Interpreting the Law of the Sea in the Context of Sea-Level Rise: The Ambulatory Thesis and State Practice

1. Introduction

‘The land dominates the sea’¹—but to what extent? This question on the limitations of the principle established by the International Court of Justice (ICJ) resonates in discussions over sea level rise and its implications on territorial sovereignty.² Indeed, while the principle acknowledges the primacy of the coastal state in claiming the adjacent maritime zones, it does not mention what were to happen if, geographically, the sea would one day dominate the land. The relevance of geography in relation to law is central in many aspects of the law of the sea, including the entitlement to maritime zones, the definition of an island and of archipelagic states.

Kate Purcell’s monograph titled ‘Geographical Change and the Law of the Sea’ is a contribution to the discussion on baselines in the face of eroding coastlines and rising seas. The book captures the current impetus to study the interactions between geography and the law. In her monograph, Purcell challenges the ambulatory baseline thesis that explains that maritime baselines and zonal delimitations shift synchronously to reflect changing coastlines and that there is an obligation upon coastal states to adjust the baselines accordingly.³ It is indeed relevant to look at the origins of the ambulatory baseline thesis, given that what the law provides for geographical change is also relevant for climate change.

The impetus to study the interactions between geography and the law is also visible in the work of the International Law Commission (ILC) that was mandated since 2018 to study the potential legal effects of sea level rise on inter alia baselines and the exercise of state sovereignty.⁴ Moreover, the interactions between geography and the law also reverberate beyond the traditional separation of the climate change and law of the sea legal regimes, as Small Islands Developing States (SIDS) have requested advisory opinions to understand the obligations states have under the United Nations Convention on the Law of the Sea (UNCLOS),⁵ and more general international law,⁶ with regards to climate change and the adverse impact it is having on vulnerable states and the (marine) environment. For many countries, including SIDS, the significance of baselines must not be undermined. Indeed, they are not only ‘crucial both to the delineation of the definition of the spatial limits to maritime jurisdictional zones and the delimitation of equidistance-based maritime boundaries’,⁷ as Schofield writes, but baselines are also consequential for state sovereignty.⁸

This review article firstly lays out, in Section 2, the legal framework on the determination of baselines and further maritime delimitation. It explains that Purcell focuses more on provisions that are exemptions to the norm of establishing baselines at the expense of the actual provision on normal baselines. In Section 3, the article evaluates the debates that have surrounded the ambulatory thesis since its phrasing in 1990. Finally, in Section 4, it examines the limitation of Purcell’s analysis by looking at state practice on the update of baselines, and concludes in Section 5.

2. Legal Framework and Structural Ambiguities

This section looks at the current legal framework established by the UNCLOS. Further, it also notes the gaps left open to interpretation through structural ambiguities and that scholars have tried to understand. The section provides the context to understand how Purcell built her argument in contradiction to the ambulatory thesis.

The UNCLOS codifies the entitlement to maritime zones and sets out how the entitlements to jurisdictional rights over the territorial sea, exclusive economic zone and continental shelf are legally—and geographically—based. Claims to maritime zones, in fact, originate from the baseline. The ‘normal’ baseline is drawn at the low-water line along the coast and is officially recognised in the hydrographic charts of the coastal state.⁹ From this baseline are drawn the delimitations of the maritime zones or the outer boundary of each zone. Exceptions in the drawing of the baseline are linked to the geography of the coast. These include the cases of atolls and fringing reefs, where the baseline may then be set at the seaward low-water line.¹⁰ Low-tide elevations, defined as ‘a naturally formed area of land which is surrounded by and above water at low-tide but submerged at high tide’¹¹ may generate entitlement to maritime zones when they are within 12 nautical miles from the coast, meaning they are still located within the territorial sea of the coastal state. Alternatively, another type of baseline—straight baselines—can be draw when special circumstances allow. Straight baselines may be drawn when the coast is deeply indented or when there is a fringe of islands along the coast. The baselines are then drawn by joining points selected along the furthest seaward extent of the low-water line,¹² and they ‘must not depart to any appreciable extent from the general direction of the coast’.¹³ The special geography of archipelagic states is also recognised, as they may draw straight archipelagic baselines by joining the outmost points of the outmost islands and drying reefs.¹⁴

