Pine Island Glacier Ice Shelf (West Antarctica) is more sensitive to climate conditions than to rheological parameters on multidecadal timescales Physical Review E

Antarctic ice shelves, floating extensions of the Antarctic Ice Sheet, regulate the ice discharge from the ice-sheet interior into the surrounding oceans and, as a result, the ice-sheet contribution to the sea level. On a timescale longer than several months, the flow of bodies of ice, such as ice sheets and ice shelves, is controlled by the ice non-Newtonian viscosity and its rheological parameters, i.e., the ice stiffness and the exponent of the rheology power-law functional form. Recent studies suggest that the value of the rheological exponent may be higher than that typically used in studies of ice shelves. It is unclear, however, what effects this difference might have on the behavior of ice shelves in general and particularly on multidecadal timescales. In order to evaluate such effects on the behavior of the Pine Island Glacier Ice Shelf, one of the fastest changing regions in Antarctica, a suite of numerical simulations has been performed. In these simulations, the ice-shelf rheological parameters have been constrained by means of inverse methods using remote-sensing observations. The results show that for the same submarine melting and different rheological parameters, the difference between the ice-shelf states (thickness and speed) is of the order of 5%. In contrast, for the same rheological parameters and different submarine melting, the difference between the ice-shelf states is significantly larger, of the order of 15% for ice speed and 40% for ice thickness. These results suggest that ice shelves have much higher sensitivity to the impacts of climate conditions, such as submarine melting, than to their rheological parameters. Grant no. NA23OAR4320198