The ocean covers 71% of the surface of the Earth, of which, marine areas beyond national jurisdiction (ABNJ) represent 54% of the seabed (the Area) and 64% of the ocean’s surface and nearly 95% of the ocean’s volume (the High Seas). The ocean therefore represents the largest biome on Earth. Yet marine organisms represent only 2% of the total number of known animal species (Briggs, 1994), albeit showing a higher degree of biodiversity compared to terrestrial ones. Although some authors relate this occurrence to a lower magnitude of environmental variability than on land, the lack of knowledge especially in the relatively undiscovered deep sea (Mayer et al., 2018) prevents a full comparative assessment in terms of biodiversity richness and status. Despite the scarce ocean knowledge, signs of stress and rapid decline in global marine biodiversity have soon become visible at all scales (Sala and Knowlton, 2006) including species extinctions (Dulvy et al., 2003), population depletions, and habitat homogenization due to overfishing, climate change, alien species introduction and pollution (McCauley et al., 2015).

In this regard, in the 2021 report of the Second World Ocean Assessment, a pool of 300 world scientists has voiced the incumbent risks of biodiversity loss (United Nations, 2021), especially in areas beyond national jurisdiction (ABNJ, i.e. the High Seas and the seabed and subsoil beyond the limits of national jurisdiction ¹ ). Similarly, in its 2020 State of World Fisheries and Aquaculture, the United Nations Food and Agriculture Organization reported a worrying trend towards the overexploitation of fish resources, with a consistent increase in stocks taken at biologically unsustainable levels, including in ABNJ (Food and Agriculture Organization, 2020).

The ocean is considered a new economic frontier (blue economy) as land-based resources have become fully exploited or exhausted, including food, minerals for the energy transition, novel bioactive compounds (Jouffray et al., 2020). Deep-sea marine ecosystems are facing unprecedented pressures from human activities that sum up with stresses from warming, heat waves, ocean acidification, that affect the ocean as climate regulator (Levin et al., 2015). Therefore, the numerous, intensive and cumulative anthropogenic impacts of fishing, shipping, even certain forms of marine scientific research (MSR), and the imminent deep seabed mining prefigure a critical scenario in terms of the ability of the ocean not only to sustain this pressure (Ardito and Rovere, 2022) but to continue providing those ecosystem services necessary for life on Earth (Mejjad and Rovere, 2021).

The international community has adopted so far several international legal instruments of a sectoral or regional character that can contribute to mitigate and possibly halt environmental degradation and biodiversity loss in the deep ocean. However, the legal framework for the sustainable use, protection, and conservation of marine biodiversity in ABNJ still remains highly fragmented and inadequate, representing one of the most debated issues of today’s international law of the sea (Rothwell et al., 2017).

This article aims at identifying legal gaps and at offering a contribution to the discussion on the best approaches to respond to the urgency of seabed impacts and biodiversity loss in ABNJ, also in the light of ongoing intergovernmental negotiations on the conclusion of an agreement implementing the United Nations Convention on the Law of the Sea on the conservation and sustainable use of biological diversity in ABNJ (BBNJ agreement) ² .

To this end, this paper adopts a multidisciplinary approach that combines scientific evidence and legal analysis in the field of protection and conservation of marine ABNJ.

The main and most important agreement in the field of the protection and preservation of the marine environment is the 1982 United Nations Convention on the Law of the Sea (UNCLOS) ³ . As a living instrument, the UNCLOS shall be read in the light of the evolution of customary international law on the protection of the environment and taking into account the conclusion of further sectoral and regional treaties in the field. Soft law instruments, programmatic global environmental agendas, as well as the pertinent international and national jurisprudence are also relevant for the evolutionary interpretation of the UNCLOS.

In a bid to allocate sovereignty and jurisdictional rights, the UNCLOS divides marine spaces on a horizontal and vertical axes. From the former point of view, it distinguishes areas within national jurisdiction, that include the territorial sea, the contiguous zone, the exclusive economic zone, and the continental shelf; and ABNJ, made up of the High Seas and the seabed and ocean floors beyond national jurisdiction the UNCLOS refers to as the Area ⁴ (Andreone, 2015).

On a vertical axis, the UNCLOS differentiates, both within and beyond national jurisdiction, the legal regimes that apply to the seabed and to the suprajacent water column (Tanaka, 2019).

