Last week, members of the TiPACCs team published a new paper in Nature Climate Changetitled “Ocean Warming as a Trigger for Irreversible Retreat of the Antarctic Ice Sheet.”

The study investigates the consequences of a regime shift in ocean conditions—from cold to warm—within the large ice shelf cavities of the Filchner-Ronne and Ross ice shelves, and its potential impact on the Antarctic ice sheet. The authors examine how much ice could be lost from the upstream catchments of these ice shelves and whether that loss would be irreversible, even if cold conditions were restored. To explore this, they used standalone ice sheet model simulations based on an ensemble of “warm-state” melt rates, which are outputs from ocean circulation model simulations conducted as part of the TiPACCs project.

The study’s main finding reveals that extreme melt rates could cause these catchments—which are currently in approximate mass balance—to contribute significantly to global sea level rise. Reversibility experiments further revealed that simply returning to present-day melt rates wouldn’t reverse the ice loss in certain areas, with some regions experiencing irreversible retreat. The Figure above shows example reversibility experiments, where the white-to-purple lines show the continued retreat of the grounding lines through time.

While the exact timing of a shift from cold to warm conditions in these ice shelf cavities remains uncertain, this research shows the potential risk of irreversible ice loss in two major sectors of the Antarctic ice sheet if such a transition occurs.