The Influence of Earth structure on a coupled Antarctic ice sheet - sea level model
Thursday, 18 December 2014: 4:15 PM
Earth structure beneath the Antarctic Ice Sheet is characterized by significant lateral variability. A stable, thick craton exists in the east, while the west is underlain by a large continental rift system and a relatively thin lithosphere. Moreover, high resolution seismic tomography indicates slow wave speeds in the shallow mantle below WAIS, suggesting a hot, low viscosity asthenosphere. Variations in viscoelastic Earth structure can impact predictions of relative sea-level change and present-day crustal deformation rates by: 1) altering the timing and geometry of load-induced Earth deformation; and 2) perturbing, via a sea-level feedback (Gomez et al., EPSL, 2013), the timing and extent of the ice-sheet retreat. In this talk we use a coupled ice sheet – sea level model to explore the sensitivity of predictions of glacial isostatic adjustment and ice-sheet evolution in the Antarctic region to variations in Earth model parameters. We begin with a large suite of simulations in which 1-D (depth dependent) viscosity structure is varied over ranges that capture depth profiles inferred beneath the West and East Antarctic. We also present a simulation that incorporate 3-D variations in lithospheric thickness and mantle viscosity. The calculations will focus both on the evolution of the region since the Last Glacial Maximum and on projections of future, climate change driven ice-sheet retreat.