As far as the legal regime applicable to the Area and its mineral resources is concerned, under article 136 of the UNCLOS, they are declared the common heritage of mankind (CHMK) ⁵ (Kiss, 1982). This legal principle, as implemented by Part XI of the UNCLOS, has the following legal and operational implications: a) the prohibition of any claim or exercise of sovereignty over the Area and its resources (article 137); b) all activities of exploration for and exploitation of mineral resources are to be carried out for the benefit of mankind and the revenues arising from them ought to be shared among the international community (article 140); c) the Area shall only be used for peaceful purposes (article 141); d) the Area and its resources shall be preserved in the interest of the present and future generations, consistently with the provisions of article 145 of the UNCLOS; and (e) activities in the Area shall take place through the management of an ad hoc international mechanism, that is the International Seabed Authority (ISA or Authority) (article 156) (Brown, 1983; Wolfrum, 1983; Joyner, 1986; Pinto, 2012).

As of today, the ISA, the organization through which States Parties manage and control activities in the Area, has concluded 31 contracts for exploration of mineral resources with 22 different operators (International Seabed Authority, 2022).

The mandate of the ISA is not limited to the issuing of exploration and exploitation licenses, as the Authority also enjoys, according to article 145 of the UNCLOS, normative powers in the field of the protection of the marine environment from harmful effects which may arise from the activities in the Area (Urdiales, 2019). Moreover, according to article 143, it is required to promote and encourage MSR and increase the ocean environment knowledge. In particular, while the Authority may also carry out MSR independently, it shall cooperate with State Parties with a view to develop research programmes for the benefit of less technologically developed States and to disseminate the results of the research ⁶ .

Indeed, according to article 256 of the UNCLOS, all States and international organizations have the right to conduct MSR in the Area, in conformity with Part XI of the UNCLOS ⁷ . While open to all States, the conduct of MSR shall abide by some fundamental principles laid down in article 240: it shall pursue peaceful purposes, be realized through appropriate means, not interfere with other legitimate uses of the sea, and respect any regulation aimed at the protection and preservation of the marine environment ⁸ . Finally, in line with the constitutive elements of the CHMK, article 143 also establishes that MSR shall be carried out for the benefit of mankind as a whole ⁹ .

With respect to the water column, the principle of the freedom of the high seas, referred to in Part VII of the UNCLOS, applies beyond national jurisdiction ¹⁰ . According to article 87 of the UNCLOS, it comprises, inter alia, freedom of navigation, fishing and of MSR. While every State has the right to exercise such freedoms, they shall take into account the interests of other States and of the international community as a whole ¹¹ , including the protection of the marine environment.

The inclusion in the UNCLOS of Part XII entirely dedicated to the protection and preservation of the marine environment, which is unprecedented in the codification of the international law of the sea (Van Dyke, 2004), can be considered as a limitation to full enjoyment of the freedom of the high seas. However, the anthropogenic approach remains central to the UNCLOS (Wolfrum and Matz, 2000), whose main objective is, in fact, to ensure the orderly and pacific exploitation and use of the sea and its resources. For this reason, both Part XI and Part VII contain only limited and general provisions with respect to the protection of the marine environment and its resources (Sands and Peel, 2018). Even the subsequent adoption of two implementation agreements - in 1994 on Part XI of the UNCLOS ¹² and in 1995 on the provisions of the UNCLOS relating to the conservation and management of straddling fish stocks and highly migratory fish stocks (Fish Stock Agreement) ¹³ - have revealed weak and inadequate to avoid biodiversity loss in ABNJ and still remain exploitation-oriented (Tladi, 2011).

A crucial development towards a protection approach is the United Nations General Assembly (UNGA) resolution 59/25 on sustainable fisheries ¹⁴ . Indeed, for the first time States and Regional Fisheries Management Organizations (RFMOs), created pursuant to article 8 of the Fish Stock Agreement, are required to consider the adoption of decisions on the prohibition of certain fishing practices (Hiddink et al., 2017), including bottom trawling, with a significant impact on vulnerable marine ecosystems (VMEs), like hydrothermal vents and seamounts ¹⁵ . The recommendation was reiterated in 2006, with resolution 61/105, by which the UNGA called upon States to take action immediately to protect VMEs from destructive fishing practices, ‘recognizing the immense importance and value of deep sea ecosystems and the biodiversity they contain’ ¹⁶ .

