Antarctica’s Sea Ice ‘Increasing Slowly,’ Scientists Say

Antarctic Sea Ice Cover Sees ’Slight Expansion,’ Scientists Say
Antarctic Sea Ice along Antarctica's Amundsen Coast as seen from an aircraft at an altitude of 20,000 feet in 2009. The ice “has experienced a slight expansion” over the past 20 years, according to a paper published in the journal Nature Geoscience. Photographer: NASA

Sea ice surrounding Antarctica is expanding due to increased winds, according to a paper published today in the journal Nature Geoscience.

“The total Antarctic sea-ice cover is increasing slowly,” Paul Holland, the lead author of the report, said in a statement. The report didn’t say how by much the ice is expanding.

Arctic ice covering the other pole shrank to the smallest ever in September, one of the most visible effects of climate change. Increasing wind activity near the South Pole over the past 19 years has had the opposite effect on the ice cover, said Ron Kwok, co-author of the report.

“In certain areas, it’s moving the ice edge out toward the ocean,” Kwok said in an interview.

Antarctica, unlike the Arctic, is significantly more vulnerable to strong winds because the northern ice cap “is landlocked, except for certain passages into the ocean,” said Kwok, a National Aeronautics and Space Administration researcher at the Jet Propulsion Laboratory in Pasadena, California. “It’s less sensitive to wind.”

Ice cover in the Ross Sea region close to the South Pacific Ocean, has expanded the most, he said, while in other areas, “where the wind is pushing toward the coast, it’s shrinking.”

The Arctic ice cap shrank to 3.41 million square kilometers (1.32 million square miles) on Sept. 16, the lowest in a satellite record that dates back 33 years, according to the U.S. National Snow and Ice Data Center in Boulder, Colorado. Satellite data for the Antarctic ice cover dates back 19 years.

The NSIDC deems an area of ocean to have ice cover if a section that measures 25 square kilometers is 15 percent covered. That means strong winds may spread dense ice over a wider area without changing the total volume.

“We don’t know the thickness,” Kwok said. “We don’t know the volume of the ice very well. It’s something that we’re still trying to understand.”

(Corrects name of ocean region in sixth paragraph of story published Nov. 11.)
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