A 600-square-mile iceberg, about the size of two New York cities, breaks off the Antarctic sea ice

One of the most watched ice shelves on the planet has just undergone a major change. On Sunday, a massive chunk of Antarctica’s Brunt Ice Shelf – a chunk the size of two New York City towns – broke free.

The British Antarctic Survey said on Monday the iceberg measures 1,550 square kilometres, or just under 600 square miles.

It is the second major sea ice break, known as a calving, in two years, although scientists have long predicted it will happen. According to the British Antarctic Survey, cracks have been growing naturally across the entire sea ice for a decade.

The Brunt Ice Shelf sits across the Weddell Sea from the site of another headline-grabbing ice shelf, the Larsen C Ice Shelf on the Antarctic Peninsula. Last year the Larsen C Ice Platform – which was about the size of New York and was long considered stable – collapsed in the sea.

It was the first time in human history that Antarctica experienced such a collapse. It happened after a atmospheric river brought unusually warm air to the region, and many pointed to climate change as a possible factor.

This map of Antarctica shows the location of various Antarctic ice shelves.

Agnieszka Gautier, National Snow and Ice Data Center

But according to BAS glaciologist Dominic Hodgson, Brunt’s latest iceberg break “is not related to climate change”.

“This calving event was expected and is part of the natural behavior of the Brunt Ice Shelf,” Dodgson said.

A major fissure in the Brunt Plateau, known as the Chasm, had been dormant for decades, but in 2012 scientists detected a major shift. It has been growing steadily since 2015, and in December last year researchers said it was “spreading across the entire sea ice”.

This is the second time in two years that an iceberg has calved from the pack ice.

The last one, known as A74, formed in February 2021 – not even 5 years after a new crack known as the Halloween Crack formed. It is slightly smaller than the last rupture and has since drifted into the Weddell Sea.

The newest iceberg will be named by the US National Ice Center. Researchers believe it will likely follow the path of the A74 into the sea.

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