For Purcell, the ambulatory thesis is founded upon the negative reading of Articles 7(2) and 76(9) that provide the stability of outer limits in time.¹⁵ Article 7(2) concerns baselines of deltas and ‘other natural conditions (where) the coastline is highly unstable’ which shall ‘remain effective until changed by the coastal State’. Article 76(9) concerns the outer limits of the continental shelf that are considered as ‘permanent’.¹⁶ In focusing on those two Articles, the author omits to explain the importance of UNCLOS Article 5 when describing the different types of baselines at the start of the book.¹⁷ Thereby, she highlights the exceptions to normal baselines. Consequently, this places a rather disproportionate emphasis on Articles 7(2) and 76(9) to explain the ambulatory thesis.¹⁸ Only when looking at the potential changes to normal baselines in chapter seven does Purcell explain how she interprets Article 5.¹⁹

This stands in contraction to scholars that found the origins of the ambulatory thesis in Article 5 on normal baselines.²⁰ Indeed, Caron read Article 5 in light of Articles 7(2) and 76(9). There, he found that as both Articles offer the possibility to fix straight baselines and the outer limits of the continental shelf, the normal baselines of Article 5 are ambulatory as it was not specified otherwise. This ‘negative implication based on textual interpretation’²¹ points to the fact that although the UNCLOS is silent on sea-level changes, it does provide for the adjustment of baselines. The implications that can be drawn from the ambulatory theory and the questions that they raise will be discussed now.

3. Questions Arising from the Ambulatory Thesis

As explained in the previous section, the legal framework establishing baselines does not provide for future realities that anticipate global mean sea level rise between 0.19 and 0.23 m higher than in the baseline period 1995–2014 by 2050 and could lead to an increase spanning from 0.38 to 0.77 m average depending on the mitigation efforts.²² This increase in sea level would especially impact coastal and low lying countries and communities, as they also face coastal erosion and storm surges.²³ Generally, ‘relative sea level rise is very likely to virtually certain (depending on the region) to continue in the 21^st century, contributing to increased coastal flooding in most low-lying coastal areas (high confidence) and coastal erosion along most sandy coasts (high confidence)’.²⁴ These peer-reviewed conclusions from the Intergovernmental Panel on Climate Change (IPCC) represent the compilation of the latest science on the topic. The UNCLOS is silent on sea-level rise and on the adjustment of baselines with changing sea levels. Hence, legal scholars have tried to understand what the current legal framework would entail for such future sea-level rise realities, with some scholars advancing the ambulatory baselines theory.

In 1990, Caron made the case of the ambulatory thesis,²⁵ explaining that the absence of fixed normal baselines under Article 5 in contrast to the wording of Articles 7(2) and 76(9) negatively implied that baselines are ambulatory and so are the outer boundaries of the maritime zones and the corresponding sovereign rights of coastal states.²⁶ Soons also argued for this interpretation of the law, finding that ‘the coastal State is supposed to make the necessary changes, for example when the discrepancy between the former and the new situation has become quite substantial or when through various causes the instability of the coastline has been substantially reduced’.²⁷ Caron further specifies the legal possibilities open to remediate to ambulatory baselines:²⁸

(…) the international community could retain the current system of using ambulatory baselines to determine the boundaries of maritime zones or it could freeze the boundaries of some or all of the maritime zones on the basis of presently accepted baselines. Implementation of such a freeze could be accomplished in at least three ways: the assertion of a new rule; the liberal interpretation of existing rules such as the allowance for the freeze of baselines off of deltas as provided in article 7(2) of the 1982 Convention; or the assertion of historic rights over waters that would otherwise be lost.

