Ocean Carbonate System Intercomparison Forum

Summary

Recent literature has highlighted several ongoing challenges regarding the consistency of seawater CO₂ measurements with estimates from alternate input pairs. These gaps in our knowledge of the ocean carbonate system are probably related to carbonate constant uncertainties, frequently-unknown concentrations of organic bases in seawater, and unrecognized measurement uncertainties. CO₂ measurement intercomparability is also challenged by the large and growing variety of instruments and approaches used for measurements and the lack of robust assessments or certified reference materials for some methods. While measurement strategies diversify and evolve, the need remains for consistent records of key measurements over time to assess marine CO₂ cycling and its impacts: e.g. dissolved inorganic carbon (DIC) records for anthropogenic carbon storage and changes in the biological pump, partial pressure of CO2 (pCO₂) records for air-sea CO2 flux estimates, pH records for ocean acidification (OA) monitoring, and seawater alkalinity (AT) records for assessing the impacts of OA on carbonate mineral cycling. It is therefore more critical than ever that scientists develop a strategy for identifying and addressing carbonate system intercomparability uncertainties, thus enabling existing and future data to be reconciled into internally-consistent data products with associated uncertainties. We therefore propose a forum between experts in carbonate system parameter measurements, data documentation, and interconversion to debate the nature of the problems, advocate for needed research to resolve these problems, and provide guidance for data product assembly and documentation.

Contact the working group at ocsif@whoi.edu

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