A Coupled Ice Sheet–Sea Level Model Incorporating 3D Earth Structure: Variations in Antarctica during the Last Deglacial Retreat

Abstract

A gravitationally self-consistent, global sea level model with 3D viscoelastic Earth structure is interactively coupled to a 3D dynamic ice sheet model, and the coupled model is applied to simulate the evolution of ice cover, sea level changes, and solid Earth deformation over the last deglaciation, from 40 ka to the modern. The results show that incorporating lateral variations in Earth’s structure across Antarctica yields local differences in the modeled ice history and introduces significant uncertainty in estimates of both relative sea level change and modern crustal motions through the last deglaciation. An analysis indicates that the contribution of glacial isostatic adjustment to modern records of sea level change and solid Earth deformation in regions of Antarctica underlain by low mantle viscosity may be more sensitive to ice loading during the late Holocene than across the last deglaciation.

Holocene Formation of Henry Ice Rise, West Antarctica, Inferred From Ice‐Penetrating Radar

“…Sometime later the ice shelf made contact with the bathymetric high at the northern end of HIR (Stage 2). Although our data do not explain the cause of regrounding, it was most likely a result of crustal rebound due to GIA following ice unloading (Kingslake et al, ), which is predicted to be large in this area following the LGM (Argus et al, ; Gomez et al, ; Whitehouse et al, ).…”

“…This gives where and ρ w are the depth‐averaged density of the ice and density of sea water. We account for uncertainty in w GIA by considering a range of 5–13 mm/year, covering the present‐day rates from GPS measurements taken on bedrock outcrops around the Weddell Sea sector (4–5 mm/year; Bradley et al, ), and modeled relative sea‐level change for the area over the past 6 kyr (∼12.5 mm/year; Gomez et al, ). Eustatic sea‐level change is at least an order of magnitude slower than this during the period (Lambeck et al, ), so we consider this to be included within the uncertainty range.…”

“…This provides a mechanism for the readvance invoked by Bradley et al (). These processes may be particularly important for the WAIS, where mantle viscosity is relatively low and GIA can respond on relatively short time and length scales (Barletta et al, ; Gomez et al, ).…”

Separating Geophysical Signals Using GRACE and High‐Resolution Data: A Case Study in Antarctica

“…The genuineness of a GIA uplift in ASE was then confirmed by once they constrained spatial wavelength of GIA using forward models. The pronounced GIA-induced uplift is supported by recent GIA models that consider late Holocene IMC which seem to dominate present-day GIA rates in regions that have a thinner lithosphere and a lower mantle viscosity (Barletta et al, 2018;Gomez et al, 2018). The pronounced GIA-induced uplift is supported by recent GIA models that consider late Holocene IMC which seem to dominate present-day GIA rates in regions that have a thinner lithosphere and a lower mantle viscosity (Barletta et al, 2018;Gomez et al, 2018).…”

“…Although heavily depending on the regional upper mantle viscosity, Nield et al (2016) have shown that GIA model-predicted rates in this region can reach up to −17 mm/year. A negative GIA-induced signal is also predicted from a coupled model with the 3-D Earth model by Gomez et al (2018) when ice cover changes over the last 3 kyr are considered. A negative GIA-induced signal is also predicted from a coupled model with the 3-D Earth model by Gomez et al (2018) when ice cover changes over the last 3 kyr are considered.…”