Select marine carbon dioxide removal (mCDR) techniques are now subject to guidance adopted by the International Maritime Organization (IMO) on Friday, a move observers say could impact the emergent market for ocean-based CDR credits, according to Carbon Pulse. The decision, taken by Parties to the London Convention and London Protocol meeting at IMO Headquarters in London, establishes assessment frameworks for three techniques: ocean fertilization, ocean alkalinity enhancement and ocean sinking of biomass. For developers raising money against future ocean CDR credits, and for buyers underwriting those purchases, the new rules define what counts as legitimate activity on the water.
Three Techniques, One Assessment Structure
The resolution adopted on 9 October 2026 gives governments tools to determine, on a case by case basis, whether proposed activities constitute legitimate scientific research and whether they can proceed without unacceptable risks to the marine environment, per the International Maritime Organization. The frameworks target three methods. Ocean fertilization stimulates primary productivity by adding nutrients to seawater to encourage phytoplankton growth, which absorbs carbon dioxide from the atmosphere. 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 involves deliberately placing biological material, such as marine or terrestrial plant matter, into the ocean to store carbon, according to IMO and All About Shipping.
The choice of methods is deliberate. These are the techniques closest to commercial experimentation, and the ones where the line between research and deployment has become hardest to police.
Five Stages, Precaution at the Core
Each framework covers initial screening, environmental assessment, risk management, decision making and post project review, and assessments can be revisited as new information becomes available, per IMO. Under the frameworks, all proposals must demonstrate a legitimate scientific purpose, thoroughly assess environmental risks, ensure proper stakeholder consultation and peer review, and include rigorous monitoring and transparent reporting.
Parties emphasized that scientific knowledge remains limited and that research should proceed cautiously, with environmental protection as the top priority, according to IMO. “At a time when marine geoengineering is attracting increasing scientific, commercial and public attention, they provide regulators and researchers with rigorous and transparent tools for assessing proposed activities and protecting the marine environment,” said IMO Secretary-General Arsenio Dominguez, per the IMO announcement.
A Governance Regime Built Over Two Decades
The London Convention of 1972 and the London Protocol of 1996 provide, at international level, the only explicit governance of marine geoengineering, according to IMO’s marine geoengineering page. In 2008, Parties adopted resolution LC-LP.1(2008), deciding that ocean fertilization activities other than legitimate scientific research should not be allowed. Ocean fertilization remains the only marine geoengineering activity listed under the Protocol’s new Annex 4, per IMO.
The package adopted this week extends that logic. It updates an assessment framework first adopted in 2010 for ocean fertilization and adds two new frameworks for ocean alkalinity enhancement and ocean sinking of biomass, according to the Sabin Center for Climate Change Law. In a 2023 statement, Parties said alkalinity enhancement and biomass sinking should be treated similarly to ocean fertilization, meaning some legitimate scientific research may be allowed but deployment should be deferred, per the Sabin Center.
Carbon Credits Remain the Unresolved Question
The sharpest divide in the negotiations concerns money. A number of Parties are arguing that the sale or pre-sale of carbon credits would be impermissible, while others argue that projects using carbon credit sales should be assessed on a case by case basis, according to the Sabin Center.
That question is commercially decisive. Most mCDR startups finance field trials through advance credit purchases, so a finding that credit sales disqualify research from the frameworks would cut the sector’s primary funding channel. The frameworks do not settle the issue, but they make the legitimate scientific research test the gateway through which every proposal must pass, and observers say the guidance could impact the emergent market for ocean-based CDR credits, per Carbon Pulse.
What Buyers and Developers Should Watch
Implementation now runs through national law. The London Convention has 87 Parties and the London Protocol has 56, and both treaties require Parties to adopt domestic laws governing ocean dumping, according to the Sabin Center. The pace and strictness of that transposition will determine where mCDR trials can realistically operate.
Three threads matter for the market. First, whether the first assessments under the new frameworks classify credit-financed trials as legitimate research. Second, whether the monitoring and transparent reporting requirements converge with the measurement standards voluntary registries are building for marine CDR methodologies. Third, whether the deferral of deployment, reaffirmed in 2023, holds as commercial pressure grows. Buyers with exposure to ocean-based removal credits in forward portfolios should map each contract to the flag and coastal state jurisdictions where the underlying activity would occur.
