Using Antarctic subglacial relic landscapes to inform past ice sheet retreat in the warm Pliocene.

The resilience of the East Antarctic Ice Sheet (EAIS) to anthropogenic climate change has critical implications for future global sea level. Constraining how the ice sheet has responded to past periods of naturally elevated carbon dioxide and global warmth can provide vital clues as to its future stability. Relic fluvial landscapes preserved beneath the EAIS have been used to place limits on retreat into the Aurora Subglacial Basin (ASB) in the warm Pliocene (approx. 3 million years ago). Here, we use high-resolution ice sheet model (ISM) simulations to better understand if the preservation of this landscape precludes significant glacial retreat in this sector in at least the past 3 million years. We apply a subglacial topography map that resolves mesoscale landscape features within the model and create an ensemble of simulations with varying retreat into the ASB. Nearly all simulations feature predominantly cold-based ice caps on the landforms through warm interglacial periods of the Pliocene, meaning the fluvial landscape could have been preserved, even with significant grounding line retreat into the ASB. This study highlights the utility of well-resolved subglacial landscapes when paired with numerical model simulations in informing past ice sheet retreat. This article is part of the Theo Murphy meeting issue 'Next generation ice-sheet bed measurements'.