News & information on Antarctica & the Southern Ocean

Antarctic sea ice may have reached its maximum extent for the year on 2 October

Antarctic sea ice extent Photo: National Snow and Ice Data Center

Antarctic sea ice may have reached its maximum extent on October 2, 2018, at 18.15 million km2  (7.01 million square miles). If the downward trend continues, it will be the fourth lowest maximum in the satellite record—higher than the 1986, 2002, and 2017 maxima. It is 180,000 km2 (70,000 square miles) above the record low Antarctic maximum set in 1986, at 17.97 million km2 (6.94 million square miles). It is also 560,000 km2 (216,000 square miles) below the 1981 to 2010 average maximum extent of 18.71 million km2 (7.22 million square miles). 

This year’s maximum date of October 2 is about nine days later than the 1981 to 2010 median date and ten days later than the 1981 to 2010 average date. With spring sunshine and warmth increasing daily, the likelihood of a major sea ice expansion is small. However, some years, as in 2002, the maximum was reached on October 12, the latest in the satellite record. There are also brief increases in ice extent as late as October 22 that do not result in new maxima.

In 2018, the Southern Ocean has been true to form. Overall, September sea ice extent has been at near-record lows over the period of satellite observations. A peak in ice extent early in September was followed by a steep decline through mid-month. By the third week of September, extent increased steadily. After a few days of minimal decline, extent reached its maximum on October 2.

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