Photo 2 (IMAGE) Desert Research Institute Caption Photo 2 shows U.S. and Norwegian researchers traversing the East Antarctic ice sheet to collect the ice cores used in the study. Credit Credit: Stein Tronstad/NPI Usage Restrictions Use with credit License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.