Greenland Ice Sheet meltwater still flows in winter

Meltwater flowing into a moulin © CIRES

Liquid meltwater can sometimes flow deep below the Greenland Ice Sheet in winter, not just in the summer, according to work published today.

That finding means that scientists seeking to understand sea-level rise and the future of the Greenland Ice Sheet need to collect data during the dark Arctic winter with scant hours of daylight and temperatures that dip below -40 degrees.

When evidence suggested that some of Greenland’s glaciers were storing meltwater through the winter, Lincoln Pitcher, a Visiting Fellow at CIRES, part of the University of Colorado Boulder, set out for southwest Greenland to see if any of this meltwater was also leaving the ice sheet during winter.

A stream of meltwater on the surface of the Greenland Ice Sheet enters a moulin connecting to the glacier’s bed, 700 meters below. Surface meltwater lubricates the bed and temporarily speeds up the ice sheet’s movement toward the sea every summer. From left, Blaine Morriss (Dartmouth College) and Lauren Andrews (University of Texas). Location: west coast of the Greenland Ice Sheet. Photo by Matt Hoffman, Los Alamos National Laboratory

In February 2015, he and his colleague Colin Gleason of the University of Massachusetts at Amherst dragged a ground-penetrating radar across frozen rivers downstream of the edge of the ice sheet and drilled boreholes to see if any water was leaving the ice sheet and flowing beneath river ice.

They surveyed rivers draining five Greenland Ice Sheet outlet glaciers and discovered meltwater flowing at just one site, the Isortoq River.

The team concluded that it is possible the bed of the Greenland Ice Sheet can stay wet and drain small amounts of water year-round.

This finding is important for understanding how meltwater from the ice surface moves through the ice sheet, is retained, refreezes and/or ultimately drains into rivers and/or the global ocean.

10 facts about the Arctic Circle

  1. Bird poop keeps it cool
    A study recently published in Nature found that the massive amounts of bird guano in the Arctic release gases that contribute to cloud cover, which in turn slightly reduces the temperature of the surrounding air.

2. It comes to life in winter
In some Arctic Ocean habitats, wildlife is even more active during the region’s long, desolate winter than it is in the summer. According to a recent study in Current Biology, “Biodiversity, abundance, growth, and reproduction in habitats studied were at similar or higher levels than in warmer months.” Researchers counted lots of plankton, crustaceans that aren’t often observed during summer, as well as certain cod and haddock species and a surprising number of birds.

3. It’s home to the world’s biggest, most secure seed storage facility
More than 800 miles beyond the Arctic Circle lies the Svalbard Global Seed Vault, a storage facility run by the Norwegian government. The structure, which was built into the permafrost, holds seeds for more than 4000 plant species—including life-sustaining food crops—keeping them safe in the event of natural or manmade disasters.

4. The first man to read the North Pole was overlooked for decades
Robert Peary (1856-1920) claimed to have been the first man to reach the geographic North Pole, in 1909. Today, however, experts believe that it was his assistant, an African-American man by the name of Matthew Henson (1866-1955), who actually deserves the distinction. By the time Peary and Henson neared their destination, Peary was struggling with a bad case of frostbite, leaving him unable to walk. (He had to be pulled along on a sled instead.) As they got closer to the North Pole, Henson and two guides went ahead on foot, but accidentally overshot their destination—which meant that Henson technically reached the Pole about 45 minutes before Peary did.

5. Lots of people live there
Despite its harsh conditions, more than 4 million people call the Arctic region home. The Arctic Circle encompasses parts of the U.S., Russia, Finland, Sweden, Iceland, Greenland, and Norway. Its economy amounts to around $230 billion annually, which is about the same as Portugal and Ireland.

6. There’s an Intergovernmental Arctic Forum
Countries whose borders fall within the Arctic Circle are part of the Arctic Council, which, according to its website, “is the only circumpolar forum for political discussions on Arctic issues, involving all the Arctic states, and with the active participation of its Indigenous Peoples.” The Council works to assess, and come up with solutions for, the environmental and social issues faced by the people and wildlife living there.

7. The word Arctic is derived from the Greek word Arktos
Arktos means “bear,” and refers not to the region’s native polar bears, but to the constellation containing the North Star, Ursa Minor. (Ursa is Latin for “bear.”)

8. The Arctic Ocean is the world’s smallest
It comprises 5.4 million square miles. By comparison, the Atlantic Ocean covers 41.1 million square miles, and the Pacific 62.46 million square miles.

9. The North Pole is much warmer than the South Pole
The Arctic is mostly ocean surrounded by land, while Antarctica is mostly land surrounded by ocean. So while significant portions of both are covered in sheets of ice, the water underneath the Arctic ice cap (which sits only about a foot above the water) can trap heat and help warm the surrounding air. In Antarctica, as Scientific American put it, “the surface of the ice sheet at the South Pole is more than 9000 feet in elevation—more than a mile and a half above sea level.” (Higher elevations, of course, result in colder temps.) The average summer temperature at the North Pole is 32°F. At the South Pole, it’s -18°F.

10. Santa;s North Pole home was dreamed up by a 19th century cartoonist
The famous political cartoonist Thomas Nast began drawing illustrations of Santa Claus as part of an advertising campaign for Harper’s Weekly in the 1860s. In a few of his drawings, he made reference to the fact that Santa’s mailing address was the North Pole—a place that had already captured the world’s imagination, as they watched a number of explorers attempt to reach the frigid destination. As for the real St. Nicholas? He was born in what is now Turkey.

SOURCE 1, SOURCE 2, SOURCE 3

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