Differences in calving styles at tidewater glaciers explained by horizontal stress balance

The crevasse-depth approach to calving remains promising but in its classic form struggles to produce calving without including additional stresses, such as from meltwater in surface crevasses, which may not be realistic. Here, we present new analytical results that account for stress concentration under crevassing, following recent work by Buck (2023). Focusing on grounded tidewater glaciers, we further consider non-zero ice tensile strength and the potential influence of basal friction. This results in a revised version of the crevasse-depth law that produces plausible calving regimes without needing to invoke added external stresses. The revised law has an ice thickness threshold of approximately 400 m, below which the ice tensile strength is able to resist full-thickness calving, suggesting that glaciers with thicknesses above or below this threshold should have differing dominant calving style. We discuss strong observational support for this finding, and consider the role of the revised formulation in the search for an overall calving law.