The mentioned resolutions have the merit to highlight the linkage between fisheries and biodiversity through reducing the pressure on the most vulnerable marine areas, although they do not achieve the broader goal of the conservation of the integrity of VMEs from all anthropogenic threats. This is a vulnus that, as this contribution will be showing, is at risk of hampering their effective protection.

A major gap stemming from the UNCLOS is the lack of strict rules in the field of environmental protection of the Area and its biodiversity (Wolfrum, 2020). Indeed, as previously mentioned, according to article 145, only mining activities in the Area are subject to an environmental monitoring by the ISA. No other human endeavor in the Area undergoes any global environmental obligation, except for the very general provision of article 192 of the UNCLOS, according to which States have to protect and preserve the marine environment. In other terms, article 145 - and any measure the ISA adopts pursuant to this provision with a view to protect the Area - is only oriented to contrast the impacts of deep-sea mining in the areas where it is carried out, rather than to protect and preserve the Area lato sensu ¹⁷ .

This is attributable to the wrong belief - which was widespread at the time when the UNCLOS was negotiated - that the Area resembled a dark desert, characterized by low temperatures and high pressures incompatible with plant and animal life (Glowka, 1996; Mgbeoji, 2004).

Another major gap relates to the disregarded ecosystem interaction between the water column and the seabed and subsoil and to the vertical division of the whole marine environment into distinct legal maritime zones.

The sea, unlike the air, contains the nutrients necessary for the growth of microscopic plants in the water column that, further to providing half the oxygen produced by plants on Earth (Field et al., 1998), sustain the entire marine food chain, including benthic communities attached to the seabed in close relationship with the subsoil. Although most of the ocean is aphotic, benthic communities thrive in the dark deep sea relying on food webs from the water column except for chemosynthetic communities that rely on symbiotic bacteria that provide them with energy in habitats dominated by toxic compounds such as hydrocarbons and hydrogen sulfide (e.g. Bernardino et al., 2012).

This interdependence was only in part acknowledged in the preamble of the UNCLOS, which states that ‘the problems of ocean space are closely interrelated and need to be considered as a whole’ ¹⁸ . Some authors consider this recital a reference to the ecosystem and integrated approaches to which ocean governance should be committed (Wolfrum, 2020). However, either because of the limited knowledge of the marine environment at the time when the UNCLOS was negotiated, and as a result of the division of marine areas based on a zonal approach, the UNCLOS has been unable to provide a solid basis for the coordination among the many international instruments selectively governing the protection of ABNJ with a view to ensure that ecological units are adequately safeguarded (Tanaka, 2019).

In the light of these normative gaps and of the environmental concerns voiced by the society, the international community questioned the capacity of the existing legal and institutional frameworks to adequately protect ABNJ and to conserve their biodiversity. This marked the beginning of long debates in various international fora, and particularly at the United Nations (Papastavridis, 2020).

A turning point towards a more effective protection of such ecosystems was the decision of the UN General Assembly to convene an intergovernmental conference to conclude a third agreement implementing the UNCLOS, on the conservation and sustainable use of marine biological diversity of ABNJ (BBNJ agreement) ¹⁹ . The negotiations, which entered a substantive phase in 2018, focus on a package deal, identified in 2011 and to be addressed together and as a whole, consisting of marine genetic resources (MGR), including questions on the sharing of benefits, measures such as area-based management tools (ABMTs), including marine protected areas (MPAs), and environmental impact assessments, capacity-building and the transfer of marine technology (Berry, 2021).

Pending the conclusion of the BBNJ agreement, this section aims to analyze the existing legal framework allowing for the creation of ABMTs, including MPAs in ABNJ.

Among the several approaches adopted in the last decades to implement the obligations relating to the protection of the marine environment, the creation of ABMTs was considered the most useful way to tackle the need to sustainably use biological resources and to effectively protect the marine environment on a spatial basis (Vierros et al., 2016), in compliance with the relevant international environmental law and policy principles, including the precautionary and ecosystem approaches.

While no agreed definition of ABMTs exists yet, they can be described as measures designed for a geographically defined area, through which one or several sectors or activities are managed to achieve a wide variety of objectives, from the protection of specific ecological and geomorphological processes to the preservation of endangered species, to the conservation of cultural, ecological and historical sites of a recreational nature ²⁰ .

