Introduction

Increasingly, research is being undertaken to determine the potential for marine carbon dioxide removal (mCDR) technologies to enhance ocean-based carbon sinks as a tool to mitigate climate change. Approaches to mCDR come in diverse forms with different implications for marine ecosystems and the coastal communities that depend upon them for their livelihoods. International and domestic legal frameworks for the regulation of mCDR are incomplete and even inconsistent, as illustrated by the history of attempts since 2007 to reach agreement on mCDR under international legal instruments designed to address marine pollution prevention (see Webb on London Convention and London Protocol). What is clear is that piecemeal codes of conduct and good governance frameworks for mCDR are emerging to fill the legal governance gap, including those designed to better enable early stage mCDR deployment to qualify as carbon trading credits.  

In this blog I will first briefly introduce mCDR and its potential role in climate transition, then describe examples of emerging codes and good governance frameworks for mCDR. I will then tentatively explore whether existing responsible business conduct guidance tools that incorporate business responsibilities for human rights in accordance with the UN Guiding Principles on Business and Human Rights (UNGPs) are equipped to handle the challenges associated with the development and deployment of novel mCDR approaches as part of a just climate transition.

What is mCDR and what role might it play in climate transition?

In an ideal world, the climate change crisis would be solved by simply putting a stop to greenhouse gas (GHG) emissions. In the real world the challenge is far more complex. Much work remains to be done to transition away from greenhouse gas (GHG)-intensive industry (notably fossil fuels), yet the global commitment to do so is being seriously challenged in 2025 by the international and domestic climate policy rollbacks of the Trump administration in particular. Even if the global commitment to phase out fossil fuels were strengthened, some hard-to-abate sectors may struggle to achieve carbon neutrality despite innovations (such as cement and steel). As a result, many argue that some type of carbon dioxide removal will be necessary to help achieve net-zero emissions goals, despite the risk that countries will rely on carbon removal in net-zero pledges to avoid actual reductions, a risk also confronting businesses.  

The ocean covers over two-thirds of the earth’s surface and is a significant carbon sink, absorbing approximately one quarter of GHG emissions. As attention is increasingly being paid to the need to develop mCDR approaches (see eg Ocean Vision’s mCDR Ecosystem Database), a wide range of actors from private sector to government, as well as international organisations and NGOs, are stepping up to support mCDR research and deployment in differing capacities. Notably, funders of mCDR go beyond public funding sources to include philanthropic foundations, venture capital funders, and pre-purchase funding (of carbon credits). Among pre-purchase funders is Microsoft with purchases from Ebb Carbon announced in 2024. 

Methods of mCDR are diverse, and there is no consistent categorization. While the Waterloo Climate Institute (WCI) proposes three categories (biological pump enhancements, chemical mCDR and electrochemical mCDR) (WCI Box 1 p5), the Aspen Institute proposes four categories in its 2023 Code of Conduct for Marine Carbon Dioxide Removal Research (Aspen Code Box 3, p12): 

1. Biological carbon sink enhancement (including macroalgae cultivation and sinking, nutrient or iron fertilization, recovery of coastal ecosystems and blue carbon),
2. Chemical carbon enhancement (including ocean alkalinity enhancement and electrochemical approaches),
3. Physical carbon sink enhancement (including artificial upwelling and downwelling), and 
4. Other approaches (including hybrid approaches such as the creation of biofuels from macroalgae cultivation combined with carbon capture and storage, or carbon dioxide extraction from seawater and geological storage).

Irrespective of categorization, what is clear is that different approaches appear to have more ready potential than others, due to a higher knowledge base, greater potential durability of storage, greater scalability, and lower costs (WCI, Table 1). Yet uncertainty exists over the degree of environmental and human rights risks as well as any potential of co-benefits of each approach. 

Overall, there is much that is unknown, including whether carbon removals by any mCDR method can be credibly accounted for. Concerns have been raised about the funding of mCDR research through the pre-purchase of carbon credits on voluntary markets as this could create incentives to hide negative findings and publicly disclose only the positive (WCI, p8). Moreover, the private sector start-ups that are raising venture capital funding with the aim to commercialize new ocean-CDR techniques risk colliding with the London Convention and London Protocol restrictions that prohibit commercialization while supporting legitimate scientific research (Webb pp20-21). Coastal blue carbon or ecosystem recovery projects appear to have the most potential in terms of low environmental risks and greater potential for co-benefits, with diverse methods of financing receiving attention, ranging from bonds to impact investing, payment for ecosystem services, and carbon credits. 

