Marine carbon dioxide removal (mCDR) permitting is governed primarily by the United Nations Convention on the Law of the Sea (UNCLOS) and the London Protocol, which collectively regulate ocean dumping, marine scientific research, and environmental protection. Project developers must navigate these overlapping international frameworks by securing rigorous environmental impact assessments and proving their activities constitute constructive placement rather than illegal waste disposal.
1. Introduction to Marine CDR and the Regulatory Challenge
As the global community faces the urgent need to limit global warming to 1.5 degrees Celsius, reducing emissions alone is no longer sufficient. Active carbon dioxide removal (CDR) at a gigaton scale is required to avert catastrophic climate impacts. The oceans, covering over 70% of the Earth’s surface and holding roughly 50 times more carbon than the atmosphere, represent a highly promising frontier for carbon sequestration.
Marine carbon dioxide removal (mCDR) encompasses various biological, chemical, and physical approaches designed to enhance the ocean’s natural carbon uptake capacity. These include ocean alkalinity enhancement (OAE), ocean iron fertilization (OIF), direct ocean capture (DOC), and macroalgae cultivation. However, deploying these technologies at scale introduces unprecedented legal, environmental, and jurisdictional challenges.
Because the oceans are highly interconnected and largely constitute a global commons, mCDR activities can have transboundary ecological consequences. Consequently, project developers must navigate a complex, overlapping web of international treaties, regional agreements, and national laws. The two primary pillars of international ocean governance governing these activities are the United Nations Convention on the Law of the Sea (UNCLOS) and the London Convention/London Protocol (LC/LP).
2. The UNCLOS Framework: Jurisdictional Zones and Environmental Duties
Often referred to as the "constitution of the oceans," the United Nations Convention on the Law of the Sea (UNCLOS) establishes the legal framework for all marine activities. Signed in 1982, UNCLOS balances the rights of sovereign nations to utilize marine resources with their collective duty to protect and preserve the marine environment.
Maritime Jurisdictional Zones
UNCLOS divides the ocean into distinct zones, each determining which national or international body has regulatory authority over an mCDR project:
- Internal Waters and Territorial Sea: Extending up to 12 nautical miles from a nation’s coastal baseline. Here, the coastal state exercises full sovereignty. Any mCDR project in this zone is governed primarily by national environmental laws.
- Exclusive Economic Zone (EEZ): Extending from the edge of the territorial sea up to 200 nautical miles. Within the EEZ, the coastal state has sovereign rights for exploring, exploiting, conserving, and managing natural resources. It also maintains jurisdiction over marine scientific research (MSR) and the protection of the marine environment. Developers must obtain direct authorization from the coastal state to operate here.
- The High Seas: Marine areas beyond 200 nautical miles, outside national jurisdictions. The High Seas are open to all states, but activities are subject to general UNCLOS obligations and international oversight, making unilateral mCDR deployment highly controversial and legally risky.
Key UNCLOS Obligations for mCDR
Two major components of UNCLOS directly impact the permitting and execution of ocean-based carbon removal:
Article 194 (Duty to Prevent Pollution): States must take all necessary measures to prevent, reduce, and control pollution of the marine environment from any source. UNCLOS defines "pollution" broadly as the introduction by humans of substances or energy into the marine environment which results or is likely to result in deleterious effects such as harm to living resources and marine life. Because technologies like ocean alkalinity enhancement involve releasing alkaline materials (e.g., olivine, slaked lime) into seawater, regulators heavily scrutinize these projects to ensure they do not legally constitute pollution.
Part XIII (Marine Scientific Research): Article 238 grants all states the right to conduct marine scientific research. However, this research must be conducted exclusively for peaceful purposes and with the consent of the coastal state if executed within an EEZ. For early-stage mCDR pilots, framing projects as Marine Scientific Research (MSR) rather than commercial deployment is a critical pathway to securing initial permits.
3. The London Convention and London Protocol (LC/LP): Regulating Ocean Dumping
While UNCLOS provides the overarching jurisdictional framework, the International Maritime Organization (IMO) London Convention and Protocol serves as the primary international regulatory mechanism directly governing the addition of substances to the ocean for carbon removal.
The 1972 London Convention (LC) and its more restrictive 1996 successor, the London Protocol (LP), were established to prevent marine pollution caused by the dumping of wastes and other matter. While the older Convention allowed dumping unless explicitly prohibited, the London Protocol adopts a strict precautionary approach: all dumping is prohibited unless a substance is explicitly listed on Annex 1 (the "reverse list").
Insight Box: The Legal Paradox of "Dumping" vs. "Placement"
Under Article 1 of the London Protocol, "dumping" is defined as any deliberate disposal of wastes or other matter at sea. However, Article 1.4.2.2 clarifies that dumping does not include the "placement of matter for a purpose other than the mere disposal thereof, provided that such placement is not contrary to the aims of this Protocol." This distinction is the legal linchpin for mCDR. Developers must successfully argue that adding alkaline minerals or iron is a "placement" for the constructive purpose of climate mitigation, not the "dumping" of industrial waste.
