Arctic sea ice minimum in 2009 reach on September 12th.

The total ice area in the Arctic reached its 2009 minimum on September 12 with approximately 4.5 mill sq. km. This is approximately 10 days earlier and almost 1 mill sq km. more than the record minimum of 2007. Compared to the minimum of 2008, this year’s total ice area minimum is ca. 700,000 mill. sq. km. higher.

Although the total ice area in the Arctic has increased the last 2 years, this year’s minimum is still well below the average minimum of 1979-2006 by about 1.5 mill sq. km.
So far throughout 2009, the total ice area has kept below the 1979-2006 average, except in April and May when it reached the average (see figure). However, due to the increased melting during previous years, the Arctic ice is now made up of a larger amount of thinner ice, since less ice has survived the summer melting seasons to become thicker, multi-year ice. At http://arctic-roos.org, the Nansen Centre coordinated Arctic ice monitoring website, it is shown that while the total ice area has on average decreased by approximately 5% per decade since 1979, multi-year ice has decreased approximately 9% per decade during the same period.

At http://artic-roos.org, it is shown that the 2009 minimum has not yet been reached for the Arctic ice extent. Arctic ice extent can be seen as the outermost boundary of the Polar ice cap, and this value will always be higher the Arctic ice area.

While we see the gradual decrease of Arctic ice as an effect of global warming, a large part of the past 3 year’s extreme minimums can be explained by natural variability, due to shifting atmospheric patterns. The record minimum year of 2007 was characterized by a cloud-free Arctic summer combined with warm winds from the Bering Strait toward the North Pole, that both increased melting and pushed the ice northward. This year’s higher ice minimum can be seen in relation to an atmospheric circulation pattern that pushed the Arctic ice toward the Siberian coast inhibiting the outflow of ice from the Arctic.

For more information contact Ola M. Johannessen, ola.johannessen@nersc.no , tel. 90135336 or Tor Olaussen, toro@nersc.no, tel 45513322.

Daily Arctic ice updates with daily satellite images and climatological trends can be found at

http://arctic-roos.org/observations/satellite-data/sea-ice/ice-area-and-...