| 24 Apr 2026
West Antarctic Ice Retreat Temporarily Halted with Transient Rheology in Future Climate Projections
Abstract. Projections of sea-level change and Antarctic Ice Sheet (AIS) stability under anthropogenic climate change hinge upon accurately describing physical feedbacks that link ice dynamics (marine and terrestrial) with the gravitational, rotational and deformational response of the solid Earth to ice and ocean loading changes. In turn, the rate of AIS melting can lower the rate of global mean temperature rise, by promoting sea ice growth and amplifying Earth’s albedo. The marine West Antarctic Ice Sheet (WAIS) is vulnerable to runaway grounding line retreat. However, the rapid viscoelastic rebound of the bedrock in response to ice retreat has been shown to stabilize its grounding line, aided by the low-viscosity mantle beneath the WAIS. Such bedrock deformation is typically modelled with idealized Maxwell viscoelasticity, despite that rock deformation experiments show that additional “transient” creep mechanisms occur over societally relevant (~decadal-centennial) timescales that are missing from the Maxwell model. Here, we simulate future AIS evolution, coupled with self-consistent solid Earth deformation and sea level change, for various emissions scenarios (RCP 2.6, 4.5, 8.5), incorporating transient deformation. This more complete treatment of solid Earth deformation delays grounding line retreat as compared to Maxwell projections, with differences of tens of kilometres persisting for decades at Pine Island and Thwaites Glaciers. Though transient deformation slows glacier retreat, it is unable to prevent the bulk of ice loss and sea-level rise on longer, centennial timescales. Even still, deviations in AIS meltwater flux with transient deformation could affect the pace of global temperature rise in climate model predictions.
Summary
The manuscript studies the interaction between climate change, ice sheet dynamics and the solid earth in West Antarctica. The authors introduce a new modeling approach to the solid earth rheology – a transient viscoelastic rheology, which responds on decadal to centennial time scales relevant to modern ice loss due to anthropogenic climate change – and compare it to the established Maxwell rheology. They find that the retreat of the West Antarctic Ice Sheet in different climate scenarios is consistently slower in simulations with the transient model and the bedrock uplift is stronger. This effect is less pronounced for scenarios with little ice loss and increases for higher ice loss scenarios. However, the long-term response of the ice sheet to a changing climate does not seem to be affected.
General comments
In my opinion the paper is already very good. The topic is of scientific interest and relevant to the community. The methods seem appropriate for the question at hand. The presentation of the research is clear and well structured. The visual representation is compelling. I also appreciate the sensitivity analyses in the supplement.
There are a few points I would like to address:
To add clarity, I would suggest some additional figures with grounding line position along the transect versus time. This might allow the reader to see at once how much slower the grounding line retreats in the transient viscosity model.
Reese, R., Winkelmann, R., and Gudmundsson, G. H.: Grounding-line flux formula applied as a flux condition in numerical simulations fails for buttressed Antarctic ice streams, The Cryosphere, 12, 3229–3242, https://doi.org/10.5194/tc-12-3229-2018, 2018.