Quantifying millennial timescale grounding-line retreat in East Antarctica

01.01.2019 bis 31.05.2022

Ice rises strongly modulate the flux of the Antarctic ice sheet towards the ocean by providing an additional backstress that restricts ice flow. This mechanism for flow restriction is important because it influences rates of sea-level rise from the Antarctic ice sheet. Models for past and future sea-level change have so far never fully included this effect not only because the observational constraints needed for models are inadequate, but also because virtually all models use a reduced set of physical equations which may not fully capture the non-local effects of ice rises. In this study, I test the hypotheses that: (1) commonly applied physical simplifications to the ice-flow equations (Stokes equations) result in a negative bias in both the timing and magnitude of expected sea-level change, and (2) if the ice dynamics are properly evaluated (e.g. via a Full-Stokes model) then ice rises can be utilised across all of Antarctica as an archive of millennial timescale grounding-line retreat. If hypothesis 2 is correct, then ice rises can be used to constrain the next-generation of ensemble ice- flow models in areas where other constraints on past ice-sheet extends are sorely lacking. I test these hypotheses by simulating the coupled system consisting of ice sheet, ice shelf, ice rise and a dynamic grounding in 3D. This state-of-the-art modelling approach combined with in-situ geophysical data enables the quantification of ice rise effects on ice-sheet stability and sea-level variations. In close collaboration with my national and international partners, this project will make significant contributions in reducing uncertainties of sea-level rise projections for Antarctica and provide constraints on paleo ice-sheet simulations that quantify Antarctica’s contribution to sea-level change in the early Holocene.