The rapid acceleration of Greenland Ice Sheet mass loss over,; particularly the last two decades, is well documented.However, limits in; early remote sensing restricted the details with which we could examine; local changes on an ice-sheet-wide scale, particularly in areas of slow; motion, along shear margins and complex coastal terrain. We explore the; localcharacter of rapid contemporary change marine-terminating glaciers; using satellite-derived ice sheet surface velocities,glacier terminus; advance/retreat history, and surface elevation-change data from the; 1980s to the present. Widespread glacierterminus retreat is a strong and; more consistent climate response indicator than velocity change, but; local changes in velocityare critical indicators of rapid ice sheet; reconfiguration. Ice thickness changes related to changing ice dynamics; often providethe first evidence of processes that initiate outlet; glacier retreats and mass loss, such as the development of sub-ice; shelfcavities and subglacial hydrology changes. Reconfiguration is; observed locally as narrowing zones of fast-flow, ice flowrerouting,; shear margin migration, and likely glacier outlet abandonment. These; patterns are apparent in all ice sheet sectorsand observable from; space-borne instruments. The rapid reconfiguration now well underway in; Greenland has wide-rangingimplications, including expected changes in; subglacial hydrology, ice discharge, freshwater flux to the ocean, and; transport ofnutrients and sediment. Lacking detailed observations of; earlier deglaciations and current limits on ice-sheet modelcapabilities,; the expanding details of these combined observational records may; provide a valuable analog for studying pastice sheet dynamics and; projecting future ice loss.
