The Southern Ocean plays a key role for climate and climate change. It is the largest oceanic sink of anthropogenic CO2, absorbing each year between 5 and 10 percent of the global CO2 emissions from human activities. The evolution of the Southern Ocean CO2 sink this century will therefore play an important role for modulating the pace of climate change. Several factors can influence the efficiency of the Southern Ocean CO2 sink. These include the rate and level of change of CO2 in the atmosphere, the associated changes in climate including warming and winds, and the changes in marine ecosystems and biogeochemistry that occur within the ocean in response to anthropogenic drivers. CELOS will contribute to understanding how each of these sets of processes will impact the Southern Ocean CO2 sinks, and to determine how to keep track of its evolution with metrics. In particular, winds in the Southern Ocean have been observed to increase in the past 50 years. This increase has been the increase in greenhouse gases. The relative evolution of greenhouse gases and ozone recovery could therefore be important this century, and this has not yet been explored. CELOS provides a unique contribution in the form of a limited set of model simulations that go beyond what is already done, and an analysis that explores scientific boundaries in a way never done before.