... which are described as a shift in the equipotential surface of the gravitational field (the geoid). This isostatic imbalance results in a low geoid in the formerly glaciated areas. The adjustment process reduces the geoid depression through the inflow of mantle material. A prominent example can be found in northeastern Canada, where the geoid is lowered by about 40 m, showing that isostatic equilibrium has not yet been reached after the retreat of the Laurentian ice sheet. For this area, however, it must be noted that at least 50 percent is due to a density anomaly and thus to mantle convection (e.g. Mitrovica & Vermeersen, 2002, Ice Sheets, Sea Level and the Dynamic Earth. American Geophysical Union, Washington). Today's changes in the ice sheets, on the other hand, dominate the geoid due to their direct mass attraction, whereas the elastic response of the solid Earth is comparably small. In Antarctica or Greenland, the mass changes observed with GRACE are thus caused by recent melting as well as by GIA.
References:
Dahle, C., Boergens, E., Sasgen, I., Döhne, T., Reißland, S., Dobslaw, H., Klemann, V., Murböck, M., König, R., Dill, R., Sips, M., Sylla, U., Groh, A., Horwath, M., Flechtner, F. (2025): GravIS: mass anomaly products from satellite gravimetry. - Earth System Science Data, 17, 611-631. doi:10.5194/essd-17-611-2025
Eicker, A., Schawohl, L., Middendorf, K., Bagge, M., Jensen, L., Dobslaw, H. (2024): Influence of GIA uncertainty on climate model evaluation with GRACE/GRACE‐FO satellite gravimetry data. - Journal of Geophysical Research: Solid Earth, 129, e2023JB027769. doi:10.1029/2023JB027769
Dobslaw, H., Bergmann, I., Dill, R., Forootan, E., Klemann, V., Kusche, J., Sasgen, I. (2015): The updated ESA Earth System Model for future gravity mission simulation studies. - Journal of Geodesy, 89, 505-513. doi:10.1007/s00190-014-0787-8
Sasgen, I., Konrad, H., Ivins, E. R., van den Broeke, M. R., Bamber, J. L., Martinec, Z., Klemann, V. (2013): Antarctic ice-mass balance 2002 to 2011: regional re-analysis of GRACE satellite gravimetry measurements with improved estimate of glacial-isostatic adjustment. - The Cryosphere, 7, 1499-1512. doi:10.5194/tc-7-1499-2013
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