Core-top calibration of benthic carbon isotopes

What is it about?

Carbon isotopes measured in shells of microscopic organisms (foraminifera) that live on the sea floor (benthic) are used routinely in paleoceanography to reconstruct circulation and carbon cycling in the ocean. The reconstructions are based on the assumption that carbon isotope ratios measured in the shells represent the ratios in the (dissolved inorganic) carbon (DIC) of the surrounding sea water at the bottom of the ocean. Here we have tested this assumption and show that while the sea water isotope ratio of DIC is the primary influence on the shells, there are secondary influences from carbonate ion concentrations and pressure (depth). A new calibration including those secondary effects may lead to improved reconstructions of ocean circulation and carbon cycling.

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Why is it important?

It helps us to better understand and quantify uncertainties of this widely used paleoclimate proxy.

Perspectives