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The iceberg, which will likely be dubbed A68, weighs more than a trillion tonnes, has a volume twice that of Lake Erie, and is about 5,800 square kilometers in size—roughly the size of Delaware.
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"The Larsen C Ice shelf in Antarctica is primed to shed an area of more than 5000 square kilometers [approx. 3,100 square miles] following further substantial rift growth," wrote the Project MIDAS team, which has been studying the ice shelf.
"After a few months of steady, incremental advance since the last event, the rift grew suddenly by a further 18 kilometers [about 11 miles] during the second half of December 2016."
During the last Antarctic winter, the rift averaged about three miles per month of growth. In December, NASA released a set of images that found the crack measured 70 miles in length, 300 feet wide and one-third of a mile deep.
The sudden acceleration of the split in the ice has scientists convinced that a massive calving event is imminent.
"If it doesn't go in the next few months, I'll be amazed," Professor Adrian Luckman, project leader from Swansea University, told BBC News.
By itself, the iceberg that is set to break off won't lead to a rise in sea levels, as the ice shelf already floats on the ocean. However, the Larsen ice shelf acts as a buttress against continental glaciers that could then be free to slide into the sea. BBC reports that if all the ice that Larsen C holds back were released into the ocean, global waters would rise by 10 cm, or four inches.
Globally, sea levels have risen about eight inches since 1901. Its effects can be seen in increased flooding in South Florida, coastal erosion in Louisiana, intrusion of seawater into ground aquifers and stronger storm surges such as those seen in Superstorm Sandy.
Long-term satellite observations show that Antarctic glaciers are rapidly retreating. A separate rift in the East Antarctic is forcing a British research station to relocate.
The Larsen C is the latest section of the huge ice shelf to break off. Larsen A collapsed in 1995. In 2002, Larsen B began to break apart. Within six weeks, a 1,235 square mile chunk of ice slipped away.
When the Larsen C ice shelf breaks off, it "will fundamentally change the landscape of the Antarctic Peninsula," said the U.K.-based Project MIDAS team.