Antarctic ice shelf disintegrating as result of climate change, say scientistsMarch 26, 2008Satellite imagery from the University of Colorado at Boulder's National Snow and Ice Data Center shows a portion of Antarctica's massive Wilkins Ice Shelf has begun to collapse because of rapid climate change in a fast-warming region of the continent. While the area of collapse involves 160 square miles at present, a large part of the 5,000-square-mile Wilkins Ice Shelf is now supported only by a narrow strip of ice between two islands, said CU-Boulder's Ted Scambos, lead scientist at NSIDC. "If there is a little bit more retreat, this last 'ice buttress' could collapse and we'd likely lose about half the total ice shelf area in the next few years." In the past 50 years, the western Antarctic Peninsula has experienced the biggest temperature increase on Earth, rising by 0.9 degree F per decade. "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 breakup," said Scambos, who first spotted the disintegration activity in March. Satellite images indicate the Wilkins began its collapse on Feb. 28. Data revealed that a large iceberg, measuring 25.5 by 1.5 miles, fell away from the ice shelf's southwestern front, triggering a runaway disintegration of 220 square miles of the shelf interior. The Wilkins Ice Shelf is a broad sheet of permanent floating ice on the southwest Antarctic Peninsula roughly 1,000 miles south of South America. 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 breakups such as the Larsen B ice shelf breakup in 2002, said Scambos. A narrow beam of intact ice about 3.7 miles wide was protecting the remaining shelf from further breakup as of March 23. 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." After images from NASA's Moderate Resolution Imaging Spectroradiometer, or MODIS, and data from the ICESat satellite showed that a portion of the ice shelf was in a state of collapse in March, Scambos alerted colleagues around the world. The British Antarctic Survey flew over the shelf, collecting video footage and other observations. BAS glaciologist David Vaughan, who said the ice shelf is supported by a single strip of ice strung between two islands, said the 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 used high-resolution color satellite images of the area from Taiwan's Formosat-2 satellite operated by the National Space Organization to analyze the activity. "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," Cheng-Chien said. In addition, Andrés Rivera and Gino Cassasa at the Laboratory for Glaciology and Climate Change at the Center of Scientific Study in Chile acquired images of the Wilkins from the ASTER instrument aboard NASA's Terra satellite. The combined efforts 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." The Wilkins is one of a string of ice shelves that have collapsed in the West Antarctic Peninsula in the past 30 years. The Larsen B became the most well-known of these, disappearing in just over 30 days in 2002. The Prince Gustav Channel, Larsen Inlet, Larsen A, Wordie, Muller and Jones ice shelf collapses also underscore the unprecedented warming in this region of Antarctica, said Scambos. University of Colorado at Boulder |
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| Related Ice Shelf Current Events and Ice Shelf News Articles Peering under the ice of a collapsing polar coast Starting this month, a giant NASA DC-8 aircraft loaded with geophysical instruments and scientists will buzz at low level over the coasts of West Antarctica, where ice sheets are collapsing at a pace far beyond what scientists expected a few years ago. Andrill demonstrates climate warming affects Antarctic ice sheet stability A five-nation scientific team has published new evidence that even a slight rise in atmospheric concentrations of carbon dioxide, one of the gases that drives global warming, affects the stability of the West Antarctic Ice Sheet (WAIS). Greenland and Antarctic ice sheet melting, rate unknown The Greenland and Antarctica ice sheets are melting, but the amounts that will melt and the time it will take are still unknown, according to Richard Alley, Evan Pugh professor of geosciences, Penn State. Satellite data reveals extreme summer snowmelt in northern Greenland, CCNY professor says The northern part of the Greenland ice sheet experienced extreme snowmelt during the summer of 2008, with large portions of the area subject to record melting days. Wilkins Ice Shelf hanging by its last thread The Wilkins Ice Shelf is experiencing further disintegration that is threatening the collapse of the ice bridge connecting the shelf to Charcot Island. Since the connection to the island in the image centre helps to stabilise the ice shelf, it is likely the break-up of the bridge will put the remainder of the ice shelf at risk. Antarctic ice shelf 'hangs by a thread' British Antarctic Survey has captured dramatic satellite and video images of an Antarctic ice shelf that looks set to be the latest to break out from the Antarctic Peninsula. A large part of the Wilkins Ice Shelf on the Antarctic Peninsula is now supported only by a thin strip of ice hanging between two islands. It is another identifiable impact of climate change on the Antarctic environment. ANDRILL's 2nd Antarctic drilling season exceeds all expectations A second season in Antarctica for the Antarctic Geological Drilling (ANDRILL) Program has exceeded all expectations, according to the co-chief scientists of the program's Southern McMurdo Sound Project. NASA researchers find snowmelt in Antarctica creeping inland On the world's coldest continent of Antarctica, the landscape is so vast and varied that only satellites can fully capture the extent of changes in the snow melting across its valleys, mountains, glaciers and ice shelves. New clues to ozone depletion Laerge quantities of ozone-depleting chemicals have been discovered in the Antarctic atmosphere by researchers from the University of Leeds, the University of East Anglia, and the British Antarctic Survey. Hundreds of Antarctic Peninsula glaciers accelerating as climate warms Hundreds of glaciers on the Antarctic Peninsula are flowing faster, further adding to sea level rise according to new research published this week in the Journal of Geophysical Research. Climate warming, that is already causing Antarctic Peninsula increased summer snow melt and ice shelf retreat, is the most likely cause. More Ice Shelf Current Events and Ice Shelf News Articles |
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