Revision 1

Accepted · first revision · record

Title: Is West Antarctic retreat already irreversible?
Plain: Much of the West Antarctic ice sheet rests on bedrock that deepens inland, so once the ice front starts retreating it may keep going on its own. The question is whether that process has already begun for glaciers like Thwaites.
Precise: For the Amundsen Sea sector (Thwaites and Pine Island glaciers), determine whether grounding lines have passed a marine ice-sheet instability threshold such that retreat continues under present or even reduced ocean forcing, accounting for bedrock uplift, ice-shelf buttressing and basal friction laws. An answer is a yes or no with the committed sea-level contribution (Amundsen Sea sector potential about 120 cm, whole West Antarctic ice sheet about 330 cm) and its timescale.
Settled by: Ensemble ice-sheet models constrained by observed grounding-line migration and bed topography that show whether retreat reverses when ocean forcing returns to preindustrial values.
Kind: well-posed
Answer type: yes-no
References: (empty)
Literature status: contested
Status note: (empty)
Posed since: 1978