Tyka (2025): Efficiency metrics for ocean alkalinity enhancements under responsive and prescribed atmospheric pCO2 conditions

Michael D. Tyka IN: Biogeosciences 22, 341-353, https://doi.org/10.5194/bg-22-341-2025

Ocean alkalinity enhancement (OAE) and direct ocean removal (DOR) are emerging as promising technologies for enacting negative emissions. The long equilibration timescales, potential for premature subduction of surface water parcels, and extensive horizontal transport and dilution of added alkalinity make direct experimental measurement of induced CO₂ uptake challenging. Therefore, the challenge of measurement, reporting, and verification (MRV) will rely to a great extent on general circulation models, parameterized and constrained by experimental measurements. This paper examines the commonly used metrics of OAE efficiency, their exact physical meanings, the assumptions inherent in their use, and the relationship between them.

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