Evolution of Ice Tensile Strength With Grain Size: Implications for Future Mass Loss From Pine Island Glacier

Abstract Fracture development weakens glacier ice, enabling more rapid flow and mass loss. Modeling this fracture evolution depends on a threshold parameter representing the strength of ice. However, the value of ice strength is treated as fixed in space and time despite evidence that it evolves with ice material properties. We investigate the effect of evolving ice strength as a function of ice grain size, the average size of ice crystals, on fracture evolution and estimates of mass loss from Pine Island Glacier. Coupling ice strength to grain size produces temporal and spatial variation in ice strength and, consequently, different spatial patterns in fracture density than using a constant ice strength. This enhances mass loss and may explain the discrepancy between ice strength estimates in ice sheet observations and laboratory experiments. These results suggest the importance of understanding the evolution of ice material properties and its role in ice fracture.