UN Secretary General António Guterres on Monday urged world leaders to ratify a treaty that would allow nations to establish protected marine areas in international waters, warning that human activity was destroying ocean ecosystems.
Speaking at the opening of the third UN Ocean Conference in Nice, Guterres cautioned that illegal fishing, plastic pollution and rising sea temperatures threatened delicate ecosystems and the people who depend on them.
“The ocean is the ultimate shared resource. But we are failing it,” Guterres said, citing collapsing fish stocks, rising sea levels and ocean acidification.
Oceans also provide a vital buffer against climate change, by absorbing around 30 per cent of planet-heating CO2 emissions. But as the oceans heat up, hotter waters are destroying marine ecosystems and threatening the oceans’ ability to absorb CO2.
Sea levels will rise — by metres, not centimetres — and the time to prepare is now. Drawing on ancient clues and the latest science, Johanna Wagstaffe explains what Earth’s past reveals about our coastal future — and why smart planning today could protect millions in the decades and centuries to come.
“These are symptoms of a system in crisis — and they are feeding off each other. Unravelling food chains. Destroying livelihoods. Deepening insecurity,” said Guterres.
The High Seas Treaty, adopted in 2023, would permit countries to establish marine parks in international waters, which cover nearly two-thirds of the ocean and are largely unregulated.
So far, only an estimated one per cent of international waters, known as the “high seas,” have been protected.

The drive for nations to turn years of promises into meaningful protection for the oceans comes as President Donald Trump pulls the United States and its money out of climate projects, and as some European governments weaken green policy commitments as they seek to support anemic economies and fend off nationalists.
U.S. won’t ratify treaty — and isn’t bound by it
The United States has not yet ratified the treaty and will not do so during the conference, said Rebecca Hubbard, director of The High Seas Alliance.
“If they don’t ratify, they are not bound by it,” she said. “The implementation will take years, but it is critical we start now and we won’t let the U.S. absence stop that from happening.”
A group of leading ocean and climate scientists, including Canadians, is calling for a ban on deep-sea mining just as U.S. President Donald Trump moves to fast-track undersea mining approvals.
French President Emmanuel Macron, the conference’s co-host, told delegates that 50 countries had now ratified the treaty and that another 15 had promised to do so.
The treaty will only come into force once 60 countries ratify it. Macron’s foreign minister said he expected that would happen before the end of the year.
The United States has not sent a high-level delegation to the conference.
“It’s not a surprise; we know the American administration’s position on these issues,” Macron told reporters late on Sunday.
Prince William on Sunday said protecting the planet’s oceans was a challenge “like none we have faced before.”