The basin’s vulnerability stems from its bathymetry. Much of the bedrock beneath the Wilkes Subglacial Basin sits below sea level and deepens inland, a configuration known as a retrograde bed slope. That geometry is the essential ingredient for what glaciologists call marine ice-sheet instability. When the grounding line, the boundary where grounded ice begins to float, retreats onto such a slope, the ice at the grounding line becomes progressively thicker, increasing the outward flux of ice and driving further retreat. The result is a positive feedback that can continue even if the climate forcing that triggered it stabilises. Classic theoretical work on grounding-line dynamics, notably the stability analysis published by Christian Schoof in 2007, formalised this behaviour, and the Wilkes Subglacial Basin is now recognised as one of the largest marine-grounded basins in East Antarctica where the feedback could operate at scale.

The review’s synthesis of palaeoclimate evidence is perhaps its most striking element. Marine sediment cores recovered from the continental shelf offshore Wilkes Land, together with ice-sheet model simulations, indicate that substantial retreat of the basin’s ice occurred during past warm periods, most notably during the Pliocene epoch roughly three to five million years ago, when atmospheric carbon dioxide concentrations were comparable to today’s. Geochemical proxies in deep-sea sediments record deglacial events with clear biogeochemical responses downstream of the basin, and iceberg-rafted debris in Southern Ocean sediments testifies to episodes of enhanced ice discharge. Model reconstructions of specific Pleistocene interglacials, including Marine Isotope Stages 31, 11 and 5e, suggest repeated episodes of ice loss from the basin, although the review is careful to note that the precise temperature thresholds at which such retreat was triggered remain uncertain.

That uncertainty matters because it bears directly on the question of commitment. If the basin retreated substantially during interglacials only modestly warmer than the pre-industrial climate, then the margin of safety under current warming trajectories may be thin. Recent analyses of Pliocene sea level, drawing on geographically diverse geological archives, imply global mean sea levels several metres above present during that epoch, and the Wilkes Subglacial Basin is one of the few sectors of East Antarctica with sufficient ice volume to account for a meaningful share of that rise. The review’s authors, an international team led by Matt King of the University of Tasmania and including specialists spanning glaciology, oceanography, geophysics and palaeoceanography, argue that reconciling sedimentary archives with model simulations is essential to pin down how much warming the basin can absorb before retreat becomes self-sustaining.

Observations of the present-day ice sheet add a further layer of concern. Satellite altimetry, gravimetry and interferometric synthetic aperture radar measurements reveal multidecadal retreat of the grounding line in parts of the Wilkes Land sector, along with thinning and, in places, collapse of key fringing ice shelves. The Cook Ice Shelf and the Ninnis and Mertz glacier systems, which drain large portions of the basin, have shown measurable change, including velocity increases at Cook Glacier linked to ice-shelf loss and a documented subglacial flood event. Intriguingly, the review highlights that this retreat has not yet been accompanied by clear upstream surface lowering across the basin interior, leaving the ultimate cause of the observed changes unattributed. Whether the signal reflects ocean-driven melt at the ice front, atmospheric variability, or internal ice-sheet dynamics remains an open and pressing question.

The oceanographic context is shifting in ways that favour further change. Relatively warm, salty circumpolar deep water, which can melt ice shelves from below, has been shifting poleward in the Australian-Antarctic sector, increasing the risk of warm-water intrusions onto the continental shelf through the deep glacial troughs that dissect the Wilkes Land margin. At the same time, meltwater from Antarctic ice shelves is freshening the surface ocean, suppressing the formation of dense Antarctic bottom water that drives global deep-ocean circulation. Recent studies have documented reduced abyssal overturning and ventilation in the Australian-Antarctic Basin, and modelling suggests that sustained Antarctic meltwater release could slow the abyssal ocean’s overturning circulation within decades. A major retreat of the Wilkes Subglacial Basin would amplify this meltwater flux, with consequences that ripple through ocean circulation, carbon cycling and marine ecosystems far beyond the Southern Ocean.

