In Sea Ice News #14, we noted that the Arctic refreeze was the fastest ever. According to NSIDC, Arctic sea ice extent doubled in October.
Arctic rapidly gaining winter ice
Ice extent doubled in October. The rate of increase since the 2012 minimum was near record, resulting in an October monthly extent 230,000 square kilometers (88,800 square miles) greater than the previous low for the month, which occurred in 2007.
Despite this rapid growth, ice extent remains far below normal as we begin November. Average ice extent for October was 7.00 million square kilometers (2.70 million square miles). This is the second lowest in the satellite record, 230,000 square kilometers (88,800 square miles) above the 2007 record for the month. However, it is 2.29 million square kilometers (884,000 square miles) below the 1979 to 2000 average. The East Siberian, Chukchi, and Laptev seas have substantially frozen up. Large areas of the southern Beaufort, Barents and Kara seas remain ice free.
As of November 4, sea ice extent stood at 8.22 million square kilometers (3.17 million square miles). This is 520,000 square kilometers (201,000 square miles) below the extent observed in 2007 on the same date, and ice extent remains 2.04 million square kilometers (788,000 million square miles) below the 1979 to 2000 average for this date.
Due to the rapid ice growth during October, Arctic sea ice extent for October 2012 was the second lowest in the satellite record, above 2007. Through 2012, the linear rate of decline for October Arctic ice extent over the satellite record is -7.1% per decade.
While overall the Arctic rapidly gained ice throughout October, the rate of ice growth was not the same everywhere. Ice growth in the Beaufort and Chukchi seas averaged about 8,500 square kilometers (3,300 square miles) per day and large areas still remain ice free. In the eastern Arctic there was rapid ice growth in the East Siberian and Laptev seas exceeding, respectively, 28,000 and 18,000 square kilometers per day (11,000 and 7,000 square miles per day). As a result, most of the region is now completely frozen over. The slowest rates of ice growth have occurred in the Kara Sea (less than 3,000 square kilometers, or 1,000 square miles per day). In large part because of extensive open water in the Kara and Barents seas, air temperatures for October in this area at the 925 hPa level (about 3,000 feet above the surface) were 3 to 4 degrees Celsius (5 to 7 degrees Fahrenheit) above average, with unusual warmth becoming more pronounced near the surface. October air temperatures over the ice-free southern Beaufort Sea were also far above average.
Source: NSIDC
See all the data on the WUWT Sea Ice Reference Page
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We need some metric for the tonnage of shipping using the NW Passage each summer. Then we can celebrate as it increases, mourn decreases.
I still wonder if we aren’t seeing the same shift in ice patterns we are seeing in the Antarctic. A rapid building of ice along one side, and a deficit on the other. Unlike the Antarctic most of our Arctic ice measurement is done in the water… it would be interesting to see if there is any increase of accumulated snow/ice along the Russian or Canadian/Alaska land masses as compared to other years of course. http://www.natice.noaa.gov/ims/loop/nhem-1mo-loop.html
Sea Ice is measured as greater than 15% ice cover in a unit area. The ice per unit area could “disappear” in two ways, simply stay put and melt, or disperse. The 2007 event was due to high winds dispersing the sea ice rendering the unit areas with less than 15% ice cover, therefore “ice free”. The fast “regrowth” of ice was caused by winds/currents pushing the ice puzzle back together along with refreeze.
Winds and dispersion are rarely mentioned in the NSIDC articles. If the ice pack is held together by wind, ice melt will reduce. If the ice is dispersed due to wind, each unit of ice will melt faster as there is open ocean around each ice unit that warms adding to the “normal”melt rate due to temperature rise in the summer.
Are we seeing a long term change in wind circulation in the Arctic that may in fact be cyclical?
Curious minds want to know.
Sugel says:November 7, 2012 at 3:51 pm
But over the last three decades, satellites have observed a 13 percent decline per decade in the minimum summertime extent of the sea ice.
As compared to what? Three decades is the whole observation period. Three decades ago was probably a peak in Arctic ice, since it had been cooling since the 1940s.
Look at the amount of multi year ice leaving the Arctic this year , it will be interesting to find out how this changes during the Arctic winter.
http://www.aari.ru/odata/_d0015.php?lang=1&mod=0&yy=2012