A Manhattan-Sized Iceberg Breaks Off Greenland's Petermann Glacier

The European Space Agency's Sentinel-1 satellite has captured a major calving event at the Petermann Glacier in northwestern Greenland. A day earlier, images had shown visible cracks forming in the glacier's floating ice tongue, and by the following day, a massive block of ice had broken away from its eastern edge.

The result was a tabular iceberg covering roughly 76 square kilometres — about the size of Manhattan. Its thickness is estimated at up to 150 metres, making it the largest calving event from Petermann's floating ice shelf in the past 14 years.

Scientists had been expecting it for years

"Petermann Glacier has long been one of Greenland's largest glaciers, with an extensive floating ice shelf. We've been anticipating this calving for years, and it has finally happened. It's a reminder of just how quickly glaciers can change," said Adam Garbo of the University of Ottawa.

Similarly large calving events from this glacier were recorded in 2008, 2010 and 2012, after which its floating section remained relatively stable. However, radar measurements taken in April this year revealed deformations and cracks that gradually widened over time.

Keeping an eye on the ice giant

Researchers believe this August's calving won't be the last: two more sections of the glacier, measuring roughly 97 and 87 square kilometres, could break off in the future. Scientists plan to monitor developments using satellite imagery and aerial surveys.

Equally close attention will be paid over the coming years to the fate of the iceberg that has already broken free. Ocean currents will gradually carry it away and break it into smaller pieces. In rare cases, an ice mass this large can pose a risk to shipping and Arctic infrastructure.

"While large tabular icebergs are fairly common in the Southern Ocean around Antarctica, Arctic ice islands of this scale are much rarer," noted Anne Crawford of the University of Stirling.

According to her, studying such calving events helps scientists understand how the separation and subsequent breakup of ice affects glacier behaviour, ocean conditions and sea level rise. The current calving itself will barely affect sea levels, since the ice was already floating in the water beforehand. However, the shrinking of the glacier's floating shelf could accelerate the flow of land-based ice into the ocean, which indirectly contributes to rising sea levels.

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Around Prague, based on reporting by novinky.cz