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Archive for March 26th, 2008

A Fast-Warming World

Posted by feww on March 26, 2008

Antarctic Ice Shelf Collapse Highlights a Fast-Warming World

Satellite images from the National Snow and Ice Data Center at the University of Colorado at Boulder reveal a massive ice shelf the size of Connecticut (13,680 square kilometer, or 5,282 square mile) collapsing because of rapid climate change in a fast-warming region of Antarctica.

Satellite images show the Wilkins Ice Shelf breaking up. The large image recorded March 6; right, from top to bottom, February 28, February 29, and March 8. Credit: National Snow and Ice Data Center/NASA

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

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.”

An 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 chunks. 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.

Collapsing Ice Shelves

Disintegration of Mega-iceberg A53a, South Atlantic

In April 2005, the A53a iceberg broke off the Larsen Ice Shelf on the Antarctic Peninsula drifting north where it encountered warmer temperatures and, nearly three years later, began to disintegrate. Image Credit: NASA Earth Observatory

The mega-iceberg A53a (upper image) measured about 50 kilometers by 22 kilometers, seven times the area of Manhattan Island, in mid-January 2008 when astronauts took the photographs for this mosaic. Ted Scambos, glaciologist and Lead Scientist at the National Snow and Ice Data Center [he stitched together three detailed images of mega-iceberg A53aby to make this image,] said, “This is an iceberg worth watching, because, being water-saturated, it may well show a sudden, crumbling, disintegration, spreading fine blue micro-icebergs over the ocean surface.”

The lower image shows A53a in the process of breaking off from the Larsen Ice Shelf in late 2004; the future ice berg is indicated by a dashed line in the image. The wider view of the ice shelf is based on the MODIS Mosaic of Antarctica image map. Some features acquired during the iceberg’s calving have been maintained in the years since.

Icebergs of the southern Atlantic Ocean contain rock material from Antarctica, eroded by the moving ice, and also wind-borne dust from deserts in Africa, South America, and Australia. The finest powdery rock material acts as nutrients for sea organisms. As the sediment-laden icebergs melt, they enrich the surrounding seawater with minerals. The area of enrichment is significantly larger when a mega-iceberg disintegrates into many small pieces. Caption [slightly edited] by M. Justin Wilkinson, NASA-JSC.

Larsen B

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.

Mapping the new ice front line towards Cape Foyn: Edge parallel crevasses indicate future calving. Photo courtesy of S. Tojeiro, Fuerza Aerea Argentina, 13 March 2002

View from east to west nunataks Grey, Bruce, and Bull. Photo courtesy of Pedro Skvarca, Instituto Antártico Argentino, 13 March 2002.

Additional images taken from the space by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth.

Posted in Antarctica, Climate Change, Ice Shelf, Satellite image, Warming World, Wilkins | 4 Comments »