In this Nov. 22, 2012 photo released by scientist Nancy Bertler, doctoral students, Holly Winton, left, and Aja Ellis, work on an ice core on Roosevelt Island, Antarctica. The continent's pristine ... more 
In this Nov. 22, 2012 photo released by scientist Nancy Bertler, doctoral students, Holly Winton, left, and Aja Ellis, work on an ice core on Roosevelt Island, Antarctica. The continent's pristine habitat provides a laboratory for scientists studying the effects of climate change. (AP Photo/Nancy Bertler) less 
1 / 30
Associated Press | Photo By Nancy Bertler
Sat, Apr 6, 2013 8:20 AM EDT