Purcell dismisses the importance of Article 5 in establishing the ambulatory thesis and considers it as relying on the negative interpretation of the law of the sea, namely Articles 7(2)—on fixing straight baselines in the event of a regression of the low water line in deltaic coasts—and 76(9)—on fixing permanently the outer boundaries of the continental shelf.²⁹ Purcell further challenges the ambulatory baseline thesis by highlighting that the Articles upon which Caron and Soons base the thesis are not necessarily linked to coastal changes, especially Article 76(9). Purcell then also looks at how the permanent limits of the continental shelf were drafted, noting the use of a distance criterion for clarity and stability in distinguishing between the continental shelf of a coastal state and the international seabed.³⁰ She finds that the outer limits of the continental shelf are permanent independently of the baseline because of the physical property of the continental shelf.³¹ This focus does not consider what distinguishes both Articles 7(2) and 76(9) from other Articles in the UNCLOS. Geographical points remain effective in time ‘notwithstanding subsequent regression’ for straight baselines of deltas and ‘permanently’ for the outer limits of the continental shelf. A provision shall be interpreted in accordance with the ordinary meaning of the terms of the treaty in its ‘context and in the light of its object and purpose’.³² The terms of Articles 7(2) and 76(9) effectively fix these geographical features, regardless of changing sea levels. For this purpose, the wording of Article 5 needs to be reviewed. Purcell analyses Article 5 of the UNCLOS concerning normal baselines in Chapter seven, explaining that states may draw their baselines from the low-water line or from nautical charts, but that neither of those are meant to fix baselines.³³

Purcell spends time interpreting both Articles 7(2) and 76(9) in light of the treaty’s object and purpose and the travaux préparatoires leading up to the UNCLOS III and of the travaux préparatoires of the Convention on the Territorial Sea and Contiguous Zone³⁴ and the Convention on the Continental Shelf.³⁵ Purcell explores a reading of the law that does allow for possible relocation of baselines and the maritime delimitation at the discretion of the coastal state. She finds that the ambulatory thesis should be understood as an exception to the main rule.³⁶

The main point of contention between both interpretations of the law is whether it provides for the baselines being automatically adjusted or whether the coastal state must draw the baselines again, subject to the possibility of them being contested. Purcell finds that the rules governing the definition of maritime limits and boundaries must be distinguished from the rules that govern their existence and evolution. These rules—about the evolution of baselines in time—would liken a permission rather than an obligation to update maritime limits and boundaries, as such, the revision of baselines is discretionary. Thus, although Purcell takes a different approach to interpretation, she seems to come to the same conclusions as the solutions available to avoid the legal consequences of ambulatory thesis.³⁷

Contemporary voices that do echo the ambulatory thesis include Schofield, who accepts the ambulatory baseline theory as the leading thesis and tries to find ways of solving the legal issues it creates regarding eroding islands and statehood.³⁸ The International Law Association also found in its conclusions that the ‘normal baseline is ambulatory moving seaward to reflect changes to the coast caused by accretion, land rise, and the construction of human-made structures associated with harbour systems, coastal protection and land reclamation projects, and also landward to reflect changes caused by erosion and sea-level rise’.³⁹ When recognising the ambulatory thesis, its implications must also be envisaged. The first being the significant loss in territory incurred by coastal states as the low-tide elevations and fringing reefs within the 12 nautical miles limit would become permanently submerged, thereby resulting in loss of width the of general entitlement to maritime zones. The second issue that the ambulatory thesis raises is the threat such interpretation of the UNCLOS would pose on islands that would become unhabitable due to sea-level rise. The latter would then effectively fall under the legal definition of a ‘rock’, which ‘cannot sustain human habitation or economic life of their own’ and is thus devoid of exclusive economic zone or continental shelf.⁴⁰ The next section will therefore look into the current state practice and the work of the ILC on the impact of sea-level rise on international law.

4. Legal Implications of Shifting Baselines

Baselines and sovereignty are intricately linked. Purcell’s monograph fosters a more complex understanding of the ideas of sovereignty and its relationship with land:⁴¹

The law neither expressly provides nor implies that such a serious displacement of sovereignty and sovereign rights – prejudicial not only to the interests of the coastal State but to the stability of the legal order as a whole – should accompany ‘the meaningless plungings of water and the wind’ against the changeable coast.

The principle of stability is significant in Purcell’s argument against the ambulatory thesis.⁴² The uncertainty raised by the legal implications of interpreting baselines as ambulatory is in fact important in justifying her position.⁴³ Indeed, the threat of sea-level rise to the territory of small islands developing states and the impact on statehood—the criteria upon which baselines are determined—are critical. As the ILA Baselines Committee noted: ‘the effects of sea-level rise on ambulatory baseline had impacts much beyond simply the law of the sea and recommended the establishment of a new Committee to deal with the effects of sea-level rise in international law’.⁴⁴

