Add to ORKGA large volume of the East Antarctic Ice Sheet drains through the Totten Glacier (TG) and is thought to be a potential source of substantial global sea level rise over the coming centuries. We show the flow and surface height of floating part of TG, which buttresses the grounded component, have varied substantially over two decades (1989–2011), with variations in surface height and basal melt rates highly anti-correlated (r=0.70, p <0.05). Coupled glacier/ice-shelf simulations confirm ice flow and thickness respond to both basal melting of the ice shelf and grounding on bed obstacles. We conclude the observed variability of TG is primarily ocean-driven and enhanced ice-sheet dynamism, leading to upstream grounded ice loss, will occur from t...