Nov. 12 — A glacier in northeast Greenland that holds enough water to raise global sea levels by more than 18 inches is breaking apart and melting into the Atlantic Ocean, losing mass at a rate of 5 billion tons a year, according to a new study.
The glacier, called Zachariae Isstrom, entered a phase of “accelerated retreat” in 2012, and has broken loose from a floating ice shelf that had been keeping it moored and stable, researchers said in an article published in the Nov. 12 issue of the journal Science.
The researchers used data from aerial surveys and satellite-based observations used by international space agencies to determine that the bottom of the glacier is being eroded by warmer ocean water mixed with increasing amounts of melting ice.
North Greenland glaciers like Zachariae Isstrom have been stable historically, even as those in the south of Greenland have been melting, said lead author Jeremie Mouginot, an assistant researcher in the department of earth system science at the University of California, Irvine. “This is one of the first that is starting to change and discharge more ice,” Mouginot told Bloomberg BNA Nov. 10. “We fear that other glaciers in the region will follow the same path in the coming decades.”
Warmer ocean water mixed with increasing amounts of melting ice—a product of warmer air temperature—is eroding the bottom of the glacier, the researchers said.
Zachariae Isstrom and another large glacier, Nioghalvfjerdsfjorden—which also is receding—make up 12 percent of the Greenland ice sheet, and if both fully collapsed, sea levels would rise by more than 39 inches, the researchers said.
The researchers were able to get the data through the World Meteorological Organization's Polar Space Task Group, which coordinated with space agencies. “We hope we can continue to push the space agencies to acquire data” and that funding for similar projects will be available in the future, Mouginot said.
Meanwhile, a separate study found that climate change is causing precipitation to fall as rain, rather than snow, in many areas that rely on slow-melting snow for agriculture and other uses, which could lead to water shortages in parts of the American West, southern Europe, the Middle East and central Asia.
The study, published Nov. 12 in the journal Environmental Research Letters, analyzed 421 drainage basins spanning the Northern Hemisphere, combining multiple climate models with present water-use patterns and demographics. They further analyzed 97 basins that are likely to decline, given present water demands, zeroing in on 32 of those with the largest populations that are most sensitive to changes.
Among the regions that could be affected: Northern and Central California; the Colorado River and Rio Grande River basins; the Atlas Basin of Morocco, and the Ebro-Duero Basin, which feeds water to Portugal and much of Spain and Southern France.
“Water managers in a lot of places may need to prepare for a world where the snow reservoir no longer exists,” lead author Justin Mankin, a postdoctoral fellow at Columbia University's Earth Institute, said in a statement announcing the study's release.
The study indicates that climate change will put additional stress on regions already struggling with water-scarcity issues, particularly where irrigation is supplemented by shrinking supplies of groundwater, Yoshihide Wada, a researcher at Utrecht University, said in the Nov. 12 statement.
To contact the reporter on this story: Nora Macaluso in Lansing, Mich., at Nora Macaluso
To contact the editor responsible for this story: Greg Henderson at firstname.lastname@example.org
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