Decontaminating tide gauge records for the influence of glacial isostatic adjustment: The potential impact of 3‐D Earth structure

Abstract

[1] We investigate the potential impact of lateral variations in mantle viscosity and lithospheric thickness on predictions of present-day relative sea-level change due to glacial isostatic adjustment (GIA). We consider three viscoelastic Earth models. The first is a 1-D model with a lithospheric thickness of 120 km and upper and lower mantle viscosities of 5 Â 10 20 Pa s and 5 Â 10 21 Pa s, respectively. The second model includes global lithospheric thickness variations and lateral heterogeneities in upper mantle viscosity ranging over three orders of magnitude, while the third model includes lateral variations in lower mantle viscosity alone. We find that the impact of 3-D structure is significant. Indeed, the difference between the 3-D and 1-D model predictions at $300 sites with tide gauge records longer than 40 years duration is greater than 0.2 mm/yr and 0.5 mm/yr for 50% and 25% of the sites, respectively. The maximum difference exceeds several mm/yr. We conclude that efforts to decontaminate tide gauge records for ongoing GIA, to determine the rate and origin of global sea-level rise, should incorporate 3-D mantle structure into the GIA modelling. Citation: Kendall, R. A., K. Latychev, J. X. Mitrovica, J. E. Davis, and M. E. Tamisiea (2006), Decontaminating tide gauge records for the influence of glacial isostatic adjustment: The potential impact of 3-D Earth structure, Geophys.

The contribution of glacial isostatic adjustment to projections of sea‐level change along the Atlantic and Gulf coasts of North America

“…As indicated in Figures 3 and S4, the greatest differences occur in locations proximal to the ice margin. These results are compatible with previous studies that considered the influence of lateral structure on rates of sea-level change at tide gauge stations [Kendall et al, 2006;Davis et al, 2008]. Our 3D model results also provide a partial explanation of why analyses based on 1D models (including this study) have not been capable of producing high quality fits at all locations along the U.S. Atlantic coast Roy and Peltier, 2015].…”

Glacial Isostatic Adjustment modelling: historical perspectives, recent advances, and future directions

“…Whitehouse et al (2006) showed that inclusion of 3D Earth structure perturbs uplift rate predictions across Fennoscandia by an amount greater than current GPS 585 accuracy, with significant implications for inferences of past ice-sheet history, while Kendall et al (2006) demonstrated that relative sea-level change predictions will be biased by >0.2 mm/yr at ~150 global tide gauge sites if 3D Earth structure is neglected, with maximum differences exceeding several mm/yr. Since solid Earth deformation depends on both the surface load history and Earth rheology, non-uniqueness is a problem when solving for these two unknowns.…”

Projected 21st Century Sea-Level Changes, Observed Sea Level Extremes, and Sea Level Allowances for Norway

“…Note that the sea level model is based on the "sea level equation" [43] and includes subsequent improvements to allow for coastline migration and changes in Earth rotation [44,45]. GIA models allow the calculation of vertical and horizontal land motion, sea level, gravitational, rotation and stress changes associated with a selected ice-Earth model combination.…”

“…The ice sheet, glacier and land water storage regional uncertainties are calculated by multiplying their global uncertainties by the respective normalized "sea level equation" patterns [43][44][45]. The methods used to compute uncertainties associated with GIA (obsvlm and gravgia) are given in Sections 2.1 and 3.1.…”