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 Case Study: Animation of Larsen B breakup

When gigantic icebergs break off from Antarctica, the images are dramatic and frequently make the news. The recent collapse of the Larsen B ice shelf in West Antarctica (closest to South America), covered an area larger than the state of Rhode Island and sent thousands of icebergs drifting into the Weddell Sea. This was the largest single event in a series of retreats of the Larsen Ice Shelf in recent years.

Ice inland are thick plates of ice fed by glaciers. The shelves flow over the edge of the continent and float on the ocean around much of Antarctica. The Antarctic Peninsula, where the Larsen shelf is located, has experienced greater warming than other parts of the continent. Over the last five years, the shelf shrunk by about 5700 square kilometers (2200 square miles).

While the Antarctic Peninsula is warming faster than the global average, other parts of this huge continent are cooling, and some of the ice shelves are gaining mass. For example, the Ross Ice Shelf (closest to New Zealand) is thickening as the glacier streams that flow over it slow down. At the same time, this ice shelf has also calved its share of giant icebergs: in March 2000 and again in March and May 2002.

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Case Study: Animation of Larsen B breakup - This animation, created from a series of satellite images taken from January to March 2002, shows the collapse of a portion of the Larsen Ice Shelf on the Antarctic Peninsula. Source: NASA’s Terra Satellite, animation by Ted Scambos, National Snow and Ice Data Center, University of Colorado, Boulder

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question If much of Antarctica is getting colder, does that mean global warming is slowing down or reversing itself?

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 research connection  

The dynamics of an ice sheet and ice shelf are complex and not completely understood. Scientists studying the flow rates of the Ross Ice Shelf aren’t sure whether the ice is responding to an internal process or to the climate of parts of Antarctica.

They also can’t say for sure whether the collapse of the Larsen B Ice Shelf is attributable to a warming trend. Researchers at the National Snow and Ice Data Center, Portland State University, and elsewhere think that there is a link between warmer temperatures and ice shelf stability. They theorize that pools of melting ice on top of the glacier may enhance the fracturing and eventual collapse of portions of the ice shelf.

 related sites - Monster iceberg breaks off Antartica ice shelf.

National Oceanic and Atmospheric Administration: Icebergs - Images of Iceberg C019 and C-18.

San Francisco Chronicle - Media goofed on Antartic data: Global warming interpretation irks scientists.

San Francisco Chronicle: Understanding Antarctic Cooling - Map of Antarctica, showing locations of ice shelves and wind patterns.

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