The 2024 advisory opinion of the International Tribunal for the Law of the Sea (ITLOS) on climate change is an illustrative example of how translation in international litigation is not a purely administrative matter, but rather part of a process by which scientific findings become legally enforceable concepts. 

The case

The United Nations Convention on the Law of the Sea (UNCLOS)  is a multilateral treaty that establishes the principal international legal framework for the oceans. It addresses maritime zones, navigation, fisheries, seabed resources, dispute settlement and the protection of the marine environment. Part XII contains States Parties’ duties to protect and preserve the marine environment and to prevent, reduce and control marine pollution. In 1982, UNCLOS created the International Tribunal for the Law of the Sea (ITLOS), an independent international court to decide disputes about the interpretation and application of that Convention.

The Commission of Small Island States on Climate Change and International Law (COSIS) is an organization of nine small island states (Antigua and Barbuda, Tuvalu, Niue, Vanuatu, Saint Lucia, St Vincent and the Grenadines, St Kitts and Nevis, and the Bahamas) that are disproportionately affected by climate change. Its goal is to represent its members in their fight against climate change in international law. 

In 2024, COSIS filed a Request for an Advisory Opinion, asking ITLOS to clarify States Parties’ duties under UNCLOS, the United Nations Convention for the Law of the Sea, which sets the legal rules for all ocean space, marine resources, and maritime boundaries, and defines national rights and duties on the water. 

The request revolved on two related questions: 

1. the obligations to prevent, reduce and control marine pollution caused by anthropogenic greenhouse-gas emissions, and
2. the obligations to protect and preserve the marine environment from climate-change impacts. 

The Tribunal’s answer was that anthropogenic greenhouse-gas emissions are capable of constituting “pollution of the marine environment” under UNCLOS, and that States Parties therefore have concrete duties to address their ocean-related effects. Those duties include taking all necessary measures to prevent, reduce and control that pollution, protecting and preserving the marine environment, cooperating internationally, using the best available science, monitoring risks and carrying out environmental assessments where required.

The role of translation

The case involved the rendition of scientific evidence as treaty vocabulary. The Tribunal examined evidence concerning greenhouse-gas emissions, atmospheric and ocean processes, ocean warming and ocean acidification, then interpreted those phenomena through Article 1(1)(4) of UNCLOS.

That provision defines “pollution of the marine environment” in terms of the human introduction, directly or indirectly, of “substances or energy” into the marine environment that results, or is likely to result, in deleterious effects. ITLOS concluded that anthropogenic greenhouse-gas emissions could fit this legal definition: carbon dioxide is a substance, heat is energy, and their climate-related effects include ocean warming and acidification.

This involved preserving a complex and precise chain of meaning:

“Anthropogenic GHG emissions”→”carbon dioxide and heat”→”marine environmental effects”→”UNCLOS pollution”→”duties to prevent, reduce and control”

For this reasoning to apply, terms had to remain stable across languages. A translation that treats “pollution” as a generic synonym for environmental damage might obscure the legal issue. In the ITLOS proceeding, the specific “pollution” category mattered because it determined which UNCLOS provisions governed emissions and what duties followed from them.

The ITLOS advisory opinion is a demonstration of how climate proceedings require more than adequate translation of words and phrases between languages: rather, they require the disciplined transfer of whole concepts and frameworks between scientific knowledge and legal obligation.

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Climate cases often bring together evidence from many sources, e.g., scientific assessments, government records, national laws, technical reports, expert opinions, witness statements, and institutional submissions. The same key terms can appear hundreds of times across the record.

Without a controlled approach to translation, there is a risk of terminological drift: the same scientific phenomenon gradually being described in slightly different ways in different documents. Over time, those differences can generate uncertainty about the claim itself. 

For example, “ocean acidification” should not be alternated casually with phrases such as “marine acidity,” “acidification of waters,” or “chemical degradation of the sea” if the proceeding depends on maintaining a direct scientific and legal connection to defined climate impacts. Alternative phrasing may be appropriate for readability, but the core term should be controlled and translated consistently.

In climate proceedings, a stable translation of key terms can help ensure that the science submitted to a tribunal remains the science the tribunal evaluates, and that the legal obligations it identifies remain faithful to both the evidence and the relevant treaty.