1. Introduction
As the International Law Commission (ILC) recently observed, innovations in technology both pose challenges and provide opportunities for international law. It made this observation in a law of the sea context, in its consideration of the topic of the prevention and repression of piracy and armed robbery at sea, where technological innovations impact both how crimes are carried out and how piracy and armed robbery at sea are combatted.Footnote 1 This is a pattern repeated across many areas of the law of the sea in the evolution of which technological and scientific developments have played a significant part.Footnote 2 Indeed, a significant impetus for the negotiation of the United Nations Convention on the Law of the Sea (UNCLOS)Footnote 3 was the impact of ‘revolutionary developments in science and technology, and the influence of these forces in international law’.Footnote 4
Historically, examples of the impact of technological developments on the law of the sea abound, from weapons technology and the ‘cannon shot rule’ where coastal State sovereignty extended as far as its (terrestrial-based) military force could reach,Footnote 5 to the impact of the (technology-led) industrial revolution and the quest for markets and heightened demand for raw materials reinforcing the doctrine of the freedom of the high seas.Footnote 6 Resource exploitation at sea has been another area of dynamic response to technological innovation. For living resources, the discovery first of salting,Footnote 7 and then freezing, fish for preservation enabled early distant water fishing, increasing pressure on coastal fish stocks and eventually leading to expanded maritime claims. An example is Latin American 200-nautical mile claims driven, inter alia, by resource concerns to secure protection from ‘growing American fleets’.Footnote 8 Today, the deep sea fishing industry is ‘supported by a battery of technological innovations including global positioning systems, multi-beam sonar, and stronger and more powerful cables and winches’,Footnote 9 with the consequent increased pressure on fish stocks leading, inter alia, to enhanced regulation of fishing methods and gear.Footnote 10
A similar picture emerges with respect to non-living resources. Swiftly overcome by technological developments was the Geneva Convention on the Continental ShelfFootnote 11 with its provisions on the outer limits of the continental shelf based on the limits of exploitability ‘soon seen as obsolete in light of technological progress and was radically modified in [UNCLOS]’ with the latter’s provisions, inter alia, for a deep seabed mining regime.Footnote 12 Relatedly, energy at sea,Footnote 13 from the exploitation of the petroleum resources of the continental shelf to renewable energy,Footnote 14 and the development of offshore transportable nuclear power plants,Footnote 15 has seen legal regulation responding to technological developments.
Beyond questions of resource access and use, a whole host of other human activities at sea are impacted by technological developments.Footnote 16 Technology-enabled monitoring, control and surveillance over a diverse range of human activities at sea for good (e.g. safety of life at sea; environmental monitoring;Footnote 17 fisheries enforcement) or for ill (e.g. criminal activities; monitoring of borders; repelling migrants)Footnote 18 is increasingly evident. And the use of ‘technology-enabled ocean governance’ has been highlighted for the effective implementation of area-based management tools,Footnote 19 such as high seas marine protected areas (MPAs) in the Agreement under UNCLOS on Conservation and Sustainable Use of Marine Biological Diversity of Areas Beyond National Jurisdiction (BBNJ Agreement) when it enters into force on 17 January 2026.Footnote 20
Last but not least is the focus of this contribution, which is the recent emergence of marine geoengineering as a novel technological response to the current climate emergency. Marine geoengineering offers a lens through which to assess the impact of new technologies on the development of the law of the sea and how this normative framework,Footnote 21 with UNCLOS at its heart, is of continuing relevance in meeting new technological challenges.Footnote 22 Section 2 will first briefly explain marine geoengineering and the current state of play; then consider the regulatory response of the specialised global dumping regime of the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter (London Convention) and its ProtocolFootnote 23 to marine geoengineering research. Section 3 considers the general regulatory framework provided by UNCLOS, and the relationship between this and the London Convention regime. Section 4 concludes by highlighting the continuing relevance of UNCLOS in providing the general legal framework for the regulation of marine geoengineering activities supplemented by, and linked with, bespoke regulation of identified marine geoengineering activities under the London Convention and Protocol.
