On April 17th, NASA scientists released a photo bearing some rather peculiar details. The image, which displayed a frosty area of the Beaufort Sea in the Arctic Ocean, was taken in coordination with NASA's Operation IceBridge, a program which maps ice in the region on an annual basis, both on land and at sea.
However, visible within the satellite photo was also a series of unexplained holes in the ice which left some of the NASA mission scientists baffled.
The photo (see above) was procured by John Sonntag with Operation IceBridge, who reported on NASA's Earth Observatory page. “We saw these sorta-circular features only for a few minutes today. I don’t recall seeing this sort of thing elsewhere.”
According to NASA's statement, the unusual circular features "are more of a curiosity than anything else."
Other scientists commented on the equally unusual "wave-like" formations that appeared near the holes in the photograph. Sea ice geophysicist Don Perovich of Dartmouth College said, “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.’”
In Petrovich's view, it could be that left-to-right motion that occurs when two floes of thin ice collide--a phenomenon called "finger rafting"--might partially explain some of the unusual features.
However, IceBridge project scientist Nathan Kurtz, while acknowledging the appearance of the finger rafting displayed in the photo, maintains that the circular features are anomalous. “I’m not sure what kind of dynamics could lead to the semi-circle shaped features surrounding the holes," Kurtz was quoted saying. "I have never seen anything like that before.”
One novel theory as to what could have caused the circular formations has less to do with the geophysics of ice, and instead suggests a possible mammalian source. Specifically, it is believed that seals may have carved their way through the ice in order to create "breathing holes."
The idea is not without precedent since several varieties of seals are known to do this (see photo above). Another theory is that processes involving convection might explain the circular formations, which is not an uncommon occurrence even on larger bodies of water.
On April 20, 2009, an unusually large (2.7 miles wide) circular formation appeared on the surface of Lake Baikal, Russia's largest landlocked body of water. The photograph, which was also obtained by NASA's Earth Observations experiment, showed "a circle of thin ice... the focal point for ice break up in the very southern end of the lake." Of course, numerous stories of unusual phenomena associated with Lake Baikal over the years led to speculations online that the underlying cause might have been an underwater base, or that it might even be associated with alleged UFO sightings at the location reported by the Russian Navy.
Of course, similar annular features are common occurrences on much smaller bodies of water as well (especially those whose depths are far too shallow to allow for subaquatic bases of any kind). Resulting from processes similar to those already referenced above by Don Petrovich known as "slush fingering", a variety of features that are similar both to Baikal's large "ice circle," as well as the features observed more recently on the surface of the Beaufort Sea, can and do often occur. For an excellent summary of how slush fingering leads to the formation of ice circles on the surface of ponds, I recommend Jon Nelson's post on this at the Story of Snow blog, which can be viewed here.
So the question remains of the mysterious holes in the Arctic Ocean ice... are they the result of natural convection, or are seals gnawing through the ice to make room to breathe? In either case, the most likely explanation for this mystery appears to be a natural one.