The legal problem: Lacunae in the existing legal framework for maritime boundaries, islands and archipelagos in the face of sea-level rise

5The legal framework for the establishment of maritime boundaries, maritime zone islands and archipelagos is found in the 1982 United Nations Convention on the Law of the Sea (UNCLOS)8 and other rules and principles of international law. The starting point for establishing a coastal State’s maritime zones is the baseline from which the breadth of the territorial sea is measured. There are several provisions in the UNCLOS concerning baselines. The normal baseline is the low water baseline, as codified in Article 5 of UNCLOS. Exceptionally, straight baselines may be used in accordance with Articles 7, 9 and 10. The archipelagic baseline applies for archipelagic States if certain requirements are met under Article 47 of UNCLOS.9

6Significantly, the UNCLOS was negotiated before climate change and the impacts of sea-level rise were on the international agenda. There is consequently no reference in the text of the UNCLOS or the records of its negotiation showing that sea-level rise was taken into consideration. Over time, the reliance on the low-water line was to prove problematic, at least in principle. In particular, Article 5 does not expressly provide for any requirement that the low-water line be periodically reviewed and updated by the coastal State. There is moreover no express requirement for States to update their baselines and large-scale charts officially recognized by the coastal State, and to re-establish their maritime zones because of sea-level rise. This legal lacuna has raised questions as to whether the baseline is ambulatory and therefore imposing upon the coastal State an obligation to modify it as the coastal configuration changes. There is also the question of the potential impact of sea-level rise on archipelagic baselines and archipelagic waters, and the status of those islands which, under Article 121 of UNCLOS, are entitled to the full suite of maritime zones. Would States lose these entitlements?

7In the scenario of an ambulatory baseline, one that changes with different sea levels, and where the coastal State would be under an obligation to re-establish a new baseline, the consequences, including socio-economic and geo-political, could be quite serious. This is therefore not only a legal issue but one that has other repercussions, including environmental. It is also a problem that is directly linked to the current international legal framework which was concluded before climate change and unprecedented levels of sea-level rise emerged. Consequently, existing international law, in particular the UNCLOS, does not directly or expressly provide clear answers to these legal questions. There is a lacuna.

8The 1982 UNCLOS provides a framework for the creation of maritime zones and their respective entitlements, but no indications regarding the consequences of physical changes to the coast resulting from events such as climate change and sea-level rise. Is there an obligation to adjust the baselines and the outer limits of the maritime boundaries or can these be preserved regardless of changes resulting from sea-level rise? The only reference to the permanency of a maritime zone is in relation to the continental shelf, in Articles 76(5) and (8) of UNCLOS.

9The problem is that if baselines and the outer boundaries of maritime zones follow the landward coastal regression because of sea-level rise, this would result in a concurrent landward shift of the rights and obligations of the coastal State and third-party States in the maritime zones drawn from these baselines. For example, part of the internal waters would become territorial sea, part of the territorial sea would become contiguous zone and/or exclusive economic zone (EEZ), and part of the EEZ would become high seas, with implications for the specific rights of the coastal State and third States, and their nationals (innocent passage, freedom of navigation, fishing rights, etc.).

10Additionally, sea-level rise poses a risk to an archipelagic State’s baselines. If the outermost small islands or drying reefs become submerged because of sea-level rise, the existing archipelagic baseline could be impacted. This would result in the loss of the archipelagic State’s baseline if the requirements provided in Article 47(1) and (2) of the UNCLOS can no longer be met. In other words, the archipelagic State could lose those rights that are part of the archipelagic waters, which are similar to those of the territorial sea of a coastal State.

11One of the most economically valuable zones for a coastal State is unquestionably the EEZ over which it exercises sovereign rights, covering an area up to 200 nautical miles from the baselines from which the breadth of the territorial sea is measured. The ocean territory created by EEZs can be several times larger than a State’s land territory. This is especially the case of the Pacific Island region. The total area of Pacific Island region EEZs is approximately 30 million square kilometres. The EEZs in this region are rich in biodiversity and contain a variety of marine resources. Coastal States enjoy the exclusive sovereign rights to explore, exploit, conserve, and manage the living and non-living natural resources of the waters super-jacent to the seabed, and of the seabed and its subsoil.10 They also each have the exclusive competence to determine the total allowable catch of the living resources in their EEZ, in accordance with the conditions specified under UNCLOS.11 Third States have access to the surplus living resources that the coastal State lacks the capacity to harvest.12 Importantly, under Article 56(1)(b)(iii) of UNCLOS, a coastal State has jurisdiction to protect and preserve the marine environment.

