Everything You Know About Paleo-Climate May Be Wrong

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. "We don't believe the ice cores can be interpreted purely as a signal of temperature," says Anders Carlson, a University of Wisconsin-Madison geosciences professor. "You have to consider where the precipitation that formed the ice came from." --e-Science Earth & Climate, 25 June 2012