Remnant of Antarctica’s Larsen B Ice Shelf Disintegrates

Twenty years after the Antarctic Peninsula’s Larsen B Ice Shelf disintegrated in spectacular fashion, a remaining portion of that ice shelf dramatically broke apart last month, according to NASA’s Earth Observatory.

The space agency’s satellite images show the so-called remnant “Larsen B embayment” collapsing from January 19 to January 21. Scientists are still investigating the cause of the breakup, but it appears that warm, wet weather — once unheard of in this part of Antarctica — may have melted and destabilized the embayment.

The Larsen Ice Shelf, formed over the course of more than 12,000 years and 750 feet thick in places, is located on the northeastern side of the Antarctic Peninsula on the Weddell Sea — the once-completely frozen body of water where Ernest Shackleton and the men of the Endurance expedition were trapped in sea ice in 1914 and 1915. The Antarctic Peninsula has been steadily warming in recent decades, causing the Larsen A Ice Shelf to collapse in 1995 and the 1,250-square-mile Larsen B — a shelf floating atop the Weddell Sea — to collapse in early 2002.

The Larsen B embayment was a portion of the defunct ice shelf that refroze in 2011 and was attached to the Scar Inlet Ice Shelf. Last month, the embayment broke apart, taking with it a portion of the Scar Inlet Ice Shelf. The combined Larsen ice shelves — A, B, C, and D — once extended along the 1,000-mile length of the eastern Antarctic Peninsula. Since 1995, however, the Larsen Ice Shelf has shrunk from 33,000 square miles to 26,000 square miles.

Antarctica’s ice shelves float on the ocean, and their loss does not, in itself, increase global sea levels. But the shelves act as dams that hold back the land-based glaciers behind them, and the loss of the shelves dramatically increases the rate at which the glaciers flow into the sea, which does raise sea levels. Christopher Shuman, a glaciologist with the University of Maryland, Baltimore County and NASA, said that with sea ice now gone in the Larsen B embayment, “the likelihood is that backstress will be reduced on all glaciers in the [embayment] and that additional inland ice losses will be coming soon.”

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