September Sea Ice Outlook: June Report

Release Date: 
24 June 2009

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The outlook for arctic sea ice for September 2009, based on May data, indicates a continuation of low pan-arctic sea ice extent and no indication that a return to historical levels will occur. The June Sea Ice Outlook Report is based on a synthesis of 15 individual pan-arctic estimates (plus six regional contributions) utilizing a range of methods; two additional pan-arctic contributions provide background information on recent sea ice observations.

The June Outlook indicates a similar, or slightly increased, extent compared to the 2008 value of 4.7 million square kilometers. However, there is a small but important probability of a major sea ice loss event this year, given that the ice is thinner and younger than previous years, combined with a possibility of atmospheric conditions that cause significant ice retreat.

Figure 1. Distribution of individual outlook values for September 2009 sea ice.Figure 1. Distribution of individual outlook values for September 2009 sea ice extent.

The range of individual outlook values is from 4.2 to 5.0 million square kilometers with an aggressive outlook of 3.2 million square kilometers. All estimates are well below the 1979–2007 September climatological mean value of 6.7 million square kilometers. Half of the responses are in the range of 4.9–5.0 million square kilometers; the remaining estimates are in the range of 4.2–4.7 (Figure 1). The uncertainty / error values, from those groups that provided them, are close to 0.5 million square kilometers, thus many of the values overlap.

Interestingly, the outlook values for the June Report were in fairly close agreement and the range of estimates was much lower than in 2008. This is likely the result of improved and more consistent approaches in the individual outlooks, as the community has applied the insights and lessons learned regarding oceanic and meteorological factors from the 2008 Outlook effort.