2. Future technological changes within and beyond UNCLOS: marine geoengineering
2.1. What is marine geoengineering?
Marine geoengineering is:
deliberate intervention in the marine environment to manipulate natural processes, including to counteract anthropogenic climate change and/or its impacts, and that has the potential to result in deleterious effects, especially where those effects may be widespread, long-lasting or severe.Footnote 24
It is common to divide geoengineering into two broad categories.Footnote 25 One is solar radiation management (SRM) methods, which aim to reduce the amount of solar energy absorbed by the earth’s surface. In the maritime context, examples include increasing ocean albedo/reflectivity (e.g. microbubbles or foam; marine cloud brightening) and enhanced ocean alkalinity (e.g. by adding lime or carbonate minerals to the oceans). The other category comprises carbon dioxide removal (CDR) methods to remove CO2 from the atmosphere, with marine examples including ocean fertilisation (by adding iron or macronutrients such as nitrogen and phosphates), carbon storage in the ocean (e.g. liquid CO2 placed in the water column) and ocean pumping (e.g. artificial upwelling). The fundamental difference between them is that SRM methods address the symptoms (global heating) while CDR aims to provide a ‘cure’ (reduce CO2 concentration in the atmosphere).
The first assessment of the wide range of proposed marine geoengineering activities was published in 2019 and catalogues 27 approaches in total (including variations of approaches).Footnote 26 The report highlights the ‘wide range of knowledge gaps which currently exist, ranging from testing of underlying principles, side effects, to practical challenges and uncertainties for upscaling’, concluding that for none of the approaches identified was there adequate information to permit robust scientific assessment, much less for comparison with other approaches to climate intervention. Nor has there been extensive research on the potential interactions between the various marine geoengineering techniques.Footnote 27
While the picture is not a static one, so far dedicated field studies have been conducted for only one marine geoengineering technique: ocean fertilisation.Footnote 28 Regulation of marine geoengineering was kick-started by a proposed commercial ocean fertilisation project by Planktos Inc. off the Galapagos Islands, which prompted expressions of concernFootnote 29 and ultimately legislative response by the London Convention and Protocol, discussed further in Section 2.2. While ocean fertilisation may have the potential to reduce the amount of CO2 in the atmosphere, thereby contributing to the mitigation of climate change, it may also have significant adverse effects on the marine environment since many of the proposed techniques involve the deposit of substances in the ocean.Footnote 30 Scale is also problematic, with difficulty in drawing a firm line between research (especially large-scale field trials) and deployment, as is the potential for dual use (commercial/research), as highlighted by the Planktos example.
Nonetheless, recourse to geoengineering may be necessary in order to meet the temperature goal set forth in the Paris Agreement (PA) in 2015.Footnote 31 As early as 2007, the Intergovernmental Panel on Climate Change (IPCC) identified potential mitigation measures including ‘geoengineering options, such as ocean fertilisation to remove CO2 directly from the atmosphere’ whilst also noting that such methods remain ‘largely speculative and unproven, and with the risk of unknown side-effects’.Footnote 32 The need for caution is underscored in some of the written statements submitted to ITLOS in the context of its recent Advisory Opinion on Climate Change and International Law (CCAO), which refer brieflyFootnote 33 to geoengineering and emphasise the need for a precautionary approach in using emerging technologies.Footnote 34 These reflect the widespread agreement which exists on the need to apply a precautionary approach in addressing emerging marine geoengineering technologies in ocean governance and decision-making,Footnote 35 with precaution a key principle under the London Convention and ProtocolFootnote 36 and reflected in UNCLOS.Footnote 37 It is to these instruments that this article now turns.
2.2. Marine geoengineering under the London Convention and Protocol
The London Convention and ProtocolFootnote 38 establish a global regime prohibiting dumping and the placement of matter that is contrary to the aims of the treaties. While the Convention adopts a ‘permitted unless prohibited’ approach, the Protocol adopts a more stringent ‘prohibited unless permitted’ reverse listing approach with only those (few) substances listed in Annex 1 permitted to be dumped or placed at sea.Footnote 39 For the purposes of marine geoengineering, it is the ‘placement of matter’ which is most pertinent, with its application in practice determined on a case-by-case basis.Footnote 40 This flexibility has allowed the London Convention and Protocol regime to be extended to address emerging issues concerning potential threats to the marine environment,Footnote 41 including marine geoengineering.
