Image:Antarctica Without Ice Sheet.png

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1 Description
2 Image Data
3 Copyright
4 References

Description

Image showing Antarctic ice sheet thickness and temperature variations since 1970.

Image showing climate change during the last 65 million years. Large changes in the Antarctic ice sheet have not occurred for more than 10 million years, and Antarctica has probably been partially glaciated for ~34 million years.

This is topographic map of Antarctica after removing the ice sheet and accounting for both isostatic rebound and sea level rise. Hence this map suggests what Antarctica may have looked like 35 million years ago, when the Earth was warm enough to prevent the formation of large-scale ice sheets in Antarctica.^[1]

Isostatic rebound is the result of the weight of the ice sheet depressing the land under it. After the ice is removed, the land will rise over a period of thousands of years by an amount approximately 1/3 as high as the ice sheet that was removed (because rock is 3 times as dense as ice). Approximately half the uplift occurs during the first two thousand years [1]. If the ice sheet is removed over more than a few thousand years, then it is possible that a majority of the uplift will occur before the ice sheet fully disappears.

As indicated in the map, Antarctica consists of a large continental region (East Antarctica) and group of seas and smaller land regions (West Antarctica). Since the West Antarctic ice sheet is partially anchored below sea level, this region is less stable and more likely to be affected by global warming. Even so, it is likely that during the next century increased precipitation over Antarctica will offset melting.^[2]

Even in the event of severe sustained warming, it would take many thousands of years for Eastern Antarctica to be fully deglaciated.

Image Data

This image was based on the BEDMAP study of Antarctic sub-glacial topography.^[3] To account for post-glacial uplift, ice sheet thickness was smoothed on a 160 km scale (to include the effect of crustal flexing) and then 35% of ice thickness was added to bed rock elevation. An additional adjustment of 65 m was included to account for sea level rise due to ice sheet melting.^[2]

Copyright

This image was prepared by Robert A. Rohde for Global Warming Art.

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References

^ [abstract] [full text] [DOI] Zachos, James, Mark Pagani, Lisa Sloan, Ellen Thomas, and Katharina Billups (2001). "Trends, Rhythms, and Aberrations in Global Climate 65 Ma to Present". Science 292 (5517): 686–693.
^ ^a ^b [full text] Intergovernmental Panel on Climate Change (2007a). Climate Change 2007 - The Physical Science Basis: Contribution of Working Group I to the Fourth Assessment Report of the IPCC. Cambridge: Cambridge University Press. ISBN 978 0521 88009-1.
^ [abstract] Lythe, Matthew B., David G. Vaughan, and the BEDMAP Consortium (2001). "BEDMAP: A new ice thickness and subglacial topographic model of Antarctica". Journal of Geophysical Research 106 (B6): 11335–11351.