Parties to the London Convention and London Protocol, meeting as LC 48/LP 21 under the International Maritime Organization, have adopted formal assessment frameworks covering three marine carbon dioxide removal (mCDR) techniques: ocean fertilization, ocean alkalinity enhancement (OAE), and the ocean sinking of biomass. The resolution, announced after the annual meeting in London, restricts all such activities strictly to legitimate scientific research and explicitly defers commercial-scale deployments on ecosystem-uncertainty grounds.

The decision hands national regulators a structured procedure for evaluating proposals case by case. The core question each assessment must answer: does a proposed offshore trial constitute legitimate scientific research, or does it amount to unproven ocean dumping?

What do the frameworks cover?

The adopted texts span the full project lifecycle. Regulators evaluating an mCDR proposal will now work through a defined sequence:

• initial screening of the proposal;
• environmental risk assessment;
• risk management planning;
• stakeholder consultations, including consultations with Indigenous Peoples;
• post-project monitoring and review.

The framework provisions require rigorous risk assessments and post-project reviews for every qualified project. The consultation requirement with Indigenous Peoples adds an integrity dimension that project developers have not previously faced in a structured international instrument of this kind.

The decision establishes that activities beyond the research stage cannot be considered at present. That language reinforces a precautionary approach to marine geoengineering across international waters and effectively closes the door — for now — on permits for full-scale commercial operations in the three covered technique categories.

What does this mean for carbon credit monetization?

The guidance lands directly on the emerging market for ocean-based carbon removal credits. Environmental organizations, including the Center for International Environmental Law (CIEL), read the criteria as barring projects designed primarily to generate or sell carbon offsets from qualifying as legitimate scientific research.

That interpretation creates a potential integrity hurdle for developers whose business models depend on credit issuance. If a project's primary purpose is offset generation, the CIEL reading suggests it fails the research-legitimacy test.

There is a narrow opening, however. Draft texts indicate that payment for direct services rendered during experimental trials may remain permissible. Developers could therefore still contract with buyers to fund trial execution — paying for the research service itself — without structuring revenue around carbon credit sales from the intervention.

The distinction between paying for a service and buying an offset will likely become a central compliance question for mCDR companies and the registries that would issue credits against their activities.

How does this fit the broader marine geoengineering rulebook?

Scope matters here. The newly adopted assessment frameworks apply strictly to surface and water-column marine geoengineering. They operate under different rules than offshore geological carbon capture and storage (CCS) in sub-seabed formations, which sits under a separate regulatory track within the London Protocol system.

A ratification gap also shapes enforcement. The binding 2013 amendments to the London Protocol — which would establish a fuller regulatory regime for marine geoengineering — remain pending full international ratification. Until that threshold is reached, the new frameworks function as best-practice guidance that member states are expected to embed in domestic permitting processes.

In practice, that means national regulators — the agencies issuing permits for offshore trials — become the operative enforcement layer. The IMO frameworks supply the assessment criteria; individual states decide whether to apply them, and how strictly, in their own waters and for vessels flying their flags.

Why the research-only restriction matters for developers

The three covered techniques represent distinct material pathways for removing carbon from the atmosphere and storing it in the ocean. Ocean fertilization adds nutrients to stimulate plankton blooms; ocean alkalinity enhancement adds alkaline materials to shift seawater chemistry and increase CO2 uptake; biomass sinking transports organic material to the deep ocean for sequestration.

Each carries unresolved ecological questions. The precautionary posture adopted at LC 48/LP 21 reflects those uncertainties: parties concluded that ecosystem impacts are not yet understood well enough to authorize deployment beyond controlled research.

For project developers, the framework sets a compliance roadmap rather than a prohibition. A proposal that survives initial screening, passes environmental risk assessment, embeds risk management, conducts stakeholder and Indigenous consultations, and commits to post-project monitoring can proceed as research. Anything that cannot meet that bar — or that regulators judge to be dumping rather than science — stops at the dock.

The post-project review requirement also builds a feedback loop into the regime. Trial results feed back into the evidence base that will eventually determine whether parties lift the research-only restriction and open a pathway to commercial-scale mCDR under the London Protocol.

What happens next

Two milestones now decide the trajectory of marine carbon removal. First, watch how national regulators apply the frameworks in domestic permitting — the EPA's recent pilot permit for a marine carbon removal project in Louisiana signals that US trials are already moving through this pipeline, and each new permitting decision will test whether the IMO guidance holds as de facto law.

Second, track ratification of the 2013 London Protocol amendments. Full ratification would convert best-practice guidance into binding international obligation and lock the research-only restriction — or its successor rules — into treaty law. Until one of those doors opens, every ocean fertilization, alkalinity enhancement, and biomass sinking proposal worldwide will live or die on its ability to prove it is science, not commerce.