IMO Adopts First Global Assessment Frameworks for Ocean Carbon Removal Research

On October 9, the last day of a week-long meeting at the International Maritime Organization's headquarters in London, the world's maritime governments did something they had been avoiding for years: they wrote rules for experimenting with the ocean's climate machinery. Parties to the 1972 London Convention and the 1996 London Protocol adopted a resolution establishing formal assessment frameworks for three marine geoengineering techniques: ocean fertilization, ocean alkalinity enhancement, and the sinking of biomass into the deep sea. For a corner of climate technology that has operated in a legal gray zone, the rulebook has finally arrived.

The timing matters. Startups working on ocean-based carbon dioxide removal, collectively called marine CDR or mCDR, are edging from lab experiments toward open-water field trials. Several of the proposed techniques would operate in international waters, beyond any single country's jurisdiction, which puts them under the dumping treaties administered by the IMO. Until now, only ocean fertilization had a formal assessment framework, one first adopted in 2010. The October 9 package updates that framework and adds two new ones, extending precautionary oversight to exactly the methods closest to commercial testing.

What the rulebook actually requires

Each framework follows the same five-stage structure: initial screening, environmental assessment, risk management, decision making, and post-project review. Assessments can be revisited as new information becomes available, so an approval is not a one-time pass. To proceed, a proposal must demonstrate a legitimate scientific purpose, thoroughly assess environmental risks, consult relevant stakeholders, pass peer review, and commit to rigorous monitoring and transparent reporting.

The bar is deliberately research-first. The parties emphasized that scientific knowledge remains limited, that research should proceed cautiously with environmental protection as the top priority, and that no activities beyond the research stage can be considered until further scientific evidence exists. IMO Secretary-General Arsenio Dominguez said the frameworks give regulators and researchers rigorous and transparent tools for assessing proposed activities and protecting the marine environment.

Three techniques, one gateway

The three methods differ in mechanism but share a legal status. Ocean fertilization adds nutrients to seawater to stimulate phytoplankton growth, which draws carbon dioxide from the atmosphere. It has the longest regulatory history: in 2008, the parties adopted resolution LC-LP.1(2008), deciding that fertilization activities other than legitimate scientific research should not be allowed, and it remains the only marine geoengineering activity listed under the Protocol's Annex 4. Ocean alkalinity enhancement adds alkaline substances to seawater to increase the ocean's capacity to absorb atmospheric CO2 and counteract acidification. Ocean sinking of biomass deliberately places marine or terrestrial plant matter into the ocean to store carbon in the deep sea.

The choice of these three is deliberate. They are the techniques closest to commercial experimentation, and the ones where the line between research and deployment has become hardest to police. In 2023, the parties had already signaled the direction: alkalinity enhancement and biomass sinking should be treated similarly to ocean fertilization, meaning some legitimate scientific research may be allowed while deployment is deferred. This week's resolution turns that signal into procedure.

The frameworks make the legitimate scientific research test the gateway every ocean CDR proposal must pass, and how assessors treat credit financing under that test is the industry's central uncertainty.

The money question the rulebook ducks

The sharpest divide in the negotiations concerned money. A number of parties argued that the sale or pre-sale of carbon credits would make an activity impermissible, while others argued that projects using credit sales should be assessed case by case. The frameworks do not settle the issue. That omission is commercially decisive, because most marine CDR startups finance field trials through advance credit purchases. A finding that credit sales disqualify research from the frameworks would cut the sector's primary funding channel.

Observers told Carbon Pulse the new guidance could impact the emergent market for ocean-based CDR credits, and the logic is straightforward: the frameworks make the legitimate scientific research test the gateway through which every proposal must pass. Whether the first assessments under the new rules classify credit-financed trials as legitimate research is now the question every developer and buyer is watching. Buyers with ocean-based removal credits in forward portfolios would be prudent to map each contract to the flag and coastal state jurisdictions where the underlying activity would occur, since implementation runs through national law and both treaties require parties to adopt domestic dumping legislation.

Two decades of ocean governance behind it

The London Convention and London Protocol are, at international level, the only treaties that explicitly govern marine geoengineering, which is why this decision landed in London rather than at a climate conference. The arc is long: the 2008 fertilization decision, the 2010 assessment framework, the 2023 statement extending the same treatment to alkalinity enhancement and biomass sinking. Friday's resolution operationalizes that arc.

The meeting itself, the 48th Consultative Meeting of the London Convention and the 21st Meeting of the London Protocol (LC 48/LP 21), ran October 5 to 9 at IMO Headquarters and was chaired by Radia Razack of South Africa. Alongside the geoengineering frameworks, the parties approved guidance on end-of-life management of fiberglass-reinforced plastic vessels, developed with the UN Environment Programme, and agreed to intersessional work examining how the London instruments align with the High Seas Treaty, the BBNJ Agreement on marine biodiversity beyond national jurisdiction. The ocean governance calendar is filling up fast.

Why carbon buyers should care

Three threads will determine how this rulebook reshapes the market. First, whether the first assessments under the new frameworks treat credit-financed trials as legitimate research, which decides whether the sector's funding model survives contact with the law. Second, whether the monitoring and transparent reporting requirements converge with the measurement standards voluntary registries are building for marine CDR methodologies, since mismatched standards would force developers to satisfy two masters. Third, whether the 2023 deferral of deployment holds as commercial pressure grows.

There is a broader lesson here for the whole carbon removal sector. Headline targets, like the EU's discussed 250 million tonnes of removals inside its emissions trading system, are only as real as the definitions behind them: permanence thresholds, eligibility rules, and accounting standards. The IMO's decision does for the ocean what Germany's cross-border CO2 storage agreements did for European carbon management earlier this month: it moves a category from aspiration to administration. And unlike direct air capture plants on land, which answer to a single permitting authority, ocean methods have never had a clear one. Now they do, and it expects science first, commerce later.