2015 Antarctic Sea Ice Extent Breaks Streak of Record Highs

Eric Chaney
Published: October 21,2015

New images from NASA show a dramatic change in the maximum extent of Antarctic sea ice observed in 2014 and 2015.

A new map released by NASA shows a dramatic change in the level of sea ice around Antarctica, but scientists at the agency’s Goddard Space Flight Center say the change is simply a “return to normalcy” after a streak of record-breaking high ice years.

The maximum extent of Antarctic sea ice in 2015 was considerably lower this year than in the past three years, each of which have been record breaking.
(NASA)

Each of the previous three years broke a new record for the largest maximum extent of sea ice around the southern pole in the satellite era. In 2014, Antarctic sea ice reached is maximum extent on September 20, covering 7.78 million square miles. In 2015, the maximum extent covered just 7.27 million square miles, 16th on the list and the lowest since 2008. According to the National Snow and Ice Data Center, this year’s maximum extent was slightly above average for all measurements taken between 1981 and 2010 average and occurred relatively late in the year compared to past years.
NASA reports indicate that the growth of Antarctic sea ice was erratic this year. Sea ice was at much higher than normal levels throughout much of the first half of 2015 until, in mid-July, it flattened out and even went below normal levels in mid-August. The sea ice cover recovered partially in September, but not enough to match recent years.
(MORE: Antarctic Sea Ice Reaches Record High in 2014)
Data for the new maps were acquired by the Advanced Microwave Scanning Radiometer 2 sensor on Japan’s Global Change Observation Mission 1st–Water (GCOM-W1) satellite. In 2015, sea ice coverage was greater than average around the Antarctic Peninsula, the Weddell Sea, and the Wilkes Land coast, according to an analysis by the National Snow & Ice Data Center. The Ross Sea and the Indian Ocean-facing coast had below average sea ice.
Scientists still don’t know all of the factors that play into the development of Antarctic sea ice.

The maximum extent of Antarctic sea ice in 2015 didn't quite make it to the record levels experienced in 2013 and 2014.
(NASA)

“Part of it is just the geography and geometry,” Goddard research scientist Walt Meier said in 2014. “With no northern barrier around the whole perimeter of the ice, the ice can easily expand if conditions are favorable.”Many other factors are thought to play into ice development as well, including Antarctic wind patterns, snowfall, and even El Niño.
“There hasn’t been one explanation yet that I’d say has become a consensus, where people say, ‘We’ve nailed it, this is why it’s happening,’” Claire Parkinson, a senior scientist at Goddard said in 2014. “Our models are improving, but they’re far from perfect. One by one, scientists are figuring out that particular variables are more important than we thought years ago, and one by one those variables are getting incorporated into the models.”
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