Gauging Greenland's Subglacial Water

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Science  16 Aug 2013:
Vol. 341, Issue 6147, pp. 721-722
DOI: 10.1126/science.1242672

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The supply, storage, and flow of water under an ice sheet are crucial for its overall dynamics. The density difference between ice and water limits subglacial water pressure to the pressure from overlying ice. Near this limit, the ice gradually becomes decoupled from the base (see the figure), water-filled cavities form, and sediments become weakened. The velocity of ice moving over the bedrock increases due to reduced friction and faster sediment deformation. Subglacial water pressure is therefore the key parameter that controls basal motion, ice flux, and the future evolution of an ice sheet. On page 777 of this issue (1), Meierbachtol et al. present a detailed record of water pressure variability under one region of the Greenland ice sheet.