Pine Island Glacier acceleration is now one of the clearest warning signs of accelerating ice loss in Antarctica. New satellite observations show that the glacier in West Antarctica is moving faster than ever due to the failure of the ice shelf that once restrained it.
Scientists have confirmed that structural damage to the Pine Island Ice Shelf has removed nearly all buttressing forces. Without this natural brake, ice is flowing into the ocean at an increasing rate. Because Pine Island Glacier is the largest Antarctic contributor to sea-level rise, this acceleration has global implications.
One of Antarcticaโs most important glaciers is now moving faster than ever. Scientists have identified the cause: the failure of the ice shelf that once restrained it.
The Pine Island Glacier in West Antarctica is the fastest-flowing glacier on the continent. It is also the single largest contributor to Antarctic sea-level rise. Over recent decades, the glacier has accelerated dramatically. New research shows that this change is driven by the rapid weakening of the Pine Island Ice Shelf. This floating barrier once acted as a powerful natural brake.
Critical Pillar of Antarctic Stability
Pine Island Glacier is a giant within Antarcticaโs ice system. Along with its neighbour, Thwaites Glacier, it forms one of the most unstable regions of the West Antarctic Ice Sheet. If this ice sheet were to collapse completely, global sea levels could rise by about 5.3 metres (17 feet). Such a rise would permanently reshape coastlines worldwide.
At the glacierโs seaward edge lies the Pine Island Ice Shelf. This vast floating platform extends into the Amundsen Sea. The shelf plays a crucial mechanical role. It buttresses the grounded glacier upstream and slows ice flow into the ocean. It also shields the glacierโs base from warm seawater. Before its decline, the shelf restrained ice equal to about 51 centimetres (20 inches) of potential global sea-level rise.
That protection is now rapidly vanishing.
Researchers led by Sarah Wells-Moran (University of Chicago) analysed satellite data from the Copernicus Sentinel-1 mission. They combined these observations with records dating back to the 1970s. This approach revealed a clear and sustained acceleration:
- 1974: ~2.2 km per year
- 2008: ~4.0 km per year
- 2017โ2023: nearly 5.0 km per year
This represents a 20% increase in just six years. Since the early 1970s, the glacierโs speed has increased by 113%.
The acceleration aligns with major structural changes. Ice discharge rose by more than 75% between 1973 and 2013. Over the same period, the glacierโs grounding line retreated more than 30 kilometres inland.
Why the Ice Shelf Is Failing
The team compared satellite observations with ice-flow models. Their results point to a clear driver. Warm ocean water is penetrating deeper beneath the ice shelf. This water thins the shelf from below and promotes fracturing.
Over time, the shelfโs side margins have weakened. They have effectively โunzippedโ from neighbouring ice. Large sections have detached as a result. The shelf has lost much of its structural strength.
Today, the Pine Island Ice Shelf provides almost no buttressing. Without this support, the glacier flows into the ocean far more rapidly.
Long-Term Warning For Sea Levels
Glaciologists describe this change as serious and enduring. Sue Cook (University of Tasmania) notes that normal iceberg calving cannot explain the acceleration. Damage along the glacierโs shear margins appears to be essential. Ted Scambos (University of Colorado) warns that the weakened shelf may enhance ocean circulation in Pine Island Bay. This circulation could draw in even more warm water. Nerilie Abram (Australian Antarctic Division) stresses that the shelfโs rapid failure shows how Antarctic ice loss will affect sea levels for centuries.
This is not a sudden collapse. However, it is a clear warning. The acceleration of Pine Island Glacier reveals how sensitive Antarctic ice is to ocean warming. It also suggests that key tipping points may already be underway.
References
Near-total loss of buttressing stresses observed on Pine Island Ice Shelf, West Antarctica
EarthArXiv
๐https://eartharxiv.org/repository/view/11574/
DOI:https://doi.org/10.31223/X5047F