In line with the set management objectives, the level of protection afforded by these tools may vary considerably. Being a composite category (United Nations, 2021), ABMTs do not necessarily entail the prohibition of certain human activities, but more often promote their rational and sustainable conduct (Frank, 2020). Indeed, the flexibility of ABMTs makes it possible to achieve a certain management and conservation goal without excessively burdening those who engage in activities that can be carried out in an environmentally sustainable way (Scovazzi, 2014). They can range from seasonal closures of marine areas to certain activities, to the creation of multipurpose MPAs, selected through scientific criteria and sometimes parts of a network ( Table 1 ).

Despite no provision of the UNCLOS explicitly refers to ABMTs and MPAs, the power to create them, and hence their legal basis, can be found in some of its obligations. First of all, article 192 concisely establishes a general obligation for all States to protect and preserve the marine environment with no limits of application ratione loci, meaning that this obligation applies to all marine areas identified under the UNCLOS. Then, Article 194 (5) further requires States to take those measures necessary to protect and preserve rare or fragile ecosystems as well as the habitat of depleted, threatened, or endangered species and other forms of marine life.

Furthermore, article 197 of the UNCLOS sets further key obligations for the establishment of such areas in ABNJ: the obligation to cooperate both at a procedural and a substantive level to act in good faith to this end and, at least, to participate in those fora aimed at the protection of the marine environment ²¹ .

As far as sustainable fisheries and marine living conservation are concerned, in 2006, with resolution 61/105 the UN plenary body requested the RFMOs not only to identify conservation areas, but also to ‘immediately’ take appropriate protective measures, including the closure of vulnerable sectors to bottom fishing activities ²² to combat biodiversity loss from bottom trawling (Hiddink et al., 2017).

Since then, many RFMOs have adopted measures limiting bottom fishing (Caddell, 2020), especially when carried out with bottom trawls (Caddell, 2016) ²³ .

Several AMBTs have been established by RFMOs since the first closure established by the Northeast Atlantic Fisheries Commission (NEAFC) in 2002 in the Rockall Area, between the United Kingdom and Iceland, where bottom fishing was prohibited in the Reykjanes ridge to protect its flora and fauna (Drankier, 2012) ( Figure 1A ; Table 1 ).

Even in the framework of the activities in the Area ²⁴ , the ISA considered the possibility of developing ABMTs to protect the most fragile ecosystems of the ocean regions targeted for mineral exploration and exploitation. Indeed, pursuant to article 145 of the UNCLOS, in 2012 the ISA adopted the first, and so far only, regional environmental management plan (REMP) for the Clarion-Clipperton Fracture Zone ²⁵ , the mining province where most of the exploration licenses have been issued and where the first exploitation of polymetallic nodules could take place ²⁶ (Christiansen et al., 2022).

The REMP identified nine initial marine areas of particular environmental interest (APEIs) where the exploration and exploitation of mineral resources are prohibited for five years with the objective of protecting biodiversity and ecosystem structures and functions associated with mining areas ²⁷ . The creation of four additional APEIs in the Clarion-Clipperton area was also decided in December 2021 ²⁸ .

As interest in exploration and exploitation of mineral resources has rapidly expanded in other mining areas, the ISA is also convening workshops and collecting data to compile other REMPs and identify APEIs in the Mid-Atlantic Ridge, in the Indian Ocean, as well as in the North-west Pacific and South Atlantic. ²⁹

Along with ABMTs, there is no single definition of an MPA too, as many of the several treaties allowing for their creation both within and beyond national jurisdiction provide a different one.

Among the international instruments with a global character aimed at the conservation of biodiversity (Ricard, 2019), the Convention on Biological Diversity (CBD) is the sole treaty providing for a process for the designation of possible MPAs in ABNJ, through the decisions of its Conference of the Parties (CoP).

Article 2 of the CBD reflects a widely accepted definition of protected area that could well be adapted to MPAs. It is considered ‘a geographically defined area which is designated or regulated and managed to achieve specific conservation objectives’ ³⁰ . At the core of this definition lies that MPAs enjoy special protection vis-à-vis the surrounding areas, as a result of the more stringent regulation of human activities taking place therein (Molenaar and Oude Elferink, 2002).

In the context of this designation effort, in 2008 its CoP also adopted seven scientific criteria for the identification of ecologically or biologically significant areas (EBSAs) also in the high seas and in the Area, i.e. ocean areas of recognized importance in terms of their ecological and biological characteristics for the ecosystem services they provide to humans ³¹ .

To date, more than 270 areas within and beyond national jurisdiction have been identified as EBSAs (Oral, 2020). However, the growing number of selected EBSAs does not amount to the establishment of as many MPAs in ABNJ (Druel, 2012; Warner, 2017). The States Parties to the CBD have, in fact, stressed that the designation of an EBSA by the CoP is ‘a scientific and technical exercise’ from which no legal obligation, in terms of their establishment and management, arises ³² . In order for EBSAs in ABNJ to become proper tools for the protection of the marine environment, it would be necessary for them to be associated with a binding conservation and management measure, which is the essence of any effective MPA ³³ .

In the CBD framework, MPAs are deemed to be the most effective conservation tool (Heffernan, 2018) to the extent that they offer a degree of long-term in situ conservation of entire ecosystems against multiple stressors in specific areas of the ocean. In particular, there is some scientific agreement that large, long-term, no-take, well enforced networks of MPAs can help protect, recover and maintain fish stocks, ecosystem resilience and habitat structure, thus providing greater ecologic and socio-economic benefits (Edgard, 2014).

The two case studies presented in this paper intend to disclose some of the risks associated, in the long term, with the lack of a clear governance regarding both legal and geomorphological aspects in ABNJ, as described in the previous paragraphs. In particular, the main issues hampering an effective protection of marine ABNJ are: 1) the almost total lack of regulation of human activities in the water column against the specific legal regime for the seabed and the subsoil; 2) the fragmentation of legal regimes applicable to both domains; and, finally, 3) the difficulty of cooperation among the regional, sectoral or even universal legal frameworks involved in the governance of marine ABNJ.

In this context, when addressing the need of protecting the high seas ecosystem as a whole, the analysis of the competences and the powers of the ISA and the relevance of the regional or sectoral organizations or treaties competent in each marine space are crucial.

The issues discussed in the previous paragraphs, and in particular the analysis of the two case studies, allow to draw some conclusive remarks.

As shown in the case studies, many human activities are carried out in areas beyond national jurisdiction and they often overlap each other, resulting in a number of conflicts of use and threats to the marine environment. In this context, several factors hindering the establishment and effectiveness of ABMTs and MPAs that are tools for the protection of the marine environment and its biodiversity have been highlighted. Two of them are particularly relevant. On the one hand, the non-universal application of the treaties that allow for the establishment of ABMTs in the areas under analysis which are only binding upon their parties. On the other hand, the non-cross-sectoral nature of the protection and conservation measures adopted under these treaties.

A concrete example of cooperation trying the overcame the latter issue, despite only on a regional and sectoral basis, relates to the Collective arrangement between the OSPAR Commission and the NEAFC ⁶² . Its main objective is to promote the exchange of information on the activities of each organization and on the adopted conservation and management measures, with the aim of coordinating the ABMTs and promoting the protection of ABNJ of the North-East Atlantic ( Figure 1A ). Initial contacts between OSPAR, NEAFC and the ISA started in 2008 and mainly related to the proposed creation of the Charlie Gibbs MPA in an area beyond national jurisdiction of the North-East Atlantic Ocean ( Figure 1A ). As the only organization having a mandate on the exploration and exploitation activities of the Area and on the protection of the marine environment from their harmful effects, the States Parties to OSPAR advanced to the ISA a proposal for a collective agreement. However, in 2015 some ISA Council members considered it premature to proceed towards a formal coordination with other international organizations and opposed to the conclusion of the agreement. Contrary to the original expectation to involve all the international organizations with a mandate in ABNJ in the region, the Collective agreement was only concluded between OSPAR and NEAFC. Despite this, since their first joint meeting in 2015, the ISA has participated to the work as an observer, highlighting the recognized relevance of a joint action for the protection of marine ecosystems.

The Collective arrangement is just an example to highlight the desirability of promoting cooperation among organizations and conventional regimes on a regular and even permanent basis. In this scenario, a more structured system of cooperation among States and international organizations is crucial as it would allow for the identification of the most appropriate tools for the protection and preservation of a certain geographical area from the cumulative impacts of human activities at sea. A globally accepted system to create universal ABMTs including cross-sectoral MPAs that extends, at the same time, to the high seas and the Area and that relates to the numerous human activities that may take place in the same areas, is highly desirable to counter the existing piecemeal approach. This can be achieved through the ongoing negotiation process for the BBNJ agreement, provided that it will be given sufficient room to allow for coordination between the existing specialized organizations and frameworks and for the creation of new ABMTs and MPAs by its CoP.

Finally, this research has highlighted the relevance of ISA to proactively exercise in the Area powers and functions in the field of protection of the marine environment and coordination among different human activities taking place in ABNJ, including MSR. This is an important element to take into account when considering the role that the ISA could play in the framework of the new BBNJ agreement, with respect to some of its parts, like those concerned with MGR and the creation of cross-sectoral ABMTs.

The dataset generated and analyzed for this study is derived from the integration of several sources and databases including: EEZ: Flanders Marine Institute (2019). Maritime Boundaries Geodatabase: Maritime Boundaries and Exclusive Economic Zones (200NM), version 11. Accessed online on August 2022: https://www.marineregions.org/. https://doi.org/10.14284/386 ECS claimed by States: UNEP Grid-Arendal. Accessed online on August 2022: http://continentalshelf.org/onestopdatashop/6350.aspx. FAO Fishing Areas. Accessed online on August 2022: https://data.apps.fao.org/map/catalog/static/search?any=FAO_AREAS_CWP&fast=index. Underwater features names: the GEBCO Gazetteer of undersea feature names. Accessed online on August 2022: https://www.ngdc.noaa.gov/gazetteer/. Hydrothermal vents: InterRidge Vents Database ver. 3.4. Accessed online on August 2022: https://vents-data.interridge.org/. MPA: UNEP-WCMC and IUCN (2021), Protected Planet: The World Database on Protected Areas (WDPA) and World Database on Other Effective Area-based Conservation Measures (WD-OECM). Accessed online on August 2022:https://www.protectedplanet.net/en/thematic-areas/marine-protected-areas. OSPAR MPA: Marine Protected Areas (OSPAR) Global view. Accessed online on August 2022: https://carto.mpa.ospar.org/fr/1/ospar.map and OSPAR 21/13/1, Annex 23 on the establishment of the North Atlantic Current and Evlanov Sea basin Marine Protected Area. Accessed online on August 2022: https://www.ospar.org/documents?v=46308. EBSA: Convention on Biological Diversity, CHM version 2022.25.0. Accessed online on August 2022: https://chm.cbd.int/database/record?documentID=204107. https://chm.cbd.int/database/record?documentID=200105. https://chm.cbd.int/database/record?documentID=204068. https://chm.cbd.int/database/record?documentID=204106. IODP: drilled holes. Accessed online on August 2022: https://www.iodp.org/resources/maps-and-kml-tools. VME NEAFC: Fishing closures. Recommendation 10:2021 to amend Recommendation 19:2014 on the Protection of Vulnerable Marine Ecosystems in the NEAFC Regulatory Area, as amended. Accessed online on August 2022: https://www.fao.org/faolex/results/details/en/c/LEX-FAOC201787/. VME and Benthic Protected Areas SIOFA/SIODFA: CMM 2020/01 Conservation and Management Measure for the Interim Management of Bottom Fishing in the Agreement Area (Interim Management of Bottom Fishing). Accessed online on August 2022: https://www.apsoi.org/sites/default/files/documents/cmm/CMM%202020_01%20Interim%20Bottom%20Fishing%20Measures_0.pdf. VME NAFO: Fishing closures. Northwest Atlantic Fisheries Organization Conservation and Enforcement Measures 2020. https://www.nafo.int/Data/GIS#. Accessible as online visualization map at: http://www.fao.org/in-action/vulnerable-marine-ecosystems/vme-database/en/vme.html. ISA exploration contract areas: PMN and PMS shapefiles. Accessed online on August 2022: https://www.isa.org.jm/minerals/maps. ISA protection measures (AINP, SINP): Draft REMP for the area of the northern Mid-Atlantic Ridge with a focus on polymetallic sulphide deposits. Accessed online on August 2022: https://isa.org.jm/news/draft-regional-environmental-management-plan-northern-mid-atlantic-ridge-open-consultation.

All the authors equally contributed to writing, reviewing and editing of the manuscript. MR conceived, planned and realized the figures and the table and their captions. GAr conceived and realized the table. All authors contributed to the article and approved the submitted version.