Where the law is silent, state practice relating to adaptation to sea-level rise is relevant and consequential. The work of the ILC on sea-level rise in relation to international law offers an additional source of state practice not reviewed in the book.⁴⁵ Comments by governments have been submitted to the ILC since 2021, after the publishing date of Purcell’s book. These submissions of states based on their practice and their national legislations regarding the adjusting of baselines are evidence of their interpretation of the UNCLOS provisions on baselines.⁴⁶ In fact, they provide insight on their formal position on the permanency of baselines. State practice represents another tool when interpreting the baseline provisions of the UNCLOS.⁴⁷

Consistent to her analysis, Purcell claims that ‘the bulk of State practice is consistent with the conclusion that maritime limits are not ambulatory’.⁴⁸ While acknowledging the disparate state practice is due to the discretionary character of the baseline provisions, she mentions the state practice of the USA and the Netherlands as exceptions because their baselines are, in fact, ambulatory.⁴⁹ This view does not show the nuances in state practice of states that do not necessarily reject the ambulatory thesis but interpret its legal implications differently.

Some states, like the Netherlands, have indeed been adjusting their baselines according to the low water level.⁵⁰ The Netherlands attributes these changes to: ‘a high re-survey frequency and a dynamic seabed, the low water line has a dynamic behaviour (…) low tide elevations within the distance of the 12 nautical miles appear and disappear’.⁵¹ While the Netherlands mention the adjustment of their baselines, effectively understanding the baselines as ambulatory, they do not pronounce themselves on whether it is an obligation under the UNCLOS and whether it leads to subsequent adjustments of its maritime zones. Similarly, Ireland considers its normal baselines based on the low-water level to be ambulatory and finds there is no obligation to deposit details of normal baselines with the Secretary-General.⁵² In addition, Poland also confirmed that it used the lowest level of water to measure its baseline and that ‘such a regulation remains in line (…) with Article 5 of the UNCLOS’.⁵³

Many states, including the Federated States of Micronesia, France, Germany, and the Maldives, on the other hand, explicitly consider that while the UNCLOS allows for states to modify and adjust their baselines, entitlements to maritime zones remain fixed. Indeed, Germany ‘finds that UNCLOS allows for freezing of once duly established, published and deposited baselines and outer limits of maritime zones’.⁵⁴ The Maldives add: ‘(the) entitlements are fixed and will not be altered by any subsequent physical changes to a States’ geography as a result of sea-level rise’.⁵⁵ They base their claim on the principles of stability and certainty of international law;⁵⁶ and on the considerations of equity and fairness that the maritime entitlements of Small Islands Developing States to be protected.⁵⁷

With respect to the question on whether the adjustment of baselines is an obligation or not, the Pacific Island Forum Declaration confirmed that Pacific Islands do not intend to review their baselines or the entitlement of their maritime zones.⁵⁸ Indeed, they found that the UNCLOS imposes no such obligation to review baselines and outer limits of maritime zones or to review charts. Colombia⁵⁹ and New Zealand underline this position, with New Zealand stating that ‘in the event that New Zealand experiences coastal regression as a result of climate change related sea-level rise, New Zealand does not intend to update its notification of March 2006 (deposition of ten nautical charts showing their baselines)’.⁶⁰ The United States supported this, noting that they ‘recognised that new trends are developing in the practices and views of States on the need for stable maritime zones in the face of sea-level rise’, adding that they ‘will work with other countries toward the goal of lawfully establishing and maintaining baselines and maritime zone limits and will not challenge such baselines and maritime zone limits that are not subsequently updates despite sea-level rise caused by climate change’.⁶¹ In addition, a report from the House of Lords on the status of the UNCLOS, called for the UK government to ‘take a formal position that baselines should remain fixed in their current positions’ to ensure that ‘no states, including the UK and its Overseas Territories, lose their current maritime entitlements’.⁶² Effectively, this position is the one adopted by Purcell when she interprets Article 5 as ‘a matter of permission rather than obligation.’⁶³.

