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Archive for the ‘Ice Shelf’ Category

The Great Antarctic Peninsula Ice Shelf Extinction

Posted by feww on February 23, 2010

Public Release: USGS

Ice shelves disappearing on Antarctic Peninsula

Glacier retreat and sea level rise are possible consequences

Ice shelves are retreating in the southern section of the Antarctic Peninsula due to climate change. This could result in glacier retreat and sea-level rise if warming continues, threatening coastal communities and low-lying islands worldwide.

Click Images to Enlarge!


Southern Portion of Antarctic Peninsula. This image identifies the southern portion of the Antarctic Peninsula, which is one area studied as part of this project. Research on the southern Antarctic Peninsula is summarized in the USGS report, “Coastal-Change and Glaciological Map of the Palmer Land Area, Antarctica: 1947—2009” (map I—2600—C). Source: U.S. Geological Survey


Multi-year ice. ARCTIC OCEAN – A multi-year ice floe slides down the starboard side of the Coast Guard Cutter Healy Aug. 11, 2009, as the ship heads north into even thicker ice. “You can tell that this is a multi-year ice floe by the light blue melt ponds that have formed on top of the floe,” said Pablo Clemente-Colón, chief scientist at the U.S. National Ice Center. Credit: Patrick Kelley, U.S. Coast Guard


Southern Antarctic Peninsula. This image shows ice-front retreat in part of the southern Antarctic Peninsula from 1947 to 2009. The southern portion of the Antarctic Peninsula is one area studied as part of this project, and is summarized in the USGS report, “Coastal-Change and Glaciological Map of the Palmer Land Area, Antarctica: 1947—2009” (map I—2600—C). Source: U.S. Geological Survey

U.S. Geological Survey says its research is the first to document that every ice front in the southern part of the Antarctic Peninsula has been retreating overall from 1947 to 2009, with the most dramatic changes occurring since 1990. The USGS previously documented that the majority of ice fronts on the entire Peninsula have also retreated during the late 20th century and into the early 21st century.

The ice shelves are attached to the continent and already floating, holding in place the Antarctic ice sheet that covers about 98 percent of the Antarctic continent. As the ice shelves break off, it is easier for outlet glaciers and ice streams from the ice sheet to flow into the sea. The transition of that ice from land to the ocean is what raises sea level.

“This research is part of a larger ongoing USGS project that is for the first time studying the entire Antarctic coastline in detail, and this is important because the Antarctic ice sheet contains 91 percent of Earth’s glacier ice,” said USGS scientist Jane Ferrigno. “The loss of ice shelves is evidence of the effects of global warming. We need to be alert and continually understand and observe how our climate system is changing.”

The Peninsula is one of Antarctica’s most rapidly changing areas because it is farthest away from the South Pole, and its ice shelf loss may be a forecast of changes in other parts of Antarctica and the world if warming continues.

Retreat along the southern part of the Peninsula is of particular interest because that area has the Peninsula’s coolest temperatures, demonstrating that global warming is affecting the entire length of the Peninsula.

The Antarctic Peninsula’s southern section as described in this study contains five major ice shelves: Wilkins, George VI, Bach, Stange and the southern portion of Larsen Ice Shelf. The ice lost since 1998 from the Wilkins Ice Shelf alone totals more than 4,000 square kilometers, an area larger than the state of Rhode Island.

The USGS is working collaboratively on this project with the British Antarctic Survey, with the assistance of the Scott Polar Research Institute and Germany’s Bundesamt fűr Kartographie und Geodäsie. The research is also part of the USGS Glacier Studies Project, which is monitoring and describing glacier extent and change over the whole planet using satellite imagery.

Related Info:

Contact: Jessica Robertson
jrobertson@usgs.gov
United States Geological Survey

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Posted in Antarctic Peninsula, Antarctica, Ice Shelf, Larsen Ice Shelf | Tagged: , , , , , , , | Leave a Comment »

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 »