Glacial heterogeneity in Southern Ocean carbon storage abated by fast South Indian deglacial carbon release.

Past changes in ocean C disequilibria have been suggested to reflect the Southern Ocean control on global exogenic carbon cycling. Yet, the volumetric extent of the glacial carbon pool and the deglacial mechanisms contributing to release remineralized carbon, particularly from regions with enhanced mixing today, remain insufficiently constrained. Here, we reconstruct the deglacial ventilation history of the South Indian upwelling hotspot near Kerguelen Island, using high-resolution C-dating of smaller-than-conventional foraminiferal samples and multi-proxy deep-ocean oxygen estimates.