The High Seas Treaty signals a “new era of global ocean governance”, but experts warn that it will not stop irreversible damage.
The highly anticipated High Seas Treaty has come into force today, marking a “historic milestone” for global ocean conservation.
Covering almost half of the planet’s surface, the High Seas lie beyond national borders and form part of the global commons. Until now, there was no legal framework dedicated to protecting biodiversity in these international waters and ensuring the benefits of their resources were shared fairly among nations.
However, following decades of negotiations, a Treaty text was finalised in March 2023, setting clear obligations on how to ensure ocean resources are used sustainably. To come into effect, 60 country ratifications (final approval and consent to be legally bound by a treaty) were required – a milestone that was achieved on 19 September last year.
While experts have praised the agreement as a “turning point” for multilateral cooperation and ocean governance, concern remains around potential loopholes.
What are the High Seas, and why are they so important?
The High Seas is often used to describe all areas beyond national jurisdiction, including the seafloor and water column (the vertical section of water from the surface to the bottom). This equates to international waters that cover more than two-thirds of our ocean - almost 50 per cent of the planet’s surface area.
Once considered barren and desolate, scientists now regard the High Seas as one of the largest reservoirs of biodiversity on Earth. It plays an important role in regulating the climate, supporting “crucial” carbon and water cycles.
In fact, it is estimated that the economic value of carbon stored by the High Seas ranges from $74 billion (around €63.62 billion) to $222 billion (€190.85 billion) per year.
However, human activity poses a growing problem for the High Seas. According to the High Seas Alliance (HSA), which advocated for the treaty, destructive fishing practices such as bottom trawling and illegal fishing are harming High-Seas marine life.
This, combined with plastic and chemical pollution, emerging activities such as seabed mining, and waters being acidified by rising temperatures, puts the High Seas under severe threat.
What will the High Seas Treaty do?
Now international law, the Treaty will empower nations to establish a connected network of High Seas marine protected areas (MPAs) - which can be adopted by a vote when consensus cannot be reached. This helps prevent a single nation from blocking MPAs being established.
It also supports developing countries through capacity building and the transfer of marine technology so that they are better empowered to develop, implement, monitor and manage future High Seas MPAs.
Several legal obligations apply from today. For example, any planned activity under a Party's control that could impact the High Seas or seabed must follow the Treaty’s environmental impact assessment process, and governments need to publicly notify such activities.
Parties must also promote the Treaty’s objectives when participating in other bodies such as those that govern shipping, fisheries and seabed mining.
“At this halfway point of this critical decade, one of the world’s most ambitious ocean initiatives is entering a new era of systemic change in ocean governance,” says Jason Knauf, CEO of The Earthshot Prize.
“This reflects a renewed commitment to our ocean, its wildlife, the millions of people that rely on its health, and the global goals set for 2030. The High Seas Treaty shows us that meaningful progress is achieved through vision, perseverance and leadership.”
Will our oceans be properly protected?
While the High Seas Treaty has been praised by governments, NGOs and environmentalists around the world, concern still surrounds how effective the agreement will be in protecting our oceans.
“Today is a day of celebration for biodiversity and multilateralism, but the job of protecting the ocean is far from complete,” says Sofia Tsenikli of the Deep Sea Conservation Coalition (DSCC)
“The High Seas Treaty raises the bar significantly, but on its own, won’t stop deep-sea mining from beginning in our ocean.”
Several countries that ratified the High Seas Treaty, such as Japan and Norway, have shown interest in digging up vast stretches of the seabed in the race for critical minerals used in green technology.
“Governments cannot credibly commit to protecting marine biodiversity while allowing an industry that would irreversibly destroy life and ecosystems that we barely understand to proceed," Tsenikli adds.
A recent deep-sea mining test found that the controversial practice impacts more than a third of seabed animals, while a report published in 2024 by the Environmental Justice Foundation found that deep-sea mining is not actually necessary for the clean energy transition.
It’s why the DSCC is calling on all members of the High Seas Treaty to use its momentum to establish a deep-sea mining moratorium at the International Seabed Authority.
Dr Enric Sala, founder of Pristine Seas, also warns that the Treaty cannot overlook the value of protecting ocean areas that belong to national governments, as this is where most fishing and other damaging human activities take place.
In a statement, he says the protection of national waters "cannot be put on the backburner”.
“New MPAs – whether they’re established in the High Seas or nearshore – will only be effective if they are strictly protected and fully monitored for illegal activity,” Dr Sala adds.
“This is the only way we can ensure that marine reserves deliver benefits to climate, biodiversity and economies.”
