Law of the sea ruling is an ‘important milestone’ for climate and ocean action

Posted on May, 21 2024

Landmark new Advisory Opinion from the International Tribunal for the Law of the Sea (ITLOS) defines obligation for countries to reduce emissions and safeguard marine ecosystems
Hamburg, Germany (21 May 2024): WWF strongly supports the new Advisory Opinion published today by the International Tribunal for the Law of the Sea, which for the first time at a global level defines the legal obligations of states to act on climate change to protect marine ecosystems. These obligations arise under the UN Convention on the Law of the Sea, to which 164 UN member states and the EU are parties.

The Advisory Opinion highlights that states have an obligation to take measures to prevent, reduce and control greenhouse gas emissions to avoid harm to the marine environment, informed by science and relevant international rules, and to conserve and restore marine ecosystems to enhance resilience to climate change and protect natural carbon stocks. The Tribunal makes it clear that states must collaborate to implement all relevant international  agreements to protect the marine environment, including from greenhouse gas impacts.

Commenting on the Advisory Opinion, Pepe Clarke, WWF Oceans Lead, said: “This is an important milestone for the climate and marine ecosystems. It sends a strong signal that reducing emissions and conserving marine ecosystems must be a priority for governments. For decades the environmental, economic and societal imperative to address the climate and nature crises has been clear, but now this Advisory Opinion further establishes that states also have a legal obligation to act. 

The future of small island states and coastal communities depends on decisive global action to reduce emissions and conserve the marine environment. The small island states that initially brought this case are most immediately vulnerable to the impacts of climate change and ocean acidification, but the benefits of tackling the climate and nature crises will be felt by all countries and communities

A healthy ocean can help keep our climate in balance, support economic development and allow habitats and wildlife to thrive. This will only be possible if states positively respond to this opinion and take action now to fulfill their obligations.

WWF made an amicus submission to ITLOS for consideration as part of this opinion, which argued climate-related obligations include rapidly reducing emissions while conserving and restoring the marine environment. 

While non-binding, this opinion could have far reaching implications for national decisions. In light of this opinion, WWF urges countries to include measures that sufficiently reduce greenhouse gas emissions and safeguard marine ecosystems in their biodiversity plans (NBSAPs) and climate plans (NDCs). 

This opinion follows other significant legal rulings from international and national courts that have underlined the legal obligations of states to act on climate and nature, such as the recent ruling by the European Court of Human Rights that found human rights were being compromised due to lack of climate action. The Inter-American Court of Human Rights and the International Court of Justice (ICJ) – the highest legal body in the UN system – are also currently considering advisory opinions on climate obligations.

WWF will now also make an amicus submission to the ICJ, responding to the questions posted in the request for an advisory opinion, drawing on our expertise regarding climate change and links to nature and biodiversity. We intend to highlight existing states’ obligations to protect nature and biodiversity as key for climate change mitigation and adaptation. We will outline how greenhouse gas emissions and other observable climate change effects already bring severe harm to nature and people, thereby violating existing international environmental law. Finally, we will also recall the role which nature can also play in helping to tackle climate change.


Robin Harvey
​Izrael Muhamad 

Notes to Editors

Information on the tribunal, the case and WWF’s brief:
  • ITLOS Advisory Opinion is available here 
  • WWF’s amicus brief submission is available here 
  • A legal request from the Commission of Small Island States was lodged in December 2022 with the International Tribunal for the Law of the Sea (the Tribunal). The UN Convention on the Law of the Sea (UNCLOS) establishes the legal order applicable to the world’s seas and oceans. 
  • The Commission of Small Island States asked the Tribunal for an Advisory Opinion on what the specific obligations of the state parties to the Convention are: 
    • (a) to prevent, reduce and control pollution of the marine environment in relation to the deleterious effects that result or are likely to result from climate change, including through ocean warming and sea level rise, and ocean acidification, which are caused by anthropogenic greenhouse gas emissions in the atmosphere
    • (b) to protect and preserve the marine environment in relation to climate change impacts, including ocean warming and sea level rise, and ocean acidification.
Information on climate change and oceans:
  • About 70% of the Earth’s surface is ocean, which is critical to life on Earth and for regulating the global climate system. 
  • Due to its size and reflective capacity, the ocean has absorbed more than 93% of the heat generated by anthropogenic global warming since 1971 (see IUCN Explaining Ocean Warming report, p17).
  • The ocean has absorbed about 20 to 30% of the carbon dioxide produced by human activities since the 1980s, leading to ocean acidification. This has resulted in changes to ocean chemistry that are unprecedented in 65 million years (see WWF Climate, Nature and our 1.5°C future report, p12-13).
  • Excessive heat and energy warming the ocean is leading to a cascade of melting sea-ice, sea level rise, marine heatwaves, ocean acidification and deoxygenation which, cumulatively, is causing lasting impacts on marine biodiversity and increasing the risk of irreversible loss of marine and coastal ecosystems.
  • According to the IPCC, hundreds of local losses of species have been driven by increases in the magnitude of heat extremes and mass mortality events on land and in the ocean (see Intergovernmental Panel on Climate Change AR6 Synthesis Report, p15).
  • Coral reefs, which make up some of the most species-rich habitats on Earth, are suffering heavily: scientists expect major damage to reef-building corals with 1.5°C global warming and warm water corals to all but disappear above 2°C (see WWF Climate, Nature and our 1.5°C future report, p18). In April 2024 NOAA announced a mass coral bleaching event
  • The loss of nature in our ocean is also having severe impacts on people, particularly for the billions who rely on fish and other seafood for their primary source of protein, as well as livelihoods.