By NED POTTER
July 19, 2012
Flying in orbit over the northwestern coast of Greenland, NASA's Aqua satellite has shot successive images as a chunk of a glacier -- estimated to be about twice the size of New York's Manhattan island -- broke free and began to slide down the narrow channel the glacier fills.
Move the red slider in the image below all the way to the right and you'll see Greenland's Petermann Glacier as Aqua saw it on the morning of July 16. Move it to the left, and you'll see the same area a day later. The key area is in the right-center of each image.
The ice breaking away is about 46 square miles in size. It is moving to the north, toward the top of your screen. All glaciers naturally lose ice, or "calve," as they slide downstream; the Petermann calved a large chunk twice as large in 2010.
But to have two such events in two years is notable to the scientists at NASA, NOAA and different universities who have been watching it.
Ian Howat of Ohio State University said this could be natural: "We're still in the phase of scratching our heads and figuring out how big a deal this really is," he told The Associated Press.
Eric Rignot of NASA went further: "This is not part of natural variations anymore," he said. Average temperatures in northern Greenland and the Canadian Arctic have increased by about 4 degrees Fahrenheit in the last 30 years, according to NASA.
Most scientists who study the Arctic climate agree that it has been warming, but it's complicated. The northern ice cap is substantially smaller than it was even a decade ago. In some places, though, polar ice is, in fact, becoming thicker.
So they are watching the Petermann Glacier. Eric Rignot of NASA's Jet Propulsion Laboratory said, "It is not a collapse but it is certainly a significant event."