Landmark Ruling: ITLOS Advisory Opinion 2024

Landmark Ruling: ITLOS Advisory Opinion 2024

In a groundbreaking development on May 21, 2024, the International Tribunal for the Law of the Sea (ITLOS) issued an advisory opinion that marks a significant milestone in the legal battle against climate change. This opinion was in response to a request from the Commission of Small Island States on Climate Change and International Law (COSIS), which sought to clarify the obligations of nations under the United Nations Convention on the Law of the Sea (UNCLOS) concerning climate change mitigation.

Representing small island nations that are particularly vulnerable to the effects of climate change, such as rising sea levels and ocean acidification, COSIS’s initiative led to a pivotal moment in international climate change litigation. This editorial aims to dissect the implications of the ITLOS advisory opinion, examining its impact on international legal frameworks, the specific obligations it outlines for UNCLOS parties, and its broader ramifications for global climate change policy and governance.


Issues Involved

The heart of the case heard by the International Tribunal for the Law of the Sea (ITLOS) revolves around the critical need to clarify the obligations of nations under the United Nations Convention on the Law of the Sea (UNCLOS) concerning climate change mitigation. Small island states, disproportionately affected by the rising sea levels and ocean acidification resulting from climate change, sought this clarification. The issues at stake are profound, involving the interpretation of what constitutes marine pollution under UNCLOS and determining the extent of the responsibility of states to curb greenhouse gas emissions that contribute to this pollution. 

The advisory opinion’s outcome has the potential to reshape the global approach to managing marine pollution and tackling the broader implications of climate change. By engaging with these complex legal and environmental challenges, the tribunal’s decision could set a precedent for how international law addresses the intricate nexus between maritime law and global climate policies, emphasizing the urgent collective action required to safeguard vulnerable communities and ecosystems from the escalating impacts of climate change.

International Legal Frameworks: UNCLOS, ITLOS, and COSIS


The United Nations Convention on the Law of the Sea (UNCLOS) serves as a cornerstone in the governance of ocean activities, establishing a comprehensive legal framework that encompasses various aspects such as navigation, fishing, and the conservation of marine resources. It defines the rights and obligations of states concerning maritime zones, emphasizing cooperation for the sustainable management and protection of the marine environment. As a widely ratified international treaty, UNCLOS plays a pivotal role in fostering global maritime order and environmental stewardship.


The International Tribunal for the Law of the Sea (ITLOS) stands as a key pillar in the enforcement of maritime law, offering a platform for the resolution of disputes arising under the United Nations Convention on the Law of the Sea (UNCLOS). By adjudicating conflicts and providing legal clarity on maritime issues, ITLOS upholds the rule of law at sea, contributing to the peaceful and orderly use of ocean resources. Moreover, its role in interpreting UNCLOS provisions ensures that nations navigate the complex legal landscape of international maritime affairs with certainty and fairness.


The Commission of Small Island States on Climate Change and International Law (COSIS) represents a collective endeavor by small island nations to confront the legal challenges posed by climate change. Aimed at bolstering legal frameworks and advocating for the interests of vulnerable island communities, COSIS embodies the spirit of cooperation and resilience. Through its initiatives, the commission seeks to amplify the voices of small island states in global forums, striving for equitable solutions to the pressing issue of climate change and its impacts.

Obligations under UNCLOS

The International Tribunal for the Law of the Sea (ITLOS) advisory opinion sheds light on the obligations of UNCLOS parties about greenhouse gas emissions, emphasizing the duty to prevent, reduce, and control marine pollution, including that from CO2 emissions. This clarification underlines the role of UNCLOS in addressing ocean acidification and warming, marking a significant step in the integration of environmental considerations into the legal framework governing the seas. It underscores the importance of proactive measures to safeguard marine environments against the backdrop of global climate change.

Implications of Climate Crisis Regulation

The ITLOS opinion marks a pivotal moment in the evolution of international law, addressing the inadequacies of traditional legal principles in managing the global and multifaceted nature of the climate crisis. By prioritizing collective interests and aligning legal obligations with scientific evidence and international climate agreements, the opinion offers a fresh perspective on the legal response to climate change. Hence, it underscores the urgency of adopting a more ambitious stance in the global fight against climate change, challenging states to reevaluate their legal and moral commitments to environmental stewardship.

