Scientists still have very little insight into how much water flows under the middle of Greenland's Ice Sheet, or where it goes, because of how hard it is to reach the thick ice, then drill under it or measure a thin film of water with radar. Yet understanding the water flow is an important part of predicting how the ice sheet will behave as the climate warms. The uncertainty means conflicting models of water movement, called basal hydrology, are often published in research journals within weeks of each other.
"When it comes to basal hydrology under the big ice sheets, we are basically scratching our heads at this point," said Michael Studinger, project scientist for NASA's Operation IceBridge, who was not involved in the study. "That's why you see contrasting results coming out." (IceBridge is a mission that uses airplanes outfitted with various instruments to measure changes in the polar ice sheets every year.)
The canyon predates the ice sheet that permanently covered Greenland about 1.8 million years ago, Siegert said. The channel curls across northwestern Greenland, ending in a deep fjord filled by Petermann Glacier. The find opens a whole new set of ideas to explore for scientists studying the glacier's rapid retreat.
"If there is a channel that can transport subglacial meltwater all the way from the interior of Greenland to the coast, that flows right into Petermann Glacier, you change the whole water circulation there and have a big impact on stability," Studinger said in an interview. "This is one of the biggest glaciers in Greenland and it produces a lot of big icebergs," he said.
The new canyon isn't the first amazing polar discovery from Bamber and his colleagues, who are experts in creating models of the polar regions, but it is one of the most incredible, they say. Siegert compared it to learning of Lake Vostok in Antarctica. "When Jonathan came into my office and put (the) papers on my desk, it was a jaw-dropping experience," Siegert said.
The gorge popped out of airborne radar data collected by NASA's Operation IceBridge and many other Arctic surveys. The radar onboard the IceBridge plane penetrates the ice, revealing the landscape below. Hints of a linear feature in northwest Greenland had appeared in earlier bedrock maps, but no one ever had enough detail to find the canyon until now, Bamber said.
"It wasn't exactly a 'Eureka' moment, but as we worked up the data, we realized there was something there that looked pretty extensive," Bamber said. "We looked at some profiles across it just to make sure it was what we thought it was, and it very much looked like a river profile," he said. "I thought, 'Well, crikey, we've discovered a 500-mile-long paleoriver.'"
Email Becky Oskin or follow her @beckyoskin. Follow us @OAPlanet, Facebook & Google+. Original article on LiveScience's OurAmazingPlanet.
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