Not just going with the flow: does biological production rather than deep water formation drive the Southern Ocean carbon sink?

The Southern Ocean (SO) is thought to have absorbed ~40% of all global human-derived (anthropogenic) carbon dioxide and >75% of anthropogenic heat, thus being disproportionately influential in mitigating increasing atmospheric CO2 levels and related climate effects. Current explanations of SO carbon uptake and historical climate transitions focus on the interaction between the surface and deep ocean around Antarctica, i.e. processes that impact intermediate and dense water formation as part of the global overturning circulation (buoyancy fluxes, sea ice production), and how the marine carbon system responds to them. However, new results suggest that in fact open-ocean biological production / carbon export away from dense water formation regions is the key process by which CO2 is removed from the atmosphere, forcing us to reframe our understanding of how the SO carbon system functions. This project will test this changed paradigm using new observations from satellites, research cruises, autonomous biogeochemical float deployments and a biogeochemical ocean assimilation model to deconvolve the carbon system in the Atlantic sector of the Southern Ocean. The focus will be on identifying the balance between physics and biology in driving SO carbon uptake, and how these are likely to change into the future.