A giant iceberg the size of Manhattan broke off from the Petermann Glacier along Greenland’s northwest coast in August. Since then, scientists have been tracking its journey as it floats through a narrow waterway and bumps into icy obstacles.
Images taken by NASA-USGS Landsat satellites revealed a close run-in between the newly formed ice island and a small rocky outcrop in the Nares Strait. The ice island appears to slam directly into Joe Island, but it luckily survived the brief encounter and continued on its way. These sorts of collisions, however, usually mark the beginning of a berg’s breakup.
Collision ahead
The ice island detached from Petermann Glacier’s ice tongue—a floating sheet of ice that extends 43 miles (70 kilometers) out into the Arctic Ocean—on August 4. The recent calving event marked the glacier’s largest loss of floating ice since 2012, with the ice island measuring in at 29-square-miles (76-square-kilometers) in size and up to 492 feet (150 meters) thick.
In the week since it calved, the ice island drifted away at an average of 1.8 miles (3 kilometers) a day. It made its way down a deep glacial fjord known as Petermann Fjord and headed toward Nares Strait, a waterway between Ellesmere Island and Greenland.
As it continued toward the fjord’s junction with the waterway, the ice island rammed into Joe Island. The tiny island sits directly at the mouth of the Petermann Fjord, placing it in the path of floating ice islands that have broken off from the Petermann Glacier.
“We were certainly watching closely as it interacted with Joe Island and were impressed that it survived the interaction without further fragmentation,” Adam Garbo, a doctoral student in glaciology at the University of Ottawa who led the team behind the calving event’s detection, said in a statement.
Watching ice melt
Joe Island is usually the first obstacle encountered by wayward ice islands, and it can mark the beginning of the end for some. In 2010, a massive ice island four times the size of Manhattan broke in two after smashing into Joe Island.
Following its close encounter, the ice island was swept out of the fjord by wind and surface currents. Satellite images showed the newly formed ice island pivoting away from Joe Island and continuing southwest through Nares Strait. As it continues on its lonesome journey, the ice island will fracture into smaller pieces due to tides, winds, currents, and melting.
Petermann is one of Greenland’s largest marine-terminating glaciers, which frequently sheds large icebergs and discharges them into the ocean. Several icebergs have broken off from the glacier in recent years, including a 97-square-mile (251-square-kilometer) berg in 2010 and a 50-square-mile (130-square-kilometer) berg in 2012.
Scientists have been using satellites to monitor changes in Petermann Glacier since 2019, keeping a close watch on fractures and signs of instability along the glacier’s floating ice tongue. Researchers are anticipating at least two more calving events in the near future, which are projected to measure around 36.3 square miles (94 square kilometers) and 32.4 square miles (84 square kilometers).
The broken-off icebergs can travel significant distances and may pose a risk to marine activity and infrastructure while transporting fresh water to the ocean as they melt.
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