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The Delaware-sized iceberg, which left the Larsen ice floe in Antarctica in July 2017, is in motion.
During the months of July and August, the ice block of a trillion tons made a graceful pivot to the north, reveals a satellite image. Polar oceanographer Mark Brandon of the Open University in England noted the rotation of the iceberg on his blog, Mallemaroking.
The iceberg will probably jostle in its current location near the ice platform that calved it for at least a few months, periodically locking itself on shallow seamounts to the bottom of the ocean. Center in Colorado. [In Photos: Antarctica’s Larsen C Ice Shelf Through Time]
"There are a lot of little pinnacles that can catch an iceberg," Scambos told Live Science.
The Antarctic iceberg weighing more than one trillion tons turns after a long, unexpected stop: //t.co/KNs6zYj0qZ pic.twitter.com/ekbjdbnlYw
– Pam Wright (@pamwrightmedia) September 6, 2018
Berg in motion
The iceberg, dubbed A68 by scientists, broke the Larsen C ice shelf between 10 and 12 July 2017. Researchers have been following a growing crack in the satellite ice shelf for years. Of approximately 2,800 square miles (5,800 square kilometers), the iceberg is one of the largest observed since the beginning of satellite tracking.
In May and June 2018, the A68 iceberg strikes the Larsen C ice shelf and breaks into several small icebergs.
Credit: Dr. A. E. Hogg, CPOM, University of Leeds
The ability to observe the shepherdess made him famous beyond its real scientific significance, said Scambos.
"We can make it a daily event so that people can watch and see how this huge piece of ice is moving," he said. "I think now it would be the biggest object floating on the ocean."
A GIF created by polar scientist Anna Hogg of the University of Leeds shows the calving and movement of the A68 since 2017. The iceberg is currently about 45 kilometers from the Larsen ice floe, a Hogg said in an email. A68 has moved little during its first year of emancipation from the pack ice after getting hooked (or "beached") to the bottom of the Weddell Sea. In particular, Scambos said that a small seamount called the Bawden Ice Rise pinned the Berg in place.
The iceberg was swaying up like a ball bath toy. Last year she crashed on the Larsen ice floe, Hogg said, including incidents in May and June of this year that broke several small icebergs.
Around July 12, 2018, A68 was released from some of its strandings and began to swing northward, like a needle moving in the opposite direction, wrote Brandon in a statement sent to Live Science. The iceberg has since rotated about 90 degrees.
Pulling currents
The bumps and snags of the A68 are interesting to follow, said Scambos, but so far the iceberg is behaving as scientists have expected. As the tides rise and fall, the icebergs will ride on them, floating closer, then farther, from the ice shelf into a spiral path, he added.
"Finally, whatever, with snags and turns and turns and probably a little inherent rotation … it will drift north," he said. [Photos: Diving Beneath Antarctica’s Ross Ice Shelf]
The Bergs in this region eventually float on currents beyond the tip of the Antarctic Peninsula, said Scambos, and eventually found themselves in a current called "West Wind Drift" or "Antarctic Circumpolar Current". This current will shoot the berg in warmer waters, where it will break and melt, Scambos said.
"I suspect the final break will occur during a summer period when there has been a lot of melting and flooding of the iceberg surface," Scambos said. The liquid water will flow into the cracks on the surface of the iceberg, further fracturing them and separating the ice from the inside. The final split could happen quickly, said Scambos, in a few days.
Scientifically more interesting, Scambos said that will happen on the seabed that A68 leaves behind. Scambos said that the area from which the berg had just been released has probably not been exposed to the sky for 120,000 years. Because ice shelves prevent nutrients from reaching the ocean, the bottom under the shelves is usually almost sterile. Now this seabed will suddenly be exposed to the sun.
"It's a bit like the Oklahoma rush for things that crawl along the seabed and want to claim," Scambos said.
Two expeditions from 2019 are planned to study this phenomenon closely: one on board the Polarstern research vessel and the other aboard the South African ship Agulhas II, which will also search for the remains of the ship Endurance of Sir Ernest Shackleton. This ship was trapped in the ice and crushed in 1915, paving the way for an attempt at extreme survival while Shackleton and his men launched a lifeboat in the same currents that now lead the A68's movements into the seas Antarctic.
Original article on Live Science.
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