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Grounding Line Forensics: West Antarctica
Understanding Discharge Variability in the West Antarctic Ice Sheet

Christina Hulbe

One of the outstanding issues in forecasting future sea level rise is correct estimation of ice sheet mass balance, in particular, changes in mass balance due to variations in the rate of flow across the ice sheet grounding line. Here, variability in the discharge of ice from the Ross Sea sector of the West Antarctic Ice Sheet (WAIS) is discussed. Previously, scenarios for change in the WAIS emphasized runaway retreat or stagnation on millennial time scales. We identify a new scenario: century-scale off/on cycles. This variability is investigated using satellite-remote sensing of surface features in the Ross Ice Shelf and ice-sheet internal layers observed using ice-penetrating radar, together with numerical models of ice shelf flow. The variability is a product of ice sheet thermodynamics and is unrepresented in state-of-the-art climate forecasts.

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