Task 2.2: Determine the dynamics behind past abrupt transitions in sea ice cover, and in particular the role of ocean stratification and mixing.
Answering ice2ice’s main research question requires a better understanding of the dynamics and processes governing the Arctic sea ice and ocean system. State-of-the-art Global Climate Models (GCMs) are unable to accurately simulate the observed temperature and salinity structure of the Arctic ocean. We will improve crucial model components so far poorly represented in state-of-the-art GCMs. The first step will be to employ detailed process models (e.g. Björk et al.,1989) to study the stability and possible thresholds in the Arctic ocean-sea ice system. Our improved understanding of the system and the interaction of warm Atlantic water with the Arctic halocline and sea ice will be further investigated using coupled GCMs (NorESM and EC Earth). In the GCMs, we will also test the impact of enhanced mixing as Arctic sea ice is reduced. Current work (Jochum et al. 2012) shows that the Arctic ocean is much more sensitive to wind stress variations than hitherto assumed. Applying our knowledge of Arctic Ocean dynamics and wind mixing to one of the key unanswered questions posed by the paleoclimate record has never been done before, and is highly relevant for our understanding of current climate changes in the Arctic.