Satellite imagery captured the rupture, which happened about 10 years after satellite surveillance detected the growth of a previously dormant crack in the ice known as Chasm-1, and nearly two years after one slightly smaller iceberg named A74 separated from the same pack ice. A sinkhole is a crack in the sea ice that extends 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, principal investigator at the University of Colorado Boulder, wrote in an email that while the iceberg “is a huge mass of ice, about 500 billion tons…it’s nowhere near the largest big iceberg never seen, which rivaled 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 to grow.
However, “the new fracture puts the base approximately 10 miles from the ocean, and further fractures could occur over the next few years, forcing another costly relocation of the station,” Scambos wrote. The new iceberg is expected to follow a similar path to the A74 in the Weddell Sea and will be named by the US National Ice Center.
Unlike some icebergs and collapsed ice shelves that have been related to climate changethe BAS press release said the rupture is a “natural process” and that there is “no evidence that climate change played a significant role”.
Rather, the sinkhole began to deepen due to “the accumulation of stresses…due to the natural growth of sea ice,” Hilmar Gudmundsson, a glaciology researcher at Northumbria University, said in a statement. BBC History 2019.
Scambos compares the calving of the iceberg to a chisel on a wooden board. “In this case, the chisel was a small island called ‘MacDonald Ice Rise,'” Scambos wrote. “The ice was pushed against this rocky seamount by the ice flow, forcing it to split and eventually break up the floating pack ice.”
“These calvings of large icebergs, sometimes as large as a small state, are spectacular. But they are only part of how the Antarctic ice sheet works,” Scambos said. “Most of the time they have nothing to do with climate change.”