Ice shelves are floating buttresses to glaciers on the mainland.
Image: NASA/Wikimedia Commons
A massive iceberg the size of Delaware is likely to crack off of an ice shelf in West Antarctica sometime soon, British scientists have confirmed.
This would destabilize the ice shelf, known as the Larsen C, and put it in a precarious position. Ice shelves act like floating buttresses to the mainland glaciers, so If the giant Larsen C were to collapse into the sea, glaciers from West Antarctica would end up sliding into the ocean, and ultimately raising sea levels—possibly by many feet.
Scientists from the MIDAS Project, an academic group that studies ice melt and its impact on shelf stability in Antarctica, have been following the progression of a giant crack in the Larsen C for the last two years. Scientists have been keeping a close watch because of past calving events and shelf collapses that have occurred in the same region.
The project team has said that the rift, as they're calling the huge crack, is a geographical event, and not one directly attributable to climate change, but it could hasten climate change-related effects when it breaks away, by weakening the Larsen C ice shelf as a whole.
If the Larsen C collapsed, it would cause glaciers from land to spill into the sea—which would in turn raise sea levels and perhaps contribute to increased Antarctic glacial melting.
This past December, satellite observations revealed that the rift grew 18km in just a matter of weeks. "After a few months of steady, incremental advance since the last event, the rift grew suddenly by a further 18km during the second half of December 2016. Only a final 20km of ice now connects an iceberg one quarter the size of Wales to its parent ice shelf," said the MIDAS Project on its website.
That 20km thread of ice is now the only thing keeping a 5,000 sq km iceberg from cracking off and drifting out to sea. When this happens—researchers say the breakup is inevitable—it will be one of the ten largest icebergs ever recorded to break away in a calving event like that. The iceberg itself won't raise sea levels, but it will destabilize Larsen C.
The breaking away of this iceberg—10 percent of the Larsen C ice shelf—would make the whole shelf "less stable," said project member Martin O'Leary, of Swansea University in Wales, in a public statement. "If it were to collapse there would be nothing holding the glaciers up and they would start to flow quite quickly indeed."
The 80 km-long rift is currently about 100 meters wide, but slices down half a kilometer into the ice shelf. These shelves are typical hundreds of meters thick. Climate change has certainly aided in the growth of the rift. 2016 was the hottest year on record—by a significant amount—thanks to a one-two punch from greenhouse gases and an El Niño event.
Project Leader Adrian Luckman, also of Swansea University, told the BBC News, "If it doesn't go in the next few months, I'll be amazed."
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