A huge iceberg almost the size of Los Angeles has broken off the Brunt Ice Shelf, which borders the Antarctic coast of Coats Land. The iceberg has been estimated to measure 1,270 square kilometers (490.3 square miles). Over the next weeks and months, researchers will see if it will move away from the southernmost continent or remain near the ice shelf.
The entire Brunt Ice Shelf has been considered at risk of major break-off for the last decade. Several chasms have formed over time, but a new one – nicknamed the North Rift – started heading towards another chasm back last November.
By January, the rift was moving at about one kilometer (0.6 miles) per day through the 150-meter (492-foot) thick floating ice shelf. This was a clear indication that a calving event was imminent. It has now been confirmed.
“Our teams at BAS have been prepared for the calving of an iceberg from Brunt Ice Shelf for years. We monitor the ice shelf daily using an automated network of high-precision GPS instruments that surround the station, these measure how the ice shelf is deforming and moving,” Professor Dame Jane Francis, Director of British Antarctic Survey, said in a statement.
“We also use satellite images from ESA, NASA and the German satellite TerraSAR-X. All the data are sent back to Cambridge for analysis, so we know what’s happening even in the Antarctic winter, when there are no staff on the station, it’s pitch black, and the temperature falls below minus 50 degrees C (or -58F).”
Two previous cracks in the Brunt Ice Shelf known as "Chasm 1" and "Halloween Crack" were a major concern for the British Antarctic Survey. So much so that in 2016, the Halley Research Station was relocated 32 kilometers (20 miles) inland. The following year, the BAS decided not to have staff present there during the winter months, when evacuation would be difficult.
These two cracks have not grown for a while, but it is clear how dangerous these events can be when you can go from a crack to a huge iceberg in a matter of months.
“This is a dynamic situation. Four years ago we moved Halley Research Station inland to ensure that it would not be carried away when an iceberg eventually formed. That was a wise decision. Our job now is to keep a close eye on the situation and assess any potential impact of the present calving on the remaining ice shelf. We continuously review our contingency plans to ensure the safety of our staff, protect our research station, and maintain the delivery of the science we undertake at Halley,” Simon Garrod, Director of Operations at British Antarctic Survey, explained.