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The western edge of iceberg A68 as seen during an Operation IceBridge flight on Nov. 12, 2017. NASA / Nathan Kurtz
The world’s largest iceberg, which broke free from Antarctica in 2017, is about to escape the boundaries of the continent’s perennial sea ice and make its way into the open ocean, according to the BBC.
The massive iceberg, named A68, weighed up to a trillion tons, and measured 2,300 square miles, when it broke off from the Larsen C ice shelf in 2017. To put that in perspective, the iceberg is more than seven times the size of New York City, and it’s larger than both Rhode Island and Delaware.
Experts say that it has lost very little of its size since breaking off the ice shelf, according to Yahoo News.
However, when it meets the harsh, choppy waters of the Southern Ocean it is expected to weaken and lose its integrity.
“With a thickness to length ratio akin to five sheets of A4, I am astonished that the ocean waves haven’t already made ice cubes out of A68,” said professor Adrian Luckman from Swansea University, UK, to the BBC. “If it survives for long as one piece when it moves beyond the edge of the sea-ice, I will be very surprised.”
Two weeks ago, Luckman tweeted, “Not long before it breaks free of the pack ice.”
After the iceberg broke off, it remained fairly close to land. However, this summer in Antarctica the iceberg has drifted much more rapidly than was expected. The iceberg has been drifting northward along the southernmost continent’s eastern shore, meaning it is headed towards an area of the Atlantic Ocean dubbed “iceberg alley” by researchers, according to the BBC.
When the iceberg broke free, it reduced the size of the Larsen C ice shelf by 12 percent, according to Yahoo News.
At first, sea ice kept the iceberg hemmed in, said the European Space Agency. However, it reported that prevailing strong winds coming off the ice shelf gave the iceberg a push that allowed it to reach ocean waters that turned it clockwise so it could float away toward warmer waters, as Yahoo News reported.
Twenty years ago, an iceberg nearly twice the size of A68 broke off from the Rose ice shelf and drifted north towards Great Britain’s South Georgia Islands, which are at 54 degrees south. That iceberg, called B15, is now less than one-fifth of its original size and it’s halfway between the South Sandwich Islands and South Georgia, according to the BBC.
Icebergs like A68 and B15 need constant monitoring since they pose risks to ships.
While researchers watch A68’s movement, they are also keeping a close eye on two other icebergs poised to break free from the ice shelf. One, which is half the size of New York City, is riven with cracks and will likely crumble once it breaks free.
“I expect that the new iceberg will break into many pieces soon after it calves,” said Luckman to the BBC.
The other, at roughly 600 square miles, is about twice the size of New York City. Its imminent breaking from the ice shelf forced Britain’s Halley research station to move so it would not be in harm’s way, as the BBC reported.