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Finally, the new model of Antarctic deglaciation reconciles the global constraint upon the global mass loss during deglaciation provided by the Barbados record of relative sea level history when coupled with the Northern Hemisphere counterpart of this new model.2002), is not well constrained by radiocarbon dating of relative sea level (RSL) histories alone, as is the case for both Fennoscandia and Laurentia (e.g. (The abbreviation ‘ka’ is employed herein to indicate thousands of years Before the Present, BP.) Whitehouse (2012a) have compiled estimates of ice thickness change during deglaciation of Antarctica based on exposure age dating at 62 locations, thereby usefully enriching the constraints on the deglaciation history that drives the postglacial rebound process of the southern continent (Fig. Moreover, the increasing quantity and quality of GPS observations of vertical motion are also constraining glacial isostatic adjustment in Antarctica (Capra (2012a). Poorly constrained rates of RSL fall are given in parentheses. Poorly constrained rates of RSL fall are given in parentheses.RSL sites: AP (Ablation Point), BI (Beak Island), JRI (James Ross Island), L (Larsemann), MB (Marguerite Bay), PIB (Pine Island Bay), S (Soya coast), SC (Scott Coast), SSI (South Shetland Islands), TNB (Terra Nova Bay), V (Vestfold hills), W (Windmill islands). RSL sites: AP (Ablation Point), BI (Beak Island), JRI (James Ross Island), L (Larsemann), MB (Marguerite Bay), PIB (Pine Island Bay), S (Soya coast), SC (Scott Coast), SSI (South Shetland Islands), TNB (Terra Nova Bay), V (Vestfold hills), W (Windmill islands).RSL data from Laurentia (Canada), which has a postglacial rebound signal with half wavelength about 1500 km constrains the viscosity of the top 500 km of the lower mantle.The postglacial rebound signal in Antarctica has a half wavelength of about 600 km, about the same as Fennoscandia.At the 42 locations not influenced by modern ice loss, the quality of the fit of postglacial rebound model ICE-6G_C (VM5A) is characterized by a weighted root mean square residual of 0.9 mm yr, indicating large ice loss from this area during deglaciation that is poorly sampled by geological data.Horizontal deformation of the Antarctic Plate is minor with two exceptions.First, O'Higgins, at the tip of the Antarctic Peninsula, is moving southeast at a significant 2 mm yr, in viscous response to the early Holocene unloading of ice from the current locations of the ice shelf centers.ICE-6G_C (VM5A) fits the horizontal observations well (wrms residual speed of 0.7 mm yr Pa s, half that in W12A.
Secondly, the net contribution of Antarctica ice loss to global sea level rise is 13.6 m, 2/3 greater than the 8 m in W12A.
Therefore, Antarctica viscous response approximately follows that given by the upper-mantle viscosity, that is, 0.5 × 102013).
Therefore, Antarctica viscous response approximately follows that given by the upper-mantle viscosity, that is, 0.5 × 10In constructing the Antarctica component of the new model ICE-6G_C (VM5a), we will continue to assume that the viscoelastic structure may be approximated as spherically symmetric.
Furthermore GRACE observations of time-dependent gravity are also providing important constraints on the current rate of loss of grounded ice.
However, the accuracy of these estimates depends strongly on the quality of the model of the global process of glacial isostatic adjustment (GIA) that must be employed to decontaminate the gravity observations from the lingering influence of the mass loss that occurred during the last deglaciation event of the current ice-age (e.g.
2), the viscosity of the sublithospheric mantle as a function of depth (Fig. Errors in the knowledge of deglaciation history, the mantle viscosity profile, or lithospheric thickness may propagate into the inference of the other two parameters.