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Rift.
After a nearly 30-kilometer fracture on the retreating Pine Island Glacier in early September, about 115 km 2 of ice – an area more than five times that of Manhattan – has now fallen to the sea.
The largest piece of ice is four times larger than Manhattan.
This iceberg calving event reinforces the ongoing history of melting and retreating Antarctic glaciers, particularly because of the relatively warm oceans that eat away at the ice from below.
"This retreat and weakening is almost entirely motivated by thinning caused by the melting of the oceans," said Stef Lhermitte, a geoscientist specializing in remote sensing at the Delft University of Technology (The Netherlands), by e-mail.
This last calving – although important – was the sixth largest event of its kind on the Pine Island Glacier since 2001.
Ice trays – which are the ends of massive Antarctic glaciers that float above the ocean – break regularly in the sea.
But today, with ice flowing from below, ice is pouring into the sea faster than it can be replenished naturally.
Relatively warm ocean waters brightening an ice floe from below.
"In the early 2000s, it was every six years or so, but the frequency of calving has increased since 2013," Lhermitte said.
"The resulting icebergs also disintegrate faster, as was the case with the iceberg of yesterday."
These ice creams are very important.
Specifically, they act as plugs, often pinning to the bottom of the sea and preventing the formidable Antarctic ice sheets from flowing freely in the ocean.
With more retreat of the ice, as in the latter case, the pack ice loses more and more ground and becomes more and more vulnerable to collapse.
In short, the cork could disintegrate in the ocean, which could unleash yards – not feet – of sea level rise.
At the beginning of the year 2000, significant calving events occurred every five years or so (2001, 2007, 2011), but there were four since 2013 (2013, 2015, 2017 and 2018). . As a result, the glacier front has declined sharply since 1972-2013 and is now about 5 km further inland than in 2015-17. 2/2 pic.twitter.com/8O7gPyQAmh
– Stef Lhermitte (@StefLhermitte) October 30, 2018
These major collapses are relatively new and largely unprecedented in the history of humanity. So we do not know how quickly that could happen – maybe this century or so soon after.
"We really do not know how fast they are going to collapse," said Josh Willis, NASA's oceanographer, in September.
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