Ankara: A new international study reveals that incorporating damage to oceans and marine ecosystems nearly doubles the social cost of carbon, adding about $48 per tonne to standard climate cost calculations that have largely ignored these impacts.
According to Anadolu Agency, the study, published in Nature Climate Change, was conducted by researchers from universities in the United States, Germany, Canada, Italy, and the Netherlands. It integrates ocean-based impacts of carbon emissions into the social cost of carbon (SCC), a crucial metric guiding climate policy. The researchers assessed the effects of climate change on 'blue capital,' which encompasses the natural, economic, and social benefits derived from oceans, seas, and coastal ecosystems.
The study analyzed climate impacts on coral reefs, mangroves, fisheries, aquaculture, and port infrastructure. Findings indicate that damages to marine systems have been largely overlooked in influential indicators like the SCC, which estimates the economic harm caused by each additional tonne of carbon dioxide emitted into the atmosphere.
To calculate the ocean-based component of the SCC, researchers modeled two scenarios: a reference scenario including climate impacts and another reflecting the effect of an additional megatonne of carbon dioxide emitted into the atmosphere in 2020. The study revealed that the blue social cost of carbon in 2020 totaled $48.3 per tonne, with $22.1 attributed to fisheries, $14 to coral reefs, $10.1 to mangroves, and $2.1 to ports. These figures represent ocean-related damages not included in standard SCC calculations, resulting in a significant underestimation of the true cost of carbon.
Professor of economics at Anadolu University, Ceyda Erden Ozsoy, highlighted that oceans act as a 'natural bank' regulating the climate while sustaining economic activity. She explained that blue carbon refers to the capacity of coastal and marine ecosystems to absorb and store carbon dioxide from the atmosphere, with mangrove forests, seagrasses, and salt marshes functioning as natural sinks that slow climate change. Blue capital encompasses all economic and welfare benefits provided by oceans and marine ecosystems.
Ozsoy emphasized that the social cost of carbon measures the total damage to people and the economy caused by each additional tonne of carbon dioxide emissions, including impacts on health, food systems, infrastructure, and quality of life. She noted that integrated assessment models are commonly used to calculate the social cost of carbon, monetizing market and non-market impacts to estimate per-tonne costs.
The study quantifies the monetary value of damage to marine ecosystems for each additional tonne of emissions, making visible impacts often ignored in SCC calculations. Ozsoy explained that rising greenhouse gas concentrations alter the chemical and physical structure of oceans, weakening ecosystems and undermining their natural regulatory functions. Oceans absorb part of the additional atmospheric emissions and shape the climate system's response.
Ozsoy warned that ocean-based damages are expected to reduce fish stocks, undermine food security, and increase health risks, with the loss of coral reefs and mangroves leaving coastal areas more exposed to natural disasters and economic losses. The study's message is clear: if the true cost of carbon is higher than assumed, climate policies must be stronger, involving both reducing emissions and placing oceans at the center of policy design.