As the public hearings on the request for an advisory opinion on the Obligations of States in respect of Climate Change drew to a close on 13 December, the Court began its deliberation with much material to reflect on. The request introduced by the United Nations General Assembly in April 2023 – even if not explicitly raising the question of the continuity of statehood – enabled 96 States and 11 international organizations to examine in greater depth certain arguments raised by island States in recent years, particularly by those facing an existential threat (namely ‘atoll States’). For instance, the claims formulated by the Commission of Small Island States on Climate Change and International Law (COSIS), the organization which was already behind the ITLOS opinion of 21 May 2024, are quite illustrative in that regard. Represented, among others, by Professor Webb, the Commission relied on an impressive range of fundamental principles of international law :
« I will address the survival of States, linking it to the principles of State continuity, territorial integrity and sovereignty over natural resources. Survival is fundamental to a people’s right to self-determination (…) » (p. 56, § 2).
This declaration reflects other declarations made by the leaders of the Pacific Island Forum in 2023 and of the Alliance of Small Island States in 2024. To put it simply, island States invoke two categories of rules to preserve their existence despite rising sea levels: rules deriving from statehood (principles of continuity, territorial integrity and permanent sovereignty over natural resources) and other rules belonging to peoples (the right to self-determination). Tuvalu and others (see here, § 4.36, and here, §111(c)) appear to connect this initial group of rules to the controversial right recognized by the ICJ in 1996: the right of every State to survival.
If one can understand why such positive rules of international law might be relevant in the face of an existential threat such as sea-level rise, it may be difficult for international lawyers to apprehend how those rules should be applied by the ICJ. Although the legal literature dedicated to such issue is increasingly consistent, crucial questions remain as to both the clear legal basis on which a continuity of statehood would be based, and the concrete modalities by which this continuity could be truly established and not let to a mere legal fiction.
The aim of this short contribution is to examine the prospects offered by the rules invoked by ‘sinking’ island states: are they merely applying positive law, or are they pushing for a progressive development of the law? It is essential to answer this question, as the International Law Commission’s study group is about to submit its final report on those aspects (§§ 379 et seq.).
In our view, although island States may assert that their claims reflect the lex lata, it must be acknowledged that these claims are more aligned with lege ferenda or, at best, constitute an ambitious – although needed – interpretation of existing international law. To be clear, this is not about questioning the undeniable legitimacy of the island states’ demands, nor about adopting some “austere skepticism” that overstates the role of law – a law that, as always when it comes to the creation and disappearance of states, will most probably adjust with the reality of the international society. On the contrary, our view is grounded on State practice and the international community’s relatively passive stance toward the claims of island States. While it does not oppose them, it stops short of offering unconditional support (Japan or the UNGA, § 341, with some notable exceptions).
Against this backdrop, island states are pursuing bilateral agreements with allies, as seen in the Tuvalu-Australia treaty. This treaty allows Tuvalu to exercise its right to self-determination, strengthening its claims to statehood and sovereignty amid the existential challenges posed by rising sea levels.
Fundamental Principles of International Law Applied to Sea-level Rise: The Times They Are a-Changin’?
According to the 2024 AOSIS declaration, there is no doubt that “continuity of statehood in the face of climate change-related sea-level rise is consistent with important principles and rights of international law”. Island States assert the permanence of statehood (See Tonga in January 2024, A/78/PV.53, p. 3), even though the principle of continuity does not inherently aim to preserve States against existential threats. Instead, continuity operates in two distinct scenarios where the preservation of a State is incidental.
In the first scenario, the principle of continuity functions as a presumption to ensure legal certainty amid factual uncertainty. While the principle of continuity does apply when a State faces “a shock grave enough to cast a doubt on its survival” (p. 4), the rule’s purpose is not, in itself, to shield the State from such shocks. Rather, the solution provided is aimed at assessing whether the international obligations are still enforceable against the State whose status is being questioned. This problem is analogous to Plutarch’s philosophical puzzle of the ship of Theseus: if a ship’s planks are replaced over time, is it still the same ship? And if the removed planks form a new vessel, which one carries the ship’s identity? Similarly, international lawyers determine whether a State persists despite territorial or structural changes. While this inquiry can serve defensive purposes, the principle of continuity alone is insufficient. Therefore, some argue its application must be supplemented by other norms, especially when addressing the consequences of serious breaches of international obligations.
