WORKSHOP: LESSONS FROM THE 2007 ICE MINIMUM Understanding: Sea ice prediction Near-term Seasonal forecast, e.g. summer 2008 Summer 2009 … Long-term Decadal Mid-century

WORKSHOP: LESSONS FROM THE 2007 ICE MINIMUM Winter sea-ice extent (3/2008) highest in last 4 years Johannessen, Env. Res. Lett. (submitted)

WORKSHOP: LESSONS FROM THE 2007 ICE MINIMUM Drobot et al., Science (submitted); Maslanik et al., GRL (2007)

WORKSHOP: LESSONS FROM THE 2007 ICE MINIMUM Based on ice age patterns, ice cover is preconditioned for another ice retreat  2007 Probability of new record minimum in 2008: 64% to 84% Drobot et al., Science (submitted); Maslanik et al., GRL (2007)

WORKSHOP: LESSONS FROM THE 2007 ICE MINIMUM

WORKSHOP: LESSONS FROM THE 2007 ICE MINIMUM Annual sea-ice extent 1900–2007 (observed – green, and IPCC modeled mean ensemble – black) and predictions for 2007–2050 under projected CO2 scenarios of the IPCC. Johannessen, Env. Res. Lett. (submitted)

WORKSHOP: LESSONS FROM THE 2007 ICE MINIMUM Annual sea-ice extent is inversely, linearly proportional to CO2 Unless 2007 is an anomaly and not the beginning of a rapid end, then this statisticla model is not on target.. Moreover, no feedbacks, possibly non-linear Johannessen, Env. Res. Lett. (submitted)

WORKSHOP: LESSONS FROM THE 2007 ICE MINIMUM Understanding: Sea ice prediction Has the ‘tipping’ point already been passed? Considerations: Accelerators Decelerators Reversal mechanisms