Larsen C break up visible from space

We've been following the inevitable break up of the massive Delaware-sized iceberg Larsen C Ice Shelf. Today's news that it finally broke off is not a surprise, but is still newsworthy. Perhaps the best view of the massive new iceberg come from space. The final 8 mile crack is clearly visible as the giant iceberg called A68 breaks free.

Here's more detail on the new iceberg from Project MIDAS.

A one trillion tonne iceberg – one of the biggest ever recorded - has calved away from the Larsen C Ice Shelf in Antarctica. The calving occurred sometime between Monday 10th July and Wednesday 12th July 2017, when a 5,800 square km section of Larsen C finally broke away. The iceberg, which is likely to be named A68, weighs more than a trillion tonnes.  Its volume is twice that of Lake Erie, one of the Great Lakes.

The final breakthrough was detected in data from NASA’s Aqua MODIS satellite instrument, which images in the thermal infrared at a resolution of 1km, and confirmed by NASA’s Suomi VIIRS instrument.

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Here's a good animation of the scale of A68.

Canary in the coal mine?

One important note. The calving of A68 by itself will not have much effect on sea level rise. The longer range concern for climate scientists is the breakup of ice shelves the Larsen C will effectively "uncork" land based glaciers. That process raises sea level. Just how fast that happens is a climate change wildcard.

Here's some perspective from today's New York Times piece on Larsen C.

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At the remaining part of Larsen C, the edge is now much closer to a line that scientists call the compressive arch, which is critical for structural support. If the front retreats past that line, the northernmost part of the shelf could collapse within months.

“At that point in time, the glaciers will react,” said Eric Rignot, a climate scientist at the University of California, Irvine, who has done extensive research on polar ice. “If the ice shelf breaks apart, it will remove a buttressing force on the glaciers that flow into it. The glaciers will feel less resistance to flow, effectively removing a cork in front of them.”