Collapse of the West Antarctic Ice Sheet after local destabilization of the Amundsen Basin

• Published in: Proceedings of the National Academy of Sciences
• Main Authors: Feldmann, Johannes, Levermann, Anders (Prof. Dr.)
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2015
• Subjects: Institut für Physik und Astronomie; Amundsen Basin; Amundsen Sea; Antarctic; The Antarctic; West Antarctic Ice Sheet; West Antarctica; amundsen basin; Antarc*; Antarctica; Ice Sheet; Ice Shelf; Ice Shelves
• Online Access: https://publishup.uni-potsdam.de/frontdoor/index/index/docId/38443; https://doi.org/10.1073/pnas.1512482112

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.