Mid-twentieth Century Bellingshausen Sea Sector Ice-shelf Thinning Identified from Venable Ice Shelf Grounding History

Sub-ice shelf pinning points provide buttressing to the Antarctic Ice Sheet, which regulates sea-level rise by reducing ice discharge across the grounding line. Satellite-derived ice rises or rumples have been identified on Antarctic ice shelves as sub-ice-shelf pinning points where the ice-shelf bottom is anchored to the seafloor, and they have been used to extend the ice-shelf thickness change record back to 1973 (Miles & Bingham, 2024). We use combined analysis of Landsat imagery with aerogravity-derived bathymetry to present a history of intermittent grounding of the Venable Ice Shelf on a seafloor high since ~1935. We interpret crevasse patterns in satellite imagery over this former pinning point as evidence of mid-twentieth-century ice-shelf thinning in the Bellingshausen Sea sector, allowing us to extend the ice-shelf thickness record beyond the satellite era. Investigation of additional Antarctic ice shelves with similar analysis reveals other paleo-pinning points, which can extend the ice-shelf thickness record beyond the satellite era in key locations.