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Abstract:
In north Greenland, which holds more than 2.7 m of sea level equivalent, the ice flows through ice shelves, as in Antarctica. These floating platforms are the most vulnerable parts of the ice sheets as the advection of warm, salty ocean waters increases basal melting, which can trigger an increase in ice flow into the ocean. Here we study the recent dynamic and geometric changes of all present and former ice shelves along the north coast of Greenland. We document the evolution of the surface elevation using data from the GIMP project, from NASA's instruments (ICESat-1/2, ATM, LVIS, GLISTIN-A) and generate DEMs using ASTER imagery between 2000-present. We also monitor changes in surface ice velocity and grounding zone evolution using a combination of optical and radar data. We use the elevation time series to monitor the temporal evolution of the ice shelves volumes and combine them with the surface flow velocity to calculate basal melt rates in a Lagrangian framework at unprecedented level of resolution. Finally, we compare our observations with nearby CTD measurements, the TOPAZ4b reanalysis of Arctic ocean physics provided by Copernicus Marine Service and model outputs from the Modèle Atmosphérique Régoinal. We show that basal melting, grounding line retreat and fracturing are rapidly increasing and is followed by an increase in ice discharge into the ocean. These observations demonstrate that significant changes are occuring in a region that has long been considered stable, which may have dramatic consequences for the ice sheet contribution to sea level rise.
