States have legal duty to cut greenhouse emissions, says top maritime court

Greenhouse gases are pollutants that are wrecking the marine environment, and states have a legal responsibility to control them, an international court has stated in a landmark moment for climate justice.

Wealthy nations must cut their emissions faster than their developing peers, the court also decided.

The statements were part of an advisory opinion on climate change issued on Tuesday by the international tribunal for the law of the sea (Itlos). The tribunal is responsible for interpreting and upholding the 1982 UN convention on the law of the sea (Unclos), an international treaty representing 169 countries.

It is the first time such a document has been issued by an international court.

The opinion was requested by the Commission of Small Island States on Climate Change and International Law (Cosis), a group of nine Caribbean and Pacific island nations led by Antigua and Barbuda and Tuvalu, who are particularly vulnerable to climate breakdown and had become frustrated with the pace of international talks.

In its unanimous opinion, the tribunal stated that the oceans are warming and becoming more acidic as a direct result of carbon dioxide emitted from human activities, resulting in harm to living resources and marine life, hazards to human health and hindrance to marine activities such as fishing.

In their submissions to the tribunal, most countries accepted that greenhouse gases were a form of pollution, but they disagreed on how exactly governments should have to respond to that threat.

Wealthy countries such as the UK and Australia, as well as those in the EU, had contended that climate change was already being dealt with at an international level through the United Nations Framework Convention on Climate Change, which resulted in the Paris agreement in 2015. Under this agreement, countries set their own climate targets and there is no international mechanism for ensuring that they stick to them.

But the tribunal said following the Paris agreement was not enough; the law of the sea imposed specific legal obligations on states and there were consequences for those that did not comply.

The tribunal also says that wealthier nations must shoulder a bigger portion of the burden and support developing states with funding and technical assistance.

As well as cutting emissions from land-based sources, the tribunal says states must control greenhouse gases from international shipping and aviation. This was welcomed by Opportunity Green, an NGO that tries to hold the shipping industry accountable for its emissions.

While the document is not in itself legally binding, such opinions are highly influential and set the framework for future climate lawsuits.