The ICJ’s Historic Nod to Self-Determination and Climate Change Impacts

This post analyses the July 2025 advisory opinion from the International Court of Justice (ICJ), Obligations of States in Respect of Climate Change (Advisory Opinion), with respect to the principle and right of self-determination. While the ICJ did not explicitly rely on the principle and right of self-determination in its core discussion of “the most directly relevant applicable law” [114], the ICJ did not completely ignore it. In discussing the specific impacts of sea-level rise, the Court observed the possibility of “adverse consequences” on vulnerable States, including forced displacement and impacts on territorial integrity and permanent sovereignty over natural resources. “[S]ince these principles are closely connected with the right to self-determination, sea level rise is not without consequences for the exercise of this right.” [357].

While the Court’s discussion in paragraph 357 is brief, it is also remarkable. The Court’s conclusion that certain climate change impacts, particularly sea-level rise, will have consequences on the self-determination of affected States represents a novel application of the right to self-determination by the Court beyond its prior treatment in the context of decolonization (e.g., Western Sahara (1975), Chagos Archipelago (2019)) or occupation (Legal Consequences arising from the Policies and Practices of Israel in the OPT (2024)). The Court further appears to be aligning its own jurisprudence with the conclusions of the International Law Commission (ILC) and related recommendations from the International Law Association (ILA) concerning the relevance of self-determination in protecting the existence and survival of peoples from climate impacts. In that sense, paragraph 357 represents the Court’s opening statement of a potentially much larger doctrinal exploration of climate change and self-determination in the years ahead. 

Self-Determination in Relation to Existential Climate Impacts

The relevance of self-determination in relation to climate change impacts, particularly for vulnerable States, has been identified by the ILA and the ILC as part of their overlapping but separate assessments on sea-level rise. In a 2024 report focused on statehood and sea-level rise, the ILA specifically identified self-determination as an “important element” (p. 49) in shaping decisions related to the preservation of statehood and the protection of rights of the population, concluding that the right of self-determination “becomes particularly significant for peoples affected by sea level rise when most or all of the territory of low-lying SIDS becomes uninhabitable or submerged” (p. 23). Separately, the ILC released its final conclusions on sea-level rise and international law in 2025, capping a six-year review conducted by an open-ended Study Group. In their final consolidated report, the Co-Chairs of the Study Group articulated that the right to self-determination was “a fundamental principle” to be taken into account under all three subtopics reviewed by the Study Group: the law of the sea, statehood, and the protection of persons (para 409). The final report of the Study Group itself concluded that the right to self-determination supports the continuity of statehood in the context of climate change-related sea-level rise and that peoples cannot be deprived of the continuity of statehood without their consent (paras 38, 39). Respect for self-determination also requires good faith consultation as to alternative solutions that can preserve the identities of peoples and their international legal personality (para 39). Fundamental principles of international law, including that of self-determination, “should not be undermined by sea-level rise” (para 53).

The ICJ acknowledged the work of the ILC in the advisory opinion [361] and affirmed certain aspects of its conclusions, for example, that UNCLOS does not require States parties “to update their charts or lists of geographical co-ordinates that show the baselines and outer limit lines of their maritime zones once they have been duly established” in the context of climate-change related sea-level rise [362]. The separate opinions and declarations appended to the advisory opinion suggest a level of disagreement regarding the proper analysis of self-determination, statehood, and sea-level rise, with some expressing a degree of dissatisfaction on the lack of engagement on the topic. Vice President Sebutinde, noting that the issue of self-determination had been raised by many States (including small island States) in the context of sea-level rise and statehood, advocated for a more thorough discussion of self-determination and climate change impacts including “confirming in the operative paragraph 457 the obligation incumbent upon all States to take all necessary measures to protect the right of the most vulnerable States to self-determination” [8]. Judge Aurescu urged more analysis related to UNCLOS and the law of the sea, including with respect to the ICJ’s conclusion that there is no obligation under UNCLOS to update charts or lists of geographical co-ordinates that show the baselines and outer limit lines of their maritime zones once they have been duly established [2]. Judge Aurescu suggested that this conclusion could be derived, inter alia, “from the obligation to respect the right to self-determination (closely connected, inter alia, with territorial integrity and permanent sovereignty over natural resources)” [3].

In contrast, Judge Tomka wrote in his declaration that he would have preferred a “more prudent approach” on the question of statehood and self-determination [10]. In his view, self-determination and statehood were “heavily tied to territory”; therefore, the inexistence of land from climate change impacts “would tend to result in the demise of that [impacted] State as a subject of international law” [8]. Judge Tomka conceded that “a growing number of States” had expressed to the ILC the view that “statehood may survive even in the case of the total disappearance of territory” [6]. However, the discussions before the ILC were not sufficient in Judge Tomka’s view to indicate “a collective opinio juris reflecting a new rule of

custom” that was “judicially cognizable” [ibid]. For jurists and scholars holding the same views as Judge Tomka, more will be needed from States, including “a firm and public position on this issue” before it can be said that “a customary rule has crystallized around this point” [ibid]. 

