Ocean warming threatens the viability of 60% of Antarctic ice shelves.

Abstract

The disappearance of ice shelves, the floating margins of the Antarctic ice sheet that restrain the ice flow into the ocean^1-3, would strongly accelerate the Antarctic contribution to sea-level rise^4-6. Their viability in a warming world has motivated substantial work that focuses on the influence of the warming atmosphere^7-10. Here we revisit the concept of ice-shelf viability in a holistic manner, taking into account mass loss due to both the atmosphere and the ocean to estimate when it becomes almost impossible for the ice shelves to maintain their present-day shape. We show that for a scenario in which global warming remains largely below 2 °C, only 1 out of 64 ice shelves will become likely non-viable by 2300. For a scenario in which global warming reaches nearly 12 °C by 2300, many ice shelves become non-viable once global warming exceeds 4.5 °C, loss that is mainly due to an increase in ocean-induced melt. By 2150 and 2300, 26 and 38 ice shelves, respectively, become likely non-viable. Loss of ice-sheet regions restrained by these 38 ice shelves represent a sea-level rise potential of 10 m. Our estimates are latest bounds for reaching non-viability, and ice-shelf collapse could occur even earlier, in particular owing to the synergy with hydrofracturing.