The plumbing of Greenland's ice

摘要

The interface between the base of an ice sheet or glacier and its underlying bed is of fundamental importance in controlling the speed at which the ice flows. Of particular significance is how friction at the ice-bed interface is affected by the routing of meltwaters across the ice-sheet or glacier bed. On page 80 of this issue, Andrews and colleagues make a fundamental advance in our understanding of the hydrology underlying the Greenland Ice Sheet and of how the evolution of the subglacial drainage system controls ice motion during the course of the summer melt season - when water is generated by melting of snow and ice at the ice-sheet surface. The authors demonstrate that, during the latter part of the melt season, variations in water pressure in subglacial channels control daily patterns of ice motion, but a longer term slowdown in ice flow is dependent on decreasing water pressures in areas away from the channels.