Giant Crack in Antarctic Ice Creating
January 9, 2017
Researchers are closely watching part
of a giant shelf of ice in Antarctica that could soon become an iceberg.
It's part of the Larsen Ice Shelf which floats off the coast of
Growing, Growing, Gone!
Scientists who study the ice-covered continent have been watching the
Larsen Ice Shelf for nearly a decade.
Martin O'Leary is a Research Officer at Swansea University and a member
of Project MIDAS, a U.K.-based Antarctic research project. He tells VOA
"we've been monitoring this crack since around 2010, when it started to
become significantly larger than the surrounding cracks. It's been of
particular interest since around 2014, when it became clear that the
berg was going to be a large one."
By "large one," O'Leary means a chunk of ice that represents between 9
and 12 percent of the entire country-sized shelf.
But in just the past few months, the rift has been growing quickly, an
estimated 18 kilometers just during the month of December.
Today, a strip of ice about 20 kilometers long is the only thing holding
an iceberg O'Leary says is now "around 5,000 sq km" (about half the size
of Lebanon) onto the Antarctic mainland.
What is an ice shelf?
Larsen C is called an ice shelf because, while it is still attached to
the land, it is already floating out at sea. The Larsen Ice Shelf is
actually a series of three interconnected shelves, that grew out from
the Antarctic Mainland over tens of thousands of years.
Larsen A, the most northern of the three segments, and the smallest,
broke free from the mainland in 1995.
The larger Larsen B Ice Shelf, an estimated 3,200 square kilometers of
ice, averaging a thickness of 220 meters, disintegrated into the sea in
Nov. 10, 2016 aerial photo released by NASA, shows a rift in the
Antarctic Peninsula's Larsen C ice shelf. According to NASA, IceBridge
scientists measured the Larsen C fracture to be about 70 miles long,
more than 300 feet wide and about a third of a mile deep.
And now Larsen C, larger still, with an ice thickness averaging 350
meters, looks to lose the next big chunk of the ice shelf. Adrian
Luckman, another member of the MIDAS team, told the International
Business Times, "If it doesn't go in the next few months, I'll be
amazed…it's so close to calving that I think it's inevitable."
What happens if it goes?
If that huge chunk does separate from Larsen C, what does it mean for
ocean levels around the world? Luckily - not much. The shelf is already
displacing a lot of water because it's already floating on the ocean.
Scientists are classifying the calving as a geographic event, as opposed
to a climate event. It is something that will change the Antarctic
landscape and is not necessarily a result of climate change.
O'Leary backs that up, saying this event "...is a natural process which
occurs once every few decades [(the last major event on Larsen C was in
Of greater concern is what this suggests for the future of Larsen C.
removal of a large chunk of ice," O'Leary says, "may make the ice shelf
more vulnerable to the effects of climate change in the future."
In other words, the loss of ice may make Larsen C a bit more unstable,
and more prone to more calving events like this one, and eventually to
the collapse of the whole shelf.
There's not enough information to predict if or when that might happen,
but if it does, it's possible that the ice which the Larsen shelf holds
on the land could start sliding into the sea.
Predictions suggest that could raise world sea levels by as much as 10