Accounting for Ocean Impacts Nearly Doubles the Social Cost of Carbon

This article argues that traditional measures of the social cost of carbon (SCC) have largely overlooked the impacts of climate change on "blue capital," which includes marine ecosystems and infrastructure. The authors integrated the latest ocean science and economic data into a climate-economy model to capture the repercussions for corals, mangroves, seaports, fisheries, and mariculture. This integrated approach estimates the welfare effects of these ocean-based damages on a global scale. By conceptualizing an "ocean-based SCC" or "blue SCC," the study identifies a massive component of climate damage currently missing from standard global indicators. The research emphasizes that the ocean is vital to a thriving society, supporting both market economies and non-market values like coastal protection.

The study finds that the inclusion of marine capital impacts leads to a dramatic increase in the estimated cost of carbon emissions. It highlights that blue capital is especially critical to low-income countries, where it represents a larger share of the national GDP compared to wealthier nations. Changes in ocean chemistry and physical conditions, driven by anthropogenic emissions, are directly threatening these essential resources. The model suggests that without accounting for these ocean-related impacts, policymakers are making decisions based on incomplete and significantly underestimated damage functions. This work advocates for a comprehensive "blue economy" framework that reflects the true interdependence of the environment and the global economy.

The 2020 blue SCC is estimated at US$48 per tCO2, which represents an almost doubling of the SCC estimate from the same model when ocean impacts are excluded. Under a lower discount rate of 2%, this blue SCC value increases significantly to US$168. The study also notes that the elasticity of substitution between blue capital components is the most influential parameter in these calculations. Furthermore, different Shared Socioeconomic Pathways (SSPs) result in varying temperature increases by 2100, such as 3.58 °C under SSP2 and up to 4.18 °C under SSP3. These figures illustrate the profound financial implications of failing to protect marine ecosystems.

Bastien-Olvera, Bernardo A., Octavio Aburto-Oropeza, Luke M. Brander, William W. L. Cheung, Johannes Emmerling, Francesco Granella, Massimo Tavoni, Jasper Verschuur, and Katharine Ricke. "Accounting for Ocean Impacts Nearly Doubles the Social Cost of Carbon." *Nature Climate Change* (January 2026). https://doi.org/10.1038/s41558-025-02533-5