| Summary: | Abstract [1] Predictions are presented of secular changes in the geoid arising from glacial-isostatic adjustment (GIA) following the Last Glacial Maximum and from present-day mass changes in the Greenland Ice Sheet (GIS). Geoid displacement from ongoing GIA is dominated by ice-load changes outside of Greenland at lower spherical-harmonic degrees (<30), and modified at higher degrees by the recent (last few thousand years) GIS history. Ice-margin mass changes dominate the present-day GIS geoid response, although comparable signals are obtained when considering the uncertainty range in the higher-elevation changes (>2000 m). Spatial variability is noted when the present-day GIS response is expanded to degree and order 32. This is detectable by GRACE when assuming an optimistic accuracy, but is too small by a factor of ca. 3 for an alternate accuracy estimate. Present-day GIS geoid displacement rates are generally less than the equivalent response from ice-mass changes in Antarctica, Patagonia and Alaska.
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