Ocean circulation, CO2 paper

oc3 june 19 fig4A recent Science Advances paper from members of PAGES' Ocean Circulation and Carbon Cycling (OC3) working group aims to accurately quantify ocean carbon components to measure carbon dioxide (CO2) concentrations during glacial periods.

The prevailing hypothesis for lower atmospheric CO2 concentrations during glacial periods is an increased efficiency of the ocean’s biological pump. However, tests of this and other hypotheses have been hampered by the difficulty to accurately quantify ocean carbon components.

Authors Samar Khatiwala, Andreas Schmittner and Juan Muglia use an observationally constrained Earth system model to precisely quantify these components and the role that different processes play in simulated glacial-interglacial CO2 variations.

They find that air-sea disequilibrium greatly amplifies the effects of cooler temperatures and iron fertilization on glacial ocean carbon storage even as the efficiency of the soft-tissue biological pump decreases.

These two processes, which have previously been regarded as minor, explain most of their simulated glacial CO2 drawdown, while ocean circulation and sea-ice extent, hitherto considered dominant, emerge as relatively small contributors.

Access the paper here. Find out more about OC3 here.

This study benefited from discussions at the OC3 2018 workshop in Cambridge, UK.