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Retreat of Pine Island Glacier controlled by marine ice-sheet instability

2014; Nature Portfolio; Volume: 4; Issue: 2 Linguagem: Inglês

10.1038/nclimate2094

1758-6798

Lionel Favier, G. Durand, Stephen Cornford, G. Hilmar Gudmundsson, Olivier Gagliardini, Fabien Gillet‐Chaulet, Thomas Zwinger, A. J. Payne, A. M. Le Brocq,

Arctic and Antarctic ice dynamics

At present the Pine Island Glacier in West Antarctica is thinning and its grounding line has retreated. This work uses three ice-flow models to investigate the stability of the glacier and finds that the grounding line could retreat a further 40 km, which is equivalent to a rise in sea level of 3.5–10 mm over a 20 year period. Over the past 40 years Pine Island Glacier in West Antarctica has thinned at an accelerating rate1,2,3, so that at present it is the largest single contributor to sea-level rise in Antarctica4. In recent years, the grounding line, which separates the grounded ice sheet from the floating ice shelf, has retreated by tens of kilometres5. At present, the grounding line is crossing a retrograde bedrock slope that lies well below sea level, raising the possibility that the glacier is susceptible to the marine ice-sheet instability mechanism6,7,8. Here, using three state-of-the-art ice-flow models9,10,11, we show that Pine Island Glacier’s grounding line is probably engaged in an unstable 40 km retreat. The associated mass loss increases substantially over the course of our simulations from the average value of 20 Gt yr−1 observed for the 1992–2011 period4, up to and above 100 Gt yr−1, equivalent to 3.5–10 mm eustatic sea-level rise over the following 20 years. Mass loss remains elevated from then on, ranging from 60 to 120 Gt yr−1.