Oceans are one of the key natural carbon sinks, meaning that they absorb more carbon dioxide (CO₂) than they release. By absorbing ~25-30% of all anthropogenic carbon dioxide emissions, oceans create a considerable value to society.

Once quantified and assessed, the information on the value of the annual ocean sink is relevant for many reasons:

• for inclusive wealth accounting and sustainable development assessments,
• for justifying improving the accuracy of ocean carbon sink estimates and thus forecasting potential weakening of the ocean carbon sink, and
• for assessing deliberate efforts to increase the ocean sink through marine carbon dioxide removal (CDR) technologies.

A recent study, published by a team including Johannes Karstensen of GEOMAR (a partner in ObsSea4Clim), evaluates the value of ocean carbon sink using two approaches: one based on the cost of reducing emissions (abatement cost-based approach) and one based on the cost of damage cause by climate change (damage-based approach). The results show that the two methods give different estimates of this value, with significant variations between countries. The article suggests that the abatement cost-based approach is more reliable for valuing the ocean carbon sink. More specifically, it provides more reliable economic assessment estimates of improved ocean monitoring services and incorporating the ocean’s carbon absorption into climate policies.

Interested in the methodology and detailed results of this study? Read the full article published in Communications: Earth and Environment in Open Access:

Rickels, W., Meier, F., Peterson, S., Rühland, S., Thube, S., Karstensen, J., Posern, C., Wolff, C., Vafeidis, A., Grasse, P., Quaas, M. (2024). “The ocean carbon sink enhances countries’ inclusive wealth and reduces the cost of national climate policies”, Communications Earth and Environment, Vol. 5, No. 513. DOI:10.1038/s43247-024-01674-3