Kevin Welsh, an Australian scientist who was with the 2010 expedition, said that analysis of sediment cores containing fossil pollen showed it was "very warm" 52 million years ago, at 20 degrees Celsius (68 F). "There were forests existing on the land, there wouldn't have been any ice, it would have been very warm."
Higher levels of carbon dioxide are thought to be the major reason for ice-free conditions during the period. The CO2 estimates were between 990 to a couple of thousand parts per million.
The current CO2 level is 395 ppm and the most extreme predictions made by the Intergovernmental Panel on Climate Change (IPCC) see Antarctica being ice free by the end of the century."