Experiments demonstrate catastrophic collapse of Antarctic ice will not happen

Minchew and Behn (2019) have tested the theory that massive ice cliffs on the coast of Antarctica could collapse, causing rapid and catastrophic sea level rise. In their paper: Marine Ice Cliff Instability Mitigated by Slow Removal of Ice Shelves, they note:

The seaward flow of ice from grounded ice sheets to the ocean is often resisted by the buttressing effect of floating ice shelves. These ice shelves risk collapsing as the climate warms, potentially exposing tall cliff faces. Some suggest ice cliffs taller than ~90 m could collapse under their own weight, exposing taller cliffs further to the interior of a thickening ice sheet, leading to runaway ice‐sheet retreat. This model, however, is based on studies of pre‐existing cliffs found at calving fronts.

If the ice shelf is removed rapidly, deformation may be concentrated, forming vertical cracks and potentially leading to the collapse of small (e.g., 90‐m) cliffs. However, if we consider ice‐shelf collapse timescales longer than a few days (consistent with observations), deformation is distributed throughout the cliff, which flows viscously rather than collapsing. We expect including the effects of such ice‐shelf collapse timescales in future ice‐sheet models would mitigate runaway cliff collapse and reduce predicted ice‐sheet mass loss.

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