Environmental Science and Engineering Seminar

Most of the mass loss from the Antarctic Ice Sheet occurs through glaciers and ice streams, where fast-flow is partially controlled by rapid ice deformation in the margins. Deformation drives thermomechanical and recrystallization processes that alters ice rheology and influences further deformation, a feedback which may destabilize glaciers. However, few models account for the feedback between deformation and recrystallization and fewer models incorporate these feedbacks into projections of ice-sheet behavior. Here, I evaluate the effects of dynamic recrystallization in glacial shear zones. I derive an idealized model for grain-size that accounts for migration recrystallization, a process likely active in regions of rapid deformation. I show that recrystallization processes may make these regions of ice streams more vulnerable to fracture and may locally reduce ice viscosity, encouraging fast flow. I further propose a framework for incorporating softening effects of deformation-induced processes into models of ice flow, which will enable the inclusion of rheological feedbacks into projections of ice-sheet behavior.