IUCN WCEL welcomes the Advisory Opinion on climate change by the International Tribunal on the Law of the Sea

On 21 May 2024, the International Tribunal for the Law of the Sea (ITLOS) published its Advisory Opinion in response to the request by the Commission of Small Island States on Climate Change and International Law (COSIS). The Tribunal was asked to clarify states’ obligations under the United Nations Convention on the Law of the Sea (UNCLOS) in the context of climate change and ocean acidification.

IUCN - represented by the World Commission on Environmental Law (WCEL) - took part in the advisory proceedings with written and oral statements. WCEL chair and IUCN legal counsel Prof. Christina Voigt attended the delivery of the Tribunal’s Opinion in Hamburg. IUCN WCEL wishes to congratulate the Tribunal to its historical Advisory Opinion.

In its Opinion, the Tribunal warned that the Ocean is at severe risk due to the impacts of climate change. It detailed the threat that global temperature increases and higher CO₂ concentrations pose to the marine environment. In an unprecedented manner, the Tribunal established that anthropogenic greenhouse gas (GHG) emissions from any source constitute «pollution» in the context of Art. 194 UNCLOS, according to which states must take all necessary measures to prevent, reduce and control such pollution. Moreover, it found that states have the legal obligation under Art. 192 to protect and preserve the marine environment against the detrimental impacts of climate change, including through effective adaptation measures. Where the marine environment has been degraded, this obligation calls for measures to restore marine habitats and ecosystems.

Importantly, under Art. 194 states have stringent due diligence obligations which are informed by the risk at stake and relevant international standards, including those in the Paris Agreement.

It is encouraging to see that the Advisory Opinion in large parts follows IUCNs line of argumentation. (See IUCNs written submission - with thanks to Prof. Cymie Payne, chair of the Ocean Law Specialist Group of WCEL, for coordinating this effort)

ITLOS’ historical Opinion has significant ramifications. It is clear now that under UNCLOS, parties have the substantive legal obligation to protect the Ocean from climate change impacts. This is an obligation of conduct to act with the necessary care required (due diligence) in reducing GHG emissions, taking into account the emission timeline and pathways for staying within the 1.5^oC temperature threshold. This obligation complements the Paris Agreement.

This finding aligns well with the decision by the European Court on Human Rights in Klimaseniorinnen which established the indispensable goal of carbon neutrality by 2050 and the need to take adequate, progressive measures to reach it - the absence of which amounting to human rights violations.

The ITLOS Opinion lays an important fundament for UNCLOS as a legal basis to address climate change and ocean acidification and to protect marine ecosystems - and will have wide repercussions across the landscape of international law; not the least when the International Court of Justice will render its Advisory Opinion on states’ obligations to protect the climate system.