In this July 19, 2011 photo, attached by rope to a waiting helicopter, Arctic researcher Carl Gladish of New York University hammers a steel stake into ice, securing a newly-deployed GPS seismometer, or Geopebble, designed to track glacial movement near the edge of the Greenland ice sheet, atop Jakobshavn Glacier, outside Ilulissat, Greenland. The chief researcher, NYU's David Holland, hopes to eventually deploy scores of the devices to help measure ice loss in Greenland. (AP Photo/Brennan Linsley)
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