An Estimate of Global Mean Sea-level Rise Inferred from Tide-gauge Measurements Using Glacial-isostatic Models Consistent with the Relative Sea-level Record

Abstract

This study is concerned with the influence of the glacial-isostatic adjustment caused by the last Pleistocene deglaciation on the present-day sea level. The viscoelastic deformation caused by the time-variable ice and ocean loads is simulated by computing the resulting perturbations for a spherical, self-gravitating, incompressible, Maxwell-viscoelastic earth model. The associated variation of the earth rotation is described in terms of the Liouville equation, which is solved by means of the MacCullagh formulae. This allows the determination of the vertical displacement and geoid height and, thus, the solution of the sea-level equation. We test several viscosity and ice models and evaluate them by comparison of the computed response with the Holocene relative sea-level record. Using the optimum combination of viscosity and ice models, we then estimate the influence of the last Pleistocene deglaciation on the tide-gauge measurements. A comparison between the observational and residual linear trends for the tide-gauge measurements shows a significant reduction of the variance and geographical variability for the latter, in particular for the formerly ice-covered regions of North America and Scandinavia. The favoured value determined for the global mean sea-level rise is (1.46±0.2) mm a )1 .

New estimates of secular sea level rise from tide gauge data and GIA modelling

“…Among those listed in Table 1, we find a consistency (i.e. the ranges of estimates are overlapping) with previous results by Mitrovica & Davis (1995), Church et al (2001), Nakada & Inoue (2005), Church & White (2006) and Hagedoorn et al (2007). Though the statistical meaning of the error bar on the GMSLR estimate by Bindoff et al (2007) is not explicitly stated, our estimate is clearly consistent with the results of the last IPCC report.…”

“…This criterion, which has been often implicitly or explicitly applied in previous studies (see e.g. Hagedoorn et al 2007), will be referred to as criterion (VI). In what follows, starting from set SGX, criteria (II)-(IV) and (VI) are employed to define a new of preferred TGs (set SG01), which will be adopted in Section 4.3 to produce new GMSLR estimates.…”

“…Applying criterion (VI), several sites have been removed from the SGX set for possible contaminations from human-driven subsidence, as in the case of Venice (see e.g. Hagedoorn et al 2007;Carbognin et al 2010), whose sea level trend exceeds significantly those at other Mediterranean TGs located at approximately the same latitude (e.g. Trieste).…”

“…For instance, D97 excluded Sydney and Newcastle and did not consider the TG of Fremantle, apparently without any explicit motivation. We also note that more recently, Hagedoorn et al (2007) considered various Australian sites in their study, including Sydney and Fremantle but excluding Newcastle.…”

Sea-level evolution of the Laptev Sea and the East Siberian Sea since the last glacial maximum

“…To consider the water and ice redistribution consistently, we apply the method of Hagedoorn et al [13] to solve the sea-level equation introduced by Farrell and Clark [9]. In this solution method, sea-level variations are determined on the same grid as the glacial load.…”