The more we see ourselves as separate from nature, the more alienated we become from it. We have a similar relationship with the oceans, even though they cover more than 70% of our planet. For a very long time, humanity viewed the ocean as a vast, distant entity apart from itself and continually placed a distance between us and these immense waters.
Yet the ocean has always been beside us, present in the air we breathe, the food we eat and the climate that makes our lives possible - compelling proof that the greatest distances are created not by geography or maps, but in the mind.
Our perception is nevertheless changing and this distance is beginning to close. The most important step came in 2023, after 20 years of negotiations, when the United Nations adopted the historic High Seas Treaty to protect biodiversity in areas beyond national jurisdiction. The fair sharing of marine genetic resources and the benefits derived from them, and expansion of marine protected areas, are among the priorities of the treaty, which entered into force in early 2026.
A New Relationship with the Ocean
World Oceans Day, observed every year on 8 June to raise awareness of oceans affected by climate change, biodiversity loss and pollution, adopted a theme this year focused on closing the distance between humanity and the ocean.
Entitled "Reimagine: Beyond the World We Know, a New Relationship with the Ocean", the theme seeks to accelerate humanity's transition from passive beneficiaries of the ocean's generosity to active guardians of its future.
The oceans cover 70% of the planet and produce at least 50% of the world's oxygen. They host most of the planet's biodiversity and provide the principal source of protein for more than one billion people worldwide. They are also vital to the economy, with approximately 40 million people expected to work in ocean-based industries by 2030.
By absorbing approximately 90% of the excess heat caused by human activity, the oceans serve as a major line of defence against climate change. They also absorb a significant share of excess carbon dioxide from the atmosphere. This changes the chemistry of seawater and is pushing ocean acidification towards a critical threshold. Plastic waste and microplastics are now found in every ocean basin, and pollution is also present in deep-sea ecosystems.
What Could Deep-Sea Mining Deliver?
In recent years, the oceans have faced another kind of threat. As the world takes important steps towards a green transition, electrification is increasing demand for critical minerals including cobalt, lithium, nickel and certain rare-earth elements.
The search for these important natural resources has therefore extended from land to the ocean floor, placing deep-sea mining increasingly on the agenda.
This creates a dilemma. Can minerals needed for a lower-carbon future be extracted from the seabed without damaging the world's largest and most important ecosystem? Because much of the deep sea remains unexplored, the full environmental risks are unknown.
Supporters argue that deep-sea mining could help meet countries' growing demand for critical minerals as decarbonisation, digitalisation and infrastructure investment advance. They also point to projections that global demand for nickel, cobalt and rare-earth elements could double by 2040 under a net-zero emissions scenario.
The Risks Are Extensive
The environmental risks of deep-sea mining are considerable. The activity principally targets minerals contained in potato-sized polymetallic nodules on the ocean floor. Copper, cobalt, zinc and nickel are among the most valuable elements found in these nodules.
The US Geological Survey estimates that the Clarion-Clipperton Zone alone, between Mexico and Hawaii in the Pacific Ocean, contains approximately 21.1 billion dry tonnes of nodules. Yet more than 5,000 new species have been discovered in this region alone.
One of the most important risks concerns the ocean carbon cycle. The oceans are the world's largest carbon sink, and microscopic organisms play a critical role in this climate-regulating system. Biodiversity loss caused by deep-sea mining could affect the ocean carbon cycle and reduce its capacity to limit global warming.
Mining could also kill marine life through wastewater, overheating and toxic effects, causing long-term degradation of species and ecosystems. Because polymetallic nodules provide an important habitat for deep-sea organisms, scientists agree that mining-related habitat loss could drive some species to extinction and that these ecosystems, even if recovery were possible, would take a very long time to recover.
The risks are not confined to the seabed. Under current designs, waste discharged from mining vessels could spread kilometres beyond the mined areas, threatening open-ocean fish and invertebrates that are important to international fisheries.
The Circular Economy and Advanced Recycling Are the Principal Alternatives
Alongside these risks, many experts directly challenge the claim that deep-sea mining is necessary for the green transition. Expanding a circular-economy model and implementing advanced recycling systems are the leading alternatives for securing valuable minerals. It has been demonstrated, for example, that almost all lithium can be recovered from used electric-vehicle batteries.
According to the International Energy Agency, recycled copper could meet approximately 40% of total demand by 2050.
Opposition is not limited to scientists. In recent years, Indigenous peoples, fishing communities, environmental organisations, financial institutions and governments have joined scientists in seeking a moratorium or complete ban on deep-sea mining. Nearly 1,000 marine scientists and policy experts from more than 70 countries have signed a call for a moratorium, while 38 countries have called for a precautionary pause or ban.
Deep-sea mining will clearly be debated more widely in the coming years. Yet we should remember that, for the first time in a generation, humanity has chosen to govern a significant part of our shared ocean collectively. At this point, we cannot afford activities that could weaken one of our greatest remaining lines of defence against climate change. The ocean does not begin at the coast; it continues everywhere we breathe.
16 June 2026
