In this deliverable we have investigated the link between the ocean heat transport and the sea ice properties (extent, thickness). Observations and climate model simulations of the last decades and in a future climate scenario have been used to explore how the variations of the sea ice cover in the Arctic can be predicted months or years in advance from the ocean surface temperature. The winter Arctic sea ice extent could be predicted with some confidence from the sea surface temperature (SST) in the northern North Atlantic several years in advance. Looking at more local scale, the ice cover can be predicted one or two years in advance in all the marginal seas of the Arctic in the Norwegian climate model, when the observed SST is imposed in the model. Regarding the prediction from seasons to seasons, the result is more contrasted and the best predictions are obtained in the Barents Sea. Prediction of the sea ice cover in this region from oceanic quantities should hold in future climate as well. A particular attention was paid to the mechanisms controlling the regional link between sea‐ice and the ocean temperature north of Svalbard, a region of the Arctic where the warm water of Atlantic origin encounters sea‐ice. In this area we examined if the variations of the heat content of the ocean can be associated with variations of the volume of warm water rather than variations of the water temperature itself. Examining a one‐month duration event of sea ice retreat in the 2006 winter, one of the major events in the last two decades, we could show that wind anomalies were a major driver of the sea‐ice opening, contributing altogether to the offshore retreat of the sea ice edge and enhanced ice melt through upwelling of warm water to surface.

The Blue‐Action project has received funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement No 727852.