Ocean cooling: Constraints from changes in Earth\textquoterights dynamic oblateness (J2) and altimetry

Dynamic oblateness (J2) observations reflect changes in the latitudinal distribution of mass within the Earth system, and hence can give insights into processes involving water transport and sea level rise. We seek to use records of J2 variations deduced from satellite laser ranging, together with altimetry results, to provide an independent geodetic constraint on changes in ocean heat content (OHC). We show that the size and signature of the J2 signal presented here do not support a recently published report of rapid oceanic heat loss beginning in 2003, which was subsequently attributed to Argo and other instrumental bias effects. Our results are consistent with recent findings of a flattening of the OHC trend at this time inferred from the bias-corrected Argo data, and demonstrate that J2 observations, in combination with other observational and model data types, can provide useful constraints for monitoring and validating ongoing changes in the Earth system.