By Daniel Otunge
The International Tribunal for the Law of the Sea (ITLOS) has delivered a long-awaited Advisory Opinion on the nexus between climate change and the international law of the sea.
The opinion addresses critical issues regarding the application of the United Nations Convention on the Law of the Sea (UNCLOS) in the context of climate change.
Adopted in 1982, the Convention lays down a comprehensive regime of law and order in the world’s oceans and seas, establishing rules governing all uses of the oceans and their resources.
The Commission of Small Island States on Climate Change and International Law (COSIS) requested an advisory opinion from ITLOS under Article 2(2) of the COSIS Agreement.
COSIS’s mission is “to take collective action to protect and preserve the climate system, including the marine environment, through the promotion, progressive development, and implementation of rules and principles of international law concerning climate change.”
Its mandate includes promoting the implementation and progressive development of rules and principles of international law concerning climate change.
This opinion is significant because it addresses the interaction between UNCLOS, the global climate change regime, and states parties’ obligations to reduce greenhouse gas (GHG) emissions.
In that regard, the tribunal says, “States Parties to the Convention have specific obligations under article 194 of UNCLOS to take all necessary measures to prevent, reduce, and control marine pollution from anthropogenic GHG emissions and to endeavor to harmonize their policies in this connection.”
The ITLOS opinion couldn’t have come more opportune when urgent concrete actions are needed to cool global temperatures.
Our oceans are significant carbon sinks. They absorb over 90% of the excess heat in the climate system. Despite this critical role of the ocean in regulating global temperatures, humanity has paid scanty attention to the need to harness the interplay between climate law and international law of the sea to address the climate emergency.
Even so, attention to the link between climate change and the law of the sea has increased significantly since the formation of COSIS in 2021, culminating in the critical ITLOS opinion.
About five key issues were laid before ITLOS to provide an opinion. The first was whether Anthropogenic GHG emissions are a form of pollution of the marine environment, which it answered affirmatively, noting,
“Through the introduction of carbon dioxide and heat (energy) into the marine environment, anthropogenic GHG emissions cause downstream climate change and ocean acidification, which results in the deleterious effects illustrated in the definition of pollution of the marine environment.”
The second issue was whether States Parties have Obligations to prevent, reduce, and control pollution of the marine environment. It said yes, citing Article 194, paragraph 1 of UNCLOS, which says Parties to the Convention have specific obligations to take all necessary measures to prevent, reduce, and control marine pollution from anthropogenic GHG emissions and to endeavor to harmonize their policies in this connection.
The tribunal emphasized that in the context of GHG emissions, the obligation imposed a stringent due diligence standard on Parties due to the high risks of severe and irreversible harm to the marine environment from such emissions. ITLOS clarified that states with greater capabilities and resources are required to do more than states with lesser means, which aligns with the principle of common but differentiated responsibilities.
Thirdly, ITLOS was asked to determine whether obligations to protect and preserve the marine environment are applied to climate change.
It affirmatively stated that Article 192 of UNCLOS “can be invoked to combat any form of degradation of the marine environment, including climate change impacts, such as ocean warming and sea level rise, and ocean acidification.”
The fourth issue was whether The Role of the Paris Agreement was sufficient to address climate change in the marine environment. The Tribunal found that Article 194, paragraph 1, of UNCLOS, would not be satisfied simply by complying with the obligations and commitments under the Paris Agreement. Further, it stated that the two were complimentary in regulating marine pollution from anthropogenic GHG emissions.
The fifth issue was how to determine the Best Available Science to guide decisions on climate action; ITLOS, among other things, advised that “concerning climate change and ocean acidification, the best available science is found in the works of the IPCC, which reflect the scientific consensus.”
This opinion puts UNLOS at the center of a growing body of legal instruments for climate change. It will undoubtedly guide global administrative and judicial decisions on climate change policy and litigation. It will also help other bodies, such as the International Court of Justice, which is expected to issue similar advisory opinions soon.
The writer is a climate change law researcher.