Resolution LP.4(8): The Marine Geoengineering Amendment
In 2013, the contracting parties adopted Resolution LP.4(8), which amended the London Protocol to legally regulate marine geoengineering. The amendment defines marine geoengineering as a "deliberate intervention in the marine environment to manipulate natural processes, to counteract anthropogenic climate change and/or its impacts, and which has the potential to result in deleterious effects."
Under this amendment, a new Article 6 bis prohibits the placement of matter into the ocean for marine geoengineering activities listed in Annex 4, unless the listing explicitly allows for a permit. Currently, Ocean Iron Fertilization (OIF) is the only activity listed in Annex 4, permitted exclusively for legitimate scientific research. While the 2013 amendment is not yet globally in force, many member states treat its provisions as binding customary practice.
4. Comparing mCDR Technologies and Their Legal Classifications
Different ocean carbon removal methods interact with international maritime law in unique ways. The table below outlines the primary technological pathways, their legal classification, and the primary regulatory hurdles under UNCLOS and the LC/LP.
| mCDR Technology | Primary Mechanism | LC/LP Legal Status | UNCLOS Jurisdiction & Challenges |
|---|---|---|---|
| Ocean Alkalinity Enhancement (OAE) | Adding alkaline minerals (e.g., olivine) to increase ocean pH and draw down atmospheric CO2. | Evaluated as "placement" but under active review for Annex 4 marine geoengineering inclusion. | Regulated under Article 194. Must prove mineral dissolution does not introduce heavy metal impurities. |
| Ocean Iron Fertilization (OIF) | Adding micro-nutrients (iron) to stimulate phytoplankton blooms. | Explicitly regulated under Annex 4. Permitted only for scientific research; commercial deployment prohibited. | High Seas jurisdiction applies if beyond EEZs. Requires compliance with Part XIII (MSR) and extensive monitoring. |
| Direct Ocean Capture (DOC) | Electrochemical extraction of CO2 directly from seawater. | Not classified as "dumping" if no external substances are added. Wastewater discharge is regulated. | Regulated by the coastal state within its EEZ. Requires permits for coastal infrastructure and pipelines. |
| Macroalgae Cultivation & Sinking | Growing large-scale seaweed and intentionally sinking it to the deep ocean floor. | Sinking biomass is increasingly scrutinized as "dumping of organic matter" under the London Protocol. | Potential conflicts with navigation rights, fisheries, and benthic habitat preservation under Article 194. |
5. The Step-by-Step Permitting Process for mCDR Developers
Securing regulatory approval for an mCDR project requires a structured, multi-jurisdictional approach. Developers must transition from international legal theory to practical national compliance. Below is the step-by-step pathway to navigate the permitting landscape.
Step 1: Determine the Jurisdictional Zone
Identify exactly where your project’s marine operations will occur. Projects within 12 nautical miles require standard coastal state permits. Projects within 12 to 200 nautical miles (EEZ) require coastal state authorization but must also align with international treaties. High Seas projects face immense legal barriers and require alignment with international bodies and flag-state regulations.
Step 2: Classify the Activity (Research vs. Commercial)
Because commercial mCDR deployment is not yet supported by clear international regulatory pathways, projects should initially be structured as Marine Scientific Research (MSR). Under both UNCLOS and the London Protocol, scientific research projects benefit from more favorable permitting pathways, provided they are designed to answer specific ecological and technological safety questions before generating credits for carbon offset projects.
Step 3: Conduct a Transboundary Environmental Impact Assessment (EIA)
Under UNCLOS Article 206, states are required to conduct environmental impact assessments when planned activities may cause substantial pollution. Your EIA must cover baseline marine ecological conditions, chemical impacts of the mCDR agent, the physical footprint of the deployment vessel, and potential transboundary effects (e.g., currents carrying altered water masses into another nation’s EEZ).
Step 4: Engage National Competent Authorities
International treaties are implemented through national legislation. Developers must apply to the relevant domestic regulatory bodies. For example, in the United States, developers must work with the EPA's Ocean Dumping Management program under the Marine Protection, Research, and Sanctuaries Act (MPRSA), alongside NOAA. In the UK, the Marine Management Organisation (MMO) handles these authorizations.
Step 5: Establish Monitoring, Reporting, and Verification (MRV) Protocols
Permits are rarely "one-and-done" approvals. Regulators will require continuous, real-time monitoring to verify that the carbon is successfully sequestered and that no unexpected ecological harm is occurring. Utilizing advanced marine CDR calculators and scientifically validated MRV protocols is essential to maintain regulatory and public trust.
6. Actionable Takeaways for Project Developers
- Design for "Placement" Not "Dumping": Ensure your technology and operational processes are structured to meet the legal definition of "placement" under the London Protocol. Frame the addition of materials as a targeted intervention with a clear, constructive environmental purpose.
- Start in Highly Regulated National Waters: While international waters may seem attractive due to the lack of a single sovereign owner, the legal ambiguity actually increases project risk. Operating within the EEZ of a country with a mature, transparent regulatory system offers greater legal certainty for blue carbon project development.
- Prioritize Legitimate Scientific Research: Do not rush to commercialize. Design early phases as scientific research pilots that actively address the uncertainties highlighted by the LC/LP Scientific Groups.
- Proactively Address Transboundary Effects: Use oceanographic modeling to prove that your project’s chemical or biological plume will not drift into neighboring EEZs without prior consent.