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Monday, August 8, 2011

Jeff Masters: Record Low Arctic Sea Ice for July 2011

by Jeff Masters, wunderblog, August 8, 2011


Last month, Arctic sea ice extent was the lowest ever recorded for any July in the 1979 to 2011 satellite record, according to the National Snow and Ice Data Center. Most of the ice loss occurred in the first half of the month when high pressure made for clear skies and melting sunshine, and warm air blew into the Arctic from the south. In the first two weeks of July, air temperature over the North Pole was 11-14 °F above average. During the last two weeks of July, low pressure took over and brought cooler temperatures, although it appears this also acted to push the ice around, which resulted in a larger but thinner area of ice. New research shows that old ice continues to decline as well, which is problematic because older ice is more stable and tends to grow thicker over multiple seasons, and new ice is thin and more susceptible to melting. According to the University of Washington Polar Science Center, Arctic sea ice volume was 51% lower than average and 62% lower than the maximum (which was seen in 1979 at the beginning of the record).

Figure 1. Monthly July ice extent from 1979 to 2011 from the National Snow and Ice Data Center shows a 6.8% decline per decade.

The low amount of sea ice along Siberia has opened up the Northern Sea Route early (Figure 2), and some companies are already taking advantage. It doesn't appear possible to get through the whole passage without the aid of an ice breaker or two around the East Siberian Sea, but compared to the normal route south through the Mediterranean and Indian Ocean, it's a deal. From Yokohama, Japan, to the Rotterdam port in the Netherlands, the route through the Arctic is around 8,500 miles. If the Arctic is impassable, the route through the Pacific, Indian and Atlantic oceans is around 13,000 miles.

Figure 2. Sea ice concentration from the University of Illinois Polar Research Group. Image modified to highlight the Northern Sea Route in light blue.

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