Potential of the solid-Earth response for limiting long-term West Antarctic Ice Sheet retreat in a warming climate

Abstract

We employ a coupled model for ice-sheet dynamics and Maxwell viscoelastic solid-Earth dynamics, including a gravitationally consistent description of sea level. With this model, we study the influence of the solid Earth on the future evolution of the West Antarctic Ice Sheet (WAIS). Starting from steady-state conditions close to the present-day configuration of the Antarctic Ice Sheet, we apply different atmospheric and oceanic forcings and solid-Earth rheologies in order to analyse the retreat of the WAIS. Climate forcing is the primary control on the occurrence of WAIS collapse. For moderate climate forcing and weak solid-Earth rheologies, however, we find that the relative sea level (RSL) fall associated with the viscoelastic solid-Earth response due to unloading by WAIS retreat limits the retreat to the Amundsen Sea embayment on time scales of several millennia, whereas stiffer Earth structures yield a collapse under these conditions. Under stronger climate forcing, weak Earth structures associated with the West Antarctic rift system produce a delay of up to 5000 years in comparison to stiffer, Antarctic-average solid-Earth rheologies. Furthermore, we find that sea-level rise from an assumed fast deglaciation of the Greenland Ice Sheet induces WAIS 1

Large ensemble modeling of the last deglacial retreat of the West Antarctic Ice Sheet: comparison of simple and advanced statistical techniques

“…The best-fit range for the asthenospheric relaxation timescale TAUAST values is quite broad, including the prior reference value ∼ 3 kyr but extending to shorter times ∼ 1 kyr. This may be connected with low upper-mantle viscosities and thin crustal thicknesses suggested in recent work (Whitehouse et al, 2012b;Chaput et al, 2014), which will be examined in further work with full Earth models (Gomez et al, 2013(Gomez et al, , 2015Konrad et al, 2015).…”

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

“…Furthermore, models that consider the coupled evolution of the ice sheet-solid Earth system (see Sect. 3.1) will be highly sensitive to the underlying viscosity field (Gomez et al, 2015b;Konrad et al, 2015;Pollard et al, 2017).…”

“…It is interesting to note that LGM reconstructions for Antarctica generated using coupled models tend to contain 1-2 m less ice (expressed as sea-level 555 equivalent) than reconstructions generated using uncoupled models (de Boer et al, 2017). If the coupled model results are robust this makes it difficult to account for the global mean sea-level lowstand during the LGM (Clark and Tarasov, 2014 Considering future ice-sheet change, Adhikari et al (2014) have used one-way coupling to quantify the impact of ongoing GIA on Antarctic ice dynamics up to 2500 AD, while Gomez et al (2015b) and Konrad et al (2015) have used coupled 560 models to investigate the long-term evolution of the ice sheet, finding that GIA-related feedbacks have the potential to significantly limit, or even halt, future ice loss if the upper mantle viscosity beneath West Antarctica is low enough for rapid rebound to be triggered. A crucial factor in determining the stability of an ice sheet is the resistance provided by the surrounding floating ice shelves.…”

Joint inversion estimate of regional glacial isostatic adjustment in Antarctica considering a lateral varying Earth structure (ESA STSE Project REGINA)

“…Although much progress has been achieved in numerical modelling of the coupled ice / solid Earth system (e.g. Gomez et al 2013;Konrad et al 2015), as well as in the coverage of GPS data (Bevis et al 2009) and interpretation of the long-term trends in the satellite data, large differences remain between the various GIA solutions, causing substantial uncertainty in GRACE ice-mass balances for Antarctica (Martín-Español, 2016b).…”