Sea Ice Reaches Official Minimum, Tied for Second Lowest
September 15, 2016
Arctic sea ice appeared to reach its annual minimum extent on September 10, 2016, NASA and the National Snow and Ice Data Center (NSIDC) reported today. An analysis of satellite data showed that sea ice around the North Pole shrank to 4.14 million square kilometers (1.60 million square miles).
The 2016 sea ice minimum is effectively tied with 2007 for the second lowest in the satellite record. Since satellites began monitoring sea ice in 1979, researchers have observed a decline in the average extent of Arctic sea ice in every month of the year.
The map above shows the extent of Arctic sea ice on September 10, 2016. Extent is defined as the total area in which the ice concentration is at least 15 percent. The map was compiled from observations by the Advanced Microwave Scanning Radiometer 2 (AMSR-2) sensor on the Global Change Observation Mission 1st–Water satellite operated by the Japan Aerospace Exploration Agency (JAXA). The yellow outline shows the median sea ice extent observed in September from 1981 through 2010.
The sea ice cover on the Arctic Ocean and surrounding seas regulates the planet’s temperature, influences the circulation of the atmosphere and ocean, and affects life in Arctic communities and ecosystems. The ice cap shrinks every year during the spring and summer until it reaches its minimum extent in September. Sea ice grows during the late autumn and winter months, when the Sun is below the horizon in the Arctic Circle.
The 2016 melt season surprised scientists by changing pace several times. It began with a record-low yearly maximum in March, followed by rapid ice losses through May. But in June and July, low atmospheric pressures and cloudy skies slowed melting. Then, after two large storms blew across the Arctic basin in August, sea ice melting accelerated through early September.
“It’s pretty remarkable that this year’s sea ice minimum extent ended up the second lowest after how the melt progressed in June and July,” said Walt Meier, a sea ice scientist with NASA’s Goddard Space Flight Center. “June and July are usually key months for melt because that’s when you have 24 hours of sunlight each day. This year we lost momentum during those two months.”
In August, two strong cyclones crossed the Arctic Ocean along the Siberian coast. The storms did not have an immediate impact, as a great cyclone did in 2012. But in late August and early September, Meier noted, there was “a pretty fast ice loss in the Chukchi and Beaufort seas that might have been a delayed effect from the storms.”
Arctic sea ice appears to have reached its seasonal minimum extent for 2016 on September 10. A relatively rapid loss of sea ice in the first ten days of September has pushed the ice extent to a statistical tie with 2007 for the second lowest in the satellite record. September’s low extent followed a summer characterized by conditions generally unfavorable for sea ice loss.
Please note that this is a preliminary announcement. Changing winds or late-season melt could still reduce the Arctic ice extent, as happened in 2005 and 2010. NSIDC scientists will release a full analysis of the Arctic melt season, and discuss the Antarctic winter sea ice growth, in early October.
On September 10, Arctic sea ice extent stood at 4.14 million square kilometers (1.60 million square miles). This appears to have been the lowest extent of the year and is tied with 2007 as the second lowest extent on record. This year’s minimum extent is 750,000 square kilometers (290,000 square miles) above the record low set in 2012 and is well below the two standard deviation range for the 37-year satellite record. Satellite data show extensive areas of open water in the Beaufort and Chukchi seas, and in the Laptev and East Siberian seas.
During the first ten days of September, the Arctic lost ice at a faster than average rate. Ice extent lost 34,100 square kilometers (13,200 square miles) per day compared to the 1981 to 2010 long-term average of 21,000 square kilometers (8,100 square miles) per day. The early September rate of decline also greatly exceeded the rate observed for the same period in 2012 (19,000 square kilometers, or 7,340 square miles, per day). Recent ice loss has been most pronounced in the Chukchi Sea. This may relate to the impact of two strong cyclones that passed through the region during August.