Strengthening the Global Response to Climate Change and Sustainable Development: Reflections on the ICJ's Advisory Opinion

This opinion critically analyses the ‘advisory opinion’ of the International Court of Justice (ICJ) which concerns the obligations of States in respect of climate change (2025), and in doing so, identifies issues that remain unresolved with the advisory opinion. This opinion also considers the principle of erga omnes, which is briefly mentioned in the ‘advisory opinion’ and also discusses climate change obligations that have the character of erga omnes , that is, obligations that are owed by a State to members of the international community as a whole. It is suggested that the ICJ has missed opportunities to clarify the relationship between the obligation(s) concerning climate change, the principle of erga omnes , consent and customary international law. It is also argued that the list of obligations that were considered jus cogens by the International Law Commission could be expanded, in the context of climate change, and notes that these types of obligations are also owed to members of the international community as a whole ( erga omnes ).

This analysis discusses the advisory opinion requested by the UN General Assembly from the International Court of Justice (ICJ) in April 2023 on the obligations of states in respect of climate change. Although the ICJ’s decision cannot be expected before the autumn of 2024, important procedural anomalies have arisen, which require due regard to ensure that the ICJ can provide its advisory opinion in possession of sufficient information. In particular, firstly, not all Small Island Developing States have been notified by the ICJ and invited to submit written statements and, secondly, the amicus curiae provided by NGOs will be not accessible to the public. This analysis argues that all Small Island Developing States should have the opportunity to take part in the proceedings and the amicus curiae submitted by NGOs to the ICJ should receive proper publicity.

Currently, there are pending requests for advisory opinions regarding State obligations on climate change before both the International Court of Justice (ICJ) and the Inter-American Court of Human Rights (IACtHR). Additionally, the International Tribunal for the Law of the Sea (ITLOS) recently issued its advisory opinion on Climate Change and International Law on 21 May 2024. This article aims to compare these requests, analysing their contextual backgrounds and the extent of States’ involvement in the advisory proceedings. The aim is to examine the jurisdictional scope and future prospects of the proceedings before the two courts and the tribunal by exploring the distinct normative, practical and political strategies shaping each request. Furthermore, the article assesses how these factors influence the framing of the requests for advisory opinions and shape the contributions received by interested States. By providing a holistic analysis of these legal interpretations, the author evaluates the potential impact of the aforementioned opinions on the future behaviour of States and the development of international law. Ultimately, this analysis aims to inspire the progress of strategic climate change litigation and inform about potential enhancements in the interpretation and development of future international agreements.

This Preface to the EPL Special Issue 55 (6) 2025 on the Advisory Opinions (2024-2025) of the International Courts and Tribunals (ICTs) onClimate Change seeks to provide an overview and serves as a lead research article to introduce the legal trajectory adopted for seeking an authoritative view on the “obligations of the States” under international law and “legal consequences under these obligations for States” (worded differently before each ICT) in relation to climate change from the three ICTs. The three marathon processes for seeking Advisory Opinions (AOs) took place before the International Court of Justice (ICJ), Inter-American Court of Human Rights (IACtHR) and International Tribunal on the Law of the Sea (ITLOS). The fourth one is pending (since May 02, 2025) before the African Court of Human & Peoples’ Rights. The respective ‘requests’ were presented to these ICTs on May 29, 2023 (ICJ), January 9, 2023 (IACtHR) and December 12, 2022 (ITLOS). After going through their procedural craft of formal requests, written statements, oral presentations and specially arranged meetings (by the ICJ) with some stakeholders such as Intergovernmental Panel on Climate Change (IPCC), the three ICTs delivered their respective AOs on July 23, 2025 (ICJ, The Hague), July 03, 2025 (IACtHR, San Jose) and May 21, 2024 (ITLOS, Hamburg). Thus, the AOs of these three ICTs provide a unique legal corpus ostensibly for strengthening legal basis of the State-centric consensual regime (1992 UNFCCC, 1997 Kyoto Protocol and 2015 Paris Agreement) on climate change. These AOs have brought to the fore role of the ICTs as ‘sentinels’ even as entire climate change global regulatory process (1992-2025) seem to be floundering after 33 years in spite of grim scientific projections about the “climate emergency”. It is in this backdrop that this preface-cum-research article provides the context, a preliminary overview of the outcomes of the three ICT AOs and possible future trajectory to resolve the “climate conundrum”, beyond the three AOs.

