An international research team led in part by the University of Ottawa reports that Petermann Glacier in northwest Greenland calved a 76.4 km² ice island on August 4, 2026, marking the glacier’s largest loss of floating ice since 2012 and the largest Arctic calving event since 2020.
The newly formed tabular iceberg detached from the glacier’s floating ice tongue and is estimated to be up to 150 metres thick. With a surface area roughly comparable to Manhattan Island, the ice island offers scientists a rare opportunity to study how large Arctic ice masses form, drift and break apart over time.
The event was detected by Adam Garbo, a PhD student in glaciology at uOttawa’s Department of Geography, Environment and Geomatics, as part of ongoing collaborations among the University of Ottawa, the University of Stirling, Environment and Climate Change Canada, Lancaster University, and the University of Leeds.
Years of monitoring helped researchers anticipate the break
The calving event was detected through long-term satellite monitoring that have tracked changes at Petermann Glacier since 2019. Researchers have been following the glacier’s floating ice tongue, documenting the growth of fractures and monitoring signs of instability over several years.
“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.”
Satellite imagery from the European Space Agency’s Sentinel-1 mission showed clear deterioration along the centreline of the ice tongue on August 3. By 20:00 UTC on August 4, the new ice island had detached from the eastern side of the glacier.
Rare Arctic ice islands offer valuable scientific insight
Large Arctic ice islands are less common than the large tabular icebergs regularly seen in the Antarctic. Because they can persist for years, they provide scientists with an important window into the processes that shape glacier retreat, ocean conditions and ice hazards in polar regions.
“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.”
Researchers say the recent calving is unlikely to be the last. Two additional large ice islands are expected to detach from Petermann Glacier in the near future as long-developing rifts continue to cut across the ice tongue. Those future calving events are projected to produce ice islands of approximately 94 km² and 84 km². Together with the newly detached ice island, they would reduce the Petermann ice tongue by about 254 km², or 22 per cent.
“We’ve anticipated this break for years, and seeing it finally happen is remarkable”
Adam Garbo
— PhD student in glaciology, uOttawa’s Department of Geography, Environment and Geomatics
Monitoring drift to support Arctic navigation
Beyond its scientific importance, the new ice island also has practical implications for marine safety. As these massive blocks of ice drift and gradually fracture, they can create hazards for shipping and offshore operations.
As with previous Arctic ice shelf calvings, Environment and Climate Change Canada is closely monitoring the movement of the new ice island and assessing potential hazards to Arctic 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 to monitor the aftermath of the event using satellite imagery, aerial observations and tracking data as part of a broader effort to understand the mechanisms driving the calving and retreat of Arctic ice shelves.
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