A one trillion tonne iceberg, one of the biggest ever recorded, has broken away from the Larsen C Ice Shelf, in Antarctica. The section broken is of 5,800 square km, which means the size of U.S. state of Delaware, and its volume is twice that of Lake Erie, one of the Great Lakes.
Researchers from the MIDAS Project have been monitoring the rift in Larsen C for many years, following the collapse of the Larsen A ice shelf in 1995 and the sudden break-up of the Larsen B shelf in 2002 and reported rapid advances of the rift in January, May and June, which increased its length to over 200 km and left the iceberg hanging on by a thread of ice just 4.5 km (2.8 miles) wide.
Although weighing more than a trillion tonnes, the iceberg has no immediate impact on sea level, as it was already floating before it calved away. The calving of this iceberg leaves the Larsen C Ice Shelf reduced in area by more than 12%, and the landscape of the Antarctic Peninsula changed forever.
As explained, although the remaining ice shelf will continue naturally to regrow, Swansea researchers have previously shown that the new configuration is potentially less stable than it was prior to the rift. There is a risk that Larsen C may eventually follow the example of its neighbour, Larsen B, which disintegrated in 2002 following a similar rift-induced calving event in 1995.
Professor Adrian Luckman of Swansea University, lead investigator of the MIDAS project, said: “We have been anticipating this event for months, and have been surprised how long it took for the rift to break through the final few kilometres of ice.”
The iceberg is one of the largest recorded and its future progress is difficult to predict. 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.”
Dr Martin O’Leary, a Swansea University glaciologist and member of the MIDAS project team, explained that this is a natural phenomenon, not linked to human-induced climate change, however, it still puts the ice shelf in a very vulnerable position.
“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.”
Professor Adrian Luckman of Swansea University added that expert opinions are divided: in the coming years, the ice shelf could either gradually regrow, or may suffer further calving events which may eventually lead to collapse.
Whilst this new iceberg will not immediately raise sea levels, if the shelf loses much more of its area, it could result in glaciers that flow off the land behind speeding up their passage towards the ocean. This non-floating ice would have an eventual impact on sea levels, but only at a very modest rate.