Scientists have some new ideas about what causes the thin arc across the fjords of western Greenland. In summer, the fjords around Greenland are often filled with angular blocks of ice that have slid down from the outlets of the island's many glaciers. But on August 3, 2023, a strange arc appeared on the ice in the western fjords of Greenland.
The arc is clearly visible in a detailed version of these images (above) acquired by Landsat 9's Land Imager-2 (OLI-2) on August 3. This elongated white feature spans much of Ittilialsup-Kanglua, a tributary fjord of the Uummannak fjord system in western Greenland. It extends about 2.6 kilometers (1.6 miles) from the front of the Kangiluk Glacier.
The origin of this feature remains a mystery, but satellite images of the arc, originally published in Planet Snapshot, have spurred discussion about some possible causes. The main hypothesis proposed by Dan Shugar, a geomorphologist at the University of Calgary, is that the arc is the result of a large iceberg breaking off from the glacier front.
Icebergs that break off from a glacier, whether above or below the water's surface, displace the water, creating waves. Josh Willis, an oceanographer at NASA's Jet Propulsion Laboratory, and Mike Wood, a glaciologist at Moss Landing Marine Laboratory, agree that newly formed icebergs are a likely explanation.
"It's such a perfect circle," Willis said. "It does look to me like a wave from a calving iceberg."
He also provided an aerial photo, pictured below, of a similar circular wave caused by large chunks of ice breaking off an iceberg that he witnessed during NASA's Ocean Melt Greenland (OMG) mission in September 2021.
However, both scientists point out that another phenomenon also shifts water in the fjords around Greenland. "It's also possible that an underwater plume is pushing the ice away from the glacier surface," Willis said. "In other words, fresh meltwater from under the glacier enters the salty fjord water and rises in the form of a 'plume,' pushing away the surrounding water."
From satellite images alone, it may never be possible to determine what caused the ephemeral landscape. After this, the arc dissipates and the fjord resumes its more familiar, less geometric appearance.