Doctrinal Implications Moving Forward

Despite the brevity of the advisory opinion’s reference to self-determination, paragraph 357 nevertheless contains significant doctrinal implications concerning self-determination and climate change, particularly in relation to “forced displacement of populations” from sea-level rise and impacts on the principles of “the territorial integrity of States and their permanent sovereignty over their natural resources.” First, the Court’s conclusion that “sea level rise is not without consequences for the exercise of [the right to self-determination],” while cursory, represents a historic expansion of its jurisprudence related to self-determination and confirmation of its applicability outside the contexts of decolonization and occupation (which the Co-Chairs of the ILC Study Group also affirmed in their final consolidated report [295]). While some scholarship has argued that self-determination’s role is narrow or even irrelevant in addressing climate change impacts (for example, Stoutenburg’s conclusion in 2015 that the right was inapplicable on the issue of territorial loss and statehood in the context of sea-level rise, pp. 525-526), the ILC, ILA, and now the ICJ have expressly shifted the doctrine towards application of the right to self-determination in the face of climate impacts. And even while the ICJ did not explicitly mention self-determination in its review of applicable legal obligations (see e.g., [172] and [457]), self-determination is necessarily implicated through the ICJ’s references to the UN Charter, the International Covenant on Civil and Political Rights (ICCPR), and the International Covenant on Economic, Social and Cultural Rights (ICESCR), which each demand the dual protection and promotion of self-determination as a fundamental element of the international legal order (for example, in Articles 1(2) and 55 of the UN Charter, and common Article 1of the ICCPR and ICESCR).

Second, the Court’s conclusion that climate change impacts and sea-level rise will have consequences for self-determination serves to further develop the substantive law of self-determination. The ICJ recently summarized the law of self-determination in Legal Consequences arising from the Policies and Practices of Israel in the OPT (2024) in a manner that could be directly relevant to issues of sea-level rise and climate impacts more generally. In that advisory opinion, the ICJ concluded that territorial integrity and permanent sovereignty over natural resources were fundamentally interwoven with self-determination [237, 240], and that self-determination further protects a people “against acts aimed at dispersing the population and undermining its integrity as a people.” [239]. The ICJ further held that self-determination “is the right of a people freely to determine its political status and to pursue its economic, social and cultural development,” in turn connected to international legal concepts enshrined in UNGA Resolution 1514(XV) (1960), the 1970 Friendly Relations Declaration (UNGA Resolution 2625(XXV)) and the ICCPR and ICESCR [233, 241]. Similarly, in the climate advisory opinion, paragraph 357 explicitly references territorial integrity and permanent sovereignty over natural resources, and its mention of forced displacement can be directly connected to protecting the “integrity” of a people. The Court’s current jurisprudence on self-determination can be clearly and logically extended to address the adverse or existential impacts of climate change on vulnerable peoples and States. 

Third, the activation of self-determination in relation to climate change impacts may, as a practical matter, help to promote the existence and survival of vulnerable peoples and States in a rapidly changing climate system, including Indigenous Peoples. While the advisory opinion referenced Indigenous Peoples as a vulnerable group [382], it stopped short of any discussion of specific doctrinal protections that may apply to Indigenous Peoples under international law, including Indigenous existence and survival and related principles of self-determination as recognized, inter alia, by Articles 3 and 4 of the United Nations Declaration on the Rights of Indigenous Peoples. For many Indigenous Peoples, climate change represents an immediate existential threat wrought by emitter States, threatening their self-determination and cultural integrity. 

Fourth, comments from States submitted to the ILC on the issue of continuity of statehood (collected in paras 148-299 of the final consolidated report of the Co-Chairs of the ILC Study Group), as well as the discussion contained in the separate opinions and declarations of the ICJ advisory opinion itself, all point towards a larger reexamination of the law of self-determination in the context of adverse climate change impacts. If self-determination is necessarily implicated by issues of displacement and loss of territory and resources from climate change, then the door is seemingly now open for claims of breach of self-determination from injured peoples and States. Such claims may be cognizable not just by small island and low-lying States impacted by sea-level rise; a State rendered permanently uninhabitable by extreme heat would also face similar issues of displacement and loss of resources (including subsistence resources protected by common Article 1, section 2 of the ICCPR and ICESCR) underscored by the ICJ in paragraph 357. Arctic Indigenous Peoples, now experiencing significant environmental degradation of cold Arctic conditions, are arguably being “displaced” from such cold conditions through irrevocable loss of cultural life, even if physical displacement does not take place. The positive obligation to promote self-determination contained, inter alia, in common Article 1, section 3 of the ICCPR and ICESCR may further impose an affirmative obligation on States to promote the desired will of impacted peoples and States with respect to their international legal personality and ongoing existence and survival. Ultimately, such solutions will only work to the extent that States are willing to cooperate to effectuate them, which includes the critical task of actually stopping the emissions-generating conduct that is now producing such existential risks.