The alarm began with an accident on 2 November, when a tracked radar sled from a Philippine-led survey team tipped into a fresh crack on the Morrow Ice Shelf, 70 km (43 miles) from the team’s coastal field camp in Antarctica. Nobody was hurt, but the broken tow line and damaged sensor cable forced researchers to check their other instruments — and revealed that 620 sq km (240 sq miles) of shelf had fractured and dispersed over roughly 11 hours.
The shelf’s floating ice does not directly hold back the sea. Its collapse matters because it had been pressing against the Morrow Glacier, slowing ice flowing from land into the ocean. New satellite readings show the glacier’s centre moving at 4.6 km a year (2.9 miles a year), up from 1.8 km a year (1.1 miles a year) in 2024. Researchers say the speed-up is preliminary, but the change is too large to dismiss.
The glacier behind the fracture
Enzo A. Deverso, a glaciologist with the Manila Cryosphere Observatory, said the shelf’s break-up followed years of widening fractures and warmer water beneath its edge. The survey team’s records, checked against radar images from two separate satellites, show the ice front retreating by as much as 19 km (12 miles) in a day. “The shelf was a brace, not a lid. We have watched the brace come apart,” he said.
The team’s first model estimates that the glacier could add 3cm to 14cm (1.2 to 5.5 inches) to global mean sea level by 2100 beyond the expected rise from other sources. That is a range, not a forecast: the upper end assumes the glacier keeps accelerating and neighbouring ice streams follow it. The whole basin contains enough grounded ice to raise seas by about 0.9 metres (3 feet) over a much longer period.
The shelf was a brace, not a lid. We have watched the brace come apart.
Enzo A. Deverso, glaciologist
Sibilla R. D'amico, who directs the observatory’s sea-level group, said the 14cm figure should not be read as an imminent wave or a prediction that every coast will rise by the same amount. But extra sea-level rise would compound tides, storm surges and land sinking in parts of the Philippines. “For Manila Bay, a few centimetres are not a small number when drainage and high tides already meet,” she said.
The Philippine Climate Service urged residents not to interpret the collapse as a reason for immediate evacuation. Its director, Harsanto Hardiansyah, said the new measurements did not change coastal flood alerts and that the glacier remained thousands of kilometres away. Deverso disputed the reassurance’s emphasis: “There is no wave coming from Antarctica. There is a longer, harder problem arriving at our shorelines, and the planning clock has started.”
Coastal plans face a faster clock
Officials are discussing a rapid review of sea-level assumptions used for drainage, port and shoreline projects, along with a request for more frequent satellite coverage of the glacier. The climate service says it will publish an updated coastal-risk bulletin by 20 November. D'amico wants the review to include high-end projections rather than treating them as too unlikely to plan around.
The local consequences would build over decades, not hours. In low-lying districts around Manila Bay, higher baseline water can make routine high tides more damaging and leave less room for heavy rain to drain. Researchers say the next critical evidence will be whether the glacier’s speed remains elevated through the Antarctic summer and whether new fractures reach its grounded edge.
The sled accident did not cause the shelf to fail, the team stressed; it exposed how quickly the field picture had changed. Deverso said the damaged instrument would be replaced, but the bigger gap was time: “We can measure what has happened. We cannot yet say how far the retreat will run.”
