Antarctic shift

35 million years ago, Antarctica was suddenly (in geological terms) covered in ice and a region that had been a balmy 25 Celsius or thereabouts for 100 million years succumbed to the big chill that modern human activity only now seems to be reversing. Scientists suspected that a sharp drop in atmospheric carbon dioxide levels must have been to blame but evidence was scant. Now, a combination of computer modeling and analysis of deep-core samples from Antarctica as well as chemical and isotopic proxies are allowing scientists, such as Mark Pagani, Zhonghui Liu, and David Zinniker at Yale University in New Haven, Connecticut, Matthew Huber of Purdue University, Indiana, and their colleagues to produce evidence of this climatic chemical shift that could have implications for our predictions of future global warming, or cooling.