By Abbas Nazil
A new report released by the Intergovernmental Oceanographic Commission of UNESCO has identified major gaps in scientific understanding of how the ocean absorbs and stores carbon, warning that these uncertainties could undermine global climate predictions and weaken mitigation and adaptation planning.
The study reveals that the ocean currently absorbs about 25 percent of global carbon dioxide emissions, yet large discrepancies of between 10 and 20 percent exist in climate models estimating the scale and stability of this carbon sink.
Researchers explained that these differences arise from limited long-term data, insufficient monitoring coverage and incomplete knowledge of how warming waters, shifting ocean circulation and biological processes influence carbon storage in marine ecosystems.
The report emphasises that changes in plankton activity, microbial dynamics and interactions in coastal and polar regions remain poorly understood, making it difficult to predict how the ocean’s capacity to store carbon will evolve under rising greenhouse gas emissions.
It also warns that industrial activities and potential future climate engineering interventions could further alter natural ocean processes, introducing additional uncertainty into climate modelling and policy decision-making.
According to UNESCO Director-General Khaled El-Enany, coordinated global monitoring of ocean carbon absorption is urgent because policymakers rely on scientific data to design effective climate strategies and long-term emissions targets.
He stressed that stronger international collaboration and investment in ocean observation systems are essential to ensure that climate policies are grounded in reliable and comprehensive scientific evidence.
The report, prepared by 72 authors from 23 countries, provides the most extensive synthesis to date of uncertainties affecting the ocean carbon sink and outlines a roadmap to strengthen monitoring, modelling and global cooperation.
It calls for the establishment of a global ocean carbon observing system that integrates satellite technology, autonomous underwater platforms and sustained measurements from surface waters to the deep ocean to improve data accuracy.
Experts recommend enhancing modelling capacity while expanding scientific training and infrastructure development in underrepresented regions to achieve truly global coverage and reduce knowledge gaps.
Greater uncertainty in ocean carbon uptake has direct implications for national climate commitments because a weaker carbon sink would leave more carbon dioxide in the atmosphere, accelerating global warming.
This situation could complicate adaptation planning, especially for coastal communities already facing increasing risks from sea-level rise, stronger storms and warming marine environments.
The report also highlights that decisions regarding carbon removal strategies and ocean-based climate interventions must be supported by robust scientific assessment to avoid unintended consequences.
Since the launch of the UN Decade of Ocean Science for Sustainable Development, UNESCO has implemented more than 500 projects worldwide and mobilised over one billion dollars to advance ocean research and strengthen resilience.
These initiatives include improving ocean observing systems, expanding seabed mapping, developing early warning systems for coastal hazards and supporting ecosystem-based solutions that protect biodiversity while enhancing climate adaptation.
The organisation reiterates that reducing carbon emissions remains the most effective long-term solution to safeguarding the ocean and stabilising the climate system.
