"The research, led by Joerg Schaefer from the Lamont-Doherty Earth Observatory, a member of The Earth Institute at Columbia University, and George Denton at the University of Maine, relied on a method known as cosmogenic or surface-exposure dating, which enabled the scientists to determine how long rock surfaces have been exposed since the glaciers retreated. As cosmic rays penetrating the Earth's atmosphere strike the scoured rock, they form an isotope of the element beryllium, 10Be, at a known rate.
...
They found that almost everywhere they looked the glaciers began to pull back approximately 17,500 years ago. Additional studies from tropical South America southern Tibet have also produced similar results.
...
"It's especially surprising because Antarctica was classically thought to be too remote and climatically isolated to respond in a synchronous manner with the rest of the planet." The only place that does not fit the observed warming pattern is Greenland, which did not begin to emerge from the last Ice Age until roughly 15,000 years ago. "
http://www.eurekalert.org/pub_releases/2006-06/teia-nss060706.php
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