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Massive Iceberg Breaks Free In Antarctica

Jul 12, 2017
Originally published on July 13, 2017 12:28 am

A massive iceberg the size of Delaware has broken free from Antarctica and is floating in the sea.

Earlier Wednesday, scientists announced that the 6,000-square-kilometer (about 2,300 square miles) iceberg had come loose, after satellites detected it had calved off the Larsen C ice shelf on the Antarctic Peninsula.

"Put any adjective you like on it: a corker, a whopper — it's a really large iceberg," says Anna Hogg, a researcher with the United Kingdom's Centre for Polar Observation and Modelling at the University of Leeds.

"There have been some this big before," says Adrian Luckman, a glaciologist at Swansea University in the U.K. who leads a project to track changes in the ice shelf. But he adds, the roughly trillion-metric-ton iceberg is unusual. "This is certainly in the Top 10, maybe possibly in the Top 5."

Scientists had anticipated the breakup since a massive crack first opened up in the Larsen C ice shelf back in 2014. The crack grew rapidly, and by the end of last week, a roughly 3-mile sliver of ice was all that connected the iceberg to the shelf.

Hogg says that the breakup, while astounding in size, will not have an effect on global sea levels. That is because this chunk of ice was already floating on water when it broke off. "This is the same as if you've got an ice cube in your gin and tonic," she says. "When the ice cube melts, it doesn't raise the volume of water in that glass."

But the consequences could be significant. The larger Larsen C ice shelf is itself holding back a large volume of "grounded ice." If the entire ice shelf breaks apart, that grounded ice could flow into the ocean, changing sea levels, Hogg says.

Luckman, however, says there is no need for panic: The breakup of the ice shelf, if it happens at all, will take years or even decades. Even then it's unclear how much ice would flow into the sea.

Nor is it clear whether climate change is behind this breakup. Although climate change has been responsible for melting in other parts of Antarctica, such as the Pine Island Glacier, researchers believe the story on the Antarctic Peninsula is more complicated. "Icebergs are calving all the time in Antarctica, and really that forms part of the natural life cycle of any ice shelf," Hogg says.

Researchers will have to continue their studies to find out whether Larsen C is being affected by climate change.

Copyright 2017 NPR. To see more, visit http://www.npr.org/.

KELLY MCEVERS, HOST:

A massive new iceberg has broken off from Antarctica. Scientists made that announcement today after fresh satellite images showed the iceberg had come free. NPR's Geoff Brumfiel has more on how it happened.

GEOFF BRUMFIEL, BYLINE: The iceberg came from a place called the Larsen C ice shelf. Anna Hogg is one of the few people who's seen it firsthand. She says everything is huge.

ANNA HOGG: Giant terrain, colossal mountains, massive bits of ice. And it's phenomenally beautiful.

BRUMFIEL: Hogg is a researcher at the University of Leeds in the United Kingdom. She says this new iceberg fits right in with its mammoth landscape. It's about the size of Delaware, and that's just the part we can see.

HOGG: Because it's floating in the ocean, we only see 10 percent of the ice volume above the ocean surface. And the remaining 90 percent is actually hidden beneath the ocean water.

BRUMFIEL: So this is really just...

HOGG: Just the tip of the iceberg, exactly, yes.

BRUMFIEL: Adrian Luckman of Swansea University also in the U.K. has been tracking this chunk of ice since the first cracks appeared in 2014. He estimates this new iceberg is over a trillion tons in mass. That makes it among the largest ever observed.

ADRIAN LUCKMAN: This is certainly in the top 10, maybe possibly in the top five.

BRUMFIEL: But despite its size, Luckman says there's no need to panic.

LUCKMAN: Although it's a very big, spectacular, very interesting event - and everybody loves a huge iceberg story - the potential impact on humans is actually going to be very small.

BRUMFIEL: The iceberg was part of an ice shelf that was already floating on the water. Hogg says think about it like an ice cube in a glass.

HOGG: When the ice cube melts, it doesn't raise the volume of water in that glass.

BRUMFIEL: So sea levels won't rise, nor is it necessarily a harbinger of bigger problems like climate change. Climate has been thinning ice across Antarctica, but Hogg says this particular chunk of ice may have just broken off randomly.

HOGG: Icebergs are calving all the time in Antarctica. And really that forms part of the natural life cycle of any ice shelf.

BRUMFIEL: But there are real stakes here. The Larsen C ice shelf this iceberg came from is holding back ice on land, ice that could flow into the ocean and contribute to sea level rise. Other nearby ice shelves have broken up in recent decades, so researchers will be watching closely to see if any more cracks show up in this massive frozen landscape. Geoff Brumfiel, NPR News. Transcript provided by NPR, Copyright NPR.