States have also marked their baselines on large-scale charts with geographical coordinates submitted in accordance with UNCLOS Article 16(2) to fix them. This is consistent with the concerns on the ambulatory character of the normal baseline.⁶⁴ Schofield writes ‘the coastal State (…) can, arguably, therefore choose a chart that is advantageous to it. A coastal State threatened by sea-level rise could “officially recognize” a chart showing the threatened features in their presently above high-tide state prior to the advent of sea-level rise’.⁶⁵ Indeed, states finding that there is no obligation to review their baselines are updating their submission to the Secretary-General, depositing geographical coordinates instead of the low-water mark that is more likely to be subject to sea-level rise faster.⁶⁶ As such, Vanuatu,⁶⁷ Kiribati,⁶⁸ New Zealand⁶⁹ and the Cook Islands⁷⁰ have updated their submission in the last decades.⁷¹ In their submission, the Cook Islands added certain observations on sea-level rise, namely that ‘it is not obliged to keep under review the maritime zones reflected in the present official deposit of lists of geographical coordinates of points’. They continue that they ‘intend to maintain these maritime zones in line with that understanding, notwithstanding climate change-induced sea-level rise’.⁷²

The submissions to the ILC working group on sea-level rise are a source of information regarding states’ interpretation of the UNCLOS. They map a nuanced landscape, between states adhering to the ambulatory theory, and states finding there to be no obligation of adjusting baselines, while others positively affirm them to be fixed. These submissions, while sparse, complement the monograph by exhibiting the variations of state practices and readings of the UNCLOS.

5. Conclusion

Law and geography have coexisted as disciplines and have interacted in specific yet controversial instances such as boundary delimitations. The disruptive nature of climate change is altering this disciplinary separation and increasing the contact points between both law and geography. This is one of the important facets that Purcell brings forward at many stages of her monograph. Firstly, by delving into the UNCLOS and its predecessors, the author supplies a significant legal analysis. For her, the ambulatory character of baselines cannot be presumed, as the role of geography in the UNCLOS is consistent with subsequent physical changes of the coastlines. While her argument against the ambulatory thesis places greater emphasis on reviewing Articles 7(2) and 76(9) than Article 5, she does come to the same conclusion that there is no legal obligation to update baselines regularly, rather it is a right conferred to states. Secondly, throughout the book, Purcell showcases the importance of interdisciplinary thought in the law of the sea. She argues that as the impacts of climate change—including increased coastal erosion and sea-level rise—are amplified, the law is rather flexible and allows states to adapt to such changes. The lack of obligation to revise baselines shows that even in such a dynamic legal area, certainty and clarity must prevail. In her words: ‘The law relating to maritime jurisdiction reflects the more general truth that change is not by definition inconsistent with stability, although stability may demand reason and regularity in such change there is’.⁷³ Therefore, the combination of legal analysis with an interdisciplinary outlook provides a strong and novel case for the dynamic character of the law of the sea.

ACKNOWLEDGEMENTS

This study is supported by the London Interdisciplinary Social Science Doctoral Training Partnership (LISS DTP) from the Economic and Social Research Council (ESRC), grant ref: ES/P000703/1.

Footnotes

1

North Sea Continental Shelf (Federal Republic of Germany v Denmark) (Merits) [1969] ICJ Rep 3 para 96.

2

Kate Purcell, Geographical Change and the Law of the Sea (OUP 2019).

3

David D Caron, ‘When Law Makes Climate Change Worse: Rethinking the Law of Baselines in Light of a Rising Sea Level’ (1990) 17 Ecology LQ 621.

4

ILC, Sea-level Rise in Relation to International Law - First Issues Paper by Bogdan Aurescu and Nilüfer Oral (28 February 2020); ILC, Sea-level Rise in Relation to International Law - Second Issues Paper by Patrícia Galvão Teles and Juan José Ruda Santolaria (19 April 2022).

5

Request for an Advisory Opinion Led by the Commission of Small Island States on Climate Change and International Law (Request for Advisory Opinion Submitted to the Tribunal) ITLOS Order 2022/4 16 December 2022, 1–2.

6

‘Charter of the United Nations, the International Covenants on Civil and Political Rights and on Economic, Social and Cultural Rights, the United Nations Framework Convention on Climate Change, the Paris Agreement, the United Nations Convention on the Law of the Sea, the duty of due diligence, the rights recognized in the Universal Declaration of Human Rights, the principle of prevention of significant harm to the environment, and the duty to protect and preserve the marine environment’ in UNGA, Request for an Advisory Opinion of the International Court of Justice on the Obligation of States in Respect of Climate Change, UN Doc. A/77/L.58 (29 March 2023).

