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Arctic sea ice reaches lowest extent of year

The amount of summer sea ice in the Arctic fell this year to the second-lowest ever recorded by satellite.

NASA and the National Snow and Ice Data Center in Boulder, Colo. announced Thursday that the Arctic has reached its summer season low extent.

The 4.14 million square kilometers of ice measured on Sept. 10 is statistically tied with the minimum ice extent during the summer of 2007 for second place on the historic minimum list. This year’s minimum ice cover is more than two million square kilometers below the 1981-2010 mean.

Arctic Summer Minimum Sea Ice Extent Record, 2007-2016

YEAR EXTENT (millions of km2) DATE MEASURED
2012 3.39 Sept. 17
2016 4.14 Sept. 10
2007 4.15 Sept. 18
2011 4.34 Sept. 11
2015 4.43 Sept. 9
2008 4.59 Sept. 20
2010 4.62 Sept. 21
2014 5.03 Sept. 17
2013 5.06 Sept. 13
2009 5.12 Sept. 13
1979-2000 mean 6.70 Sept. 13
1981-2010 mean 6.22 Sept. 15
sea-ice-graph-sept-12-2016-graphic-courtesy-national-snow-and-ice-data-center
This graphic shows the minimum Arctic sea ice extent (according to a preliminary assessment) with the seasonal minimum in prior years. Graphic courtesy National Snow and Ice Data Center.

A statement released by NSIDC starkly described the conditions in the Arctic this summer:

“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.”

Cloudy skies and atmospheric pressure conditions slowed ice melt in June and July, which may have prevented this season from becoming the most ice-free summer ever observed from space.

“June and July are usually key months for melt because that’s when you have 24 hours a day of sunlight – and this year we lost melt momentum during those two months,” Walt Meier, a scientist at NASA’s Goddard Space Flight Center, said in a statement.

2016-arctic-sea-ice-minimum-sept-10-graphic-courtesy-nasa-goddard-space-center-visualization-studio-graphic-by-c-starr
This graphic shows the 2016 seasonal minimum, reached on Sept. 10, in comparison with the 1981-2010 average (shown by the gold-colored line). Graphic courtesy NASA Goddard Space Flight Center Scientific Visualization Studio; graphic by C. Starr.

The pace of melting accelerated in August when two cyclones crossed the Arctic Ocean.

Meier explained that these may have especially impacted the speed with which ice in the Chukchi and Beaufort seas melted.

The three-and-one-half decade long satellite record shows a marked decline in the mean extent of Arctic sea ice during each month of the year.

In fact, a paper published on Sept. 15 in the journal Remote Sensing of Environment concluded that no record for maximum Arctic sea ice extent has been set since 1986, while during the 37 years of satellite monitoring there have been 75 new minimum ice extent records set.

“The record makes it clear that the ice is not rebounding to where it used to be, even in the midst of winter,” Claire Parkinson, the lead author of that study and a senior climate scientist at GSFC, said.

Arctic sea ice ordinarily reaches its maximum reach for the year in March, late in the winter. The sun is not visible in the region during the winter and does not contribute much to warming of land and sea surfaces during that season.

NSIDC’s statement cautioned that the estimate released Thursday could be revised if late-summer winds or other factors causing ice melt impact the sea ice cover during the remaining days of summer.

The monitoring record dates to 1978.

Earth’s poles are the two regions of the planet that are most sensitive to warming of the atmosphere. As sea ice melts, more solar energy is absorbed by the Arctic Ocean. The deep and dark waters absorb about 90 percent of the sun’s energy that reaches them.

By contrast, expansion of sea ice during the colder autumn and winter months causes about 80 percent of the solar energy that hits the frozen surface of the region’s marine environment to be reflected to space.

 

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