The International Maritime Organization (IMO) has adopted new guidance aimed at ensuring marine geoengineering research avoids unacceptable impacts, amid growing interest in climate change mitigation technologies.

Marine geoengineering involves methods to increase the ocean’s capacity to absorb carbon dioxide from the atmosphere or store carbon for long periods. However, their potential impacts on marine ecosystems are not yet fully understood.

Meeting at IMO Headquarters in London, Parties to the 1972 Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter (London Convention) and 1996 Protocol to the Convention (London Protocol), adopted a resolution establishing assessment frameworks for ocean fertilization, ocean alkalinity enhancement and ocean sinking biomass.

The frameworks will help governments 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.

Welcoming the achievement, IMO Secretary-General Mr. Arsenio Dominguez said:

“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.”

A precautionary approach to marine geoengineering

The frameworks provide a common structure for a precautionary approach for the following three marine geoengineering methods:

• Ocean fertilization: Stimulating primary productivity in the ocean by adding nutrients to seawater to encourage phytoplankton growth, which absorbs carbon dioxide from the atmosphere;
• Ocean alkalinity enhancement: Adding alkaline substances to seawater to increase the ocean’s capacity to absorb atmospheric carbon dioxide and counteract ocean acidification.
• Ocean sinking of biomass: Deliberately placing biological material, such as marine or terrestrial plant matter, into the ocean to store carbon.

Each framework covers initial screening, environmental assessment, risk management, decision-making and post-project review. Assessments can be revisited as new information becomes available.

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.

The Parties emphasized that scientific knowledge remains limited, and that research should proceed cautiously, with environmental protection as the top priority. Further scientific research is needed before any activities beyond the research stage can be considered.

The adoption of these frameworks reaffirms the essential role of the London Convention and London Protocol in responding to new and rapidly evolving human activities in the ocean.

Other key decisions

The Parties also approved guidance on the end-of-life management of fibreglass reinforced (FRP) vessels and alternatives to at-sea disposal developed in cooperation with UNEP. They agreed on intersessional work to consider the relationship between the London Convention and London Protocol and the Agreement on Marine Biological Diversity of Areas beyond National Jurisdiction (BBNJ Agreement).

The 48th Consultative Meeting of Contracting Parties to the London Convention and the 21st Meeting of Contracting Parties to the London Protocol (LC 48/LP 21) took place at IMO Headquarters in London from 5 to 9 October 2026, chaired by Ms. Radia Razack (South Africa).

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