12The landward shift of maritime zones could, however, transform part of the EEZ of a coastal State into the open access regime of the high seas, where the freedom of the high seas and the exclusive jurisdiction of the flag State apply. Thus, areas in which the coastal State previously enjoyed exclusive sovereign rights over the natural resources, including areas that are marine protected areas, would become subject to the freedoms of the high seas and open to all States. For example, in 2015 Palau established a marine protected area that covers 80% of its EEZ.13 The landward shift of the maritime zone could alter the legal status of at least part of the protected area, turning it into the high seas where the coastal State no longer has jurisdiction.

13The situation of islands is also unclear. Article 121 of the UNCLOS essentially creates two categories of islands: those fully entitled to all maritime entitlements;14 and rocks that are not entitled to an EEZ or continental shelf, which are implicitly entitled solely to a territorial sea and possibly a contiguous zone.15 The key distinguishing elements are whether the feature can “sustain human habitation or economic life of their own”.16 The Convention does not explain what this means, and few cases have addressed Article 121(3) in detail, with the exception of the South China Sea arbitration award.17 The reclassification of a fully-entitled island to the status of a rock, at the other extreme, led to a decrease from 431,014 km2 of maritime area, to only 1550 km.18

14Moreover, there is no case to date that has addressed the consequences of climate change and sea-level rise on baselines and maritime boundaries, or on the status of islands that become submerged, or yet on archipelagic waters. In the Bay of Bengal Maritime Boundary Arbitration case, Bangladesh had requested the Tribunal to consider the future impacts of sea-level rise on basepoints. However, the Tribunal deemed future events not to be relevant:

The issue is not whether the coastlines of the Parties will be affected by climate change in the years or centuries to come. It is rather whether the choice of base points located on the coastline and reflecting the general direction of the coast is feasible in the present case and at the present time.19

The contribution of international law to addressing the challenge of sea-level rise

15The problem created by sea-level rise for maritime zones and their associated entitlements is a legal problem with very real consequences for States. Attention was drawn to it by the 1989 Malé Declaration where Small States expressed concern over the impacts of global warming and sea-level rise.20 In 1990, the legal issues created by sea-level rise were identified by scholars.21 But it took some decades for the problem to enter the legal discourse. Three events proved significant for international law to address sea-level rise. First, the establishment of the International Law Association (ILA) Committee on International Law and Sea Level Rise in 2012;22 second, the establishment in 2019 of the Study Group on Sea Level Rise in Relation to International Law by the International Law Commission (ILC); and third, the role of the Pacific Island States.23 The cumulative and complementary work of two important legal expert bodies, together with a regional group of impacted States, has produced important results in the development of international law pertaining to sea-level rise and maritime boundaries.

16In 2018, the ILA Committee on International Law and Sea Level Rise undertook an expert study of the consequences of sea-level rise on the partial or total loss of territory and maritime zones (in addition to human rights, nationality and Statehood).24 Although it acknowledged the ILA Baselines Committee’s conclusion that the baseline was ambulatory, the Committee on International Law and Sea Level Rise nevertheless ruled in favour of preserving existing lawfully established maritime baselines and boundaries, in the interest of legal certainty and predictability.25

17In 2018, the Federated States of Micronesia submitted a formal request under Article 17 of the Statute of the ILC for it to place the topic of “Legal implications of sea-level rise” on its long-term work programme agenda,26 which the ILC did in 2018.27 In 2019 the ILC placed the topic on its current work programme agenda and established a study group with five co-chairs, to address three main subjects: the law of the sea; statehood; and protection of persons. However, environmental issues were excluded from the mandate.28 The First Issues Paper (FIP) on issues related to the law of the sea was published on 28 February 2020 and addressed the issues concerning baselines, maritime boundaries, maritime entitlements, and the status of islands and of archipelagos in face of sea-level rise.29

18The initial approach of the FIP was a mapping of the legal issues, gaps, and identification where possible of States’ practices. The FIP, which was prepared by two co-chairs, made several preliminary observations. In particular, it pointed out that at the time of the negotiation of the UNCLOS, sea-level rise and its effects were not included as an issue that needed to be addressed,30 and that the ambulatory approach to baseline did not provide a solution to the problem especially as regards the rights of the coastal State in the various maritime zones. The FIP also highlighted the need to preserve legal stability, security, certainty and predictability.31

19The FIP supported the preservation of baselines and outer limits of the maritime zones measured therefrom, as well as the entitlements of coastal States, taking the position that the Convention did not prohibit expressis verbis such preservation.32 The FIP paper took the view that, as a result of the effects of sea-level rise, there was no obligation for Member States to update their depositing notifications, in accordance with the Convention, as regards the baselines and the outer limits of maritime zones measured from those baselines.33 The FIP also noted that overall, third States stand to benefit from these changes (landward shift), but at the expense of coastal States.34 In addition, such changes in maritime entitlements entail the risk of creating uncertainty, instability and the possibility of disputes. Developing States that derive significant revenue from the natural resources, in particular living resources, in their exclusive economic zones could lose at least part of this. In some cases, even a relatively small loss could have major developmental consequences. Moreover, questions arise as to the status of fisheries’ access agreements for developing States’ surplus fishing capacity, should such agreements cover areas that become part of the high seas.35

