Review article: The Foundation-Patuxent-Academy ice stream system, Antarctica

The Foundation-Patuxent-Academy system (FPAS) is a major Antarctic ice stream system, draining both East and West Antarctica, with a global sea level potential of ∼3 m. We provide a holistic catchment-scale overview of the FPAS reviewing its glaciological and hydrological systems, its glacial history, and its modelled response to past and future climate change. FPAS may be vulnerable to future change because of: (i) a deep (∼2.4 km below sea level) low-gradient retrograde bed that encourages grounding-zone retreat; (ii) a low-gradient ice surface and high tidal range, which are likely to promote flotation of grounded ice and seawater intrusion; (iii) an active and dynamic subglacial hydrological system; (iv) complex ice-meltwater-ocean interactions at the grounding zone; (v) potential for substantive expansion of the across-flow length – and cross sectional area – of the grounding zone; and (vi) susceptibility to ice flow-switching and water piracy (e.g. via the adjacent Support Force Glacier). Despite such potential vulnerabilities, existing numerical model simulations of FPAS grounding-zone retreat produce a wide and divergent range of past and future scenarios. Uncertainties in the future response of the FPAS to a warming climate result from poor constraints on its topography and hydrology, processes of ice-ocean interaction, interlinkages with the surrounding ice sheet and ice shelf, and a shortage of FPAS-specific modelling experiments. This review outlines and evaluates these critical gaps in our knowledge of the FPAS and develops a strategy to address them. This strategy would provide: (i) the first robust and comprehensive evaluation of the FPAS's vulnerability to current and near-future climate forcing; and (ii) improved constraints on projections of the future contribution of the Antarctic Ice Sheet to sea-level rise.