Rapid reconfiguration of the Greenland Ice Sheet margin

The Greenland Ice Sheet has lost mass at an accelerating rate over the last two decades, but limits of early remote sensing restricted examination of localized change at an ice-sheet-wide scale. We use satellite-derived ice-sheet surface velocities, glacier terminus advance/retreat, and surface elevation-change data spanning ~1985-2015 to explore local characteristics of what is now a rapid reconfiguration of the ice sheet coastal margin. Widespread glacier terminus retreat is a more consistent climate response indicator than surface velocities, though local velocity patterns provide indicators of ice flow reconfiguration, including narrowing zones of fast-flow, ice flow rerouting, and outlet abandonment. The implications of this observed rapid reconfiguration are wide-ranging, and likely include alteration of subglacial hydrology, iceberg discharge, liquid freshwater flux, potential nutrient and sediment flux, and mass flux. Without detailed observations of earlier deglaciations and with present limits on ice-sheet model capabilities, these observational records provide an important analogue for past deglaciation and for projecting future ice loss.