Tidewater and lake-terminating glaciers are systematically thicker

Abstract Glaciers that terminate in the ocean or lakes exhibit unique dynamics that can drive rapid change. These dynamics, governed by many complex and interacting processes, challenge calibration and validation of physics-based models. We take a data-driven approach to quantify the imprint of glacier–ocean interactions on global non-ice sheet glacier ice volumes. Using curated datasets, we build a hierarchy of models that capture the influence of ice shelves and grounded marine termini. We find that tidewater and lake-terminating glaciers are systematically thicker than glaciers ending on land. Summed globally, this effect accounts for about 20% of non–ice-sheet glacier volume. Thicker ice is observed both for glaciers with ice shelves, where buttressing supports upstream ice, and for water-terminating glaciers without shelves. We interpret this result in terms of a simple mechanical model whereby water pressure permits thicker termini than possible in air, consistent with theoretical limits on ice cliff height. Our results highlight how ice–ocean interactions shape the equilibrium geometry of glaciers, offering a large-scale complement to process-based studies of calving and frontal melt. While most global glacier models omit these interactions, our analysis motivates their inclusion in forecasts of glacier change and sea level rise.