Reply to Comment by W. R. Peltier, D. F. Argus, and R. Drummond on "An Assessment of the ICE6G_C (VM5a) Glacial Isostatic Adjustment Model"

Abstract

The empirical approximation of Purcell et al. (2011, https://doi.org/10.1029/2011GL048624) has been validated by Peltier et al. (2018, https://doi.org/10.1002/2016JB013844). In their Comment they introduced new results derived from the same ice/rheology models of ICE6G_C (VM5a) but using a different model for Antarctic bathymetry. This has greatly reduced the differences in predicted Antarctic uplift rates relative to those of Purcell et al. (2016, https://doi.org/10.1002/2015JB012742). In fact, with a ∼50% reduction in uplift rate in the Weddell Sea, the results of Peltier et al. (2018, https://doi.org/10.1002/2016JB013844) now agree more closely with the predictions of Purcell et al. (2016, https://doi.org/10.1002/2015JB012742) than with the original ICE6G_C values. Peltier et al. (2018, https://doi.org/10.1002/2016JB013844) state that the high power in their high‐frequency spherical harmonic coefficients remains in their new calculations. They also claim that Purcell et al. (2016, https://doi.org/10.1002/2015JB012742) used an inaccurate loading history in deriving their velocity field. In fact, the ice load history was unchanged; to remove any ambiguity, the ice and water load histories used in the CALSEA calculations are provided in the supporting information.