The Antarctic sea ice, although being a relatively small and thin ice blanket over the Southern Ocean, strongly impacts the Antarctic ecosystem and the evolution of the climate at both local and global scale. In particular, the Antarctic sea ice influences the oceanic heat exchanges, the carbon uptake and the sea level rise through interactions with the Antarctic ice sheet. Understanding its behavior and predicting its evolution thus constitute an issue of concern in a sustainable development context. The causes of the recent increase in Antarctic ice extent are still not firmly identified at this stage. Nevertheless, the knowledge related to the mechanisms that rule the Antarctic sea ice variability has been clearly improved thanks to the work carried out in the framework of the PREDANTAR project. This project also allowed testing different techniques, based on post-processing tools and on data assimilation procedure, aimed at improving the reconstructions and the predictions of the Antarctic ice cover. This will strongly contribute to improving future predictions and projections not only for the Southern Ocean but also at global scale. Furthermore, although this work was essentially focused on the sea ice in the Southern Ocean, the post-processing and data assimilation techniques implemented within the framework of PREDANTAR can be used to improve the predictability at decadal timescales in other regions and for other climate variables.