How can models used to predict future climate take the past into account? The ocean waters in a ring around Antarctica (the Southern Ocean) are very important in Earth’s climate system because they are the central hub of global ocean circulation. In this cold and remote region with very productive ecosystems (krill and whales), deep waters rise to the surface, allowing exchange of carbon and nutrients between the ocean waters and the atmosphere. Paleoceanographic studies document the vital role of the Southern Ocean in past periods of global climate change, driving Earth’s glacial and interglacial cycles through changes in ocean circulation and biological productivity. (Paleoceanography and Paleoclimatology)