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Study shows Antarctic ice melt accelerating

[ 2009-12-02 11:52]     字号 [] [] []  
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NEW YORK: New research published late last month suggests that the ice loss in Antarctica is accelerating, particularly in East Antarctica, the largest ice sheet.

The results indicate that "as a whole, Antarctica may soon be contributing significantly more to global sea level rise," write the US-based research team in the paper, which was published in the science journal Nature Geoscience.

By using satellite data, the researchers at University of Texas estimated a total ice sheet loss of 190 gigatons (1 gigaton equals to 1 cubic kilometers of water) a year in Antarctica from April 2002 to January 2009, with an error of 77 gigatons.

And during the same period in East Antarctica, the report says, the rate of ice loss was 57 gigatons a year, with an error of 52 gigatons, mostly in coastal regions.

"If you examine the data between January and September this year, which we haven't published yet, it's more evident that East Antarctica is increasingly losing ice along the coastal regions," said the lead author Dr Jianli Chen, a Chinese-American scientist with the Center for Space Research at the University of Texas at Austin (UT).

The number itself is not that critical, as 57 cubic kilometers' ice loss might only result in about 0.1 millimeters of sea level rise. However, what matters is that "we started seeing changes in East Antarctica," Chen said. "In the future, the trend of ice loss may become more significant."

Visually, the undergoing change in this largest ice sheet in the world is still subtle, according to co-author Don Blankenship, a glaciologist at the university's Institute for Geophysics, who is currently conducting a field study in East Antarctica.

"We now know that there are actually rocks beneath the ice, and the bottom of the ice is below the sea level. So the ocean can actually penetrate the center of the ice, warm it up and then more ice is going to the ocean," Blankenship said.

"But we don't know what the bottom of the shell looks like."

According to the scientists, the ice loss in Antarctica is different from that of the Greenland, where the ice sheet is actually melting at the surface. Instead, Antarctica is losing mass by its expedited ice flow, which happens at the edge where ocean contacts the ice sheet.

The United Nations' Intergovernmental Panel for Climate Change reported in 2007 that the sea levels would rise 7.2 to 23.2 inches by 2100, but that excludes the potential influence of melting Greenland and Antarctica.

"It may be likely that Antarctica is going to catch up with Greenland in its ice loss," Chen said. "If something changes in Antarctica, it can be a very big impact."

Isabella Velicogna, assistant professor of the Department of Earth System Science at University of California, agrees that the new study highlights the increasing ice loss scenario in Antarctica.

"It confirms all previous studies and shows that it's becoming more obvious that these glaciers are losing ice," said the scientist, who was not involved in Chen's study.

And Chen and Velicogna both disputed some news reports that claimed the ice loss is only accelerating after 2006.

"We've known that East Antarctica is losing mass for quite a while," said Velicogna.

"There's no independent evidence that shows it underwent a massive change in and after 2006."

Previous satellite remote sensing data show significant ice loss in West Antarctica, but more of a stable ice mass in East Antarctica.

The US team, instead, used the data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission, jointly launched by the National Aeronautics and Space Administration (NASA) and Germany's Aerospace Research Center and Space Agency in 2002.

The GRACE satellite maps the Earth's gravity fields by measuring the distance between two identical satellites.


(中国日报网英语点津 Helen 编辑)

Study shows Antarctic ice melt accelerating

About the broadcaster:

Study shows Antarctic ice melt accelerating

Guanny Liu is a freelance journalist from New Zealand. Born in North-Eastern China, she moved to Auckland with her family at the age of eight. Guanny has a Bachelor of Communications Studies from the Auckland University of Technology, majoring in journalism. Before coming to the China Daily website, Guanny was a journalist for the New Zealand state broadcaster, Radio New Zealand. She is in Beijing on an Asia New Zealand grant working as a copy editor for the English news department.