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

Glaciers in Antarctica’s Amundsen Sea sector are retreating and thinning due to warm ocean inflow beneath buttressing ice shelves, 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 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.