One of largest icebergs ever breaks off Antarctic ice shelf

July 12, 2017, 9:51 a.m.
Rift in Antarctica's Larsen C Ice Shelf
Photo: John Sonntag/NASA

A one-trillion-ton iceberg — one of the largest on record — has broken off the Larsen C ice shelf in Antarctica. The iceberg, which will likely be named A68, has a volume twice that of Lake Erie, according to the Antarctic research group Project Midas.

NASA satellites detected the break-away, which scientists have been anticipating for about a year. Project Midas reports that the iceberg was already floating before it broke off, so it likely won't have an immediate impact on sea level. However, the landscape of the Antarctic peninsula is permanently changed.

Larsen C is now 12 percent smaller and may be less stable. "There is a risk that Larsen C may eventually follow the example of its neighbor, Larsen B, which disintegrated in 2002 following a similar rift-induced calving event [of Larsen A] in 1995," Project Midas reports.

"This is the furthest back that the ice front has been in recorded history. We’re going to be watching very carefully for signs that the rest of the shelf is becoming unstable," said Dr. Martin O’Leary, a Swansea University glaciologist and member of Project Midas.

The future progress of the 2,300-square-mile iceberg is difficult to predict, said Adrian Luckman, professor at Swansea University and lead investigator of Project Midas. "It may remain in one piece but is more likely to break into fragments. Some of the ice may remain in the area for decades, while parts of the iceberg may drift north into warmer waters."

The ice will add to risks for ships, Reuters reports, as the peninsula is the main destination for cruise ships visiting from South America.

Before the calving

According to NASA, ice shelves are the parts of ice streams and glaciers that float, and they support the grounded ice behind them. That's why researchers raised a red flag regarding the crack on Nov. 10, 2016, when it was about 70 miles long, more than 300 feet wide and about a third of a mile deep. By February 2017, the crack was more than 100 miles long and two miles wide. The crack forked in early May, and by June, only eight miles of ice remained until the crack reached the ice front.

Researchers at Swansea University took this aerial footage of the ice shelf crack before Larsen C broke off.

Editor's note: This story has been updated since it was originally published in December 2016.