Earth orbit changes were key to Antarctic warming that ended last ice age
For more than a century scientists have known that Earths ice ages are caused by the wobbling of the planets orbit, which changes its orientation to the sun and affects the amount of sunlight reaching higher latitudes, particularly the polar regions.
The Northern Hemispheres last ice age ended about 20,000 years ago, and most evidence has indicated that the ice age in the Southern Hemisphere ended about 2,000 years later, suggesting that the south was responding to warming in the north.
But new research published online Aug. 14 in Nature shows that Antarctic warming began at least two, and perhaps four, millennia earlier than previously thought.
Most previous evidence for Antarctic climate change has come from ice cores drilled in East Antarctica, the highest and coldest part of the continent. However, a U.S.-led research team studying a new ice core from West Antarctica found that warming there was well under way 20,000 years ago.
http://www.washington.edu/news/2013/08/14/earth-orbit-changes-were-key-to-antarctic-warming-that-ended-last-ice-age/
A West Antarctica Ice Sheet Divide project researcher stands in a snow pit next to an ice core with data from 68,000 years ago. The prominent line across the middle of the ice separates one years ice and snow accumulation from the next years.