Revisiting Antarctic ice loss due to marine ice cliff instability

Edwards, Tamsin L.; Brandon, Mark A.; Durand, Gael; Edwards, Neil R.; Golledge, Nicholas R.; Holden, Philip; Nias, Isabel J.; Payne, Antony J.; Ritz, Catherine and Wernecke, Andreas (2019). Revisiting Antarctic ice loss due to marine ice cliff instability. Nature, 566 pp. 58–64.

DOI: https://doi.org/10.1038/s41586-019-0901-4

Abstract

Predictions for sea-level rise from Antarctica this century range from zero to over one metre. The highest are driven by the controversial ‘marine ice cliff instability’ (MICI) hypothesis, where coastal ice cliffs rapidly collapse after ice shelves disintegrate from surface and sub-shelf melting caused by global warming. Here we quantify ice sheet modelling uncertainties for the MICI study and show the probability distributions are skewed towards lower values (most likely value: 45 cm under very high greenhouse gas concentrations). However, MICI is not required to reproduce sea-level changes in the mid-Pliocene, Last Interglacial or 1992-2017, and without it the results agree with previous studies (all 95th percentiles are less than 43 cm). We therefore find previous interpretations of the MICI projections over-estimate sea-level rise this century. The hypothesis is still poorly-constrained: confidence in projections with MICI would require much greater diversity in models of ice shelf vulnerability and ice cliff collapse.