http://news.nationalgeographic.com/news/2008/03/080306-sea-levels.html
Sea Levels to Plunge Long Term, Study of Dino Era Says
“There’re natural processes that also contribute to sea level change and are in fact independent of ice cap melting,” said Dietmar Müller, a geologist at the University of Sydney in Australia.
In fact, the data reveal that the long-term trend in sea levels since the Cretaceous has been downward, said Müller, who led the study appearing in tomorrow’s issue of the journal Science.
When this trend is extrapolated out 80 million years from now, it suggests that even if all of today’s ice caps were to melt, sea levels would be 230 feet (70 meters) lower than they are today
With all the Antarctic ice gone the land will rise. The ocean floor surrounding Antarctica will drop are the mass of the surrounding Earth are pulled to the center of the continent. This dropping of the ocean floor will cause sea levels to drop.