The Southern Ocean surrounding Antarctica is a region where many of the world’s carbon-rich deep waters can rise back up to the surface. Scientists have thought that the vast swaths of sea ice around Antarctica can act as a lid for upwelling carbon, preventing the gas from breaking through the ocean’s surface and returning to the atmosphere. However, researchers at MIT have now identified a counteracting effect that suggests Antarctic sea ice may not be as powerful a control on the global carbon cycle as scientists had suspected. In a…