On 29 March 2023, the UN General Assembly adopted a resolution requesting an advisory opinion from the International Court of Justice on the obligations of states in respect of climate change. The icj’s opinion, if given, will be the first of an international court determining the elements of human rights obligations in the context of climate change. These issues have already been grappled with by UN human rights treaty bodies. I argue that the icj is entitled to take account of these jurisprudential developments, and should do so.

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The specific obligations of States for Internationally wrongful acts, so far skirted in the climate treaty and the subsequent political negotiations, will now be shaped by a legal view from the International Court of Justice (ICJ). The deadlines for submissions and comments have expired and hearings are to begin in August. The advisory opinion on general considerations necessary and legal consequences of acts and omissions will be shaped by the relief States seek. Under what circumstances wrongfulness arises is a substantial question of law. India should focus arguments on when wrongfulness arises as its per-capita emissions even in the future are likely to remain well below, even half, the global average and on present trends India will never cause significant harm to the environment or infringe the human rights of others.

Climate Change and the International Court of Justice

In July 03, 2025, the Inter-American Court of Human Rights (IACtHR) recognized for the first time a right to a healthy climate in its Advisory Opinion No. 32 (2025) on the “Climate Emergency and Human Rights”. The IACtHR derived the standalone right to a healthy climate from the right to a clean, healthy and sustainable environment, which the International Court of Justice in its 2025 Advisory Opinion on “Obligations of States in respect of Climate Change” considered “a precondition for the enjoyment of many human rights, such as the right to life, the right to health and the right to an adequate standard of living, including access to water, food and housing.” Based on these developments, authors trace the emergence of the right to a safe climate within and outside the Inter-American Human Rights System, both in scholarly works and domestic case law. We then examine the nature and content of the right to a safe climate, including new right holders, duty bearers and corresponding obligations that stem from this right. In this sense, the authors depart from the IACtHR's proposition and detect lacunae and corresponding opportunities for the right's further development in theory and practice. Finally, the authors analyse how this rights revolution sparked by the IACtHR Opinion may boost rights-based climate litigation, as it moves from aspiration to enforceable law.

International courts and tribunals have a unique opportunity to address the fragmentation of international law relating to climate change, sustainable development and the global energy transition. Following a decade of national and regional courts interpreting states’ climate obligations, international tribunals are now being called upon. The United Nations General Assembly’s (UNGA) request for an advisory opinion on climate change from the International Court of Justice (ICJ) on 29 March 2023 presents a pivotal moment to enhance coherence in the interrelated fields of climate change, sustainable development and energy access. This research offers a unique analysis of the advisory opinion and its implications for achieving universal energy access, highlighting the ICJ’s role in strengthening climate resilience and influence global energy policies. By examining climate jurisprudence and the ICJ’s role, this research argues that the ICJ’s opinion could provide authoritative guidance, encouraging states to align energy policies with climate obligations while ensuring equitable access to energy resources.

This contribution describes and critiques the Advisory Opinion of the International Tribunal for the Law of the Sea (‘ITLOS’ or ‘Tribunal’) on the obligations of States in relation to the sea and its marine environment that was delivered on 21 May 2024. Although the Advisory Opinion is not explicitly about sea level rise, it considers the relationship between climate change, the marine environment, and the consequence of sea level rise. The Opinion clarifies the legal obligations of States for preserving the marine environment and thereby makes a significant contribution to addressing the consequences of sea rise caused by climate change. The ITLOS Advisory Opinion was a precursor for the Advisory Opinions on climate change given by the Inter-American Court of Human Rights and the International Court of Justice in 2025. Much of this contribution relies on the ITLOS Advisory Opinion itself as well as the submissions by United Nations Member States and non-States actors. The background to the Request for an Advisory Opinion is discussed together with the questions that were submitted to the Tribunal. The submissions of States and non-State actors are described. And the unanimous Advisory Opinion of the Tribunal is described and evaluated together with the separate opinions of individual judges that accompanied it. Finally, some conclusions are drawn about the future impact of the Advisory Opinion.

