Ocean Damage Nearly Doubles the True Cost of Climate Change, Groundbreaking Study Reveals

The Blue Social Cost of Carbon

The study introduces what researchers call the blue social cost of carbon, adding 46.2 dollars per ton of carbon dioxide to existing estimates. This raises the total social cost of carbon from 51 dollars to 97.2 dollars per ton, representing a 91 percent increase. The social cost of carbon is an economic metric that estimates the total harm caused by each ton of carbon dioxide emissions, expressed in monetary terms.

Environmental economist Bernardo Bastien-Olvera, who led the study during a postdoctoral fellowship at Scripps Oceanography, emphasized the importance of this quantification. If we do not put a price tag on the harm that climate change causes to the ocean, it will be invisible to key decision makers, he explained.

Two Trillion Dollars in Hidden Damages

With global carbon dioxide emissions estimated at 41.6 billion tons in 2024, the findings suggest nearly 2 trillion dollars in annual ocean-related damages that current climate cost estimates fail to capture. The study projects market damages totalling 1.66 trillion dollars in annual global losses by 2100, with additional losses from diminished ecosystem services and reduced nutrition from fisheries impacts.

Until now, the ocean, Earth's largest carbon sink, was largely absent from standard economic calculations despite widespread degradation of coral reefs, fisheries losses, and coastal infrastructure damage that affects millions globally. The new research fills this critical gap by systematically accounting for multiple types of ocean-related impacts.

Unequal Distribution of Harm

The research reveals that the impacts of ocean degradation are not distributed equally across the globe. Island nations and small economies face disproportionate impacts due to their heavy dependence on seafood for nutrition and economic activity. This finding highlights important equity considerations in climate policy.

Researchers accounted for how ocean warming reduces key nutrients in seafood, including calcium, omega-3 fatty acids, protein, and iron. These nutritional losses can translate to increased disease risk and preventable deaths, particularly in communities that rely heavily on marine resources for sustenance.

Comprehensive Economic Methodology

The study examined multiple categories of economic impacts, including market use values such as decreased fisheries revenue or diminished trade, and non-market values such as health impacts of reduced nutrition availability from impacted fisheries and lost recreational opportunities at the ocean.

By integrating these diverse impact categories into a single comprehensive framework, the researchers provide the most complete picture to date of the true economic cost of climate change when ocean damages are properly accounted for.

Climate Engineering Risks

Published alongside the economic findings, a separate study examined how various climate intervention strategies might affect marine ecosystems. Researchers analysed eight different intervention types and found that while some carry fewer risks than others, none are free of consequences.

Among the methods reviewed, electrochemical ocean alkalinity enhancement posed the lowest direct risk to marine environments. This technique uses electric currents to separate seawater into alkaline and acidic streams, producing a chemically simple form of alkalinity with limited biological impact, though it still requires safe disposal of the acidic byproduct.

Other relatively low-risk approaches include adding carbonate minerals to seawater and sinking land plants in deep, low-oxygen environments for long-term carbon storage. However, biological carbon removal methods that rely on iron fertilisation or seaweed cultivation carry more uncertainty, potentially disrupting fisheries by depleting nutrients that ocean currents transport to productive fishing areas.

Commercial Pressures and Scientific Urgency

The researchers emphasised that commercialisation of marine carbon dioxide removal is already underway, with startups backed by investors selling carbon credits to companies such as Stripe and British Airways. Meanwhile, global emissions continue to rise as several nations retreat from emissions reduction pledges.

Scientists have an opportunity to study these ideas carefully now, before the planet reaches climate instabilities that could push society to embrace untested interventions, the climate engineering study authors wrote. That window will not stay open forever.

Policy Implications

The findings have significant implications for climate policy and carbon pricing mechanisms worldwide. By demonstrating that the true social cost of carbon is nearly double previous estimates when ocean impacts are included, the research provides a stronger economic justification for more aggressive emissions reduction policies and higher carbon taxes.

The study also underscores the need for integrated assessment models used in climate economics to incorporate ocean impacts more comprehensively. As policymakers design climate strategies and evaluate the costs and benefits of different mitigation approaches, understanding the full scope of ocean-related damages will be essential for making informed decisions.

Study co-author Kate Ricke, a climate scientist and associate professor at Scripps Oceanography and the School of Global Policy and Strategy, noted that this research represents a crucial step toward more accurate climate cost accounting. The ocean has been absorbing not just our carbon emissions, but also the economic consequences, and it is time we acknowledge that in our calculations, she stated.