Abstract

Changes in ocean melting of ice shelves are important to sea-level rise and ocean water mass transformations. Idealised modelling studies find that the melting of ice shelves varies as a quadratic function of ocean temperature. The ocean warms, the buoyant meltwater-driven circulation accelerates, and the melting increases as the product of the two. However, this result is derived from a series of equilibrium simulations, where ice shelves are subjected to a given thermal forcing until the melt rate becomes steady. In this talk I will consider instead the transient response of ice shelves to ocean temperature change, using unsteady simulations of ice shelves subjected to an oscillating temperature. For ‘slowly-varying’ forcing, the melt rate varies along the quadratic equilibrium curve, but for ‘rapidly-varying’ forcing the melting deviates from the curve in interesting ways. Ice shelves forced by warm water have high melt rates, high sensitivity of those melt rates to ocean temperature change, and a short timescale over which that high sensitivity is manifest.