Using radar and radio, researchers uncovered a previously unknown canyon that runs down the middle of the frozen continent of Greenland. It could play a role in the dispersion of melting water from the ice sheet.
As its name suggests, the Grand Canyon is pretty grand, running nearly 300 miles long, with a width that ranges from 4 to 18 miles and a depth of over a mile. Theodore Roosevelt, who declared the Grand Canyon a national monument in 1908, said the great gorge was a “natural wonder which is in kind absolutely unparalleled throughout the rest of the world.”
True enough. But the Grand Canyon may have some new company. Researchers from Canada and Britain announced that they discovered a massive new canyon underneath the thick ice sheet that covers most of Greenland. The still unnamed canyon, which snakes its way up through the center of Greenland and empties past the northern coastline, is some 500 miles long and up to half a mile deep, putting it on the same scale as the Grand Canyon. It may be that the previously undiscovered canyon could play a role in transporting the sub-glacial meltwater produced by Greenland’s dwindling ice sheet into the surrounding ocean, which acts to raise global sea levels.
Indeed, the original purpose of the research that uncovered the canyon—published in the journal Science yesterday—was to help answer one of the most pressing problems facing climate scientists: how will the sprawling Greenland ice sheet, which holds enough frozen water to raise sea levels by 20 ft. if it all melted, react to rising global temperatures? But the result of the research is even more amazing: in an age where we have cameras on every street corner and satellites can peer down to the square inch, who would have believed that a giant canyon still remained to be uncovered?
Professor David Vaughn of the British Antarctic Survey noted in a statement just how remarkable the discovery was:
A discovery of this nature shows that the Earth has not yet given up all its secrets. A 750km canyon preserved under the ice for millions of years is a breathtaking find in itself, but this research is also important in furthering our understanding of Greenland’s past. This area’s ice sheet contributes to sea level rise and this work can help us put current changes in context.
The canyon isn’t visible from above, as its locked beneath the ice sheet. But the researchers were able to find it by using radar in overflights, bouncing signals off the bedrock underneath the ice. (At certain frequencies, ice is functionally transparent to radio waves.) In the warmer geologic past, when far less ice covered Greenland, the canyon would have carried a rushing river up the center of the island, just as the Colorado River flows through the Grand Canyon today.
The discovery never would have been possible without NASA‘s Operation IceBridge, the largest-ever airborne survey of Earth’s polar ice, as well as an excellently named research project. IceBridge captured an enormous amount of data about Greenland’s ice cover, which was added to additional datasets to create a comprehensive assessment. This is science in the Big Data era—researchers are able to collect vast amounts of information and then pull the unexpected out of them.
Since it’s covered with almost three miles of ice, no human being will lay eyes on the actual Greenland canyon, so radar images will have to do for now. Unless of course the ice sheet does finally melt. But if that happens, we may have more to worry about then sightseeing.
via : http://science.time.com