A new study finds that damage to the ocean nearly doubles the economic cost of climate change, after researchers included ocean impacts in the social cost of carbon for the first time.
The research, led by scientists at the Scripps Institution of Oceanography, was published Thursday in Nature Climate Change.
The ‘Blue’ Cost of Carbon
By factoring in ocean damage — referred to as the “blue” social cost of carbon — researchers found an added $46.2 per metric ton of carbon dioxide. That brings the total cost to $97.2 per ton, a 91% increase over previous estimates.
With global carbon dioxide emissions estimated at 41.6 billion tons in 2024, the study suggests nearly $2 trillion in ocean-related damages in a single year are currently excluded from standard climate cost calculations.
Why the Ocean Was Missing
Researchers said the ocean has long been overlooked in climate economics, despite well-documented damage to coral reefs, fisheries and coastal infrastructure. Warming waters and changing ocean chemistry are disrupting ecosystems such as reefs, mangroves, seagrass beds and kelp forests.
Coastal ports and communities are also increasingly vulnerable to flooding and stronger storms linked to climate change.
Unequal Global Impacts
The study found the impacts are not evenly distributed. Small island nations and coastal economies are expected to face the greatest harm due to their reliance on fisheries, seafood-based nutrition and ocean-dependent industries.
Why It Matters for Policy
The social cost of carbon is a key metric used by policymakers to weigh the economic benefits and costs of climate action. Researchers said including ocean damage provides a more accurate picture of the true harm caused by greenhouse gas emissions — and could influence future climate and environmental policy decisions.
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