7

Clive Schofield, ‘Departures From the Coast: Trends in the Application of Territorial Sea Baselines Under the Law of the Sea Convention’ (2012) 27.4 The International Journal of Marine and Coastal Law 723, 731.

8

Rosemary G Rayfuse, ‘International Law and Disappearing States: Utilising Maritime Entitlements to Overcome the Statehood Dilemma’ (2010) 2010-52 UNSW Law Research Paper 1, 3.

9

UNCLOS, art 5.

10

ibid art 6.

11

ibid art 13(1).

12

ibid arts 7(1), 7(2).

13

ibid art 7(3).

14

ibid art 47(1).

15

Purcell (n 2) 44–48.

16

UNCLOS, art 76(9).

17

Purcell (n 2) 20–32.

18

ibid 45–48.

19

ibid 155–180.

20

David D Caron, ‘When Law Makes Climate Change Worse: Rethinking the Law of Baselines in Light of a Rising Sea Level’ (1990) 17 Ecology Law Quarterly 621-653, 634; David D Caron, ‘Climate Change, Sea Level Rise and the Continuing Uncertainty in Oceanic Boundaries: A Proposal to Avoid Conflict’ in and Jon Van Dyke (ed), Maritime Boundary Disputes, Settlement Processes and the Law of the Sea (2008); Afred HA Soons, ‘The Effects of a Rising Sea Level on Maritime Limits and Boundaries’ (1990) 37 Netherlands International Law Review 207–232; Lewis M Alexander, ‘Baseline Delimitations and Maritime Boundaries’ (1983) 503 Virginia Journal of International Law 535.

21

Rayfuse (n 8) 3.

22

Baylor Fox-Kemper and colleagues, ‘2021: Ocean, Cryosphere and Sea Level Change’ in Climate Change 2021: The Physical Science Basis. Contributions of the Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (CUP 2022) 1211–1362, 1302: the estimates depend on the emissions scenario that is modelled. The IPCC has several representative concentration pathways (RCP) and projects.

23

Roshanka Ranasinghe and colleagues, ‘Climate Change Information for Regional Impact and for Risk Assessment’ in Climate Change 2021: The Physical Science Basis (Cambridge University Press 2022) 1767–1926, 1841: ‘(…) relative sea level rise is very likely in the oceans around small islands, and along with storm surges and waves will exacerbate coastal inundation in small islands. Shoreline retreat is projected along sandy coasts of most small islands (high confidence)’.

24

ibid 1770.

25

Caron, ‘When Law Makes Climate Change Worse: Rethinking the Law of Baselines in Light of a Rising Sea Level’ (n 20).

26

ibid 634-636.

27

Soons (n 20) 220.

28

Caron (n 20) 641.

29

Purcell (n 2) 58 and 76, respectively.

30

ibid 91–96.

31

ibid 102.

32

Vienna Convention on the Law of Treaties (adopted 23 May 1969, entered into force 27 January 1980) 8 ILM 679, art 31(1).

33

Purcell (n 2) 179.

34

1958 Convention on the Territorial Sea and the Contiguous Zone (adopted 29 April 1958, came into force 10 September 1964) 516 UNTS 205.

35

Convention on the Continental Shelf (adopted 29 April 1958, entered into force 19 June 1964) UNTS 499.

36

Purcell (n 2) 215.

37

ibid.

38

Clive Schofield, ‘Rising Waters, Shrinking States: The Potential Impacts of Sea Level Rise on Claims to Maritime Jurisdiction’ (2011) 53 German Yearbook of International Law 189, 210.

39

ILA Baselines Committee, ‘Conference Report Sofia 2012’ (ILA 2012) 31.

40

UNCLOS, art 121(3).

41

Purcell (n 2) 286.

42

ibid 146–161.

43

ibid, 260, 265.

44

ILA Baselines Committee, ‘Baselines Under International Law of the Sea’ (20 August 2018) 1.

45

Purcell does review some state practice, see Purcell (n 2) 265–280.

