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Larsen Ice Shelf has Progressively Thinned

Andrew Shepherd, Duncan Wingham, Tony Payne, and Pedro Skvarca
Science, October 31st, 2003


Note: Bespoke animations are available at short notice - please contact Andrew Shepherd.

3D Movie 3D movie. Larsen Ice Shelf 3D animation. This fly-by shows the location of the Larsen Ice Shelf on the east coast of the Antactic Peninsula - the northernmost region of Antarctica. The movie is assembled from a digital elevation model of Antarctica (courtesy J. Bamber), a mosaic of AVHRR satellite imagery (courtesy NASA) and the 1992-2001 satellite measurements of Larsen Ice Shelf thickness change presented in the Science article. The colour scale shows regions of ice shelf thinning in red, thickening in blue, and no change in turquoise. Also shown is the progressive disintegration of northern Larsen Ice Shelf sections before, during, and after the period of satellite measurements. Animation produced by A. Shepherd.
Air-photo movie Air-photo movie. Animated mosaic of aerial photographs taken during the joint NASA-CECS 2002 airborne survey of the Larsen Ice Shelf. The flight path crossed the ice shelf, starting north-west of the Mobiloil Inlet, and shows the presence of heavy crevasse rifting close to the ice shelf margins where outlet glaciers flow into the ice shelf. Images assembled in the mosaic courtesy of Bill Krabil, Bob Thomas and Serdar Manizade of the NASA Wallops Flight Facility. Animation produced by A. Shepherd


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Larsen-B collapses Larsen-B collapses. Disintegration of Larsen B Ice Shelf south of the Seal Nunataks section (to the right)". Photo taken on 13 March 2002 during the Global Positioning Satellite (GPS) survey by Pedro Skvarca, Instituto Antartico Argentino.
Tabular iceberg Tabular iceberg. The production of tabular icebergs is a major mechanism of mass loss from the Antarctic Ice Sheet. Icebergs are calved during both rapid ice-shelf collapse and as part of the normal transfer of mass through the ice sheet to the surrounding ocean. This tabular berg, with a freeboard of about 20 m, is aground on the sea floor offshore of the Antarctic Peninsula. (Photo: Julian Dowdeswell).
Larsen-B iceberg Larsen-B iceberg. Remnant icebergs from the disintegrated Larsen-B Ice Shelf floating in calm waters.The photograph was taken shortly after the ice shelf collapsed rapidly in February 2002 (Photo: Colm Ó Cofaigh).
Waterfall #1 Waterfall #1. Waterfall running off the Larsen-B Ice Shelf barrier. In recent decades, summer temperatures have risen at the northern tip of the Antarctic Peninsula by up to 2 degres Centigrade, leading to enhanced surface melting. The meltwater production is then channelled along the ice shelf surface towards the ocean during the height of Austral summer. (Photo: Colm Ó Cofaigh).
Waterfall #2 Waterfall #2. Ice surface conditions on Larsen-B during the warmest recorded summer. A water-fall cascades over the ~ 30 m high Larsen B ice-front, draining meltwater off the ice shelf observed during February 2002. (Photo: Pedro Skvarca)

Figures from Article

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Figure 1 Figure 1. Rate of surface elevation change of the Larsen Ice Shelf determined from ERS radar altimeter measurements recorded between 1992 and 2001 (colour scale and 0.1 metres per year white contours). The 1990 boundaries of the Larsen-A, -B and –C ice shelf sections are highlighted with blue, green and red borders. Larsen-A collapsed prior to the ERS measurements, Larsen–B has since disintegrated, Larsen-C remains intact.
Figure 2 Figure 2. Change in surface elevation between 1992 and 2001 recorded by the ERS radar altimeters ~ 80 km west of the Larsen meteorological station at the Larsen-C ice shelf before (A) and after (B) removal of the periodic signal of ocean tide.
Figure 3 Figure 3. Larsen Ice Shelf surface elevation change (diamonds) along transect A-B in Figure 1 compared to the estimated change due to increased melt-water production. Our data show that a 31,000 square kilometre region of the Larsen Ice Shelf between 65.5 and 67.5 degrees South lowered by 0.08 ± 0.03 metres per year above the rate expected from densification, equivalent to the freeboard expression of a 21 ± 8 Gigatons per year loss of ice mass.