Grounding lines are a key indicator of ice-sheet instability, because changes in their position reflect imbalance with the surround-ing ocean and affect the flow of inland ice. Although the grounding lines of several Antarctic glaciers have retreated rapidly due to ocean-driven melting, records are too scarce to assess the scale of the imbalance. Here, we combine satellite altimeter obser-vations of ice-elevation change and measurements of ice geometry to track grounding-line movement around the entire conti-nent, tripling the coverage of previous surveys.