Larsen Ice Shelf

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Larsen A and Larsen B iceshelves marked in red

The Larsen Ice Shelf (67°30′S 062°30′W) is a long, fringing ice shelf in the northwest part of the Weddell Sea, extending along the east coast of Antarctic Peninsula from Cape Longing to the area just southward of Hearst Island. Named for Captain Carl Anton Larsen, who sailed along the ice front in the Jason as far as 68°10'S during December 1893.

In finer detail, the Larsen Ice Shelf is a series of three shelves that occupy (or occupied) distinct embayments along the coast. From north to south, the three segments are called Larsen A (the smallest), Larsen B, and Larsen C (the largest) by researchers who work in the area. The Larsen A ice shelf disintegrated in January of 1995. The Larsen B ice shelf disintegrated in February of 2002. The Larsen C ice shelf appears to be stable.

The Larsen disintegration events were unusual. Typically, ice shelves lose mass by iceberg calving and by melting at their upper and lower surfaces. The disintegration events are linked to the ongoing climate warming in the Antarctic Peninsula, about 0.5 °C per decade since the late 1940's (possibly a result of global warming).

[edit] Larsen B ice shelf

An image of the collapsing Larsen B Ice Shelf and a comparison of this to the U.S. state of Rhode Island.

During 2002-01-31–2002-03-07 the Larsen B ice shelf collapsed and broke up. 3250 km² of ice 200 m thick broke off. The shelf had previously been stable for 10 000 years, essentially the entire Holocene period since the last ice age, according to Queen's University researchers [1]. By contrast, the Larsen A Ice Shelf "was absent for a significant part of that period and reformed beginning about 4000 years ago, according to the study".

This collapse has revealed a thriving ecosystem 800 m (half a mile) below the sea. "Despite near freezing and sunless conditions, a community of clams and a thin layer of bacterial mats are flourishing in undersea sediments. [...] The discovery was accidental. U.S. Antarctic Program scientists were in the northwestern Weddell Sea investigating the sediment record in a deep glacial trough twice the size of Texas" Livescience.

[edit] Popular culture

The Larsen B Ice Shelf is the subject of a song by the band British Sea Power. "Oh Larsen B" appears on their 2005 album Open Season, and contains the lyric "my favourite foremost coastal antarctic shelf ... oh Larsen B, oh won't you fall on me ... desalinate the Barents sea".

The ice shelf has also been made the subject of a song by instrumental metal/drone band 5ive. The song, "Sleep For The Larsen B Shelf," appears on their The Telestic Disfracture album.

Larsen B Ice Shelf appeared also in the 2004 film The Day After Tomorrow where a huge chunk of ice fell off as Hall proclaimed 'the last chunk of ice that fell off was about the size of Rhode Island'. This opening sequence paves the way for the events to follow in the rest of the film.

The disintegration of the shelf is referenced in Al Gore's environmental documentary film An Inconvenient Truth as evidence in support of global warming.