Synchronous Holocene thinning of Pine Island Glacier and its tributaries influenced by ice-shelf unpinning

Abstract

Abstract Glaciers in Antarctica’s Amundsen Sea sector are retreating and thinning due to warm ocean inflow beneath ice shelves that buttress (restrain) glacier flow, but their future trajectory and implications for ice-mass loss remain uncertain. Here we present detailed cosmogenic-nuclide exposure-age data from the Hudson Mountains that document concerted thinning of Pine Island Glacier and its tributaries 8–5 ka. We contextualise this thinning using numerical ice-sheet modelling of the last deglaciation to link grounding-line dynamics and thinning characteristics. The model reconstructions attribute pauses in overall rapid thinning to ice-shelf pinning on bedrock highs, underscoring the importance of such features for ice-shelf stabilisation. Ice-flow paths from the sample sites all converge in the same grounding/calving-line region throughout the deglaciation, implying a common buttressing history and response to marine-grounding-line retreat that propagated upstream, controlling thinning. Our results support a key role for ice-shelf buttressing in influencing ice-sheet thinning in this region through the Holocene and into the future.