The June Sea Ice Outlook forecasts for the Arctic sea ice September minimum extent have been released today by SEARCH. Most groups are picking a minimum close to last year’s 4.7m km2, but the melt season is starting with an unusually small amount of multi-year ice. The report suggests that 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.” The full range of forecasts is shown in this chart:
The range of individual outlook values is from 4.2 to 5.0 million square kilometers. All estimates are well below the 1979â€“2007 September climatological mean value of 6.7 million square kilometers. Half of the responses are in the range of 4.9â€“5.0 million square kilometers; the remaining estimates are in the range of 4.2â€“4.7 (Figure 1, above). 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 forecasts showing the lowest minima are based on sea ice modelling driven by atmospheric forcings and initialised with current sea ice conditions. The projection by Jinlun Zhang (next to lowest in the chart) suggests that even with conditions like last year — that is, without the Transpolar Express of warm southerlies that set up in 2007 — the 2007 record could fall. On the other hand, a Russian scientist suggest thats Pacific sea surface temps could be priming a cooler pattern than last year.
The full report [PDF] is a very interesting read for all ice watchers (and gamblers). On this guide to the form, it looks as though I’ll lose my bets – but the weather over the next two months will be the deciding factor. Do I feel lucky…?