Ice shelf buttressing – a comparison of Antarctic ice shelves in a transient evolution

The accelerating loss of grounded ice in Antarctica at present is mainly caused by a thinning of the surrounding ice shelves and a subsequent reduction in buttressing. The adjacent ice streams speed-up due to the decrease in back-pressure from the weakened ice shelves. Most methods typically used to quantify the buttressing of ice shelves analyze the state at individual locations along the grounding line or within the shelf. Based on the stress-balance at the grounding line, we here present a method to quantify shelf-wide buttressing values in Antarctica. The Parallel Ice Sheet Model (PISM) and Úa are used in diagnostic as well as in transient experiments to compare the buttressing effect of major ice shelves in Antarctica. We show an increase in buttressing in more confined ice shelves and a decrease for higher basal melt rates. The buttressing decreases consistently across different ice shelves and idealized ocean warming scenarios. The newly-developed, shelf-wide buttressing metrics can be used to understand the role of ice shelves in changing climate conditions.