In response to the Planktos incident noted in Section 2.1, in 2008 the London Convention and Protocol parties confirmed in a Resolution adopted by consensus that ‘the scope of the London Convention and Protocol includes ocean fertilization activities’.Footnote 42 As with any other proposed dumping or placement activity, ocean fertilisation requires licensing by the designated national authority before it may proceed. In particular, the aim is to permit ‘legitimate scientific research’ to be carried out, following prior assessment, and to foreclose any other ocean fertilisation activities, for example with commercial application or deployment.Footnote 43
This was followed two years later by the adoption of an Assessment Framework for Scientific Research involving Ocean Fertilization (OFAF), requiring prior risk assessment and monitoring of activities by the competent authorities.Footnote 44 It was developed by the Scientific Groups under the London Convention and Protocol, providing States with the parameters for assessing whether a proposed ocean fertilisation activity is ‘legitimate scientific research’ consistent with the aims of the Convention. It includes a requirement for environmental assessment, including risk management and monitoring, and the OFAF applies regardless of the size or scale of the project (but differentiation is made as to the extent of the information required). The assessment framework is not static and indeed is currently under review to determine whether and what technical changes might be required in the light of changing scientific knowledge.Footnote 45
In 2013, marine geoengineering was placed on a treaty footing with the adoption of an amendment to the ProtocolFootnote 46 to regulate the placement of matter for ocean fertilisation and to provide a mechanism for the addition of other defined marine geoengineering activities to be listed in a new Annex 4. The amendments allow for legitimate scientific research to be carried out only for those geoengineering techniques listed there (‘reverse listing’), subject to a permit.Footnote 47 Although currently Annex 4 lists only ocean fertilisation, other marine geoengineering techniques can be added, future-proofing this mechanism in relation to subsequent scientific and technological developments.Footnote 48 A binding General Assessment Framework is included to inform decision-making on the permit, building on the OFAF, and under which additional bespoke assessment frameworks may be developed.Footnote 49 The possibility of adding tailor-made assessments, as has been done for ocean fertilisation, reflects a ‘no one size fits all’ approach to geoengineering governance.Footnote 50
Such updating is under active consideration notwithstanding that the 2013 amendment has not yet entered into force.Footnote 51 Four further techniques have been identified for priority evaluation and possible inclusion in Annex 4:Footnote 52 the carbon dioxide removal techniques of enhancing ocean alkalinity and the cultivation of macroalgae and other biomass for sequestration; and the solar radiation management techniques of microbubbles/reflective particles/material and marine cloud brightening. Strikingly, this list includes activities that do not involve the placement of matter into the sea, but which use the oceans as a location from which to undertake geoengineering activities. While the first three of these techniques are considered to meet the definition of marine geoengineering under the Protocol and thus could be considered by the States Parties for inclusion in Annex 4,Footnote 53 there is no agreement on whether SRM techniques like marine cloud brightening fall within the remit of the London Convention and Protocol, with further work ongoing.Footnote 54
This highlights an issue at the core of the London regime, which is that the ‘amendment [is] to an existing environmental protection treaty and its capacity to provide a comprehensive governance framework for marine geoengineering activities will therefore be limited by the aims, scope and membership of the [Protocol] itself’.Footnote 55 Furthermore important procedural issues have been raised, such as the feasibility of making ‘an amendment to an amendment’Footnote 56 or whether the more appropriate course is the adoption of a (non-binding) resolution.Footnote 57 In either case, this would signal that the London Convention and Protocol will continue to regulate marine geoengineering activities that involve the dumping or placement of matter in the oceans that poses a threat to the marine environment and provide an assessment framework to guide States in their implementation of their London Convention and Protocol obligations.
However, ratification of the Protocol itself has been slow, and the rate of uptake of the amendment very sluggish.Footnote 58 Subsequent meetings of the Parties have repeatedly encouraged ratification of the 2013 amendment not least ‘to enable the Contracting Parties to confront the challenges posed by global climate change, whilst regulating these activities on a precautionary basis to ensure protection of the marine environment and human health’.Footnote 59 Pending the entry into force of the amendments to the Protocol, OFAF ‘should continue to determine, with utmost caution, whether a proposed ocean fertilisation activity constitutes legitimate scientific research that is not contrary to the aims of the Protocol’.Footnote 60 While not legally binding, the OFAF Resolution provides a framework to guide States’ exercise of jurisdiction and control over marine geoengineering activities in fulfilment of the obligation to prevent, reduce and control pollution of the marine environment and adds content to the procedural requirement to conduct a prior environmental impact assessment and to pay due regard to other States’ rights and interests within and beyond national jurisdiction. Furthermore, it provides a reference point for assessing the necessary measures to prevent, reduce and control pollution of the marine environment required under Article 194(1) UNCLOS.
2.3. Marine geoengineering under UNCLOS
The detailed rules emerging under the London regime build on UNCLOS,Footnote 61 which establishes the general regulatory framework for activities at sea, including for marine geoengineering activities taking place in, or launched from, coastal States’ maritime zones, on the high seas and in the Area (i.e. the seabed, ocean floor and subsoil that lies beyond the limits of national jurisdiction). The applicability of its general provisions, and which State is entitled to exercise jurisdiction, will turn on where the activity takes place (location) and how it is characterised (function), for example as marine scientific research (MSR) or as pollution of the marine environment.Footnote 62
2.3.1. Marine scientific research
UNCLOS does not provide a definition of MSR, the substantive provisions of Part XIII being considered sufficiently clear to establish the intended meaning.Footnote 63 The ordinary meaning encompasses ‘any form of scientific investigation, fundamental or applied, concerned with the marine environment, i.e. that has the marine environment as its object’.Footnote 64 Much depends on the framing of the proposed research; for example, the ultimate objective of marine geoengineering research for CDR is to develop approaches to effect large-scale removal of carbon dioxide from the atmosphere, the prospects for which requires understanding the marine environment and its response to the application of particular marine geoengineering techniques.Footnote 65 And any activity constituting ‘legitimate scientific research’ under the London Convention and Protocol would undoubtedly also be considered MSR under UNCLOS.Footnote 66
In regulating MSR, Part XIII reflects the zonal approach of UNCLOS, with the rights of coastal States generally diminishing seawards from the robustness of the provisions on the territorial sea, where unauthorised MSR constitutes non-innocent passageFootnote 67 to the exclusive economic zone (EEZ), where the coastal State has exclusive jurisdiction to regulate, authorise and conduct MSR,Footnote 68 to the freedom of MSR on the high seas.Footnote 69 Any geoengineering activities carried out or authorised by the coastal State within these zones must have due regard to the rights and freedoms of other States, including navigation, and must also be consistent with their obligations under UNCLOS in relation to marine scientific research.Footnote 70 General principles for the conduct of MSR include requirements of openness, transparency and collaboration in research and the expectation that consent for MSR ‘in order to increase scientific knowledge of the marine environment for the benefit of all mankind’ will not normally be refused by the coastal State (Article 246(3)). There are certain exceptions, including for present purposes refusal of consent by the coastal State for projects involving ‘the introduction of harmful substances into the marine environment’ (Article 246(5)(b)).
However, there are limits to the application of these MSR provisions of UNCLOS—but not of UNCLOS generally—to marine geoengineering research, relating to the object and purpose of the activity. With respect to the object of the activity, the UNCLOS MSR regime excludes research conducted at sea that does not have as its object the marine environment. SRM marine geoengineering activities such as marine cloud brightening are one example where the activity in question, though ‘launched’ from, for example, a ship or installation at sea, has the atmosphere as its object, not the oceans per se.Footnote 71 As has been seen in Section 2.2, this issue has also arisen regarding the application of the London Convention and Protocol amendment to this activity.
