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Yet Another Giant Iceberg Has Broken Free From Antarctica

Satellite image taken of the new iceberg on September 24, 2017. (Image: Sentinel1)
Satellite image taken of the new iceberg on September 24, 2017. (Image: Sentinel1)

Satellite images taken this past weekend show a new 100-square-mile iceberg emerging from Antarctica’s Pine Island Glacier. The calving event did not come as a complete surprise, but it’s a troubling sign with regards to future sea level rise.

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Pine Island Glacier (PIG) is the fastest melting glacier in Antarctica—one that’s responsible for a quarter of the frozen continent’s ice loss, a whopping 45 billion tons of ice each year. Satellite images taken from September 23 to 24 show an open-water gap emerging between the ice shelf and the iceberg, which is about four times the size of Manhattan (103 square miles or 267 square km).

The new iceberg appears to be quite unstable, producing a batch of smaller icebergs as it slowly drifts out to sea. The new berg is not nearly as big as the one produced by the Antarctic Peninsula’s Larsen C ice shelf a few months ago—an enormous chunk of ice that measures about 2,240 square miles (5,800 square km).

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On Saturday, satellite observation specialist Stef Lhermitte at Delft University of Technology in the Netherlands posted a Sentinel1 image of the new PIG iceberg.

Gizmodo contacted Christopher A. Shuman, a research scientist within the Cryospheric Sciences Laboratory at NASA Goddard Space Flight Center, who confirmed the break using the MODIS and Landsat 8 satellites.

The area drained by PIG encompasses approximately 10 percent of the West Antarctic Ice Sheet, making it a critically important geological feature in terms of its contribution to sea level rise. This is now the third major calving event produced by this ice stream in four years, the others happening in 2013 (252 square miles/652 sq km) and 2015 (225 square miles/582 sq km).

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“But it isn’t the size of the bergs that are the main issue,” Shuman told Gizmodo. “It is the overall progressive retreat of the ice front with calving losses in 2013, 2015, and 2017, which is pretty rapid retreat for any very large glacier especially one this far south in Antarctica. With the first big loss in 2001, this is not a good sign for sure.” To which he added: “This is not as large a loss as in 2013 but it is a further retreat from what was a pretty stable ice front in at the beginning of this century.”

Shuman also confirmed that the rifts are forming in the center of the glacier and extending out toward the edges. This means that the rifts are forming far inland, likely the result of warm ocean water rubbing against the base of the glacier. This may explain why the calving events are happening with increased frequency (the speed of the glacier’s flow towards the sea is increasing, and it’s now moving at about 2.5 miles (4 km) per year), and why PIG appears to be thinning (the rate of thinning has quadrupled since the mid 1990s). If this current rate of thinning continues, the entire main trunk of the glacier could be afloat in about 100 years.

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The West Antarctic ice sheet is separated from the ocean by a series of large glaciers, PIG included. These glaciers are holding back tremendous volumes of ice, but as this recent calving event demonstrates, perhaps for not much longer.

George is a senior staff reporter at Gizmodo.

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DISCUSSION

StarControl

I had a funny out of the blue experiment just this weekend, that I never really thought about, and it probably seems stupid simple to smarter people than me in that regard.

I have an aquarium that during the summer gets hot. Some of my fishies dont’ like the super hot, and I’m not investing in a $400 aquarium chiller, so I keep a few frozen bottles of water in the freezer and I pop them in the aquarium every couple of hours to cool off the water to more reasonable 80 degrees. That water gets from frozen to “room temp” in something like 15 minutes.

Yestersay I had excess bottles and wanted to pour the (frozen) water in the bottle in my plants so that I don’t waste the water. I set out said bottle with frozen water (i.e. ice ;P) in direct sunlight outside at about 88F weather. It took almost 2 hours for that ice in the bottle to melt.

Again it took 15 mins or less to do so in the aquarium, not in direct sunlight. Anyway moral of this long-winded response - when ice is submerged even in slightly warm water it melts SO much faster than warm weather outside in direct sunlight.

Yes, I’m sure a ton of people are saying “well, duh!”. I apparently skipped that lesson in Physics in elementary shcool ;(.