An iceberg twice the size of New York City is in what scientists call “the final stage” of breaking off from the Brunt Ice Shelf on the Weddell Sea on northwest Antarctica. The final separation will occur when two cracks meet, separating an iceberg measuring some 580 square miles and up to 820 feet thick from the mainland.
Anticipating the separation, the Halley VI Research station, manned by the British Antarctic Survey, has been moved 14 miles inland, on the other side of the cracks.
The separation, or calving, of an iceberg is a normal part of the life cycle of an ice shelf, but recently changes in the shelf have accelerated. The edge of the Brunt Ice Shelf has evolved slowly ever since Ernest Shackleton first surveyed the coast in 1915. NASA scientists say the rise in global temperatures has sped up the loss of ice in Antarctica, and caused several icebergs to break off lately. Indeed, the largest, about the size of the state of Delaware, separated from the Larsen C Ice Shelf in July 2017.
Researchers have been watching the crack on the Brunt Ice Shelf closely since 2012, when the crack, which had been dormant for 35 years, suddenly started moving again. That crack, called Chasm 1, has grown over the past seven years, and has been moving north as fast as 2.5 miles a year.
Meanwhile, a second crack, called the Halloween Crack because that was when it was discovered in 2016, started moving east, on a collision course with Chasm 1. When the two cracks meet, probably within the next two months, the huge iceberg will break away. At that time, scientists are worried about possible further instability on the Brunt Ice Shelf. Read more: