Making waves

In 399BC, a group of Greek soldiers was desperately lost. They had been fighting in PersiaA historic region of southwestern Asia, linked to the area that is now Iran. , thousands of miles from home, only to find themselves with no supplies and no money. Finally, one day, they stumbled across the Black SeaA sea between Europe and Asia, with coastline in Russia, Ukraine, Turkey, Bulgaria, Georgia and Romania. , and their joy was unrestrained: to a man, they shouted "thalatta, thalatta!" - "the sea, the sea!"

For those Greeks, the sea was home. It was a secure source of food, a place where other people gathered, a route back to their cities. It was the very centre of their world.

Two thousand years later, we are as reliant on the sea as ever. Ocean-based industries are estimated to employ more than 40 million people. And at least half of all the oxygen on earth comes from phytoplanktonVery small plants that float near the surface of water. Sea creatures feed on them. , tiny plant-like creatures that float on the surface of the sea and live off sunlight.

That is why the UNUnited Nations. An intergovernmental organisation based in New York that aims to maintain international peace and security. has put forward a new agreement, the High Seas Treaty, which aims to make sure this vital resource will still be able to sustain us two millennia from now.

The oceans are staggeringly biodiverse. We do not even know how many organisms they hold: it is estimated that we might have encountered just 9% of all ocean species.¹

But this may soon change. Human activities, especially fishing, mining, and pollution, threaten to kill off vast swathes of this life. More than two-thirds of fish species and 90% of sharks and rays are at risk of extinction.

The new treaty, agreed over the weekend after a full decade of negotiations, promises to reverse the loss of biodiversity in the oceans and bring about more sustainable development.

Two-thirds of the world's oceans do not belong to any country. That means all nations have the right to exploit them, leaving them vulnerable to overfishing and pollution. The agreement will place 30% of this space into protected areas, where there will be limits on fishing and mining. 

The treaty still has to be formally adopted by the UN, and then signed and implemented by member nations. But many are optimistic that it could be a turning point for the oceans.

Others, however, say we must go further. Fishing and mining are only one part of the threat to the world's oceans. Climate breakdown is set to do much more far-reaching damage.

As atmospheric CO2 dissolves in seawater, the acidity of the water rises. This lowers the concentration of carbonate ions, which many sea creatures, including molluscsAny animal with a soft body and no spine, usually living in a shell. , oysters and corals, need to make their shells and skeletons.

Corals are also affected by coral bleaching. This takes place because the algae that lives in their tissues, and gives them their bright colours, cannot withstand warmer temperatures. Sustained bleaching kills the corals. Since 1950, there has been a 50% loss of warm water coral reefs, some of the world's most biodiverse and important ecosystems.²

The climate crisis is also reducing the oxygen levels of the oceans. Most larger sea animals rely on absorbed oxygen for survival. Many are already at risk of extinction.

Yes: This treaty is a great achievement. It will protect almost a third of the world's open oceans, reduce pollution, and restore biodiversityBiodiversity is all the different kinds of life you'll find in one area - the variety of animals, plants, fungi, and even microorganisms like bacteria that make up our natural world. Each of these species and organisms work together in ecosystems, like an intricate web, to maintain balance and support life. .

No: The treaty has been watered down too far. There should be an outright ban on fishing and mining in protected areas, not just a reduction. And rich countries need to commit much more money to protect the oceans.

Or... Anything we do to protect the oceans from economic activities will only go so far. The single biggest threat to the oceans is the climate crisis. Unless we stop pumping CO2Carbon dioxide. into the atmosphere, the oceans are in danger.