The Emergence of mCDR Codes of Conduct and Guidance Tools 

In the absence of clarity on the application of international and domestic legal frameworks to mCDR research and deployment, codes of conduct and good governance guidance documents are emerging. For example, an interdisciplinary team was convened to develop the Aspen Institute’s 2023 Code of Conduct (CoC) for marine CDR research. The purpose of the code is “to ensure that the impacts of mCDR research activities themselves are adequately understood and accounted for as they progress” (p4). Eight interconnected foundational principles inform the code: (1) awareness of power imbalances; (2) inclusiveness; (3) consent; (4) reciprocity; (5) reflexivity; (6) responsiveness and trust; (7) accountability; and (8) anticipation and precaution (including the precautionary principle). Various legal principles are said to have informed the development of the code, including: the customary international environmental law principle of prevention of transboundary harms; treaty and Rio Declaration expectations of ex-ante environmental review of hazardous activities as well as notification and consultation of those potentially affected; the United Nations Declaration on the Rights of Indigenous Peoples (UNDRIP)’s requirement of free, prior and informed consent; the United Nations Convention on the Law of the Sea (UNCLOS)’s declaration of the international seabed as the common heritage of humankind; and the Agreement under the United Nations Convention on the Law of the Sea on the Conservation and Sustainable Use of Marine Biological Diversity of Areas beyond National Jurisdiction (BBNJ) treaty’s preambular text that state should “act as stewards of the ocean in areas beyond national jurisdiction on behalf of present and future generations by protecting, caring for and ensuring the responsible use of the marine environment.” (p16) The Code also provides guidance on “Applying the CoC Principles to Non-Humans” and encourages researchers to reflect upon non-Western scientific paradigms including Indigenous understandings and rights of nature (p19 Box 4). The Code then provides detailed guidance on the three stages of mCDR research: planning and scoping; execution of research; and conclusion of research. However, there are no references to human rights or the United Nations General Assembly (UNGA)’s 2022 resolution recognizing the right to a clean, healthy and sustainable environment in the Code (although there are multiple references to UNDRIP, and a single reference to the International Covenant on Economic, Social and Cultural Rights (ICESCR).

In 2024, with funding from the European Union, researchers with the Ocean Governance Research Group of the Research Institute for Sustainability in Germany published a policy brief on good governance of mCDR that proposes eleven principles to guide decision-making with the aim of “deploying marine CDR as part of a global strategy to combat climate change”. These principles are grouped into: effective governance (direction; coordination; information; accountability); equitable governance (recognition and participation; fairness; ethics and justice; responsive governance (anticipation; adaptability, flexibility and learning; innovation); and robust governance (rule of law). Specific reference is made to the human right to a clean, healthy and sustainable environment as part of ethics and justice (p9). 

In April 2025, Microsoft announced that it had entered into a collaboration with Carbon Direct in order to develop a ‘new standard’ of mCDR to ensure methods are scientifically sound and effective in reducing CO2. The mCDR Standard Framework will outlines key criteria and principles including Environmental Integrity (so that removal of CO2 does not cause harm to marine ecosystems), Measurement, Reporting, and Verification (MRV) (with baselines, to build credibility), Durability (permanence of storage to prevent re-release), Social Impact (avoid adverse livelihood impacts, equitably distribute benefits and engage local communities), and Transparency and Verification (third-party reviews for accountability).

And on June 4, 2025, a new Blue Paper was released by the High Level Panel for a Sustainable Ocean Economy entitled “Principles for responsible and effective marine carbon dioxide removal development and governance.” The Blue Paper provides an overview of the state of knowledge with regard to diverse mCDR approaches, before turning to international governance frameworks and domestic implementation, and the role of national governments in ‘advancing’ mCDR. Notably, the international governance frameworks covered do not include any international human rights law instruments (pp35-46), although the reference to human rights in the Preamble of the Paris Agreement is acknowledged (p44), and the analysis considers in passing public participation and the rights of Indigenous peoples as well as other social dimensions, drawing upon other sources including the Aspen Insitute’s CoC (pp47-50). Attention is given to the need to ensure public sector financing of mCDR is increased to avoid overreliance on private sector financing and associated risks including the risk that start-up companies will sell themselves to fossil fuel industry carbon management companies (pp51-52). Unsurprisingly, the Blue Paper takes the position that international law does not bind corporations and that domestic regulation is essential (p46).

