[calenel]

The CIA factbook agrees with me that virtually all (89%) of it sits on top of Antarctica

The portions resting on the bottom are already mostly underwater.

That depends. What about a mile thick ice sheet that is just entering the water? It won't be 'mostly' submerged until the water is at least half a mile deep. At that point 55% of the ice would replaced displaced water and 45% would contribute to a rise in sea level. The ice sheet won't leave the bottom and start floating (that is the point at which it ceases to affect sea level after melting) until it has reached a depth of about 9/10 mile.

If it melts -- that is, rises in temperature to the melting point -- the near-freezing liquid would cause a slight cooling and loss of volume in the world's oceans near the surface as it spread out, hence a slight loss of depth.

A negligible effect that would be more than offset by what ever caused the ice to melt in the first place. It can be totally discounted.

[jimtorr]

While it may be true that 89% of Antartic ice sits on land, 89% does not qualify as "virtually all". 11% is still a surprisingly large proportion. I didn't think it was quite that large.

BTW, the map is from the CIA fact book? You just can never tell what those guys have exhaustively investigated, or what they've ignored.

[SunkenCiv]

Nowhere does it say that 89 per cent of the ice is on the continent. Reason? Because it isn't.

http://www.odci.gov/cia/publications/factbook/geos/ay.html

"14 million sq km (280,000 sq km ice-free, 13.72 million sq km ice-covered... about 98% thick continental ice sheet and 2% barren rock, with average elevations between 2,000 and 4,000 meters; mountain ranges up to nearly 5,000 meters; ice-free coastal areas include parts of southern Victoria Land, Wilkes Land, the Antarctic Peninsula area, and parts of Ross Island on McMurdo Sound; glaciers form ice shelves along about half of the coastline, and floating ice shelves constitute 11% of the area of the continent... the lowest known land point in Antarctica is hidden in the Bentley Subglacial Trench; at its surface is the deepest ice yet discovered and the world's lowest elevation not under seawater..."