September Sea Ice Outlook: June Report

Release Date: 
22 June 2010

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Pan-Arctic Summary

The June Outlook for arctic sea ice in September 2010 shows reasonable arguments for either a modest increase or decrease in September 2010 sea ice extent compared to the last two years (5.4 million square kilometers in 2009 and 4.7 million square kilometers in 2008). However, it is important to note that the June 2010 Outlook indicates a continuation of the overall trend in long-term loss of summer arctic sea ice, with no indication that a return to historical levels of the 1980s/1990s will occur.

Reasoning for an increase in sea ice extent from recent years assumes that the current presence of extensive second- and third-year sea ice that we saw in winter 2009/2010 indicates a build-up of multi-year sea ice and a more stable ice pack. Reasoning for a decrease in sea ice extent from recent years, perhaps approaching new record-low minimum, focuses on the below-normal sea ice thickness overall, the thinning of sea ice in coastal seas, rotting of old multi-year sea ice, warm temperatures in April and May 2010, and the rapid loss of sea ice area seen during May.

With 16 responses, the June Outlook reflected both these arguments. The range of June Outlook estimates is 4.2 to 5.7 million square kilometers, with an additional estimate of 1.0 million square kilometers (Figure 1, below).

Six respondents, with estimates of 4.9–5.3 million square kilometers, represent a prediction for persistent conditions from 2008/2009.

The remaining estimates fall into "high" and "low" extent groupings: the low extent group with a range of 4.2 to 4.7 million square kilometers, representing a continued loss of sea ice extent compared to 2008/2009, and the high extent group of 5.4 to 5.7 million square kilometers, suggesting a return to the long-term trend for summer sea ice loss.

Individual responses were based on a range of methods: statistical, numerical models, comparison with previous observations and rates of ice loss, or composites of several approaches.

Bar Chart of June Outlook Sea Ice Extent EstimatesFigure 1. Distribution of individual Pan-Arctic Outlook (June Report) values for September 2010 sea ice extent. Click to enlarge. Download High Resolution Version of Figure 1.