Projections of the basin’s future under different emissions scenarios reveal the potential speed of change. Ice-sheet model simulations indicate that, once the grounding line retreats beyond key bedrock pinning points, retreat rates of up to roughly one kilometre per year are possible, an extraordinary pace for a continental ice sheet. The timing of such events is deeply uncertain, but the review stresses a more troubling point: decisions taken this century, in effect the emissions pathway the world follows over the coming decades, may commit the basin to multimillennial change. Because the retreat feedback operates on timescales far longer than human political and economic planning horizons, the full sea-level consequences of near-term warming would unfold over centuries to millennia, locking in losses that later mitigation cannot reverse. Sea-level feedbacks, including the gravitational and solid-Earth responses to changing ice load, modulate but do not eliminate this risk.

The review also identifies the processes that remain poorly constrained and that dominate projection uncertainty. Subglacial hydrology is one: the basin sits atop thick sedimentary sequences, and groundwater systems beneath the ice can amplify sliding and mass loss through basal water feedbacks. Geothermal heat flux, which softens the ice base and feeds subglacial lakes and drainage networks, is poorly mapped across the region. The stability of fringing ice shelves, which buttress upstream flow, depends on basal melt rates, calving dynamics and the protective role of land-fast sea ice, all of which are changing. Surface melt and meltwater ponding, historically rare in East Antarctica, are becoming more sensitive to atmospheric warming, raising the possibility of hydrofracturing-driven ice-shelf disintegration analogous to events observed on the Antarctic Peninsula. Improving the representation of these processes in ice-sheet models, and grounding them in field observations, is central to narrowing the spread of sea-level projections.

The authors’ prescription is unambiguous: a coordinated, multinational and multiyear programme of fieldwork and modelling focused specifically on the Wilkes Subglacial Basin. Such a programme would combine airborne geophysics to refine bed topography and subglacial geology, seismic surveys to characterise sediment properties and mantle structure, oceanographic moorings to monitor warm-water intrusions onto the shelf, sediment coring to extend the palaeo-archive, and targeted ice-core records to constrain past ice extent. It would also feed directly into model intercomparison efforts such as ISMIP6 and its successors, which currently struggle to agree on the basin’s response to given levels of warming. The review notes that planning for such coordinated fieldwork is already under way through international scientific committees, but the scale of the challenge, in one of the most remote and logistically demanding environments on Earth, demands sustained investment across multiple national Antarctic programmes.

What emerges from the synthesis is a picture of an ice sheet sector that is neither doomed imminently nor safely stable, but poised in a state whose trajectory depends on choices made now. The Wilkes Subglacial Basin has retreated before under natural warmth, its fringing ice is already showing signs of stress, and the ocean around it is warming and freshening in ways that erode its natural defences. With three to four metres of potential sea-level rise at stake, alongside far-reaching consequences for ocean circulation and Southern Ocean ecosystems, the basin has moved from a scientific curiosity to a first-order question for climate policy. The review’s central message is that the window for reducing uncertainty through observation is open, but narrowing, and that understanding this sleeping giant of East Antarctica is no longer optional.

Subject of Research: Climate vulnerability and dynamic instability of the marine-based Wilkes Subglacial Basin Ice Sheet in East Antarctica

Article Title: Dynamic instability of the Wilkes Subglacial Basin Ice Sheet, East Antarctica

Article References: King, M. A., Bertler, N. A. N., Anandakrishnan, S., Barruol, G., Bentley, M. J., Crosta, X., Christoffersen, P., Colleoni, F., De Santis, L., Escutia, C., Etourneau, J., Evangelinos, D., Ferraccioli, F., Golledge, N. R., Harris, M., Heil, P., Hill, N. A., Hodgson-Johnston, I., Hofstede, C., … Zhao, C. (2026). Dynamic instability of the Wilkes Subglacial Basin Ice Sheet, East Antarctica. Nature Reviews Earth & Environment. https://doi.org/10.1038/s43017-026-00827-6

Image Credits: AI Generated

DOI: 10.1038/s43017-026-00827-6

Keywords: Wilkes Subglacial Basin, East Antarctic Ice Sheet, marine ice-sheet instability, sea-level rise, grounding line retreat, ice shelves, circumpolar deep water, Pliocene, palaeoclimate, ice-sheet modelling, Antarctic bottom water, subglacial hydrology