Two million-year-old ice cores provide first direct observations of an ancient climate

Morgan Kelly, Princeton Environmental Institute

Princeton University-led researchers have extracted 2 million-year-old ice cores from Antarctica that provide the first direct observations of Earth’s climate at a time when the furred early ancestors of modern humans still roamed. Gas bubbles trapped in the cores — which are the oldest yet recovered — contain pristine samples of carbon dioxide, methane and other gases that serve as “snapshots” of prehistoric atmospheric conditions and temperatures.