Ar-Rehman

Major ice loss from Greenland glacier recorded by Sentinel-1

A massive slab of floating ice broke away from Petermann Glacier in northwest Greenland on 04 August, 2026, creating a 76.4 km² ice island. An international research group led in part by the University of Ottawa says it was Petermann’s largest floating ice loss since 2012 and the biggest Arctic calving event since 2020. The tabular iceberg separated from the glacier’s floating ice tongue and may be as much as 150 meters thick. Its surface area is roughly comparable to Manhattan Island, giving researchers an unusual chance to follow how a large Arctic ice mass forms, travels, and fragments over time. The event reveals once again how rapidly Earth’s polar landscapes can change. Adam Garbo, a PhD student in glaciology at uOttawa’s Department of Geography, Environment, and Geomatics, identified the event through an ongoing collaboration involving the University of Ottawa, the University of Stirling, Environment and Climate Change Canada, Lancaster University, and the University of Leeds. Researchers had been watching this part of Petermann Glacier for years. Long-term satellite observations dating back to 2019 documented changes in the floating ice tongue, including expanding fractures and other signs that the structure was becoming unstable. “Petermann Glacier has long been one of Greenland’s largest remaining ice tongues,” says Garbo. “We’ve anticipated this break for years, and seeing it finally happen is remarkable.”

Interferometric observations of Petermann acquired in April also revealed deformation and fractures within the ice tongue, providing a detailed picture of changes which developed months prior to the calving. Petermann Glacier has a well-documented history of major calving events, including the formation of large ice islands in 2008, 2010 and 2012. However, since 2012, its floating ice tongue has remained relatively stable, despite several smaller-scale calving events. The latest calving is unlikely to be the last major change at Petermann Glacier. Two further large ice islands, with estimated surface areas of approximately 97 and 87 sq km, could detach as existing rifts continue to propagate across the floating ice tongue. Anna Crawford, from the University of Stirling, commented, “While large, tabular icebergs are relatively common in the Southern Ocean around Antarctica, Arctic ice islands are far rarer. By studying Arctic ice islands, we will gain knowledge that can be transferred across polar regions. This is critical for understanding how the calving and deterioration of ice islands impact glacier dynamics, sea-level rise and the ocean environment.”

Images from the European Space Agency’s Sentinel-1 mission showed obvious weakening along the centerline of the ice tongue on 03 August, 2026. By 20:00 UTC the following day, the ice island had separated from the glacier’s eastern side. Large tabular icebergs are common around Antarctica, but comparable Arctic ice islands are much rarer. Some can survive for years, allowing scientists to observe the forces which influence glacier retreat, ocean conditions and ice-related hazards across polar environments. “While large, tabular icebergs are relatively common in the Southern Ocean that surrounds the Antarctic Ice sheet, Arctic ice islands are far rarer,” explains Dr. Anna Crawford of the University of Stirling. “By studying Arctic ice islands, we will gain knowledge that can be transferred across Polar regions.” Because Sentinel-1 carries a radar, it can observe day and night and through cloud cover, making it particularly well-suited to monitoring remote Arctic glaciers. Using this Sentinel-1 radar imagery, an international team of researchers, partially funded through ESA’s FutureEO ARCTEX project, has been monitoring Petermann Glacier since 2019. The collaboration brings together scientists from the University of Ottawa in Canada, the Universities of Stirling, Lancaster and Leeds in the UK, and the Canadian Ice Service of Environment and Climate Change Canada, who have been documenting the gradual growth of fractures and increasing signs of instability in the glacier’s floating ice tongue.

The August event may be only the first of several major losses. Researchers expect two more large ice islands to break away from Petermann Glacier in the near future as long as developing rifts continue extending across the floating ice tongue. Those events are projected to create ice islands measuring about 94 km² and 84 km². Combined with the newly detached island, the losses would remove roughly 254 km² from the Petermann ice tongue, equivalent to about 22%. The detailed Sentinel-1 interferogram showing the location and growth of fractures on Petermann Glacier was made possible because of one-day repeat Sentinel-1 synthetic aperture radar images captured in the Sentinel-1C and Sentinel-1D tandem phase during the commissioning of the newly launched Sentinel-1D satellite. These data allowed very detailed measurements of fracture propagation across the ice shelf, and ice tongue surface motion with ocean tides, in the lead up to the iceberg calving event. Molly Hammond, a PhD student from the University of Leeds, who processed the Sentinel-1 data, said, “The changes we observed on Petermann Glacier were occurring very rapidly in the lead up to the iceberg calving event, so it was incredibly exciting to monitor the crack propagation with interferometry in near-real time. This has demonstrated the incredible value of one-day repeat synthetic aperture data.”

ESA’s Martin Wearing noted, “This type of large tabular iceberg is relatively rare in the Arctic, making this calving event a unique opportunity to study how such a vast ice mass drifts, evolves and eventually breaks apart. “Satellite missions such as Sentinel-1 provide the systematic, long-term observations needed to track these changes, helping scientists better understand the processes driving calving and the wider impacts on the polar environment, and ultimately the Earth system as a whole. “Alongside Europe’s excellent Earth observation missions, we are pleased to see the ARCTEX project supporting this work and enabling further scientific investigation of the rapidly evolving Arctic.” The research team will continue to observe both Petermann Glacier and the newly calved iceberg using satellite imagery, aerial observations and tracking data, following its movement and fragmentation over time. These measurements will provide further insight into the behaviour of large Arctic ice islands and the processes shaping the evolution of Petermann Glacier. The calving also has practical implications for Arctic navigation and offshore operations. Environment and Climate Change Canada is monitoring the iceberg’s trajectory and assessing potential risks to shipping routes and infrastructure. Such large ice masses can remain in the ocean for years, gradually breaking apart into smaller fragments that can be increasingly difficult to detect and track.

The new ice island is also important for marine safety. As enormous blocks of floating ice move through Arctic waters and gradually break into smaller pieces, they can pose risks to ships and offshore operations. Environment and Climate Change Canada is tracking the island’s movement, as it has done after earlier Arctic ice shelf calving events, while evaluating possible threats to navigation and offshore infrastructure. “These are thick blocks of ice that can drift for years,” specifies Dr. Abigail Dalton of the Canadian Ice Service, Environment and Climate Change Canada. “Over time, they fracture into smaller, harder-to-track pieces that pose hazards to vessels and resource operations.” Garbo and his collaborators will continue following the aftermath with satellite imagery, aerial observations, and tracking data as they work to better understand the processes responsible for calving and retreat across Arctic ice shelves for further study.