Greenland glacial history and local geodynamic consequences

Space-time reconstructions of the continental ice-sheets that existed at Last Glacial Maximum (LGM) have previously been produced using two entirely independent methodologies. One based upon the use of theoretical models of ice-sheet accumulation and flow and one based upon the geophysical inversion of relative sea level (RSL) histories from previously ice-covered regions. The analyses described in this paper demonstrate the significant advantages that derive from the simultaneous application of both methods to the particular case of Greenland. We thereby show that the ICE-4G reconstruction of the glaciation history of this region from LGM to present, which was based upon the geophysical inversion of RSL data alone, was reasonably accurate in the peripheral regions where RSL data were available but inaccurate in the interior of the ice-sheet, which was unconstrained by such information. We test the new model of Greenland glacial history determined by the simultaneous application of the constraints that derive from ice-sheet modelling and the geophysical inversion of RSL data by employing recently published geodetic inferences of mass-balance over the entire interior region of the ice sheet and of GPS measurements of vertical crustal motion. These observations, which were not employed to constrain the ice-sheet reconstruction, provide significant support for the new glacial history for Greenland that our analyses have led us to infer.