In the second scenario, States invoke Article 41(2) of the ILC’s Draft Articles on the Responsibility of States for Internationally Wrongful Acts, which states: “[n]o State shall recognize as lawful a situation created by a serious breach within the meaning of Article 40 (…)”. The continuity of statehood could theoretically derive from such a breach if sea-level rise is deemed to violate a peremptory norm of international law. Under this interpretation, third States would be under the obligation not to recognize the consequences of such a violation—namely, the submersion of territory and the extinction of the State. However, continuity here remains incidental as it stems from the implementation of other legal rules. This is why island States – and their allies (see the African Union, § 119) – are increasingly linking their claim to other imperative norms, particularly the right to self-determination, which raises complex questions: does recognition of continued statehood arise as a consequence of self-determination? Or does non-recognition of statehood constitute a violation of this right? Both questions hinge on the jus cogens nature of self-determination.
If self-determination indeed provides a shield for State continuity, does this imply that a State could remain “bulletproof” as long as its people oppose extinction? Such a conclusion would forever neutralize the question of whether a State exists in international law – thus also transforming the legal characteristics traditionally attached to « State continuity ». From a legal principle, continuity would shift into an irrebuttable presumption, which contrasts with State practice where it is understood as a “strong” yet rebuttable presumption.
Tuvalu is leading the efforts of island states to solidify this presumption as irrebuttable, notably through bilateral agreements like the one concluded with Australia.
The 2023 Agreement Between Tuvalu and Australia: Limits and Prospects
At a time when scenarios in which a certain continuity of statehood could be achieved are struggling to find some concrete illustration, the recent agreement between Tuvalu and Australia sets a remarkable precedent, for at least two reasons. Not only is it the first bilateral agreement on climate mobility, it is also the first treaty explicitly denying extinction of statehood to a country at risk of being submerged. We won’t go into the details of the Falepili Union here, which has already been commented on, including on this blog. Much criticized, including in Tuvalu, notably for the overwhelming strategic advantage article 4 provides for Canberra, the agreement was the subject of an Explanatory Memorandum aimed at putting an end to the debate on security aspects. Such effort contributed to the entry into force of the text on August 28, 2024. Nevertheless, the Union still poses important questions and raises the limits inherent in the conceptual structure that currently underpins the notions of territory and sovereignty in the international legal order. Firstly, to what extent is the agreement an expression of the Tuvaluan people’s principle of self-determination (it was fiercely debated in Parliament, notably in its November 2023 session, and to what extent would its implementation ultimately guarantee respect for the same principle in the event of the Tuvaluan population being entirely displaced, since no details are provided concerning its exercise on Australian territory?
The text also raises the essential question of which of the two entities, in the event of the land territory being entirely submerged, would have effective control and benefit from the resources of the (gigantic) Tuvaluan EEZ, should it be maintained despite the disappearance of the land territory (another question not yet answered by positive law).
It, therefore, remains to be seen whether this framework treaty will be clarified in the future, how successful its implementation will be, and whether it marks the first illustration of a practice set to develop. As it stands, even if enshrined in a binding instrument, bilateral recognition of the continuity of statehood for a ‘sinking state’ does not seem to guarantee the modalities of this continuity in the absence of land territory and/or in the case of the displacement of its entire population. Nor does it challenge the unbalanced relationships between powerful states and small island states exacerbated by the classic perception of territory and sovereignty. In fact, if we are, yes, a little sceptical this time, we could even see into it the triumph of powerful greenhouse gas emitters, who, at little cost and with no climate commitment, set themselves up as “friendly neighbors”, gain in security positioning, and set their sights on even larger maritime spaces.
