Antarctica’s Balmy Past

When the atmosphere had much higher levels of carbon dioxide, Antarctica was as warm as California. New research has revealed that 430 million to 50 million years ago, temperatures on the frozen continent averaged 57 degrees Fahrenheit, with part of the surrounding Pacific Ocean reaching up to 72 degrees. In this ancient era, known as the Eocene epoch, carbon dioxide in the atmosphere was five times higher than today’s levels. This is a potentially useful in-sight for scientists working to predict future climate changes.

The findings are based on a new technique that analyzes two isotopes found in fossilized bivalve shells to determine the temperature at which the ancient organisms grew. Another new technique, which analyzes krypton gas trapped in ice-locked air bubbles, is also being employed to uncover near-term climate shifts, allowing scientists to study atmospheric conditions from as far back as 1.5 million years. “Quantifying past temperatures helps us understand the sensitivity of the climate system to greenhouse gases, especially the amplification of global warming in Polar Regions,” says Hagit Affek, professor of geophysics at Yale University.