Using a new laboratory technique to analyze fossil snail
shells, scientists have gained insights into an abrupt climate shift that
transformed the planet nearly 34 million years ago.
At that time, the Earth switched from a warm and high-carbon
dioxide "greenhouse" state to the lower-carbon dioxide, variable
climate of the modern "icehouse" world. Massive ice sheets grew
across the Antarctic continent, major animal groups shifted and ocean
temperatures decreased by up to 5 degrees Celsius (9 degrees Fahrenheit).