Photos: Warming triggers massive Antarctic ice shelf collapse

by Mongabay.com on 25 March 2008

Photos: Warming triggers massive Antarctic ice shelf collapse

mongabay.com

March 25, 2008

Satellites have captured the collapse of a massive ice shelf in Antarctica. At 160 square miles the area of collapsed ice was seven times the size of Manhattan.

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.

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

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

Antarctic Temperature Trend 1982-2004. This image shows trends in skin temperatures–temperatures from roughly the top millimeter of the land or sea surface–not air temperatures. The data were collected by the Advanced Very High Resolution Radiometer (AVHRR) sensors that were flown on several National Oceanic and Atmospheric Administration (NOAA) satellites. The data come from the AVHRR’s thermal infrared channel–a portion of the light spectrum we can sense as heat but that human eyes cannot see. This image shows temperature trends for the icy continent from 1982 to 2004. Red indicates areas where temperatures generally increased during that period, and blue shows where temperatures predominantly decreased. NASA image based on data provided by Josefino Comiso, NASA-GSFC.

Scientists say the collapse is the beginning of a “runaway” disintegration of the 13,680 square kilometer (5,282 square mile) Wilkins Ice Shelf on the southwest Antarctic Peninsula. The region has experienced the largest temperature increase on the planet over the past 50 years, rising by 0.5 degree Celsius (0.9 degree Fahrenheit) 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 break-up,” said Ted Scambos, a scientist with the National Snow and Ice Data Center at the University of Colorado at Boulder (NSIDC). Scambos first spotted the disintegration via NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) and data from ICESat.

While the collapse is dramatic, Scambos says it wouldn’t trigger a rise in sea levels since the Wilkins Ice Shelf is a plate of floating ice.

“The Wilkins disintegration won’t raise sea level because it already floats in the ocean, and few glaciers flow into it,” he said. “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.”

Scambos adds that with the close of summer in the Antarctic, Wilkins is unlikely 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.”

This article is based on a news release from NSIDC