New paper explains the recent growth of Antarctic sea ice.
« on: March 31, 2013, 10:20:40 PM »
Nature Geoscience published a new study online today that I found very interesting. It sheds some more light on the reasons behind the seemingly paradoxical growth of Antarctic sea ice (Important role for ocean warming and increased ice-shelf melt in Antarctic sea-ice expansion) From the abstract:

Quote
Changes in sea ice significantly modulate climate change because of its high reflective and strong insulating nature. In contrast to Arctic sea ice, sea ice surrounding Antarctica has expanded, with record extent in 2010. This ice expansion has previously been attributed to dynamical atmospheric changes that induce atmospheric cooling. Here we show that accelerated basal melting of Antarctic ice shelves is likely to have contributed significantly to sea-ice expansion. Specifically, we present observations indicating that melt water from Antarctica’s ice shelves accumulates in a cool and fresh surface layer that shields the surface ocean from the warmer deeper waters that are melting the ice shelves. Simulating these processes in a coupled climate model we find that cool and fresh surface water from ice-shelf melt indeed leads to expanding sea ice in austral autumn and winter. This powerful negative feedback counteracts Southern Hemispheric atmospheric warming. Although changes in atmospheric dynamics most likely govern regional sea-ice trends, our analyses indicate that the overall sea-ice trend is dominated by increased ice-shelf melt. We suggest that cool sea surface temperatures around Antarctica could offset projected snowfall increases in Antarctica, with implications for estimates of future sea-level rise.

AbruptSLR

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Re: New paper explains the recent growth of Antarctic sea ice.
« Reply #1 on: April 01, 2013, 12:29:48 AM »
Jim,

This quote makes it sound like the cooler mean sea surface temperatures around Antarctica will decrease projected future snowfall on the continent (I assume because the cooler sea surface water will give off less evaporation), thus resulting in higher projected increases in the rate of SLR.  Furthermore, it sounds like the greater sea ice extent will insulate the warm CDW thus leading to more ice shelf and ice sheet melting; which will cool the sea surface even more.  This will be an interest feedback mechanism to watch.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: New paper explains the recent growth of Antarctic sea ice.
« Reply #2 on: April 01, 2013, 12:37:16 AM »
I do not know if this is an actual regional Antarctic sea ice trend, but in the linked 30-day it appears to me that sea ice forms last in the eastern side of the Weddell Sea and on the western side of the Ross Sea, and I believe that I saw the same pattern last year.

http://arctic.atmos.uiuc.edu/CT/animate.antarctic.color.0.html

If this is the case, it may support my postulation (in the "FRIS/RIS" thread) that warm CDW maybe entering the eastern side of the Weddell Sea and the western side of the Ross Sea.  If so this could contribute to the collapse mechanism that I speculate about for FRIS and RIS circa 2070.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

frankendoodle

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Re: New paper explains the recent growth of Antarctic sea ice.
« Reply #3 on: April 01, 2013, 09:03:56 PM »
I read about this on the BBC website. It does not discredit the findings last year of Paul Holland from the British Antarctic Survey (BAS). They stated that a shift in winds linked to climate change are blowing ice away from the Antarctic coast, allowing exposed water in some areas to freeze and make yet more ice.
Also, surface warming in the Southern Hemisphere is expected to take longer due to oceans comprising 81% of its surface. Them their big patches o' water sure do trap that their sunshine by golly!