Slowdown of Shirase Glacier caused by strengthening alongshore winds

Abstract. Observations have confirmed basal melt rates of up to 16 m a-1 underneath the Shirase ice tongue in East Antarctica. These high basal melt rates are caused by intrusions of warm modified Circumpolar Deep Water (mCDW) onto the continental shelf, a mechanism responsible for widespread mass loss in West Antarctica, together with parts of Wilkes Land. In contrast to those regions, the catchment of Shirase Glacier has been gaining mass, a trend attributed to increased precipitation. Here, we report on the dynamical ocean-driven slowdown, thickening and grounding line advance of Shirase Glacier, in response to strengthening easterly winds that reduce mCDW inflow and decrease basal melt rates. Our findings are significant because they demonstrate that warm water regimes are not universally associated with glacier acceleration and mass loss in Antarctica, and they highlight the overlooked role of ocean forcing in the recent mass gain of the Dronning Maud Land sector.