U-T San Diego: For nearly two decades, Jeff Severinghaus has unearthed time capsules buried in polar ice.
They chronicle past epochs of Earths history, record ice ages and act as thermometers of the prehistoric sea. The objects of Severinghaus exploration are tiny vaults of fresh air, preserved for thousands of years in some of the oldest ice on the planet.
Scientists extract these time-stamped bubbles of ancient air from ice cores drilled thousands of meters below the surface.
What we get is, ultimately,...