Antarctic Maximum Sea Ice Extent Breaks Streak of Record Highs in 2015

First Posted: Oct 16, 2015 08:50 AM EDT

The 2015 Antarctic maximum sea ice extent has broken its streak of record highs. The sea ice cover of the Southern Ocean reached its yearly maximum extent on Oct. 6.

At 7.27 square miles, the new maximum extent falls roughly in the middle of the record of Antarctic maximum extents compiled during the 37 years of satellite measurements. This year's maximum extent is both the 22nd lowest and the 16th highest. In addition, this year's maximum is quite a bit smaller than the previous three years, which correspond to the three highest maximum extents in the satellite era, and is also the lowest since 2008.

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 went below normal levels in mid-August. The sea ice recovered partially in September, but this year's maximum extent is still just 513,000 square miles below the record maximum extent, which was set in 2014.

It's like that El Niño may actually be to blame. This natural phenomenon warms the surface waters of the eastern equatorial Pacific Ocean. It likely had an impact on the behavior of the sea ice cover around Antarctica since it causes higher sea level pressure, warming air temperature and warmer sea surface temperature in west Antarctica.

"After three record high extent years, this year marks a return toward normalcy for Antarctic sea ice," said Walt Meier, one of the researchers, in a news release. "There may be more high years in the future because of the large year-to-year variation in Antarctic extent, but such extremes are not near as substantial as in the Arctic, where the declining trend towards a new normal is continuing."

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