Pan-Arctic Summary
The 2011 June Outlook suggests a modest decrease for summer 2011. With 19 responses for the pan-arctic (and 7 for the regional outlook), including several new contributors, the June Sea Ice Outlook projects a September 2011 arctic sea extent median value of 4.7 million k² (Figure 1). This compares to observed September values of 4.7 in 2008, 5.4 in 2009, and 4.9 in 2010. The range of values is 4.0-5.6 million k², but the distribution is skewed toward lower values, suggesting either persistent conditions or a substantial drop below 2008 and 2010 values and the long-term downward trend. The 2011 June Outlook differs from the 2010 Outlook by not including projections of major increases in extent. It is important to note for context that all 2011 estimates are well below the 1979–2007 September climatological mean of 6.7 million k².
Individual responses were based on a range of methods: statistical, numerical models, comparison with previous observations and rates of ice loss, and composites of several approaches. The consensus of a stable low level of sea ice extent or continued modest sea ice loss is a strong result. The range of Outlook values suggest that most uncertainty lies in the separate methods to the Outlook.
Figure 1. Distribution of individual Pan-Arctic Outlook values (June Report) for September 2011 sea ice extent.
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