Just broke loose
Southern Ocean Larsen C ice shelf had extended more than 160km in length, and just a few kilometres of remaining ice connected the nascent iceberg to the shelf. The break began several years ago but had quickened its advance in the last year.
There is a debate over whether this event can be attributed in any way to climate change. Scientists don’t have all the data that they would need to show what is happening in the environment of the floating Larsen C ice shelf, which is affected not only by air temperatures above it but also ocean temperatures below.
Antarctica’s ice shelves do calve large pieces regularly, a natural process. But at the same time, Larsen C is the next ice shelf in line in a southward progression that has previously seen the collapse of the Larsen A and Larsen B ice shelves, making this occurrence at least suspicious. “I think we’re all scratching Larsen A collapses Larsen B breaks apart Remnant of Larsen B our heads as to just what combination of changes in the ice, air, and ocean caused this,” said Scambos. “It’s unclear if this is a new trend for this area of Antarctica. The case for a climate-related cause is not nearly as good as for other areas of Antarctica.”
But Rignot is convinced of a climate role. “For me, there is no doubt that this event is not part of a natural cycle. The Larsen C ice shelf will not collapse for another few decades, most likely, but this calving is unique in the history of the ice shelf since first seen by human eyes by the Norwegian explorer Carl Anton Larsen in 1893.”
Rignot observed that Larsen C’s northern cousin Larsen B, which collapsed in 2002, is believed to have previously held its position for over 10,000 years and something similar is probably true of Larsen C.
The Antarctic continent is ringed by ice shelves, which are large, thick, Loss of piece leaves whole shelf vulnerable to future collapse, raising global sea levels by 10cm Jan 2017 Jun 2016 Nov 2010 Aug 2014 floating extensions of glaciers that have extended from the land, where they have built up due to snowfall over vast time periods, into the sea. These shelves are now vulnerable to warming air temperatures and ocean waters, which can cause them to thin, break off pieces at an unusual rate, and even collapse. And when they do so, the ice behind them is liberated to flow more rapidly into the ocean, raising seas. Scientists stress that because the trillion tonne iceberg is already afloat in the Weddell Sea, its detachment does not raise the globe’s sea level. Their fear is that its loss could speed up the outward ice flow of the remainder of the Larsen C ice shelf, which would indeed increase sea level — but glaciers in this region only have the potential to raise seas by about a cm. The greater fear is the loss of ice shelves, and glaciers, farther southward in Antarctica.