The Pine Island Glacier in West Antarctica has dramatically increased its speed since 2017, driven by the breakdown of its protective ice shelf. This acceleration raises concerns about faster sea-level rise from the region. Researchers link the changes to warming ocean waters undermining the shelf's structure.
Pine Island Glacier, Antarctica's fastest-flowing and the largest single contributor to global sea-level rise, has undergone a significant speedup. Data from the Copernicus Sentinel-1 satellite, combined with observations dating to the early 1970s, show the glacier's velocity rising from 2.2 kilometres per year in 1974 to 4 kilometres per year by 2008. Between 2017 and 2023, it surged to nearly 5 kilometres per year—a 20 percent increase over those six years and 113 percent since 1973.
This rapid movement has caused the glacier's grounding line—the transition from grounded ice to floating shelf—to retreat more than 30 kilometres. From 1973 to 2013, ice discharge from the glacier grew by over three-quarters. The West Antarctic ice sheet, including Pine Island and the nearby Thwaites Glacier, contains enough ice to elevate global sea levels by 5.3 metres if fully melted.
Sarah Wells-Moran of the University of Chicago and her team attribute the acceleration to the thinning and fracturing of the Pine Island ice shelf, which extends over the ocean and buttresses ice equivalent to 51 centimetres of sea-level rise. Warmer seawater has intruded beneath the shelf, causing its margins to detach in a process described as "unzipping." The researchers conclude that the shelf now offers "negligible buttressing" to upstream ice, hastening losses from West Antarctica.
Experts emphasize the implications. Sue Cook of the University of Tasmania notes that ice calving alone does not explain the speedup; instead, "increased damage in the shear margins of the glacier" is likely key. Ted Scambos of the University of Colorado warns that the shelf's loss could accelerate ocean circulation in Pine Island Bay, intensifying melting near the grounding line. Nerilie Abram of the Australian Antarctic Division states, "There is no doubt that ice loss from this region will continue to impact the world’s coastlines over the coming decades and centuries."
The findings, detailed in a preprint on EarthArXiv (DOI: 10.31223/X5047F), highlight the vulnerability of West Antarctica's ice to ocean warming, with potential long-term effects on global coastlines.
