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

Abstract

The Wilkes Subglacial Basin (WSB), a marine-based sector of the East Antarctic Ice Sheet, contains enough ice to increase the global-mean sea level by 3–4 m. The geometry of the WSB makes its ice sheet potentially vulnerable to unstable retreat, which could lead to rapidly increasing sea levels as well as meltwater production that could potentially disrupt ocean circulation, carbon cycling and marine ecosystems. This Review explores the climate vulnerability of the WSB in the context of future global warming. Paleo marine-sedimentary and model evidence suggests that substantial WSB ice-sheet retreat occurred during Pliocene and other past warm periods, albeit with uncertain temperature thresholds. Observations show unattributed multidecadal retreat of the grounding line and thinning and collapse of key fringing ice shelves but without clear upstream surface lowering. Projections of ice-sheet extent under future emissions scenarios indicate rapid retreat (up to ~1 km yr−1) beyond bedrock pinning points, but with uncertain timings and the possibility of commitment to multimillennial change during this century. Given the potentially severe consequences of WSB ice-sheet change, a multinational and multiyear fieldwork and modelling programme is essential to reduce projection uncertainty. The Wilkes Subglacial Basin is a marine-based sector of the East Antarctic Ice Sheet that is vulnerable to ocean-forced melting and climate warming. This Review assesses changes in ice-sheet extent in the Wilkes Subglacial Basin under past and projected warming and notes large uncertainties in temperature-related and climate-related thresholds for its major retreat.