Petermann Glacier’s floating ice tongue, which extends into the Nares Strait, is one of the longest remaining floating glaciers in Greenland. Experts say the recent calving was the glacier’s largest loss of floating ice since 2012 and the biggest calving event in the Arctic since 2020.

“We’ve anticipated this break for years,” Adam Garbo, a Ph.D. student from the University of Ottawa involved in the glacier’s monitoring program, said in a European Space Agency (ESA) press release. “Seeing it finally happen is remarkable. It’s a powerful reminder of how quickly these systems can change.”

Space Radar Recorded Massive Ice Break in a Remote Polar Region

Optical image of an ice piece breaking away from Petermann Glacier

(Image Courtesy of the ESA/Comprenicus Sentienl/M. Hammond (University of Leeds/ CC BY-SA 3.0 IGO)

Sentinel-1 captured the start of the event on Aug. 3, 2026, when a large crack appeared along the centerline of the ice tongue. One day later, a massive, flat-topped iceberg had separated from the glacier’s eastern side. The new ice island is not only roughly the size of Manhattan but is also up to 500 feet thick.

Unbothered by cloud cover or daylight conditions, Sentinel-1’s radar imaging system operates day and night and collects data on global landscape topography, ocean imagery, ocean surface winds, snow and sea ice cover, to name a few, according to ESA’s SentiWiki — a fitting tool for tracking remote polar glaciers.

A group of scientists from Canada and the U.K. has been using Sentinel-1 to document the growth, fractures and signs of instability of Petermann’s floating ice tongue in Greenland since 2019.

The Break Was a Long Time Coming, and More Could Follow

Signs of trouble had been building for months. In April 2026, researchers compared multiple radar observations using a technique called interferometry. The resulting images revealed deformation and spreading fractures in the ice tongue, providing an early look at the changes that eventually led to the August calving.

Petermann has experienced large calving events before, including major breaks in 2008, 2010, and 2012. But the latest event was the glacier’s biggest loss of floating ice in more than a decade. And researchers don’t think it will be the last: Two more large sections, measuring roughly 37 and 33 square miles, could break away as existing cracks continue to grow.

“While large, tabular icebergs are relatively common in the Southern Ocean around Antarctica, Arctic ice islands are far rarer,” explained Anna Crawford, a glaciologist from the University of Stirling, in the press release. “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.”