Charting a new seasonal outlook for the Arctic

As part of the SEARCH Arctic Seasonal Outlook Project (http://www.arcus.org/search/seaiceoutlook/index.php), NIC Science was one of 19 participants who used a variety of methods to project the 2008 September Arctic sea ice minimum extent. In the case of NIC, we examined the evolution of the ice pack in 2006 and 2007 using Arctic hemispheric charts from those years and derived statistical likelihoods. As an example, it was probable that 90% of the first year ice (FYI) would not survive the summer melt season. NIC Provisional Seasonal Outlooks were produced for end-of-June and end-of-July conditions, and are available on the SEARCH web site. In our case, our primary assumption was that the FYI would melt and at substantial rates. However, what was unique to 2008 was the amount of primary FYI in the central Arctic. What came in to question was how this ice would behave. FYI generally is thinner than MYI and melts at a slightly higher temperature. If summer 2008 was a repeat of summer 2007 the potential existed for the record low extent of 2007 to be smashed. The uniqueness of 2008 meant there existed no analogous year by which to reference atmospheric indicators and get a sense of what may happen. Existing NIC methods, while not state of the art, are not unreliable. While they may not get the ice-in/ice-out dates correct, they stand a better chance at getting the general trend of the season, at least historically. But as this project has shown, the Arctic is moving into a regime where meteorological logic becomes illogical.