Business, Human Rights and Responsible Business Conduct for mCDR?

The emergence of mCDR specific tools designed to guide responsible research practices for what might ultimately become commercially deployed climate mitigation technologies (including research that is funded through carbon credits or venture capital) raises the question of whether more general responsible business conduct (RBC) guidance tools, and especially those that embed business and human rights, might have anything to offer businesses, as well as financiers and investors, seeking to support mCDR research.  

The Global Compact has developed Sustainable Ocean Principles that build upon the UN Global Compact’s Ten Principles, and is developing practical guidance for different sectors that are designed as working documents to be updated over time. One guidance, developed in 2020 and aimed at the seaweed sector, touches on carbon sequestration. 

The 2023 targeted update of the OECD Guidelines for Multinational Enterprises on Responsible Business Conduct (OECD RBC Guidelines) includes an updated human rights chapter (now with explicit reference to the rights of Indigenous peoples and other marginalized groups, and human rights defenders) as well as an updated environment chapter (now with explicit reference to climate change as well as biodiversity loss, and degradation of marine ecosystems). Chapter IX on Science, Technology and Innovation, may be of assistance to the research stages of mCDR, and points immediately to the importance of enterprises carrying out risk-based due diligence in accordance with Chapter II “with respect to actual and potential adverse impacts related to science, technology and innovation.” (para 1) Stakeholder engagement is a key piece of the puzzle.

The environment chapter offers further insights. The Commentary states that enterprises “have an important role in contributing towards net-zero greenhouse gas emissions and a climate-resilient economy” and should implement science-based policies and transition plans, including all three scopes of GHG emissions. Importantly, “[e]nterprises should prioritise eliminating or reducing sources of emissions over offsetting, compensation or neutralization measures. Carbon credits, or offsets, may be considered as a means to address unabated emissions as a last resort. Carbon credits or offsets should be of high environmental integrity and should not draw attention away from the need to reduce emissions …” (para 77). In 2024 the OECD released a policy paper aimed at clarifying understandings of responsible business climate action, and helpfully situates its guidance within the understanding that climate, biodiversity and pollution crises are interconnected (the triple planetary crisis) as expressed in the 2022 UNGA resolution recognizing the right to a clean, healthy and sustainable environment (p8). 

Notably, the Commentary to the environment chapter of the OECD RBC Guidelines also highlights the importance of the “biodiversity mitigation hierarchy which recommends first seeking to avoid damage to biodiversity, reducing or minimising it where avoidance is not possible, and using offsets and restoration as a last resort for adverse impacts that cannot be avoided” including with regard to the marine environment (para 80). This suggests an important and often underexplored consideration in mCDR approaches – climate change has harmed the ocean and marine ecosystems, including through ocean acidification. Some mCDR approaches offer the opportunity not only to sequester carbon, but also – perhaps – to contribute to ocean restoration – at least, if sequestration is not continually being ‘offset’ by continued emissions. And the OECD RBC Guidelines, as explained in its 2024 policy paper, helpfully reminds businesses of the importance of not only preventing and mitigating human rights and environmental risks and impacts, but also of providing for or cooperating in remediation where the adverse impact was caused or contributed to by the business (pp10-12). 

Conclusion

The landscape of mCDR codes of conduct and guidance tools is quickly emerging, yet to date arguably disconnected from existing responsible business conduct guidance tools including those that embed the business responsibility to respect human rights. There is work to be done to bridge the BHR and RBC communities with those working on responsible research and deployment of mCDR. Whether and if so how select mCDR approaches might contribute meaningful solutions to ocean climate challenges can only be sincerely answered if attention is also paid to the businesses that are causing or contributing to climate crisis, with a responsibility to remedy climate harms. Offsetting increased emissions can never be a substitute for reducing emissions and remedying harms, even for the most promising approaches to mCDR.