A new report from the Intergovernmental Oceanographic Commission of UNESCO has revealed a major gap in our understanding of how the ocean absorbs and stores carbon, a blind spot that could significantly affect global climate predictions and policy decisions.

The ocean currently absorbs around 25% of global CO₂ emissions, acting as one of the planet’s most powerful climate buffers. But the Integrated Ocean Carbon Research Report finds that scientific models vary widely in estimating exactly how much carbon the ocean takes up, with discrepancies of 10–20% globally and even higher in some regions.

These uncertainties stem from limited long-term monitoring and gaps in understanding how warming waters, shifting ocean circulation, plankton dynamics and coastal processes affect carbon uptake. If the ocean absorbs less carbon in future than models predict, more CO₂ will remain in the atmosphere – accelerating global warming and complicating emissions reduction targets.

For coastal communities already facing sea-level rise, stronger storms and marine heatwaves, this uncertainty also makes adaptation planning more difficult.

The report, developed by 72 scientists across 23 countries, calls for a coordinated global ocean carbon observing system, combining satellites, autonomous technologies and deep-ocean monitoring. Strengthening international collaboration and improving climate models are central to ensuring ocean carbon science can better inform national climate strategies.

The message is clear: reducing emissions remains essential, but without clearer data on the ocean’s carbon role, mitigation and adaptation plans risk being built on incomplete foundations.

As ocean-climate pressures intensify, strengthening global ocean observation is not just scientific ambition, it is a critical investment in climate resilience.

Read more here