Antarctic ice shelf pinning point change classification 1973-2022

Mass loss of the Antarctic Ice Sheet has been primarily driven by thinning of the floating ice shelves that fringe the ice sheet, reducing their buttressing potential and causing land ice to accelerate into the ocean. However, observations of ice-shelf thickness change by satellite altimetry only stretch back to 1992 and prior information about thinning remains unquantified. Here, we present a new way of assessing ice-shelf thickness change that focusses on changes to pinning points, local bathymetric highs on which ice shelves are anchored and which are typically expressed as surface protuberances on the ice-shelves' surfaces. We utilise the full Landsat archive to map the evolution of pinning points around the Antarctic coastline over 50 years, and thus by proxy infer changes to ice-shelf thickness back to 1973. Ice shelves in the Amundsen Sea sector and in Wilkes Land were already thinning from 1973-1989, meaning the processes driving mass loss in these key sectors of Antarctica have been ongoing for at least 50 years. Ice-shelf thinning spreads rapidly into the 1990s and 2000s and is best characterised by the proportion of pinning points reducing in extent. Only 15% of pinning points reduced from 1973-1989, before increasing to 25% from 1990-2000 and 37% from 2000-2022. A continuation of this trend would further reduce the buttressing potential of ice shelves, enhancing ice discharge and accelerating Antarctica's contribution to sea-level rise. This dataset contains point shapefiles that map the direction of change in the surface area of pinning points across the Antarctic Ice Sheet from 1973-1989, 1989-2000, 2000-2022 and 1973-2022. More details are available in the README. The dataset is related to the upcoming publication Miles & Bingham (in submission).