20The Study Group of the Commission met in 2021 and after robust discussions on the FIP, concluded that additional research was necessary.36 In 2023 the Additional Paper to the FIP was completed and the Study Group reconvened.37

21Important developments, however, have taken place in the period since 2018 in relation to the evolution of international law on the issue of sea-level rise and maritime boundaries. First, on 6 August 2021, the Pacific Islands Forum (PIF) issued its landmark Declaration on Preserving Maritime Zones in the Face of Climate Change-Related Sea-Level Rise.38 The Declaration stipulates that there is “no affirmative obligation to keep baselines and outer limits of maritime zones under review nor to update charts or lists of geographical coordinates once deposited with the Secretary-General of the United Nations”.39 The 18 PIF Member States declared they would preserve their maritime boundaries once established and duly notified to the United Nations Secretary-General in accordance with the UNCLOS, and that they “intend to maintain these zones without reduction, notwithstanding climate change-related sea-level rise”.40 They further declared their intention not “to review and update the baselines and outer limits of … maritime zones as a consequence of climate change-related sea-level rise”.41 This Declaration was endorsed by the 39 Member States of the Alliance of Small Island States (AOSIS) on 22 September 2021.

22Important developments have also taken place in the Sixth Committee of the United Nations General Assembly as a growing consensus in favour of the approach for the preservation of baselines and maritime boundaries emerges. During the Committee’s 77th Session, some 67 States made statements and many expressed support for the PIF position, including the United States. Despite its support for the ambulatory baseline view, the US stated its new policy to not challenge “baselines and maritime zone limits that are not subsequently updated despite sea-level rise caused by climate change”.42 In addition to the Small Island States, the Additional paper noted that States from other regions are also “in favour of the preservation of baselines and the outer limits of maritime zones …, both explicitly and implicitly – stressing the absence of an obligation set forth by the United Nations Convention on the Law of the Sea to update the baselines – by States from Asia (Indonesia, Japan, Malaysia and Philippines), Latin America (Argentina, Chile, Colombia and Costa Rica), Africa (Algeria, Egypt and Sierra Leone), Europe (Bulgaria, Croatia, Cyprus, France, Germany, Greece, Ireland, Netherlands (Kingdom of the) and Romania) and North America (United States)”.43 What began as a regional initiative, has not become cross-regional.

23For example, France has stated that “[the] provisions of the United Nations Convention on the Law of the Sea grant coastal States room for manoeuvre when it comes to taking the initiative to modify, or maintain declared data regarding baselines and limits of their maritime zones. The Convention leaves it to coastal States to decide whether to make modifications to this data, which means that so long as a coastal State does not decide to make such modifications, the initially declared data remains in force”.44

24A common thread that has emerged has been States’ concern to preserve legal stability, security and predictability, and it is increasingly clear that many of the States link this to stability of maritime boundaries and international relations.45 In addition, there is a trend evidenced in the Sixth Committee statements, for the need to interpret the United Nations Convention on the Law of the Sea in the light of changing circumstances and/or taking into account the interests of States affected by sea-level rise.46

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25In conclusion, international law is an essential part of finding solutions to the very real, and in some cases existential, threats posed by sea-level rise. This paper has examined the particular problem related to sea-level rise and maritime boundaries, and their respective entitlements. Within a relatively short period of time, the initiatives of the PIF, together with the work of expert bodies such as the ILA and the ILC, have provoked reactions from States, converging on a common interpretation of the UNCLOS provisions concerning baselines, maritime boundaries and maritime entitlements. The strong trend towards an interpretation of the UNCLOS that accepts the preservation of lawfully established maritime boundaries is important for many reasons, including ensuring the continuation of the coastal States’ jurisdiction to protect and preserve the marine environment in their EEZ, which otherwise would be the high seas. Moreover, preservation ensures predictability, stability and peaceful relations among States as rights and obligations are not open to challenge. In theory, other legal options that could be considered include amendment of the UNCLOS or adoption of a binding agreement to the Convention. However, these options are problematic and highly unlikely to be accepted by States. Instead, this clear trend for States to adopt a common understanding of the UNCLOS and international law concerning the acceptability of preserving maritime zones and their entitlements in the face of sea-level rise due to climate change is a positive indication of the capacity of international law to respond to challenges such as sea-level rise.

26Still many issues remain, such as the status of islands that become submerged and can no longer support human habitation or an economic life of their own. Nonetheless, work continues on these pressing questions.