Researchers Sample Ice at the South Pole (IMAGE) U.S. National Science Foundation Caption Researchers sample ice to investigate the history of fossil-fuel emissions of methane, based on measurements of another hydrocarbon, ethane, in air trapped in the polar ice sheets in Antarctica. The ancient air resides close to the surface, within the perennial snowpack, and can be used to study changes in the atmosphere that occurred during the twentieth century. Credit National Science Foundation Usage Restrictions None License Licensed 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.