Investigate the implications of the freshwater flux from the ice sheet to Arctic sea ice cover-Task 3.2

To examine the effects of using a coupled ESM-ISM configuration, the experiments in Task 3.1 will be doubled to a pair of coupled and uncoupled ESM-ISM simulations. Forcing ISMs in offline mode, where ice sheet simulations are driven solely by the output from GCMs, is likely to be insufficient. This neglects feedbacks as, for example, that of increasing meltwater from the ice sheet strengthening the stratification in the adjacent ocean. This, in turn, reduces the formation of deep water feeding the lower limb of the Atlantic Meriodonal Overturning Circulation (AMOC), whereby the heat transport in the upper branch of the AMOC is weakened. In this manner, sea ice may thus ultimately show a reduced susceptibility to the imposed forcing.

These pairs of coupled and uncoupled ESM-ISM experiments will be analyzed to investigate the freshwater fluxes and feedbacks. In addition to standard coupled runs, a set of runs with more “slippery” sliding laws will be performed to initiate strong binge/purge events. These will allow us to assess the ice sheet-sea ice feedbacks under more extreme conditions and will provide a broader set of freshwater flux rates for the high resolution runs below. Freshwater fluxes will be fed into a high resolution eddy resolving ocean/sea-ice model to investigate the impact of the freshwater on sea ice formation and extent.