National Snow and Ice Data Center
University of Colorado-Boulder
Boulder, Colorado

Media Relations Contacts:
Stephanie Renfrow, NSIDC
+1 303 492-1497 (se habla Espanol)

Athena Dinar, BAS
+44 (0)1223 221414

Cheng-Chien Liu, NCKU
+886-6-2757575 X65422

This is a joint press release from the National Snow and Ice Data Center
(NSIDC), which is part of the Cooperative Institute for Research in
Environmental Sciences at the University of Colorado at Boulder; the British
Antarctic Survey (BAS), based in the United Kingdom; and the Earth Dynamic
System Research Center at National Cheng Kung University (NCKU) inTaiwan.

25 March 2008

Antarctic Ice Shelf Disintegration Underscores a Warming World

Satellite imagery from the National Snow and Ice Data Center at the
University of Colorado at Boulder reveals that a 13,680 square kilometer
(5,282 square mile) ice shelf has begun to collapse because of rapid climate
change in a fast-warming region of Antarctica.

The Wilkins Ice Shelf is a broad plate of permanent floating ice on the
southwest Antarctic Peninsula, about 1,000 miles south of South America. In
the past 50 years, the western Antarctic Peninsula has experienced the
biggest temperature increase on Earth, rising by 0.5 degree Celsius (0.9
degree Fahrenheit) per decade. NSIDC Lead Scientist Ted Scambos, who first
spotted the disintegration in March, said, "We believe the Wilkins has been
in place for at least a few hundred years. But warm air and exposure to
ocean waves are causing a break-up."

Satellite images indicate that the Wilkins began its collapse on February
28; data revealed that a large iceberg, 41 by 2.5 kilometers (25.5 by 1.5
miles), fell away from the ice shelf's southwestern front, triggering a
runaway disintegration of 405 square kilometers (160 square miles) of the
shelf interior (Figure 1). The edge of the shelf crumbled into the sky-blue
pattern of exposed deep glacial ice that has become characteristic of
climate-induced ice shelf break-ups such as the Larsen B in 2002. A narrow
beam of intact ice, just 6 kilometers wide (3.7 miles) was protecting the
remaining shelf from further breakup as of March 23 (Figure 2).

Scientists track ice shelves and study collapses carefully because some of
them hold back glaciers, which if unleashed, can accelerate and raise sea
level. Scambos said, "The Wilkins disintegration won't raise sea level
because it already floats in the ocean, and few glaciers flow into it.
However, the collapse underscores that the Wilkins region has experienced an
intense melt season. Regional sea ice has all but vanished, leaving the ice
shelf exposed to the action of waves."

With Antarctica's summer melt season drawing to a close, scientists do not
expect the Wilkins to further disintegrate in the next several months. "This
unusual show is over for this season," Scambos said. "But come January,
we'll be watching to see if the Wilkins continues to fall apart."

Real-time collaboration

Images from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) and
data from ICESat showed that the ice shelf was in a state of collapse in
March. Scambos then alerted colleagues around the world, seeking to ensure
that every means of gathering information was focused on the break-up.

British Antarctic Survey (BAS) mounted an overflight of the crumbling shelf,
collecting video footage and other observations. BAS glaciologist David
Vaughan said of the ice shelf, which is supported by a single strip of ice
strung between two islands, "Wilkins is the largest ice shelf on West
Antarctica yet to be threatened. This shelf is hanging by a thread."

Associate Professor Cheng-Chien Liu at Taiwan's National Cheng-Kung
University (NCKU) also responded, requesting high-resolution color satellite
images of the area from Taiwan's Formosat-2 satellite (Figure 3), operated
by the National Space Organization. Cheng-Chien Liu said, "It looks as if
something is slicing the ice shelf piece by piece on an incredible scale,
kilometers long but only a few hundred meters in width."

South American scientists also got involved. Andres Rivera and Gino Cassasa
at the Laboratorio de Glaciologia y Cambio Climico at the Centro de Estudios
Cientificos in Chile (CECS), acquired images of the Wilkins from the ASTER
instrument, aboard NASA's Terra satellite.

The combined efforts of these international teams have begun to provide
observational data that will improve scientific understanding of the
mechanisms behind ice shelf collapse. Scambos said, "The Wilkins is an
example of an event we don't see very often. But it's a key process in being
able to predict how sea level will change in the future."

More information

The Wilkins is one of a string of ice shelves that have collapsed in the
West Antarctic Peninsula in the past thirty years. The Larsen B became the
most well-known of these, disappearing in just over thirty days in 2002. The
Prince Gustav Channel, Larsen Inlet, Larsen A, Wordie, Muller, and the Jones
Ice Shelf collapses also underscore the unprecedented warming in this region
of Antarctica.

To view British Antarctic Survey's version of this joint release, visit the
press area of their Web site at
     http://www.antarctica.ac.uk/about_bas/news/press_releases.php

For more information on the Larsen B collapse, see
     http://nsidc.org/iceshelves/larsenb2002/index.html

IMAGE CAPTIONS:

[Figure 1:
http://nsidc.org/news/images/20080325_wilkins_figure1.jpg (987KB)]
This series of satellite images shows the Wilkins Ice Shelf as it began to
break up. The large image is from March 6; the images at right, from top to
bottom, are from February 28, February 29, and March 8. NSIDC processed
these images from the NASA Moderate Resolution Imaging Spectroradiometer
(MODIS) sensor, which flies on NASA's Earth Observing System Aqua and Terra
satellites.

Credit: National Snow and Ice Data Center/NASA

[Figure 2:
http://nsidc.org/news/images/20080325_wilkins_figure2.jpg (724KB)]
During the break-up, the Wilkins Ice Shelf broke into a sky-blue pattern of
exposed deep glacial ice. This true-color image of the Wilkins Ice Shelf was
taken by MODIS on March 6, 2008.

Credit: National Snow and Ice Data Center

[Figure 3:
http://nsidc.org/news/images/20080325_wilkins_figure3.jpg (2.07MB)]
This image shows a high-resolution, enhanced-color image of the Wilkins Ice
Shelf in Antarctica on March 8, 2008. Narrow iceberg blocks (150 meters
wide, or 492 feet) crumbled into house-sized rubble. Taiwan's Formosat-2
satellite acquired this image.

Credit: Left, National Snow and Ice Data Center; right, National Snow and
Ice Data Center/courtesy Cheng-Chien Liu, National Cheng Kung University
(NCKU), Taiwan and Taiwan's National Space Organization (NSPO); processed at
Earth Dynamic System Research Center at NCKU, Taiwan.

[Figure 4:
http://nsidc.org/news/images/20080325_wilkins_animation_low.mov (179KB)]
An animation of the Wilkins disintegration (February 28-March 17). NSIDC
processed these images from the NASA Moderate Resolution Imaging
Spectroradiometer (MODIS) sensor, which flies on NASA's Earth Observing
System Aqua and Terra satellites. For a high-resolution version, please
contact the press office.

Credit: National Snow and Ice Data Center
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