On April 14, 2018, scientists working on NASA’s Operation IceBridge — a multi-year airborne science mission to study changing ice conditions at both poles — spotted strange holes in the surface of ice in the eastern Beaufort Sea.
This image shows curious holes in Arctic sea ice, located about 50 miles (80.5 km) northwest of Canada’s Mackenzie River Delta. Image credit: John Sonntag / NASA’s Operation IceBridge Mission.
The Operation IceBridge mission is now in its tenth year making flights over the Arctic. That’s a lot of flight hours spent mapping the region’s land ice and sea ice.
But on April 14, IceBridge scientists spotted something they had never seen before.
They snapped this photograph from the window of the P-3 research plane while flying over the eastern Beaufort Sea.
“We saw these sorta-circular features only for a few minutes today. I don’t recall seeing this sort of thing elsewhere,” said IceBridge scientist Dr. John Sonntag.
According to the researchers, some aspects of the image are easy to explain.
The sea ice here is clearly young ice growing within what was once a long, linear area of open water, or lead.
“The ice is likely thin, soft, and mushy and somewhat pliable. This can be seen in the wave-like features in front of the middle ‘amoeba’,” said Dr. Don Perovich, a sea ice geophysicist at Dartmouth College.
“There might be a general left to right motion of the new ice as evidenced by the finger rafting on the right side of the image.”
“Finger rafting occurs when two floes of thin ice collide. As a result of the collision, blocks of ice slide above and below each other in a pattern that resembles a zipper or interlocking fingers.”
“It’s definitely an area of thin ice, as you can see finger rafting near the holes and the color is gray enough to indicate little snow cover,” added IceBridge project scientist Dr. Nathan Kurtz.
“I’m not sure what kind of dynamics could lead to the semi-circle shaped features surrounding the holes. I have never seen anything like that before.”
Indeed, the holes are difficult to explain.
One thought is that they have a mammalian origin: the holes may have been gnawed out by seals to create an open area in the ice through which they can surface to breathe.
The holes appear similar to photographs of breathing holes created by ringed seals (Pusa or Phoca hispida) and harp seals (Pagophilus groenlandicus).
“The encircling features may be due to waves of water washing out over the snow and ice when the seals surface,” said Dr. Walt Meier, a scientist at the National Snow and Ice Data Center.
“Or it could be a sort of drainage feature that results from when the hole is made in the ice.”
“We have seen features like this before, but do not have a solid explanation for them,” said Dr. Chris Polashenski, a sea ice scientist at the Cold Regions Research and Engineering Laboratory.
“Breathing holes for seals is one possibility; equally plausible is that the holes were caused by convection.”
“This is in pretty shallow water generally, so there is every chance this is just ‘warm springs’ or seeps of ground water flowing from the mountains inland that make their presence known in this particular area,” said Dr. Chris Shuman, a glaciologist at NASA’s Goddard Space Flight Center and the University of Maryland at Baltimore County.
“The other possibility is that warmer water from Beaufort currents or out of the Mackenzie River is finding its way to the surface due to interacting with the bathymetry, just the way some polynyas form.”
