Today, September 24, is World Maritime Day. It felt like the right day to publish our new policy paper, Unlocking Europe’s Blue Carbon Economy, which sets out why marine carbon dioxide removal (mCDR) deserves a place in Europe’s climate strategy, and three concrete steps EU policymakers can take now.
Why the ocean matters
The ocean is the largest carbon sink on the planet, and it has absorbed more than 90% of the excess heat trapped by greenhouse gas emissions. It holds far more carbon than the atmosphere and every terrestrial plant combined.
Phytoplankton, the microscopic algae that live in the ocean’s surface layer, are a big part of why. Through photosynthesis they draw down carbon dioxide the same way land plants do, and they also produce roughly half of the oxygen on Earth. When plankton die or are eaten, some of that carbon sinks into deeper water and stays out of the atmosphere for long periods, a process known as the biological carbon pump.
But phytoplankton need iron to grow, and across large parts of the ocean, iron is in short supply. Iron moves up the marine food web: plankton take it from seawater, fish eat the plankton and store the iron in their bodies, and in a natural ocean that iron cycles back to the surface as animals excrete, or die and decompose. Commercial fishing interrupts that cycle. It removes up to 30,000 tonnes of iron from the ocean every year, roughly the weight of four Eiffel Towers, as fish biomass is taken out of the system rather than recycled back into it (Moreno and Haffa, 2014).
What Ocean Iron Replenishment studies
Ocean Iron Replenishment (OIR) studies whether carefully restoring some of that lost iron to iron depleted parts of the ocean can help plankton grow again. The idea builds on something that already happens in nature: volcanic ash and desert dust falling into the ocean deliver iron and are known to trigger plankton blooms. OIR mimics that same natural process, deliberately and on a scale that can be measured and monitored.
More than a dozen controlled trials since 1993 have shown that small additions of iron increase phytoplankton growth in iron limited water. In the most successful of them, at least half of the resulting bloom sank below 1,000 metres, keeping that carbon out of contact with the atmosphere for centuries (Smetacek et al., 2012). If it works safely at scale, OIR could also help restore the marine food web that plankton sit at the base of, and support the release of cloud forming aerosols that help cool the surrounding ocean surface.
These are still open research questions, not settled conclusions. How much of the carbon actually stays in the deep ocean, which plankton species are favoured or displaced, and how the wider ecosystem responds all need larger, longer field trials with rigorous monitoring before anyone can responsibly assess how OIR could work at scale.
Three things Europe can do now
The paper sets out three concrete policy asks for European climate leaders:
- Fund a clear mCDR research and innovation agenda under FP10. CarbonGap estimates that €2.6 billion in public research support is needed for early stage carbon removal over the next seven years. The EU should dedicate funding for marine based research and ocean testing within FP10 and the European Competitiveness Fund, so the conditions under which mCDR could work can actually be established.
- Build OIR regulation and coordinated governance into the Ocean Act. Integrating mCDR policy across climate, marine and biodiversity legislation would create a clear, predictable regulatory environment, with transparent permitting pathways and environmental safeguards linked to European ocean observation infrastructure such as OceanEye.
- Establish an mCDR market framework under the Carbon Removal Certification Framework (CRCF).Transparent, robust monitoring, reporting and verification (MRV), standardised baseline modelling and independent scientific guardrails are essential to guarantee ecological safety, build public trust, and ensure that any long term carbon storage claims hold up.
Why now
The next generation of ocean iron field trials is already being planned, in the Pacific, led from the United States. The safeguards written for those trials will likely become the global default for how this kind of research is done. Europe can help write them, or inherit them.
Oceanry welcomes the opportunity to contribute to upcoming European Union workshops and policy discussions on this, and to support the launch of initial research trials in 2027 and 2028.
Download the full policy paper below:
References (see policy paper for full reference list)
Moreno, A. R., & Haffa, A. L. M. (2014). The impact of fish and the commercial marine harvest on the ocean iron cycle. PLoS ONE, 9(9), e107690.
Smetacek, V., Klaas, C., et al. (2012). Deep carbon export from a Southern Ocean iron-fertilized diatom bloom. Nature, 487, 313 to 319.
