Why do we need a Southern Ocean Observing System?

The global importance of the Southern Ocean
As a result of the unique geography of the Southern Ocean, the region has a profound influence on the global ocean circulation and the Earths climate. The Southern Ocean provides the principal connections between the Earths ocean basins, and controls the connection between the deep and upper layers of the global overturning circulation, thereby regulating the capacity of the ocean to store and transport heat, carbon and other properties that influence climate and global biogeochemical cycles.

The upwelling branch of the overturning circulation in the Southern Ocean returns carbon and nutrients to the surface layer, while the downwelling branches transport heat, carbon and other properties into the ocean interior. The balance between upwelling and release of CO2 versus uptake of carbon into the ocean interior determines the strength of the Southern Ocean sink of CO2The Southern Ocean contributes more to the ocean storage of the excess heat and carbon added to the Earth-atmosphere system by human activities than any other latitudinal band. About 40% of the total global ocean inventory of anthropogenic carbon dioxide is found south of 30°S, whilst export of nutrients by the upper limb of the overturning circulation ultimately supports 75% of the global ocean primary production north of 30°S.

Climate and sea-level rise are influences strongly by ocean-cryosphere interactions in the Southern Ocean. Changes in sea-ice extent or volume result in changes in the Earth's albedo, water mass formation rates, and air-sea exchange of gases such as CO2, and affect oceanic organisms from microbes to whales through physiological changes and changes to their habitats. Melting of floating glacial ice by warm ocean waters influences the high-latitude freshwater budget and stratification, and may affect the stability of the Antarctic Ice Sheet and the rate at which glacial ice flows to the sea.
Given the central role that the Southern Ocean plays in the global climate system, any changes in the region will have global consequences.