Antarctica’s Larsen B Ice Shelf Will Disintegrate Before the End of the Decade

Study Shows Antarctica’s Larsen B Ice Shelf Nearing Its Final Act

Antarctica’s Larsen B Ice Shelf is likely to shatter into hundreds of icebergs before the end of the decade, according to a new NASA study. Credit: NSIDC/Ted Scambos

A newly published NASA study reveals that the last remaining section of Antarctica’s Larsen B Ice Shelf is weakening and will likely to disintegrate completely before the end of the decade.

A team led by Ala Khazendar of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, found the remnant of the Larsen B Ice Shelf is flowing faster, becoming increasingly fragmented, and developing large cracks. Two of its tributary glaciers also are flowing faster and thinning rapidly.

“These are warning signs that the remnant is disintegrating,” Khazendar said. “Although it’s fascinating scientifically to have a front-row seat to watch the ice shelf becoming unstable and breaking up, it’s bad news for our planet. This ice shelf has existed for at least 10,000 years, and soon it will be gone.”

Ice shelves are the gatekeepers for glaciers flowing from Antarctica toward the ocean. Without them, glacial ice enters the ocean faster and accelerates the pace of global sea level rise. This study, the first to look comprehensively at the health of the Larsen B remnant and the glaciers that flow into it, has been published online in the journal Earth and Planetary Science Letters.

Khazendar’s team used data on ice surface elevations and bedrock depths from instrumented aircraft participating in NASA’s Operation IceBridge, a multiyear airborne survey campaign that provides unprecedented documentation annually of Antarctica’s glaciers, ice shelves and ice sheets. Data on flow speeds came from spaceborne synthetic aperture radars operating since 1997.

Khazendar noted his estimate of the remnant’s remaining life span was based on the likely scenario that a huge, widening rift that has formed near the ice shelf’s grounding line will eventually crack all the way across. The free-floating remnant will shatter into hundreds of icebergs that will drift away, and the glaciers will rev up for their unhindered move to the sea.

Located on the coast of the Antarctic Peninsula, the Larsen B remnant is about 625 square miles (1,600 square kilometers) in area and about 1,640 feet (500 meters) thick at its thickest point. Its three major tributary glaciers are fed by their own tributaries farther inland.

“What is really surprising about Larsen B is how quickly the changes are taking place,” Khazendar said. “Change has been relentless.”

The remnant’s main tributary glaciers are named Leppard, Flask, and Starbuck — the latter two after characters in the novel Moby Dick. The glaciers’ thicknesses and flow speeds changed only slightly in the first couple of years following the 2002 collapse, leading researchers to assume they remained stable. The new study revealed, however, that Leppard and Flask glaciers have thinned by 65-72 feet (20-22 meters) and accelerated considerably in the intervening years. The fastest-moving part of Flask Glacier had accelerated 36 percent by 2012 to a flow speed of 2,300 feet (700 meters) a year — comparable to a car accelerating from 55 to 75 mph (89 to 121 kph).

Flask’s acceleration, while the remnant has been weakening, may be just a preview of what will happen when the remnant breaks up completely. After the 2002 Larsen B collapse, the glaciers behind the collapsed part of the shelf accelerated as much as eightfold – comparable to a car accelerating from 55 to 440 mph (89 to 708 kph).

The third and smallest glacier, Starbuck, has changed little. Starbuck’s channel is narrow compared with those of the other glaciers, and strongly anchored to the bedrock, which, according to the authors of the study, explains its comparative stability.

“This study of the Antarctic Peninsula glaciers provides insights about how ice shelves farther south, which hold much more land ice, will react to a warming climate,” said JPL glaciologist Eric Rignot, a coauthor of the paper.

The research team included scientists from JPL, the University of California, Irvine, and the University Center in Svalbard, Norway.

NASA uses the vantage point of space to increase our understanding of our home planet, improve lives, and safeguard our future. NASA develops new ways to observe and study Earth’s interconnected natural systems with long-term data records. The agency freely shares this unique knowledge and works with institutions around the world to gain new insights into how our planet is changing.

Reference: “The evolving instability of the remnant Larsen B Ice Shelf and its tributary glaciers” by Ala Khazendar, Christopher P. Borstad, Bernd Scheuchl, Eric Rignot and Helene Seroussi, 1 June 2015, Earth and Planetary Science Letters.
DOI: 10.1016/j.epsl.2015.03.014


3 Comments on "Antarctica’s Larsen B Ice Shelf Will Disintegrate Before the End of the Decade"

  1. Erik Williams | May 22, 2015 at 2:11 pm | Reply

    Well, thank you for your overly dramatic opinion.
    “After the 2002 Larsen B collapse, the glaciers behind the collapsed part of the shelf accelerated as much as eightfold – comparable to a car accelerating from 55 to 440 mph.”

    That’s also the same as going from 1 to 8 mph. Of course that’s not dramatic enough for you, so you chose the ridiculous analogy of 55 to 440!

    Stop with the dramatic fear mongering. It is a disservice and leaves you open to criticism that detracts from the actual concern. Leave that form of journalism to Fox News and associates please.

  2. Eric Connolly | June 8, 2015 at 11:08 am | Reply

    I don’t think this is fearmongering at all. Sure, they could’ve used your 1 mph analogy but that doesn’t at all illustrate the point correctly. Especially because they were comparing other melting rates that were much less, like a 25% increase. If they used 1 mph as their base then the acceleration would seem completely insignificant. Instead they used a speed at which everyone who drives is familiar so that percentage increases would be easy to conceptualize. I also think it’s laughable that you brought up fox news in a negative light while simultaneously mirroring it’s general opinion on glo

    • Eric Connolly | June 8, 2015 at 11:11 am | Reply

      Continuation from my previous comment: *global warming. Don’t get me wrong, I despise FOX News as well. I just think you need some help if you can’t distinguish between an informative scientific article and the free for all of ignorance that is FOX News.

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