ITLOS Issues Groundbreaking Advisory Opinion on Marine Protection and Climate Change

In a historic ruling, the International Tribunal for the Law of the Sea (ITLOS) has issued an unprecedented advisory opinion on the responsibilities of states to protect the ocean from the impacts of climate change. The tribunal has unanimously determined that states are obligated to reduce their emissions to safeguard marine environments, marking a significant expansion of international legal standards.

Key Findings of the Advisory Opinion

The tribunal’s advisory opinion outlined several critical points:

  1. State Obligations to Reduce Emissions: States are required to take measures to reduce their greenhouse gas emissions to protect the ocean, thereby linking climate action directly with marine protection.
  2. Beyond the Paris Agreement: The opinion suggests that climate action may need to extend beyond the parameters of the Paris Agreement to fulfil legal obligations regarding marine protection.
  3. Differentiated Responsibilities: States with significant historical contributions to greenhouse gas emissions bear a greater responsibility to address climate-related marine pollution compared to those with smaller ecological footprints.

Implications for International Climate Policy

Lea Main-Klingst, a lawyer with ClientEarth, emphasised the significance of this ruling, particularly for small island states disproportionately affected by climate change. “Today, small island states facing some of the greatest challenges of climate change have succeeded in a world first,” Main-Klingst stated. “They brought a novel legal question to this international tribunal, which has made it clear that states worldwide must reduce their emissions to protect our ocean.”

Main-Klingst also highlighted the potential ripple effects on national policies and corporate behaviour. “Next year, states must improve the climate plans they submit to the United Nations – known as their Nationally Determined Contributions – and today’s outcome will be instrumental in pushing the countries most responsible for the climate crisis to ramp up their ambition,” she noted. “And because business must follow where governments lead, companies and financial institutions are going to feel a knock-on effect from this development, too – no matter where they operate.”

Opportunity Green’s Legal Director, David Kay, commented: “This is a seminal moment for international climate change law. The judges were clear that given the high risks of serious and irreversible harm to the marine environment, states’ obligations to address GHG emissions need to meet a very high standard, informed by the best available science and the 1.5 degree temperature goal and timeline. It’s not enough to just rely on global efforts and international organisations. With sectors such as international shipping currently off course, States urgently need to put in place effective policies to meet these legal obligations.”

Future Legal Developments

The advisory opinion sets the stage for a significant year in international climate law. The Inter-American Court is currently hearing arguments on the impact of climate change on human rights in Brazil, and the International Court of Justice is slated to consider a similar issue later this year. These proceedings are expected to further clarify the legal obligations of states in addressing climate change.

Acknowledgement of COSIS

The Coalition of Small Island States on International Law and Climate Change (COSIS) played a pivotal role in bringing this issue before the tribunal. Main-Klingst expressed gratitude to COSIS, stating, “None of this would have been possible without the Coalition of Small Island States on International Law and Climate Change – and we are incredibly grateful to them for putting this question before the court.”


The ITLOS advisory opinion is a landmark development in the intersection of climate change and marine protection. By affirming the legal obligations of states to reduce emissions and recognizing the disproportionate responsibilities of historically high-emission countries, the tribunal has set a new precedent in international environmental law. The implications of this ruling will likely influence both national policies and international legal frameworks in the coming years, fostering greater accountability and action in the fight against climate change.