Antarctica - 20 X 30 Mile Slab Of Nansen Ice Shelf Already Cracked, Beginning To Calve

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"I was on the first flight on December 10, which began with Dr. Choon-ki Lee installing a new GPS station on a large piece of ice at the front of Nansen Ice Shelf that looks ready to calve off into a tabular iceberg. There’s a huge crack, miles long and sometimes over a hundred yards wide, which runs more or less parallel to the front of the ice shelf. Over the winter, the sea surface freezes and traps small icebergs in the crack, producing a fascinatingly broken icescape." Image: Christine Dow/NASA

NASA has advised that a floating shelf of ice off the Antarctica coast of Victorialand, Antarctica​ is ready to calve an enormous iceberg into the Southern Ocean. This shelf buttresses two valley glaciers (Reeves​ and Priestly​ from emptying into Terra Nova Bay. Scientists Christine Dow and Ryan Walker noted that in just two years, a small crack grew large enough to spread across nearly the entire width of the Nansen Ice Shelf:

In early March 2016, with southern winter soon to set in, satellite imagery indicated that the cracking ice front was still attached to the shelf. Even in winter, strong winds can prevent the water beyond the shelf from freezing, so it is unclear whether the front will separate soon or hang on like a loose tooth.

Dow is talking with researchers about examining the crack during the coming summer field season. “I’m really interested to see whether this feature is occurring because of the topography around the ice shelf, or whether it was initially created by surface water flowing into a small ice surface crack,” she said. “We’re planning an intensive survey of this feature in the coming years and will hopefully get a handle on the causes.”

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Remember that ice shelf collapse does not directly contribute to sea level rise. The ice shelves are already floating on the surface. But the calving event indirectly speeds up the sea level process, because ice streams and glaciers behind them are left with a uninterrupted path to slide into the sea.

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http://www.dailykos.com/story/2016/03/15/1499598/-NASA-20-miles-across-and-30-miles-long-Nansen-Ice-Shelf-will-soon-break-off-Antarctica