Arctic sea ice declined at record rate in June
July 7th, 2010The National Snow and Ice Data Center (NSIDC) reports Arctic sea ice declined at the fastest rate ever recorded in June, and the average ice extent in June was the lowest in the satellite data record (from 1979 to 2010).
The previous record for the fastest rate of June decline was set in 1999. The linear rate of monthly decline for June over the 1979 to 2010 period is now 3.5% per decade.
Whether or not 2010 will see a new record low set for Arctic sea ice extent depends upon weather patterns. NSIDC explains:
The record low ice extent of September 2007 was influenced by a persistent atmospheric pressure pattern called the summer Arctic dipole anomaly (DA). The DA features unusually high pressure centered over the northern Beaufort Sea and unusually low pressure centered over the Kara Sea, along the Eurasian coast. In accord with Buys Ballot’s Law, this pattern causes winds to blow from the south along the Siberian coast, helping to push ice away from the coast and favoring strong melt. The DA pattern also promotes northerly winds in the Fram Strait region, helping to flush ice out of the Arctic Ocean into the North Atlantic. The DA pattern may also favor the import of warm ocean waters from the North Pacific that hastens ice melt.
June 2010 saw the return of the DA, but with the pressure centers shifted slightly compared to summer 2007. As a result, winds along the Siberian coastal sector are blowing more from the east rather than from the south. Whether or not the DA pattern persists through the rest of summer will bear strongly on whether a new record low in ice extent is set in September 2010.