A massive chunk of Greenland’s Petermann Glacier has broken away, forming an iceberg the size of Manhattan in what scientists say is the most significant Arctic calving event recorded in years.
As the dramatic event unfolded, the European Space Agency’s (ESA) Copernicus Sentinel-1 mission captured the breakup on August 4, as the 29-square-mile ice tongue detached from the eastern edge of Petermann Glacier.
The new “ice island,” also known as a tabular iceberg, is estimated to be close to 500 feet thick and was produced by an event that experts believe to represent the single largest loss of floating ice since 2012, and the most massive calving event anywhere in the Arctic since 2020.
Satellites Reveal a Rapid Iceberg Breakup
Evidence of an imminent calving event had begun showing months ago in the form of cracks in the glacier. On August 3, Sentinel-1 radar imagery revealed significant deterioration that was showing along the center of the glacier’s ice tongue.
Within hours, the massive section had separated, all as scientists and crew aboard the RRS Sir David Attenborough watched as cameras captured the remarkable display unfolding.
The crewmembers aboard the nearby vessel weren’t the only ones armed with cameras who were observing the massive breakup. For many years, an international team of researchers has been monitoring conditions on Petermann Glacier using Sentinel-1 imagery. Since 2019, a series of tracking and expanding fractures and other clear signs of instability have gradually worsened.
Additionally, interferometric measurements collected earlier in 2026 showed signs that deformation and fractures were spreading through the ice tongue in advance of a likely break, allowing scientists both on-site and observing via satellites in orbit to plan for the event.
Iceberg Break Antipated for Years
“Petermann Glacier has long been one of Greenland’s largest remaining ice tongues,” said University of Ottawa PhD student Adam Garbo, one of the many researchers involved in monitoring the glacier prior to the calving event.
“We’ve anticipated this break for years, and seeing it finally happen is remarkable,” Garbo said in a statement. “It’s a powerful reminder of how quickly these systems can change.”
This event was by no means the first time that the Petermann Glacier has undergone a major calving event. In 2008, 2010, and in 2012, similar significant ice losses were logged, although its floating ice tongue had remained mostly stable since that time.
The recent event signals the end of that period of relative stability. Additionally, researchers say two more sections—measuring around 97 and 87 square kilometers—are likely to detach as existing rifts continue to appear and gradually separate.
Sentinel-1 Spots a Massive Break Up Event
With the help of the ESA’s Sentinel-1C and the recently launched Sentinel-1D satellites, a remarkably detailed view of the calving event was made possible. During its commissioning period, Sentinel-1D and its predecessor satellite achieved one-day repeat synthetic aperture radar observations.
The resulting interferograms allowed scientists to examine how fractures propagated, and aalso how the floating ice responded to factors that include ocean water movement in the vicinity prior to the separation.
“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,” said University of Leeds PhD student Molly Hammond in a statement.
Satellites like those with the Sentinel mission are especially useful for observations in polar regions since their radar systems allow researchers to observe the Earth’s surface even when cloud coverage or darkness would normally obscure visibility. This allows the ability to continuously monitor activity around these remote glaciers, and a chance to trek the new ice island as it continues to drift.
Ongoing Monitoring After a Rare Event
“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,” ESA researcher Martin Wearing said in a statement.
Although the iceberg currently poses no practical concerns, Environment and Climate Change Canada is currently monitoring the iceberg’s movement, and will provide assessments about whether it could pose any risk to Arctic shipping and offshore infrastructure in the months ahead.
Those monitoring efforts will likely continue into the foreseeable future, since massive ice islands as large as the newly formed iceberg can survive for many years before they eventually undergo fragmenting of their own, dispersing smaller pieces into the surrounding ocean. These smaller pieces can be much more difficult to track, and thereby could pose greater risks.
For now, scientists plan to continue watching the new ice island, which will offer new insights into Arctic glacier dynamics, as well as the changes that are impacting one of Greenland’s most closely watched glaciers.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.