Comment on “Ocean mass from GRACE and glacial isostatic adjustment” by D. P. Chambers et al.

Abstract

The modern global theory of the glacial isostatic adjustment (GIA) process is a theory that directly addresses the extent to which the geoid of classical geodesy is impacted by this phenomenon. Because the geoid is, by conventional definition, the surface of constant potential that overlaps the surface of the sea in the absence of currents and tides, we may determine the impact of the GIA process upon it only by explicit analysis of the manner in which mass is redistributed among the ocean basins and the level of the sea is thereby influenced. Although the dominant contribution to GIA is that associated with the transfer of mass between the oceans and the continents, there is an additional influence due to the variations in Earth's rotational state. This influence “feeds‐back” onto the geoid. In the recent paper by Chambers et al. (2010), several arguments were presented that question earlier attempts to discuss the consequences of this feedback. These arguments are interesting and we address them in what follows.