Can the Advisory Opinion Strengthen the International Response to Climate Change?

Climate change is the justice challenge of our century, and the increasingly serious impacts of climate change on human societies and ecosystems are raising important international legal challenges. States and stakeholders are appealing to international courts for clarity concerning their responsibilities in the global response to climate change, as well as their accountability for climaterelated loss and damage. Through advisory proceedings, these institutions are being asked to clarify the legal obligations of States in addressing climate change, including the prevention of ocean impacts, the protection of human rights, and in international law more broadly. The International Tribunal for the Law of the Sea (ITLOS), the Inter-American Court of Human Rights (IACtHR) and the International Court of Justice (ICJ) are at the forefront of such proceedings with the potential to reshape international climate law and governance. In this article, expert legal scholars highlight the significance of climate advisory proceedings in these tribunals, briefly underlining the legal reasoning of the ITLOS advisory opinion, its implications for international climate governance, and the questions and arguments before the IACtHR and the ICJ. The article explores, in the context of global efforts to implement the Paris Agreement under the United Nations Framework Convention on Climate Change (UNFCCC) and other climate litigation including in international courts and tribunals, the transformative potential of recent advisory opinions sought from the ITLOS, the IACtHR and the ICJ. In their responses to the pressing need for legal clarity in a world grappling with unprecedented climate challenges, the article suggests, courts are offered an historic opportunity to shape the contributions of international law to global sustainability, justice and the survival of life on Earth.

Recent bilateral and plurilateral regional trade agreements (RTAs) increasingly incorporate climate‐related provisions, signalling a potential convergence of international trade and climate law. This trend goes beyond defensive provisions seeking to avoid conflicts between the two legal regimes, such as exceptions recognising climate change as a legitimate justification for trade restrictions. Among more proactive provisions found in newer generation RTAs, the article focuses on ‘linkage provisions’ requiring parties to effectively implement multilateral climate agreements, such as the United Nations Framework Convention on Climate Change (UNFCCC) and the Paris Agreement. While these agreements were often regarded as providing parties with much discretion or even as soft law, the recent Advisory Opinion on Obligations of States in respect of Climate Change by the International Court of Justice (ICJ) clarified their legal bindingness and concretised their legal requirements. Drawing on the findings of the Court, the article maps central climate treaty requirements on mitigation and systematises linkages between climate‐related treaties and RTAs into four categories: participation linkage, implementation linkage, adjudication linkage and enforcement linkage. The paper then analyses to what extent RTAs further concretise central climate treaty obligations and allow for their adjudication and enforcement via trade dispute resolution mechanisms. Overall, the article finds that relatively few RTAs, at present, provide textual concretisation of climate commitments but highlights that some trade agreements would in principle allow parties to initiate state–state ‘climate litigation’ and activate compliance mechanisms to strengthen effective implementation of the UNFCCC and the Paris Agreement.

for Scopus Indexing: In May 2024, the International Tribunal on the Law of the Seas (ITLOS) issued a historic advisory opinion on the obligations of States regarding climate change under the United Nations Convention on the Law of the Seas. This advisory opinion was issued in response to a request submitted by the Commission on Small Island States on Climate Change and International Law. Significantly, the Tribunal stated that: a) States must interpret their obligations under the Convention in light of the best available science; b) greenhouse gas (GHG) emissions constitute pollution of the marine environment; and c) they must take all necessary measures to reduce, prevent and control GHG emissions. ITLOS also noted that developed States have an obligation under the Convention to assist developing States in mitigating the effects of climate change. This advisory opinion marks an important first step in the fight for climate justice for small island States. Forthcoming are advisory opinions concerning climate change from the International Court of Justice (ICJ) and the Inter-American Court of Human Rights (IACHR). In this article, we explore the jurisdictional arguments some participants raised, the significance of the Tribunal’s opinion, and we contextualize the opinion in light of broader efforts towards climate justice.