Sea Level Budget over 2003–2008: A Reevaluation from GRACE Space Gravimetry, Satellite Altimetry and Argo by Cazenave et al. 2008

Thanks to Mike Jonas for alerting us to the following paper;

Cazenave et al. Sea level budget over 2003-2008: A reevaluation from GRACE space gravimetry, satellite altimetry and Argo. Global and Planetary Change, 2008; DOI:10.1016/j.gloplacha.2008.10.004

The Cazenave et al. papers provides independent confirmation of

Willis J. K., D. P. Chambers, R. S. Nerem (2008), Assessing the globally averaged sea level budget on seasonal to interannual timescales, J. Geophys. Res., 113, C06015, doi:10.1029/2007JC004517. (see also the Climate Science weblog on this paper).

The absract of the Cazenave et al. paper reads

“From the IPCC 4th Assessment Report published in 2007, ocean thermal expansion contributed by ~50% to the 3.1 mm/yr observed global mean sea level rise during the 1993-2003 decade, the remaining rate of rise being essentially explained by shrinking of land ice. Recently published results suggest that since about 2003, ocean thermal expansion change, based on the newly deployed Argo system, is showing a plateau while sea level is still rising, although at a reduced rate ( ~2.5 mm/yr). Using space gravimetry observations from GRACE, we show that recent years sea level rise can be mostly explained by an increase of the mass of the oceans. Estimating GRACE-based ice sheet mass balance and using published estimates for glaciers melting, we further show that ocean mass increase since 2003 results by about half from an enhanced contribution of the polar ice sheets – compared to the previous decade – and half from mountain glaciers melting. Taking also into account the small GRACE-based contribution from continental waters (b0.2 mm/yr), we find a total ocean mass contribution of ~2 mm/yr over 2003-2008. Such a value represents ~80% of the altimetry-based rate of sea level rise over that period.We next estimate the steric sea level (i.e., ocean thermal expansion plus salinity effects) contribution from: (1) the difference between altimetry-based sea level and ocean mass change and (2) Argo data. Inferred steric sea level rate from (1) (~0.3 mm/yr over 2003-2008) agrees well with the Argo-based value also estimated here (0.37 mm/yr over 2004-2008). Furthermore, the sea level budget approach presented in this study allows us to constrain independent estimates of the Glacial Isostatic Adjustment (GIA) correction applied to GRACE-based ocean and ice sheet mass changes, as well as of glaciers melting. Values for the GIA correction and glacier contribution needed to close the sea level budget and explain GRACE-based mass estimates over the recent years agree well with totally independent determinations.”

The conclusions read

“From the results presented in this study, we see that confronting independent estimates of ocean and land contributions to sea level with altimetry results leads to a rather coherent picture for recent years variations. This can be summarized as follows: since 2003, sea level has continued to rise but with a rate (of 2.5 +/-0.4 mm/yr) somewhat reduced compared to the 1993-2003 decade (3.1+/-0.4 mm/yr). Over 2003-2008, the GRACE-based ocean mass has increased at an average rate of ~1.9 mm/yr (if we take the upper range of possible GIA corrections as recommended by Peltier, submitted for publication). Such a rate agrees well with the sum of land ice plus land water contributions (i.e., GRACE-based ice sheet mass balance estimated in this study, GRACE-based land waters plus recently published estimates for the current glacier contribution). These results in turn offer constraints on the ocean mass GIA correction, as well as on the glacier melting contribution.

The steric sea level estimated from the difference between altimetric (total) sea level and ocean mass displays increase over 2003-2006 and decrease since 2006. On average over the 5 year period (2003-2008), the steric contribution has been small (on the order of 0.3+/-0.15 mm/yr), confirming recent Argo results (this study and Willis et al., 2008).”

Thus since 2003, there has been little if any global warming as diagnosed using ocean heat content. Since ocean heat content change has been shown to be a robust metric of global warmng and cooling; see

Pielke Sr., R.A., 2003: Heat storage within the Earth system. Bull. Amer. Meteor. Soc., 84, 331-335,

the IPCC models clearly are not accurately predicting this global climate metric on this time scale.

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