Satellite images captured the breach, which occurred about 10 years after satellite surveillance detected growth in a previously dormant crack in the ice known as Chasm-1, and nearly two years after a slightly smaller iceberg called A74 separated from the same ice shelf. A chasm is a crack in an ice shelf that extends all the way from the surface to the ocean below, while an ice shelf is a floating piece of ice that extends from glaciers formed on land.
Ted Scambos, a senior research fellow at the University of Colorado at Boulder, wrote in an email that while the iceberg “is a huge mass of ice, about 500 billion tons … it is far from the largest iceberg ever seen, rivaling Long Island.
The calving event is not expected to affect BAS’s Halley research station, which was moved further inland in 2016 as a precaution after Chasm-1 began growing.
“However, the new fracture puts the base about 10 miles from the ocean, and in the next few years a new crack may develop, necessitating another costly relocation of the station,” Scambos wrote. The new iceberg is expected to follow a similar path to that of the A74 in the Weddell Sea and will be named by the US National Ice Centre.
Unlike some previous icebergs and collapsed ice shelves that were related to climate changethe BAS press release said the outage was a “natural process” and “there is no evidence that climate change has played a significant role.”
Rather, the gap began to grow due to “the accumulation of stress … due to the natural growth of the ice shelf,” said Hilmar Gudmundsson, a glaciology researcher at Northumbria University, in BBC Story 2019.
Scambos compares calving an iceberg to a chisel on a wooden board. “In this case, the chisel was a small island called the ‘MacDonald Ice Rise,'” Scambos wrote. “The ice was pressed against this rocky seamount by an ice flow, forcing it to split and eventually break away from the floating ice shelf.”
“These large iceberg formations, sometimes as big as a small country, are impressive. But they are only part of the way the Antarctic ice sheet works,” Scambos said. “Most of the time, they have nothing to do with climate change.”
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