Photo Credit: Mark Twickler

An ice core sticks out of the metal core barrel during drilling operations at the West Antarctic Ice Sheet Divide field camp. Analysis of the ice core suggests that the last ice age ended at least two thousand years earlier than previously thought.

An early defrost

Nature paper suggests last ice age in West Antarctica ended at least 20,000 years ago

New research published online Aug. 14 in the prestigious journal Nature suggests that the last ice age in West Antarctica ended several thousand years earlier than previously thought.

The study is based on analysis of an ice core extracted from the West Antarctic Ice Sheet by U.S. researchers, a multi-year project primarily funded by the National Science Foundation . Scientists spent the better part of a decade drilling and extracting an ice core 3,400 meters long, representing a climate history of about 68,000 years. Only the first 30,000 years have been analyzed so far. [See previous article — The last core: WAIS Divide deepens borehole for research into climate change.]

The data from the ice core suggest changes in the amount of solar energy triggered the warming of West Antarctica. The subsequent release of carbon dioxide from the Southern Ocean amplified the effect and resulted in warming on a global scale, eventually ending the ice age.

The date for the end of the last ice age, or glacial period, had been pegged at 20,000 years for the Northern Hemisphere and about 18,000 years ago for the Southern Hemisphere. The new analysis implies that parts of Antarctica began warming between 2,000 and 4,000 years earlier than previously thought.

"This deglaciation is the last big climate change that that we're able to go back and investigate," said T.J. Fudge , a University of Washington doctoral student in Earth and space sciences and lead corresponding author of the Nature paper. "It teaches us about how our climate system works."

For more information, see press releases from the University of Washington and Oregon State University .