Elusive million-year-old ice core could provide clues to climate change

New Scientist : Four science teamsfrom Europe, Australia, China, and the USare racing to retrieve the first million-year-old sample from Antarctica’s ice. Ancient ice could hold clues to past changes in Earth’s climate. Using such ice samples, scientists could study the concentration of carbon dioxide in the ancient atmosphere by analyzing the air trapped in tiny bubbles within the ice. A decline in carbon dioxide concentration could explain the advent of an ice age, for example. One researcher, Robin Bell of the Lamont-Doherty Earth Observatory of Columbia University, and her colleagues have come across a potential problem with the hunt, however. They have found that ice sheets in Dome A, one of the drilling sites, is growing from the bottom up. This could mean that any ancient ice that was once there has melted and been replaced.