46

See ILC, Analytical Guide to the Work of the International Law Commission, Sea-level Rise in Relation to International Law, Comments by Governments at: <https://legal.un.org/ilc/guide/8_9.shtml#govcoms> accessed 15 June 2023. Since 2021, there have been information submitted by: Antigua and Barbuda, Belgium, Colombia, Croatia, Finland, France, Germany, Ireland, Japan, Lichtenstein, Maldives, Morocco, Federated States of Micronesia, the Netherlands, New Zealand, Philippines, Poland, the Russian Federation, Singapore, Sweden, the United Kingdom of Great Britain and Northern Ireland, the United States of America. Organisations having submitted information include: Pacific Islands Forum, Economic Commission for Latin America and the Caribbean, Food and Agriculture Organization, International Maritime Organization, United Nations Environment Programme, United Nations Framework Convention on Climate Change, International Hydrographic Organization.

47

Article 31(3)(b) of the Vienna Convention on the Law of Treaties (n 32) provides that ‘any subsequent practice in the application of the treaty which establishes the agreement of the parties regarding its interpretation’ shall be taken into account.

48

Purcell (n 2) 265.

49

ibid 266–269. This is before the latest change in policy of the US as explained in ft 57.

50

Netherlands Territorial Sea (Demarcation) Act (Wet Grenzen Territoriale Zee) of 1985.

51

ILC, Submission of the Netherlands (29 June 2022).

52

ILC, Comments by Ireland on Sea-level Rise in Relation to the Law of the Sea (29 June 2022).

53

ILC, Comments of the Republic of Poland (30 June 2022).

54

ILC, Federal Republic of Germany - Written Statement 71^st and 72^nd ILC Report (30 June 2022).

55

ILC, Information and Examples of State Practice on “Sea-level Rise in Relation to International Law (31 December 2019) 9.

56

ibid 9–13.

57

ibid 13–18.

58

Pacific Islands Forum, Declaration on Preserving Maritime Zones in the Face of Climate Change-related Sea-Level Rise (August 2021) signed by Australia, the Cook Islands, the Federated States of Micronesia, Fiji, French Polynesia, Kiribati, Nauru, New Caledonia, New Zealand, Niue, Palau, Papua New Guinea, the Republic of the Marshall Islands, Samoa, Solomon Islands, Tonga, Tuvalu and Vanuatu.

59

ILC, Comments by the Republic of Colombia with Regard to the Report of the ILC on the Work of its 72^nd Session (30 June 2022).

60

ILC, New Zealand Submission to the ILC on State Practice in Relation to the Law of the Sea and Maritime Zones (30 June 2022).

61

United States Mission to the United Nations, ‘US Remarks at a Meeting of the Sixth Committee on Agenda Item 77: Report of the International Law Commission on the Work of its Seventy-third Session’ (October 27 2022).

62

House of Lords, UNCLOS: Fit for Purpose in the 21st Century? 126.

63

Purcell (n 2) 215.

64

UN Division for Ocean Affairs and the Law of the Sea, Deposit of Charts, see: <https://www.un.org/depts/los/LEGISLATIONANDTREATIES/STATEFILES/VUT.htm> accessed 15 June 2023.

65

Clive Schofield, ‘Shifting Limits: Sea Level Rise and Options to Secure Maritime Jurisdictional Claims’ (2009) Carbon & Climate L. Rev. (2009) 405, 413.

66

ibid.

67

Circular Notes from the Division for Ocean Affairs and the Law of the Sea Office of Legal Affairs, Deposit by the Republic of Vanuatu of Lists of Geographical Coordinates of Points Pursuant to Article 16, Paragraph 2, and Article 47, Paragraph 9, of the Convention (20 July 2010).

68

Circular Notes from the Division for Ocean Affairs and the Law of the Sea Office of Legal Affairs, Deposit by the Kiribati of Lists of Geographical Coordinates of Points Pursuant to Article 16, Paragraph 2, and Article 47, Paragraph 9, and 75, paragraph 2, of the Convention (2 January 2015).

69

Circular Notes from the Division for Ocean Affairs and the Law of the Sea Office of Legal Affairs, Deposit by New Zealand of Nautical Charts Pursuant to Article 16, paragraph 2, and Article 75, Paragraph 2, and Article 84, paragraph 2, of the Convention (8 March 2006).

70

Circular Notes from the Division for Ocean Affairs and the Law of the Sea Office of Legal Affairs, Deposit by the Cook Islands of Lists of Geographical Coordinates of Points, Pursuant to Article 16, paragraph 2, and Article 75, Paragraph 2, of the Convention (16 August 2021).

71

ibid.

72

ibid.

73

Purcell (n 2) 283.