LiveScience: Greenland's massive ice sheet is accelerating its slide toward the ocean because bigger surface melts in recent years are softening the interior of the ice like a stick of butter, a new study finds. For more than a decade, scientists have reported rapid melting and shrinking at many of Greenland's outlet glaciers, which snake into the ocean. Studies suggest warmer ocean water and rising atmospheric temperatures contribute to the melting ice. The new study finds the interior ice sheet also speeded...