Ocean absorbs 25% of global CO₂ emissions annually.
Models vary widely due to limited long-term ocean data.
Uncertainty could undermine mitigation targets and adaptation planning.
The ocean is storing around 25% of global CO2 emissions; however, major blind spots remain in our scientific understanding of this process, according to the report published by Intergovernmental Oceanographic Commission (IOC) of UNESCO, with variations large enough to considerably affect how governments plan climate mitigation and adaptation strategies.
Incomplete Data Foundation of Climate Models
The Integrated Ocean Carbon Research Report found that scientific models differ widely in estimating how much carbon the ocean absorbs, with discrepancies of 10-20% globally and even greater in certain regions.
The report underscored that the reason behind these differences is limited availability of long-term data and gaps in understanding how key processes respond to climate change. This also means quantifying how changes in ocean warming and circulation affect carbon uptake, how shifts in plankton and microbial life influence long-term storage, and how coastal and polar regions exchange carbon with the atmosphere. The report further warned that present day industrial activities and the risks associated with climate engineering in the future may alter the ocean’s natural ability to absorb carbon.
3 February 2026
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Implications for Climate Targets and Adaptation
The UNESCO report stated that the recent trends indicated that climate decisions are being made without knowing how the ocean will behave. The report warned that more CO2 will remain in the atmosphere and accelerate global warming if the ocean absorbs less carbon in the future which would have a direct impact on future emissions targets.
The report recommended that decisions about potential carbon removal strategies and ocean-based climate interventions must also be grounded in more robust scientific evidence.
Bolstering Ocean Observations Needed
According to a report by the Intergovernmental Panel on Climate Change, the ocean has absorbed about 90% of the excess heat generated by greenhouse gas emissions and 25% of carbon dioxide emissions. While these processes have mitigated some effects of climate change, they have also led to significant challenges, including ocean warming, acidification, and sea level rise. These changes endanger marine life and coastal communities, where 680mn people currently live—a figure projected to exceed 1 billion by 2050.
Monitoring and gathering data from all ocean layers is among the most important ways to address the lack of knowledge about ocean carbon, underscored the UNESCO report, adding that the modelling of ocean processes and international coordination of ocean-based policies are the next steps.
