A global maritime court has found that greenhouse gases constitute marine pollution — a major breakthrough for small island states threatened by the rise in sea levels caused by global warming.
In its first climate-related judgment, the International Tribunal for the Law of the Sea said emissions from fossil fuels and other planet-warming gases that are absorbed by the oceans count as marine pollution.
It also said countries had an obligation to take measures to mitigate their effects on oceans.
The countries that brought the case called the court decision "historic" and experts said it could be influential in shaping the scope of future climate litigation involving greenhouse gas (GHG) emissions.
The court ruled in an expert opinion that "anthropogenic GHG emissions into the atmosphere constitute pollution of the marine environment" under the United Nations Convention on the Law of the Sea (UNCLOS).
Polluting countries therefore have "the specific obligation to take all measures necessary to ensure that … emissions under their jurisdiction or control do not cause damage by pollution to other states and their environment", the court said.
The UNCLOS treaty binds countries to prevent pollution of the oceans, defining pollution as the introduction of "substances or energy into the marine environment" that harm marine life.
But it does not spell out carbon emissions as a specific pollutant, and the plaintiffs had argued that these emissions should qualify.
Win for low-lying island nations
The case was brought in September by nine small countries disproportionately affected by climate change, including Antigua and Barbuda, Vanuatu and Tuvalu.
They asked the Hamburg-based court to issue an opinion on whether carbon dioxide emissions absorbed by the oceans could be considered pollution, and if so, what obligations countries had to address the problem.
Over two days of hearings in September, the leaders of the nine countries said the effects of climate change were threatening their nations' very existence.
The court's opinion is advisory and non-binding but will influence how the UN treaty is interpreted around the world.
"This is the first-ever decision by an international tribunal on climate change and the oceans and clarifies the legally binding obligations of 169 countries that are party to the [UNCLOS treaty]," the nine plaintiff countries said in a statement.
The prime minister of Antigua and Barbuda, Gaston Browne, said small island nations were "fighting for their survival".
"Some will become uninhabitable in the near future because of the failure to mitigate greenhouse gas emissions," Mr Browne said.
"We demand that the major polluters respect international law and stop the catastrophic harm against us before it is too late."
Ruling the first of its kind
The case is seen as the first big international climate justice case involving the world's oceans and experts say it could have far-reaching implications for countries' future climate change obligations.
Senior attorney at the Center for International Environmental Law (CIEL) Joie Chowdhury said in a statement that the court made its position clear.
"For the first time, an international court has recognised that the fates of two global commons — the oceans and the atmosphere — are intertwined and imperilled by the climate crisis," Ms Chowdhury said.
"Today's historic climate Advisory Opinion by the International Tribunal for the Law of the Sea unequivocally affirms that states have clear and specific obligations under international law to act urgently, ambitiously, and equitably to protect our precious oceans from the drivers and impacts of climate change."
CIEL said the ruling is the first of three key international court advisory opinions on climate change.
The others are due to be given by the Inter-American Court of Human Rights and the International Court of Justice.
Executive director at the International Institute for Environment and Development Tom Mitchell told AFP the tribunal's opinion "is an important marker on the legal responsibility for the effects of climate change, which will doubtless be influential in shaping the scope and direction of future climate litigation".
Ocean ecosystems create half the oxygen humans breathe and limit global warming by absorbing much of the carbon dioxide emitted by human activities.
But increasing emissions can warm and acidify sea waters, harming marine life and ecosystems.
Rising global sea temperatures are also accelerating the melting of polar ice caps and increasing sea levels, posing an existential threat to small island nations.
The EU's Copernicus Climate Change Service found global sea surface temperatures hit a monthly record in April for the thirteenth month in a row.
AFP/Reuters/ABC
