TY  - JOUR
A1  - Feldmann, Johannes
A1  - Levermann, Anders
T1  - Collapse of the West Antarctic Ice Sheet after local destabilization of the Amundsen Basin
JF  - Proceedings of the National Academy of Sciences of the United States of America
N2  - The future evolution of the Antarctic Ice Sheet represents the largest uncertainty in sea-level projections of this and upcoming centuries. Recently, satellite observations and high-resolution simulations have suggested the initiation of an ice-sheet instability in the Amundsen Sea sector of West Antarctica, caused by the last decades' enhanced basal ice-shelf melting. Whether this localized destabilization will yield a full discharge of marine ice from West Antarctica, associated with a global sea-level rise of more than 3 m, or whether the ice loss is limited by ice dynamics and topographic features, is unclear. Here we show that in the Parallel Ice Sheet Model, a local destabilization causes a complete disintegration of the marine ice in West Antarctica. In our simulations, at 5-km horizontal resolution, the region disequilibrates after 60 y of currently observed melt rates. Thereafter, the marine ice-sheet instability fully unfolds and is not halted by topographic features. In fact, the ice loss in Amundsen Sea sector shifts the catchment's ice divide toward the Filchner-Ronne and Ross ice shelves, which initiates grounding-line retreat there. Our simulations suggest that if a destabilization of Amundsen Sea sector has indeed been initiated, Antarctica will irrevocably contribute at least 3 m to global sea-level rise during the coming centuries to millennia.
KW  - West Antarctic Ice Sheet
KW  - sea-level rise
KW  - tipping point
KW  - instability
KW  - marine ice-sheet instability
Y1  - 2015
U6  - https://doi.org/10.1073/pnas.1512482112
SN  - 0027-8424
VL  - 112
IS  - 46
SP  - 14191
EP  - 14196
PB  - National Acad. of Sciences
CY  - Washington
ER  -