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Abstract:
Determining recent ice volume changes from satellite measurements of ice height requires an estimate of contemporaneous vertical crustal deformation. This estimate must consider two main sources of crustal deformation: (1) ongoing glacial isostatic adjustment (GIA), that is, the deformational, gravitational and rotational response to late Pleistocene and Holocene ice and ocean mass changes; and (2) modern ice mass flux. The former has generally involved the adoption of global models of GIA defined by some preferred combination of ice history and mantle viscoelastic structure, while the latter has commonly been based on a simple, spatially invariant scaling of measurements of ice height. In the case of the Antarctic Ice Sheet, a scaling by ~1.02 has typically been adopted. We quantify the uncertainty and potential bias introduced in past estimates of the GIA signal using forward modeling results of various complexity. We also use modeling results to emphasize the spatially variable structure of the mapping between ice height changes and vertical crustal deformation associated with modern ice mass flux.
