The tipping points and early warning indicators for Pine Island Glacier, West Antarctica

• Main Authors: Rosier, Sebastian H. R., Reese, Ronja, Donges, Jonathan F., De Rydt, Jan, Gudmundsson, G. Hilmar, Winkelmann, Ricarda
• Format: Article in Journal/Newspaper
• Language: English
• Published: Katlenburg-Lindau : Copernicus 2021
• Subjects: coastal zone management; collapse; glacier dynamics; glacier mass balance; global warming; ice flow; ice sheet; sea ice; sea level change; Amundsen Sea; Antarctic Ice Sheet; Antarctica; Pine Island Glacier; Southern Ocean; Thwaites Glacier; West Antarctic Ice Sheet; West Antarctica; ddc:910; Antarctic; The Antarctic; Antarc*; Ice Sheet; Pine Island; Sea ice; The Cryosphere
• Online Access: https://oa.tib.eu/renate/handle/123456789/10581; https://doi.org/10.34657/9617

Mass loss from the Antarctic Ice Sheet is the main source of uncertainty in projections of future sea-level rise, with important implications for coastal regions worldwide. Central to ongoing and future changes is the marine ice sheet instability: once a critical threshold, or tipping point, is crossed, ice internal dynamics can drive a self-sustaining retreat committing a glacier to irreversible, rapid and substantial ice loss. This process might have already been triggered in the Amundsen Sea region, where Pine Island and Thwaites glaciers dominate the current mass loss from Antarctica, but modelling and observational techniques have not been able to establish this rigorously, leading to divergent views on the future mass loss of the West Antarctic Ice Sheet. Here, we aim at closing this knowledge gap by conducting a systematic investigation of the stability regime of Pine Island Glacier. To this end we show that early warning indicators in model simulations robustly detect the onset of the marine ice sheet instability. We are thereby able to identify three distinct tipping points in response to increases in ocean-induced melt. The third and final event, triggered by an ocean warming of approximately 1.2 ∘C from the steady-state model configuration, leads to a retreat of the entire glacier that could initiate a collapse of the West Antarctic Ice Sheet.