The recent ILC Draft Guidelines on the Protection of the Atmosphere address activities aimed at ‘intentional large-scale modification of the atmosphere’ providing that these ‘should only be conducted with prudence and caution, and subject to any applicable rules of international law, including those relating to environmental impact assessment’.Footnote 72 The commentary explicitly refers to geoengineering, acknowledging that with respect to ocean-based activities ‘to the extent that “ocean iron fertilization” and “ocean alkalinity enhancement” relate to questions of ocean dumping, the [London Convention and Protocol] are relevant’.Footnote 73
This presents an ‘ocean/sky’ dichotomy which may be difficult to maintain if, for example, the effects ultimately impact on the marine environment. And to the extent that the marine geoengineering research activity directed to the atmosphere requires ‘launch’ from a vessel at sea and/or associated installations and structures, or pipelines placed there, the general provisions of UNCLOS will clearly apply within coastal State jurisdiction and regarding the exercise of jurisdiction by flag States over their vessels within and beyond national maritime zones. In the case of the latter, marine geoengineering would constitute a high seas freedom subject to the due regard requirementFootnote 74 with respect to other high seas users and activities in the Area (Article 87(2)) as well as the general requirements of UNCLOS with respect to protection of the marine environment.
Another limitation on the application of UNCLOS’ MSR provisions is that some activities may have a dual purpose, ostensibly MSR but with intended commercial application. The approach of the London Convention and Protocol thus far in adopting a precautionary approach has been to prohibit all but (defined) ‘legitimate scientific research’, excluding from its scope any research with commercial applications. While the MSR provisions of UNCLOS are not so restrictive, they likewise suggest that commercial activities would not constitute MSR. However, the general provisions of UNCLOS would apply, with the result dependent, inter alia, on location.
2.3.2. General obligation to protect and preserve the marine environment
The general environmental obligations in UNCLOS apply to marine geoengineering activities, from the general obligation to protect and preserve the marine environment, which is a cross-cutting obligation applicable to all activities at sea and which imposes both positive and negative obligations,Footnote 75 and the obligation to ensure activities under their jurisdiction or control do not cause damage by pollution to other States or to areas beyond national jurisdiction,Footnote 76 to the duties to notifyFootnote 77 and cooperateFootnote 78 and the requirement to conduct an environmental impact assessment.Footnote 79
In its CCAO, ITLOS concluded that ‘anthropogenic [greenhouse gas] emissions into the atmosphere constitute pollution of the marine environment within the meaning of … the Convention’.Footnote 80 CDR marine geoengineering activities may be characterised as climate change mitigation measures, combatting this form of pollution, whilst at the same time themselves posing a pollution risk to the marine environment.Footnote 81 This point was addressed directly by ITLOS where it touched only lightlyFootnote 82 upon marine geoengineering in confirming the application of Articles 195 and 196 UNCLOS:
Article 195 of the Convention requires States, in taking measures to prevent, reduce and control pollution of the marine environment, not to transfer, directly or indirectly, damage or hazards from one area to another or transform one type of pollution into another. In this context, some participants raised the issue of marine geoengineering. Marine geoengineering would be contrary to article 195 if it has the consequence of transforming one type of pollution into another. It may further be subject to article 196 of the Convention which requires States, inter alia, to take all measures necessary to prevent, reduce and control marine pollution resulting from the use of technologies under their jurisdiction or control. The Tribunal is aware that marine geoengineering has been the subject of discussions and regulations in various fora, including the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matters 1972 and its 1996 Protocol, and the CBD.Footnote 83
3. The relationship between UNCLOS and the London Convention and Protocol
As is frequently observed, the longevity—if not immortalityFootnote 84—of UNCLOS may be attributed to a number of factors, including its character as a ‘living instrument’Footnote 85 intended to be capable of further evolution through a variety of mechanisms such as renvoi to generally accepted international rules and standards.Footnote 86 Part XII UNCLOS reflects its framework character and the existence of other relevant global and regional rules and standards in three ways: first, Article 197 requires cooperation on a global and regional basis in formulating rules and standards for the protection of the marine environment; second, internationally agreed rules and standards are used as a benchmark under UNCLOS, which for pollution from dumping requires national laws, regulations and measures to be ‘no less effective’ in preventing, reducing and controlling pollution by dumping than global rules and standards (Article 210(6)); and, third, Article 237 addresses the relationship between the framework provisions of Part XII UNCLOS and special conventions and agreements relating to protection of the marine environment—existing (‘without prejudice’) and future agreements (obligation of consistency)—concluded in furtherance of the general principles of UNCLOS.Footnote 87
