Legal briefing for policymakers: the ITLOS advisory opinion

Background

In May 2024, the International Tribunal for the Law of the Sea (ITLOS) handed down its advisory opinion on states’ obligations under the United Nations Convention on the Law of the Sea (UNCLOS). This advice sets out how the aviation and marine industry must tackle the climate crisis and protect the seas and oceans from harm caused by greenhouse gases (GHGs). 

The advisory opinion clarified States’ obligations to limit GHG emissions. These are strict obligations that are unlikely to be achieved by simply following the Paris Agreement, or by taking part in the International Maritime Organization (IMO) or International Civil Aviation Organization (ICAO) initiatives. States need to adopt measures that follow the best available science to ensure global warming does not breach 1.5ºC. While international efforts are still short of this standard, States need to take unilateral or regional action to meet their international legal obligations. 

Traditionally, aviation and shipping have deferred to the ICAO and IMO respectively. But these UN agencies are not fully aligned with the 1.5ºC target. States, therefore, need to take further domestic and regional action to meet their legal obligations and avoid opening themselves up to legal action for failing to do so. 

The scale of the problem

• The global shipping sector accounts for 3% of global GHG emissions
• Aviation accounts for 2.5% of annual global CO2 emissions
• Aviation accounts for 4% of all global warming

What’s covered in the report?

The briefing sets out: 

• Recommendations for policymakers relating to the aviation and shipping sectors.  

• A summary of the key legal findings of the advisory opinion.

• A detailed legal analysis of the advisory opinion and its implications for the international shipping and aviation sectors. 

Among its main findings are:

• Human-caused GHG emissions constitute “marine pollution” under UNCLOS, placing numerous legal obligations on States.

• States need to take “all necessary measures” to prevent, reduce and control marine pollution from “any source” under article 194(1) UNCLOS.

• The nature of the obligation under article 194(1) is one of due diligence with a stringent standard, given.
• The high risks of serious and irreversible harm to the marine environment from GHG emissions. 

Our recommendations

1. States should adopt domestic legislation and regulation to address the climate impacts from global shipping and aviation. 
2. States need to take all necessary measures to prevent, reduce and control marine pollution caused by GHG emissions from “any source”, including shipping and aviation. 
3. States should cooperate to increase ambition and action at the International Maritime Organization (IMO) and the International Civil Aviation Organization (ICAO). 
4. Developed States should provide financial assistance to (in particular, climate vulnerable) developing States. 

Read our report in full below.