Cracks in the Greenland ice sheet have widened and deepened significantly between 2016 and 2021. (Photo credit: Tom Chudleigh (Durham University))
Enormous cracks in the Greenland ice sheet have grown much wider and deeper in just five years, according to new 3D maps, a discovery that suggests the land is moving apart faster than scientists previously thought.
Most of these cracks, called crevasses, are located at the edges of the ice sheet, where they channel ice and meltwater into the ocean. But the cracks also transport meltwater and heat deeper into the glaciers, which researchers say could trigger a “domino effect” that leads to catastrophic melting and rising sea levels.
The Greenland Ice Sheet covers 80% of Greenland and is 1.9 miles (3 kilometers) thick at its thickest point. Water from the Greenland Ice Sheet is already the main global source of sea level rise, adding 0.6 inches (14 millimeters) since the 1990s, Thomas Chudleigh, a glaciologist at Durham University in the U.K. and lead author of a new study of Greenland's cracks, said in a video.
The melting causes the glaciers of the Greenland Ice Sheet to flow more rapidly down slopes and valleys, which in turn stretches the ice sheet to the point where it cracks, Chadley explained.
“As the rate of ice sheet melt increases, we expect to see more cracks and deeper cracks,” said Chadley. “So our study aimed to determine where these cracks are located and how they are changing in the 21st century.”
Chadli and his colleagues examined the cracks in Greenland by combining more than 8,000 3D maps of the island's surface. The researchers pulled their data from the Polar Geospatial Center at the University of Minnesota, which creates 3D maps based on high-quality satellite imagery.
The researchers compared the shape, size and distribution of cracks in 2016 with 2021 to assess how the cracks are responding to global warming. Their findings, published Monday (Feb. 3) in the journal Nature Geoscience, showed that cracks in the ice sheet increased by 25% over the five-year period, with the largest increases seen in coastal regions.
Greenland Ice Sheet Cracks Grow Faster – YouTube
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“Where the ice sheet is accelerating, we see larger and deeper cracks,” Chadley said. “This is especially true for those areas of the ice sheet that are open to the ocean and that have been subject to significant warming from the ocean since the 1990s.”
The loss of ice in coastal regions has been offset by the expansion of West Greenland's Jakobshavn Glacier. The glacier moves about 165 feet (50 meters) a day on average, making it the fastest-growing glacier on Earth, Chadley said. But between 2016 and 2018, an influx of cold water from the North Atlantic slowed Jakobshavn so much that ice filled its cracks and piled up on the glacier.
As a result of ice accumulation in West Greenland, cracks in the Greenland Ice Sheet have shrunk by an average of 4% between 2016 and 2021. “This slowdown and the resulting crack closure alone have outweighed the increase in cracks in other parts of the ice sheet,” Chadley said.
Sourse: www.livescience.com
