The Southern Ocean has a unique place in our climate system. It is a region of extremes, where the world׳s strongest ocean currents, the strongest wind regime, the most extensive sea ice cover, and the largest ice sheets interact. In addition, it houses a very productive ecosystem that sequesters a significant fraction of the anthropogenic CO₂ in the ocean.

Studying the Southern Ocean has proven to be a significant challenge, for several reasons. Among those are the logistical difficulties of making observations in these remote and vast parts of the world, due also to the harsh weather conditions and extensive sea ice cover in winter months. But arguably a more important factor is the immense complexity of the Southern Ocean climate system, where so many tightly coupled components interact on so many temporal and spatial scales. A case in point is the surprising expansion of winter sea ice in the Weddell Sea in recent years, amidst significant warming trends.