Deglacial Subantarctic CO2 outgassing driven by a weakened solubility pump

The Subantarctic Southern Ocean has long been thought to be an important contributor to increases in atmospheric carbon dioxide partial pressure (pCO(2)) during glacial-interglacial transitions. Extensive studies suggest that a weakened biological pump, a process associated with nutrient utilization efficiency, drove up surface-water pCO(2) in this region during deglaciations. By contrast, regional influences of the solubility pump, a process mainly linked to temperature variations, have been largely overlooked. Here, we evaluate relative roles of the biological and solubility pumps in determining surface-water pCO(2) variabilities in the Subantarctic Southern Ocean during the last deglaciation, based on paired reconstructions of surface-water pCO(2), temperature, and nutrient utilization efficiency. We show that compared to the biological pump, the solubility pump imposed a strong impact on deglacial Subantarctic surface-water pCO(2) variabilities. Our findings therefore reveal a previously underappreciated role of the solubility pump in modulating deglacial Subantarctic CO2 release and possibly past atmospheric pCO(2) fluctuations. Using paired reconstructions of seawater pCO(2), temperature, and nutrient utilization, Dai et al. show underappreciated influences of the solubility pump on deglacial Subantarctic surface-water pCO(2) variabilities compared to the biological pump.

Automated summary

The Subantarctic Southern Ocean plays an important role in increasing atmospheric carbon dioxide partial pressure during glacial-interglacial transitions. Previous studies have focused on the biological pump but have largely overlooked the influences of the solubility pump. This research shows that the solubility pump has a stronger impact on Subantarctic surface-water pCO(2) variabilities during deglaciations compared to the biological pump.