Recent changes in the Earth\textquoterights oblateness driven by Greenland and Antarctic ice mass loss

We use temporal gravity variations from GRACE to investigate changes in a 34-year time series of Earth\textquoterights oblateness (J2) observed by satellite laser ranging (SLR). We use 2002\textendash2010 GRACE data to compute the effects of Greenland and Antarctic ice mass variations on J2 (2.0 and 1.7 \texttimes 10-11/year respectively). Their combined effect on the J2 trend during the GRACE mission is 3.7 \texttimes 10-11/year, which agrees well with the GIA-corrected SLR J2 trend over the same time period. The results suggest that at least since 2002, ice loss from Greenland and Antarctica has been the dominant contributor to the current GIA-corrected J2 trend, which apparently began sometime in the 1990s.