Specific Actions Mandated by ITLOS Opinion

The advisory opinion from ITLOS, while not specifying exact measures, underscores the necessity for states to engage in the gradual reduction of greenhouse gas emissions under Article 194(1) of UNCLOS. This nuanced approach affirms the principle that states retain a degree of discretion in addressing climate change but are nonetheless bound by their obligation to mitigate its effects. The opinion navigates the delicate balance between prescriptive measures and state autonomy, sparking a dialogue on the most effective and equitable paths to achieving significant emissions reductions.

Challenges in Determining Mitigation Action

Determining the scope and scale of mitigation actions as required by states poses a significant challenge, as highlighted by the ITLOS opinion. The precedent set by cases like Urgenda Foundation v. The Netherlands provides a reference point for ambitious and scientifically grounded emissions reduction targets. However, the opinion’s ambiguity regarding the assessment of states’ mitigation efforts leaves open questions about equitable responsibility and resource allocation. This uncertainty also accentuates the need for a principled approach that considers the capabilities and circumstances of individual states while striving for global environmental sustainability.

Legal Implications and Analysis

The ITLOS advisory opinion has profound implications for the landscape of international climate change law, offering a foundational basis for future legal and policy endeavors aimed at mitigating the climate crisis. By recognizing CO2 as a pollutant under UNCLOS, the opinion broadens the scope of legal mechanisms available for addressing greenhouse gas emissions and reinforces the notion of collective responsibility in combating climate change. However, the generality of the obligations poses challenges for enforcement and effectiveness, highlighting the need for clear, actionable strategies that align with the principles of equity and global cooperation.

Political and Policy Implications

The political and policy implications of the ITLOS advisory opinion are far-reaching, influencing the dynamics of global climate governance and accountability. The opinion serves as a catalyst for policy innovation and the development of stringent climate measures, emphasizing the critical 1.5°C temperature goal. It underscores the necessity of concerted action and financial mobilization to support vulnerable communities, particularly small island states. Despite these advancements, the opinion also brings to light the complexities of translating legal mandates into tangible outcomes, necessitating a holistic approach to climate policy that addresses the myriad barriers to effective implementation.


The International Tribunal for the Law of the Sea’s advisory opinion represents a watershed moment in the confluence of maritime and climate law. By affirming the obligations of UNCLOS parties to combat the anthropogenic emissions contributing to ocean warming and acidification, ITLOS has charted a course for a more proactive approach to climate change mitigation at sea. Moreover, this decision underscores the evolving recognition of carbon dioxide as a pollutant, setting a precedent for future legal and policy frameworks aimed at curbing greenhouse gas emissions on a global scale. Particularly noteworthy is the tribunal’s emphasis on collective responsibility over bilateral interests, a paradigm shift that could foster more unified global action against climate change.

However, the broad directives outlined by ITLOS, while groundbreaking, also highlight the inherent challenges in translating international legal obligations into tangible environmental action. The lack of specific measures for states to adhere to leaves a considerable gap between legal mandate and practical implementation, raising questions about the effectiveness of such opinions in driving real change.


The advisory opinion delivered by the International Tribunal for the Law of the Sea (ITLOS) represents a watershed moment in the interplay between international law and the global fight against climate change. It underscores the imperative for nations, especially those bound by the United Nations Convention on the Law of the Sea (UNCLOS), to acknowledge and act upon their responsibilities in mitigating the emissions that contribute to oceanic and atmospheric warming. The judgment brings into sharp focus the urgent need for a robust, actionable framework that transcends the traditional limitations of international environmental legislation. Therefore, we are pushing for a collective, ambitious approach towards achieving the 1.5°C goal set by the Paris Agreement. 

For judiciary aspirants, this opinion serves as a critical point of study and reflection—not only on the evolving nature of international environmental law but also on the broader implications of legal frameworks in addressing complex global challenges. As future legal professionals, it is essential to recognize the power and responsibility that come with the ability to interpret and apply the law in ways that promote justice, sustainability, and the collective good of global communities. This opinion does not mark the end but rather the beginning of a new chapter in climate litigation, one where legal expertise can significantly contribute to steering the global community toward a more sustainable and equitable future. It is a call to action, urging aspiring jurists to engage with and contribute to the development of legal mechanisms that address the pressing environmental challenges of our time.