Description: Decades ago, the analysis of ancient air – trapped deep inside of Antarctic glaciers – revealed an astonishing pattern of atmospheric CO2. Ever since we’ve first laid our eyes on these intriguing signals– alternating between glacial lows and interglacial highs – an overall question emerged: Where was the CO2 stored during the glacials and how was it released back to the atmosphere during deglacial transitions? In general, several carbon reservoirs like the terrestrial biosphere or permafrost soils might interact with, and drive the atmosphere on these glacial-interglacial timescales. By far the largest influence however, might come from the deep ocean. Today, this reservoir stores up to 60-times the carbon, of which is stored in the entire atmosphere. Hence, tiny changes in the oceanic C-cycle might have severe ramifications for atmospheric CO2-levels. Parallel to global CO2 atm, Antarctic temperatures rose, while the expanded ice shelves suffered from a massive deglacial collapse. The timing and succession of events pointed to the climatic role of the Southern Hemisphere in general and the Southern Ocean in particular and raised a second question: What was the physical process, which connected these deglacial events? Until today, the international community compiled numerous studies from terrestrial and marine (distal and proximal) archives to shed light onto this dynamic system. These studies revealed a closely connected system between Antarctic sea ice and ice shelves, deep-water and atmospheric circulation, oceanic stratification, the biological pump and also bipolar teleconnections. Here, we want to discuss the current scientific knowledge and present new isotopic data – measured on planktic and benthic foraminifers as well as bulk sediments – that show how Southern Ocean overturning circulation changed on glacial-interglacial timescales and influenced the residence times of circumpolar deep-waters as well as their transport onto the continental shelf regions. In combination with other parameters, the deglacial increase in Southern Ocean overturning represents a plausible link that might explain the parallel evolution of several deglacial climate parameters.