Greenland ice may exaggerate magnitude of 13,000-year-old deep freeze

Posted: 25 Jun 2012 01:29 PM PDT

Ice samples pulled from nearly a mile below the surface of Greenland glaciers have long served as a historical thermometer, adding temperature data to studies of the local conditions up to the Northern Hemisphere’s climate. But the method — comparing the ratio of oxygen isotopes buried as snow fell over millennia — may not be such a straightforward indicator of air temperature.