Monitoring, reporting, and verification for ocean alkalinity enhancement

Monitoring, reporting, and verification (MRV) refers to the multistep process of monitoring the amount of greenhouse gas removed by a carbon dioxide removal (CDR) activity and reporting the results of the monitoring to a third party. The third party then verifies the reporting of the results. While MRV is usually conducted in pursuit of certification in a voluntary or regulated CDR market, this chapter focuses on key recommendations for MRV relevant to ocean alkalinity enhancement (OAE) research. Early stage MRV for OAE research may become the foundation on which markets are built. Therefore, such research carries a special obligation toward comprehensiveness, reproducibility, and transparency. Observational approaches during field trials should aim to quantify the delivery of alkalinity to seawater and monitor for secondary precipitation, biotic calcification, and other ecosystem changes that can feed back on sources or sinks of greenhouse gases where alkalinity is measurably elevated. Observations of resultant shifts in the partial pressure of CO₂ (pCO₂) and ocean pH can help determine the efficacy of OAE and are amenable to autonomous monitoring. However, because the ocean is turbulent and energetic and CO₂ equilibration between the ocean and atmosphere can take several months or longer, added alkalinity will be diluted to perturbation levels undetectable above background variability on timescales relevant for MRV. Therefore, comprehensive quantification of carbon removal via OAE will be impossible through observational methods alone, and numerical simulations will be required. The development of fit-for-purpose models, carefully validated against observational data, will be a critical part of MRV for OAE.

Ho D. T., Bopp L., Palter J. B., Long M. C., Boyd P. W., Neukermans G. & Bach L. T., 2023. Monitoring, reporting, and verification for ocean alkalinity enhancement. In Oschlies A., Stevenson A., Bach L. T., Fennel K., Rickaby R. E. M., Satterfield T., Webb R. & Gattuso J.-P. (Eds.), Guide to Best Practices in Ocean Alkalinity Enhancement Research, Copernicus Publications, State of the Planet 2-oae2023: 12. doi: 10.5194/sp-2-oae2023-12-2023. Article.

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