Study Finds Ocean Impacts Nearly Double Economic Cost of Climate Change
Social cost of carbon is considered a more accurate accounting of harm than the calculations commonly used as the basis of carbon credits or carbon offsets offered to travelers. These calculations have been used by state governments and organizations such as the U.S. Environmental Protection Agency and Department of Energy to inform analyses of proposed policy actions to reduce greenhouse gas emissions.
Human-generated carbon dioxide emissions in the atmosphere cause damage by warming ocean temperatures, altering the chemistry of the ocean, reducing the ocean’s ability to hold oxygen necessary for species survival while increasing the severity of extreme weather, as rising temperatures provide more energy to feed extreme storms. These changes are altering the distribution of species and damaging ecosystems like coral reefs, mangroves, seagrass beds and kelp forests. There are also impacts to infrastructure like ports, which can be damaged from increased flooding and storms.
Calculating how societies depend on oceans for trade, nutrition, leisure and more
To develop the accounting, the study looked at straightforward market use values such as decreased fisheries revenue or diminished trade. It also accounted for non-market values such as health impacts of reduced nutrition availability from impacted fisheries and recreational opportunities at the ocean. Additionally, iIt considered intangibles such as the value of the inherent worth humans get from the enjoyment of ecosystems and biodiversity, which the researchers call non-use or existence value.
Researchers plugged the estimates into an economic model calibrated to varying greenhouse gas emission trajectories. Without ocean impacts included, the social cost of carbon is $51 per ton of carbon dioxide emitted into the atmosphere. When the model is run with ocean impacts, study authors calculated an additional $46.2 per ton of carbon dioxide, reaching $97.2 total per ton of carbon dioxide, a 91% increase. For a sense of scale, in 2024, global carbon dioxide emissions were estimated to be 41.6 billion tons, according to the Global Carbon Budget analysis — implying nearly $2 trillion in ocean-related damages associated with one year of global emissions, damages that are currently missing from standard climate cost estimates.
Overall, market damages are projected to be the largest cost to society, totaling global annual losses of $1.66 trillion in the year 2100. Damages in non-use values, the inherent worth we derive from enjoyment of ocean ecosystems, amount to $224 billion and non-market use values such as decreased nutrition from impacted fisheries adds up to $182 billion in annual losses.
But Bastien-Olvera, now an assistant professor at the National Autonomous University of Mexico, notes that a dollar of market damage is not the same as a dollar of cultural loss. These benefits are not perfectly substitutable, meaning that losses in one category cannot be fully offset by gains in another, so each category of damage carries a different meaning for society.