The global cost of greenhouse gas emissions is nearly double what scientists previously thought, according to a study published Thursday by researchers at the University of California, San Diego’s Scripps Institution of Oceanography.
It is the first time a social cost of carbon (SCC) assessment—a key measure of economic harm caused by climate change—has included damages to the ocean. Global coral loss, fisheries disruption, and coastal infrastructure destruction are estimated to cost nearly $2 trillion annually, fundamentally changing how we measure climate finance.
“For decades, we’ve been estimating the economic cost of climate change while effectively assigning a value of zero to the ocean,” said Bernardo Bastien-Olvera, who led the study during his postdoctoral fellowship at Scripps. “Ocean loss is not just an environmental issue, but a central part of the economic story of climate change.”
The social cost of carbon is an accounting method for working out the monetary cost of each ton of carbon dioxide released into the atmosphere. “[It] is one of the most efficient tools we have for internalizing climate damages into economic decision-making,” said Amy Campbell, a United Nations climate advisor and former British government COP negotiator.
Calculations have historically been used by international organizations and state departments like the US Environmental Protection Agency to assess policy proposals—though a 2025 White House memo from the Trump administration instructed federal agencies to ignore the data during cost-benefit analyses unless required by law.
“It becomes politically contentious when deciding whose damages are counted, which sectors are included and most importantly how future and retrospective harms are valued,” Campbell said.
Excluding ocean harm, the social cost of carbon is $51 per ton of carbon dioxide emitted. This increases to $97.20 per ton when the ocean, which covers 70 percent of the planet, is included. In 2024, global CO2 emissions were estimated to be 41.6 billion tons, making the 91 percent cost increase significant.