The Antarctic Ice Sheet Antarctic Ice Sheet.pdf · Antarctica: 90% of world’s ice volume (~10 x...
Transcript of The Antarctic Ice Sheet Antarctic Ice Sheet.pdf · Antarctica: 90% of world’s ice volume (~10 x...
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The Antarctic Ice Sheet
Global distribution of glaciers
Significance of the Antarctic glaciers
Topography, ice thickness and sub-ice maps
Flow rates: ice-streams, ice divides
Floating ice shelves
Sub-glacial lakes
Climate change and melting in Antarctica
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Significance of the Antarctic Glaciers
Antarctica: 90% of world’s ice volume (~10 x greater than Greenland). If it all melts sea level will rise by 60 to 70 m.
The ice sheet is much thicker than Greenland’s. It is considerably colder on Antarctica, with lower snow-fall
rates.
The Antarctic ice sheet is divided into eastern and western components. The eastern ice sheet is several times larger
than the western one, and about twice as thick.
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Dome A
Dome C
Dome F
1000 30002000
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Land surface above and below sea level, and areas of exposed
rock (yellow)
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Topography of the sub-ice surface. With ice Antarctica is easily the
most elevated continent. But even without ice there are large parts of
it that are very high.
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Topography after melting and isostatic rebound
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Ice thickness (from British Antarctic Survey)
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Exaggerated topography and ice thickness(The thickest ice is over 4000 m)
4000 m+
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http://www.jpl.nasa.gov/video/index.php?id=1015
There are many orders of magnitude of difference in the rate of flow of Antarctic ice, from less than 1.5 m/y along the ice divides, to over 1000 m/y in some of the ice-stream areas and on the ice shelves.
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A
F
ED
C
BI
HG
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Some ice streams are situated over areas of soft sedimentary rock, the postulated connection
being that the ice can slide faster if the underlying material will deform.
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Ice shelves• Antarctica has extensive floating ice shelves
on almost all of it’s coasts
• The largest (Ross) is about ½ the size of British Columbia
• The shelves range in thickness from a few tens of m to around 750 m
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Larsen Ice Shelf (NSIDC)
http://earthobservatory.nasa.gov/Features/WorldOfChange/larsenb.php
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Locations of approx. 150 subglacial lakes in Antarctica
Sub-glacial lakes
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NSIDC
Scambos et al. 2007
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Three projects to collect samples from subglaciallakes:
Ellesmere (UK)
Vostok (Russia)
Whillans (USA)
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Climate change in Anarctica
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