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In this July 19, 2011 photo, a large melt pool forms in the Ilulissat ice fjord below the Jakobshavn Glacier, at the fringe of the vast Greenland ice sheet. (AP Photo/Brennan Linsley)

Huge crack discovered in Antarctic glacier

A major glacier in Antarctica is melting unusually quickly because ocean currents are undermining it from below, researchers find. Scientists are gathering meaningful and accurate data of how ice sheets and glaciers are changing over time, and what this means for our planet.