Marine Ice Sheet Instability & Calving Front

This is a flowline model of a marine-terminating ice sheet — the same geometry as West Antarctica's Thwaites and Pine Island Glaciers. Ice thickness evolves under a simplified shallow-ice mass balance, the boundary between grounded ice and floating ice shelf is located every frame from the Archimedes flotation criterion, and grounding-line discharge follows the steep thickness-dependence identified by Schoof (2007). Switch the bedrock between a retrograde (reverse) slope and a prograde slope to see why bed geometry alone can turn a stable margin into a self-sustaining runaway retreat, dial up sub-shelf ocean melting to trigger it directly, and watch tabular icebergs calve off the ice-shelf front once it thins past its structural limit.