ST Explains: Why the climate ruling by the world’s top court dealing with oceans is a game changer

SINGAPORE – A landmark opinion issued by the world’s top court dealing with oceans said on May 21 that greenhouse gases emitted by human activity are pollutants and nations have a responsibility to cut emissions that are damaging the marine environment and heating up the planet.

The opinion by the Hamburg-based International Tribunal for the Law of the Sea (Itlos),

though not binding, makes clear that nations have a legal responsibility to take all necessary measures to reduce, control and prevent marine pollution caused by human-made greenhouse gas emissions.

Here’s a look at the key aspects of the opinion and why it is important.

What is the case about?

In December 2022, nine Caribbean and Pacific island nations sought the opinion of the tribunal on two questions relating to the specific obligations of states that are party to the 1982 UN Convention on the Law of the Sea (Unclos) – a key treaty establishing rules governing all uses of the oceans and their resources. Nearly 170 nations, including Singapore, are party to the treaty.

Itlos is an independent judicial body set up by the convention.

The tribunal was asked what are the obligations of parties to Unclos regarding preventing, reducing and controlling pollution of the marine environment and damage linked to global warming and greenhouse gas emissions; and, second, states’ obligations to protect and preserve the marine environment in relation to climate change impacts, including ocean warming, sea-level rise and ocean acidification.

The nine nations, including Tuvalu, Palau and the Bahamas, brought the case because small island states are suffering some of the worst impacts of climate change, such as worsening storms, rising sea levels, coastal erosion and damage to fisheries. For decades, small island states have been stepping up diplomatic and legal efforts to hold big polluters to account for the impacts of their greenhouse gas emissions. But they have struggled to make headway.

What did the tribunal say?

The tribunal’s 21 judges were unanimous in their advisory opinion that man-made greenhouse gas emissions constitute pollution under the Unclos treaty. This is the first time such a determination has been made by an international judicial body. The treaty mentions pollution but does not specifically refer to greenhouse gases.

The court said that states have a legal obligation to monitor and reduce the emissions that contribute to climate change. It spelled out specific requirements for environmental impact assessments for any planned activity that may cause substantial pollution to the marine environment.

This would apply to land-based activities that in the past might not have taken into account the atmospheric impacts of these activities on the marine environment, said Dr Nilufer Oral, director of the Centre for International Law at the National University of Singapore. 

The court said states’ targets for cutting greenhouse emissions must be based on the best available science and international rules and standards, thus setting the bar higher than the 2015 Paris Agreement, said Dr Oral. 

She said the tribunal, for the first time, has made adaptation to the adverse effects of greenhouse gas emissions part of the obligation to protect and preserve the marine environment.

Why is the opinion important?

“The opinion, while not legally binding, is authoritative. This means states must pay attention to it. The opinion has directly linked the obligation for states to reduce greenhouse gas emissions to the prevention, reduction and control of pollution from any source,” Dr Oral told The Straits Times. This pollution mainly comes from the production and burning of fossil fuels.

The Itlos ruling directs states and courts, national and international, to apply and enforce obligations under Unclos consistently to combat climate change, said Dr Constantinos Yiallourides, deputy director of the Centre for Environmental Law at Macquarie University in Sydney. 

Experts said the opinion could lead to more claims for damages against polluting nations and add weight to those claims. There has been a surge in climate-linked litigation targeting governments and companies in recent years over climate policies and carbon pollution, with a growing focus on harm to human rights.

“It is likely that other international and national courts will consider the Itlos advisory opinion when making their own assessments on climate-related cases, including challenging the legality of high-emitting activities due to their potential carbon footprint on the oceans,” said Dr Yiallourides.

For instance, the ruling is expected to influence more than 2,000 domestic climate litigation cases seeking to hold governments and corporations accountable for inadequate climate action. And it is likely to influence ongoing climate proceedings at the International Court of Justice and the Inter-American Court of Human Rights, which are also hearing key cases on states’ obligations.

“Itlos’ ruling should serve as a wake-up call for all major CO2-emitting countries to adopt more robust environmental due diligence measures to combat emissions, in accordance with Unclos and relevant international law requirements. Failure to do so could leave them vulnerable to climate litigation both internationally and domestically,” said Dr Yiallourides.

Why the focus on oceans?

The opinion means that states will have to pay greater attention to the oceans, which have absorbed 90 per cent of the excess atmospheric heat from man-made global warming and soaked up a quarter of carbon dioxide (CO2) emissions from human activity. “This has not been the case,” said Dr Oral.

The connection between oceans and climate change is clear and undisputed, said Dr Yiallourides.

“Oceans control the climate system by absorbing heat and carbon dioxide, while climate change from greenhouse gas emissions causes ocean acidification, ocean warming and sea-level rise, threatening many low-lying island nations. These island nations are urgently seeking protection under international law,” he added.

Oceans also cover about 70 per cent of the planet’s surface and are increasingly suffering from climate impacts that ultimately will affect billions of people across the globe, such as damage to fisheries and coral reefs and flooding of coastal cities, from Singapore to Miami to Mumbai.

What are some of the other reactions?

“Next year (2025), states must improve the climate plans they submit to the United Nations – known as their Nationally Determined Contributions – and the outcome from Itlos will be instrumental to push the countries most responsible for the climate crisis to ramp up their ambition,” said lawyer Lea Main-Klingst for London-based legal charity ClientEarth.

Ms Nikki Reisch, climate and energy programme director for the Centre for International Environmental Law, said: “To those that would hide behind the weaknesses of international climate treaties, this opinion makes clear that compliance with the Paris Agreement alone is not enough. Protecting the global commons of the oceans and atmosphere is a matter of life and death – not just for entire marine ecosystems and the coastal and island communities most directly dependent on them and at greatest risk from climate change, but for all of humanity and the planet as a whole.”