Petermann Glacier Calves a Massive Iceberg in Greenland in 2026

Summer is peak iceberg season in Greenland’s glacier-fed fjords, and 2026 brought a major calving event. On August 4, a huge plate-shaped iceberg broke away from Petermann Glacier along Greenland’s northwestern coast. Measuring approximately 76 square kilometers (29 square miles), the new ice island was about the size of St. Thomas in the U.S. Virgin Islands.

Iceberg calving is a natural part of a tidewater glacier’s life cycle. However, scientists closely monitor changes in Petermann Glacier because the glacier acts as an important pathway for ice flowing from the Greenland Ice Sheet into the ocean. Researchers track cracks, ice loss, glacier movement, and other signs of instability that could influence future sea-level rise.

The 2026 Petermann Glacier calving event was first identified by Adam Garbo, a glaciology doctoral student at the University of Ottawa, using imagery from the European Space Agency’s Sentinel-1 satellite. Garbo and an international team of researchers use satellite remote sensing to monitor glacier ice tongues and track changes in Greenland’s coastal ice.

Scientists reported that the iceberg, also known as an “ice island,” covered just over 76 square kilometers when it separated from the glacier. It was the largest ice island to break away from Petermann Glacier since 2012, when a calving event produced an ice island measuring approximately 130 square kilometers. Earlier major calving events occurred in 2008, producing an ice island of about 31 square kilometers, and in 2010, when an ice island larger than 250 square kilometers broke free.

The August 2026 calving event could have produced an even larger iceberg. Garbo and his colleagues had been monitoring several major cracks that appeared likely to cut through Petermann Glacier’s floating ice tongue. Instead, the ice fractured along a different crack, creating a smaller ice island than researchers initially anticipated.

“What surprised us was that the calving went through another fracture, creating a smaller ice island than we had originally expected,” Garbo said. By late August, two additional large cracks remained visible. If they eventually reach the glacier’s edge, they could produce new ice islands measuring approximately 94 and 84 square kilometers. The timing of those future calving events remains uncertain.

Garbo and glaciologist Mauri Pärt of Nichols College continued to track the iceberg with imagery from the NASA-USGS Landsat satellite program. The ice island drifted through Petermann Fjord toward the Nares Strait, moving an average of approximately three kilometers per day during the week after it separated from the glacier.

The iceberg eventually reached the junction between Petermann Fjord and Nares Strait, where it encountered a small rocky outcrop known as Joe Island, or Jor Ø. The interaction was captured by Landsat 9’s Operational Land Imager on August 23 and 24, 2026. Satellite images show the ice island maneuvering near the rocky obstacle at the entrance to the fjord.

Joe Island is one of the first obstacles encountered by ice islands leaving Petermann Fjord. Previous encounters with the outcrop have caused icebergs to split, including the large ice island produced by Petermann Glacier in 2010. Because Petermann’s floating ice tongue is relatively thin and fragile compared with ice from glaciers such as Greenland’s Jakobshavn and Helheim, as well as many large Antarctic ice shelves, researchers expected the collision could cause additional fragmentation.

“We were closely monitoring the interaction with Joe Island and were impressed that it survived the interaction without further fragmentation,” Garbo said.

The newly formed ice island was estimated to be less than 150 meters thick at the time of calving. Winds, surface currents, tides, and ocean circulation carried it out of Petermann Fjord and toward the Nares Strait. Satellite imagery later showed the iceberg changing direction as it moved away from Joe Island and continued southwest through the strait.

As the iceberg drifts, melting and mechanical stress from tides, waves, winds, and ocean currents will gradually break it into smaller pieces. Some thick icebergs calved from tidewater glaciers can become grounded on the seafloor inside a fjord. Floating ice islands may also become stranded later in their journey, as has occurred near the coasts of Coburg Island and Baffin Island.

Large ice islands and iceberg debris can travel long distances, creating potential hazards for ships, marine operations, and coastal infrastructure. At the same time, melting icebergs release freshwater into the ocean and contribute to the movement of freshwater through Arctic marine ecosystems.

NASA Earth Observatory image by Lauren Dauphin, using Landsat data from the United States Geological Survey. Story by Kathryn Hansen.

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