A massive iceberg has broken off from the Northern Hemisphere’s longest floating ice tongue, and researchers are anticipating at least two more calving events from Greenland’s Petermann Glacier in the near future.
Satellite imagery from the European Space Agency’s Sentinel-1 mission first revealed deterioration in Petermann Glacier’s ice tongue—a floating sheet of ice that extends 43 miles (70 kilometers) out into the Arctic Ocean—on August 3 before the ice island completely detached from the eastern side of the glacier the next day.
“We’ve anticipated this break for years, and seeing it finally happen is remarkable,” Adam Garbo, a doctoral student at the University of Ottawa who led the team behind the detection, said in a statement.
The recent calving event marks the glacier’s largest loss of floating ice since 2012 and offers scientists a rare opportunity to study how large ice masses form and drift apart over time.
Break away
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.
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.
The new ice island broke off from the eastern side of the glacier and is estimated to be up to 492 feet (150 meters) thick. It has a surface area roughly equivalent to the size of Manhattan at 29.5 square miles (76.4 square kilometers).
Ice islands are a massive subclass of icebergs that usually feature a flat, plateau-like top with a wide surface area compared to their height. They break off from floating ice shelves or ice tongues in northwest Greenland and northern Ellesmere Island. Arctic ice islands are far less common than large icebergs and can float on for years before deteriorating.
“While large, tabular icebergs are relatively common in the Southern Ocean that surrounds the Antarctic Ice sheet, Arctic ice islands are far rarer,” Anna Crawford, a researcher at the University of Stirling and a member of the team that detected the event, said in a statement. “By studying Arctic ice islands, we will gain knowledge that can be transferred across Polar regions.”
More to come
As the researchers continue to monitor Petermann’s ice tongue, they anticipate at least two more calving events in the near future. Rifts that have been a long time in the making continue to cut across the floating ice tongue, indicating that the recent formation of the massive ice island will not be the last.
The future ice islands are projected to measure around 36.3 square miles (94 square kilometers) and 32.4 square miles (84 square kilometers). Along with the newly detached ice island, the three are set to reduce Petermann Glacier by about 22%.
As the ice islands drift away into the ocean, they can pose a hazard to navigation, offshore infrastructure, and shipping. “These are thick blocks of ice that can drift for years,” Abigail Dalton from the Canadian Ice Service, Environment and Climate Change Canada said in a statement. “Over time, they fracture into smaller, harder-to-track pieces that pose hazards to vessels and resource operations.”
The team will continue to monitor the ice island as it floats away, tracking its movement using satellite imagery and aerial observations to learn more about what drives these calving events.
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