The Amundsen Sea Embayment in West Antarctica is experiencing the most
rapid mass loss and grounding line retreat in Antarctica. Its glaciers
are vulnerable to retreat through marine ice sheet instability. There is
uncertainty over the timing and magnitude of retreat and in particular
the response of Thwaites Glacier to thinning of its ice shelf and to
ocean forced retreat of its neighbouring glaciers. We find that the
response of Thwaites to melting of its ice shelf is limited. However,
retreat of its neighbours can drive substantial retreat in Thwaites. We
examine the impact of ice shelf buttressing on the stability of the
grounding line. Further experiments show that extreme ice shelf forcings
are required to trigger retreat in Thwaites in isolation. We also
demonstrate that long-term stability is sensitive to the treatment of
basal stress near the grounding line.