Last year, the world watched in awe as a massive trillion-ton iceberg calved off the Larsen C ice shelf in Antarctica. Dubbed A-68, the giant slab of ice broke off from the ice shelf on July 12, the Inquisitr reported at the time, but didn’t stray too far away from the place it originated — that is, until July, 2018.
After being fairly stationary for about 12 months, A-68 has dramatically shifted its position and is now on the move, spinning ceaselessly toward the ocean, reports Earther.
According to a report by polar oceanographer Mark Brandon, the monster iceberg — which measures 5,800 square kilometers and is listed as the sixth largest iceberg on record by the NASA Scatterometer Climate Record Pathfinder — has moved away from the Larsen C ice shelf, drifting northward into the ocean.
Initially, A-68 was trapped near its parent shelf for almost a year, being sloshed around by currents and winds and repeatedly getting its northern stuck in the shallow water of Bawden Ice Rise, notes Project MIDAS, a U.K.-based Antarctic research group that has been keeping tabs on the iceberg and the Larsen C ice shelf.
However, about two months ago, A-68 “started to swing northwards,” rotating in a counterclockwise direction, Brandon wrote in an August 31 blog post on Mallemaroking.
— Mark Brandon (@icey_mark) August 31, 2018
The oceanographer caught wind of the iceberg’s sudden shift after looking over a series of false-color images taken with the Suomi NPP satellite. Pieced together by Brandon and available on the NASA Worldview app, the satellite images incorporate brightness temperature data and show the cold iceberg and ice shelf in a dark purple hue on the lighter background of the warmer water around them.
As BGR points out, the images reveal that A-68 has undergone “a dramatic shift” and is currently repositioned almost perpendicularly to the Larsen C ice shelf, having rotated about 90 degrees. Estimates by NASA glaciologist Christopher Shuman point to a 40-degree rotation in the past month alone, with the iceberg pivoting 10 degrees in the last two weeks.
— James A. Whitsett,Jr (@Jayw227) September 5, 2018
No one truly knows what caused this bizarre phenomenon, which appears to have started sometime during the Southern Hemisphere winter. The iceberg’s dramatic spin — which was picked up by the satellite as soon as Antarctica began to emerge from the cover of winter’s darkness — is believed to have been triggered once A-68 broke free from whatever it was pinning it down all this time.
“It might have been shaken loose by winds or ocean currents, or it might be that the natural thinning process (from both melting and the flow of the ice) has lifted the bottom of the iceberg off the sea bed,” Martin O’Leary of Project MIDAS said in a statement. “In any case, it looks like the berg is now a lot more free [sic] to move about, so it will probably continue to rotate, and to move out to sea.”
One thing is for certain, namely that the iceberg’s frantic rotation “shows no signs of stopping,” states Earther.
After being stuck in the mud both literally and figuratively for about a year, iceberg A-68 started to rotate dramatically this summer. Here's my story on it, and a big h/t to @icey_mark for bringing this to my attention. https://t.co/mzKMhfnhRq
— Maddie Stone (@themadstone) September 3, 2018
In Bradon’s opinion, A-68 will keep on spinning “until what is currently the northern edge collides with the Larsen C ice front.”
“It has a spectacular amount of momentum and it’s not going to be stopped easily. I should think we will see some interesting collisions with the ice shelf in the next few months,” the oceanographer wrote in his blog post.