As ITLOS stated in its CCAO, ‘[t]he rules of reference contained in Part XII of the Convention and article 237 of the Convention demonstrate the openness of Part XII to other treaty regimes’.Footnote 88 And this is not only one-way traffic: just as UNCLOS depends to a large extent on external rules and standards for benchmarking of generally accepted international rules and standards (GAIRS),Footnote 89 as this article has observed, in the specialised dumping regime, external agreements rely on UNCLOS (and customary international law) for the provision of general rules on the exercise of legislative and enforcement jurisdiction.Footnote 90 This complementarity was explicitly acknowledged in the United Nations (UN) written statement submitted during the CCAO proceedings where it observed that ‘States have addressed ocean fertilization and carbon capture and sequestration under the [London Convention and Protocol] … which complement the relevant provisions under [UNCLOS] … on pollution by dumping’.Footnote 91
By becoming parties to UNCLOS, States have agreed to be bound indirectly by global rules and standards embodied in instruments to which they are not necessarily party and which change over time.Footnote 92 This is the import of Article 210(4) on pollution from dumping which explicitly notes that ‘[s]uch rules, standards and recommended practices and procedures shall be re-examined from time to time as necessary’. While it appears well-settled that the London Convention constitutes the relevant ‘global rules’ for the purposes of Article 210, the position of the Protocol is less clear. Wacht, for example, in his commentary to Article 210, notes that the global rules and standards referred to in its paragraph 6 ‘are primarily laid down in [the London Convention and Protocol]. Thus, these instruments set the international standard States have to respect when adopting national laws, regulations and measures pursuant to their obligation contained in Art. 210 (1) and (2)’.Footnote 93 Others argue that the slow rate of acceptances of the Protocol casts doubt on whether it may be considered a global rule for the purposes of Article 210 ‘until the vast majority of the Parties to the 1972 Convention have themselves accepted the newer instrument’.Footnote 94
On either view, the amendments cannot (yet) constitute such a global rule. Nonetheless, the OFAF, exhorted to be adhered to by States Parties pending the entry into force of the amendments,Footnote 95 and which was adopted by consensus, represents a de minimis threshold for the application of the due regard balancing required in the zonal provisions of UNCLOS and in the implementation of its monitoring and prior environmental assessment obligations, and fleshes out the precautionary approach required that is reflected both in the London Convention and Protocol and in UNCLOS in its application to new technologies.Footnote 96 It also constitutes ‘another reference point for assessing necessary measures’ required to be taken by States Parties under Article 194(1) to prevent, reduce and control pollution of the marine environment from any source.Footnote 97
4. Conclusion
In many respects, responses to technological developments are hard-wired into the DNA of the law of the sea in general, and into UNCLOS in particular, which ‘remains the keystone for global ocean governance’.Footnote 98 As Campbell McLachlan observes, ‘the impulse to find solutions that can be said to integrate subsequent developments with UNCLOS, rather than to derogate from it, is very strong’.Footnote 99 Even where activities are not contemplated under UNCLOSFootnote 100—and marine geoengineering activities are certainly one example—its general provisions are adaptable and applicable. As the UN Secretary-General observed in a 2023 report on the law of the sea and new maritime technologies:
As to the legal framework, and as recognized by the General Assembly, the Convention sets out the legal framework within which all activities in the oceans and seas must be carried out and, as such, continues to serve as the foundation for the governance and management of new maritime technologies. As a framework instrument, the Convention appears to be of sufficient breadth and flexibility to apply to new and emerging technologies, and this has proven true even through a period of significant technological advancement.Footnote 101
While such innovations influence the use of the oceans, the challenges they pose continue to be met within the resilient normative framework established by UNCLOS, supplemented by additional rules or guidelines building on this framework, as is the case with the London Convention and Protocol for marine geoengineering activities. Indeed, it is not an overstatement that marine geoengineering provides a ‘textbook example’ of how the law of the sea continues to adapt and evolve.Footnote 102