Who is responsible for international shipping and aviation pollution?

Summary 

• Individual countries have a responsibility under the Paris Agreement and other international conventions to account for, and address, international shipping and aviation emissions. 

• There are a number of possible ways to allocate international shipping and aviation emissions to states. The fairest, for shipping emissions, is to regulate half of emissions from ships arriving and leaving national ports. For aviation emissions, the fairest option is to regulate all emissions for departing flights.

• States should take action in their upcoming Nationally Determined Contributions (NDCs) which are due early 2025. They should also account for these emissions in national climate budgets, then reduce them in line with national legislation and regulation. 

Who is responsible for shipping and aviation pollution?

Emissions from the shipping and aviation sectors are a significant contributor to global warming. However, the international nature of these industries has led some to claim that no individual countries have responsibility for cleaning up the emissions from ships and planes that travel between two different countries. 

In recent years, a number of developments have made it more important to clarify which countries are responsible. First of all, the Paris Agreement of 2015 was a landmark event in international climate governance. It works on the basis of each state taking ‘economy-wide absolute emission reduction targets’ in line with the global temperature goal. 

Secondly, industry lobbies have argued that the sectors escape the Paris Agreement because the International Maritime Organisation (IMO) and the International Civil Aviation Organisation (ICAO) - rather than any individual state - are responsible for international shipping and aviation emissions. Not only is this a misrepresentation of the Paris Agreement, but both the IMO and ICAO have consistently failed in the past two decades to put in place enforceable measures to reduce emissions.

Lastly, courts are increasingly turning their attention towards obligations of states for emissions arising outside of national borders. The advisory opinion on climate change and the ocean issued by the International Tribunal for the Law of the Sea earlier this year specifically addressed states’ obligations to tackle emissions from shipping and aviation, including individual actions which are complementary to global efforts.   

Clarifying how states allocate shipping and aviation emissions is therefore hugely important for national and international climate efforts, an issue which was also raised during the process of the global stocktake of the Paris Agreement in 2023.

What are the different ways of allocating shipping and aviation emissions to countries?

There are a number of proposed and accepted methods to allocate shipping and aviation  emissions to national jurisdictions. Way back in 1994, the UNFCCC gathered to discuss approaches to allocate shipping and aviation emissions. 6 methods were considered:

1. Allocation of emissions from the use of bunker fuels to the country in which the bunker fuel is sold;

2. Allocation of emissions from the use of bunker fuels to the country in which the bunker fuel is sold, but listing these in separate accounts;

3. Allocation of emissions from the use of bunker fuels according to the nationality of the transporting company;

4. Allocation of emissions from the use of bunker fuels to the country where a ship or aircraft is registered;

5. Allocation of emissions from the use of bunker fuels to the country of destination of cargo or passenger;

6. Allocation of emissions from the use of bunker fuels to the country of origin of cargo or passengers.

At that time, the Intergovernmental Panel on Climate Change (IPCC) advised that option 2 was taken, but “[recognized] that a procedure for allocating these emissions will be agreed upon in the future.” Since that meeting, states have consistently postponed discussion of these methodologies.

What is the most sensible way to allocate shipping and aviation emissions?

The European Commission regulates both shipping and aviation emissions on a per-trip basis, although it accounts differently for each sector in different legislation.