Fall in global Carbon Dioxide Levels preceded formation of Antartic Ice Sheet 32 million years ago

A paper published in Science reports on an analysis of molecules from algae deposited on the ocean floor. The team estimate that there was a 40 percent CO2 decrease over a three million year period, correlating with global cooling during that time.

http://esciencenews.com/articles/2011/12/01/plunge.co2.put.freeze.antarctica