If all the ice in the world were to melt, which is approximately five million cubic miles, the level of the sea would be raised by 216 feet and create completely new shorelines and inland seas. At the rate of global warming, this would take 5,000 years.
Antarctica have been glaciated for about 8 mill years and was caused by the creation of the Antarctic circumpolar current. There have been warm periods before, like the Eemian / Sangamonian interglacial some 125,000 years ago. Not all the ice melted then, although it was a higher sea level than today.