As the global demand for critical metals surges, many nations are turning their gaze toward the final frontier: the ocean floor. A major international study, recently published in Nature Ecology and Evolution, has shed new light on the potential consequences of extracting these resources from the deep sea.
While the research suggests that the overall environmental impact might be less catastrophic than some scientists initially feared, it confirms that the local damage to marine life is both immediate and severe.
The Hunt for Green Energy Metals
The push for deep-sea mining is primarily driven by the green transition. Elements such as cobalt, nickel, and manganese are essential for renewable energy technologies but remain in short supply on land. Marine biologist Thomas Dahlgren, who participated in the research alongside Helena Wiklund from the University of Gothenburg, notes that while these metals are abundant on the seabed, the environmental cost of their extraction has long been a mystery.
“Critical metals are needed for our green transition… until now, no one has shown how they can be extracted or what environmental impact this would have,” Dahlgren explains.
Five Years at Sea: Mapping the Clarion-Clipperton Zone
To quantify these risks, an international team of marine biologists spent 160 days at sea over a five-year period. Their research focused on the Clarion-Clipperton Zone, a vast stretch of the Pacific Ocean located between Mexico and Hawaii. Following the guidelines set by the International Seabed Authority (ISA), the team conducted rigorous baseline studies and environmental impact assessments.
The findings were stark. In areas directly disturbed by mining equipment, researchers observed:
• A 37 percent decline in total animal numbers.
• A 32 percent reduction in species diversity.
These paths cut by mining machinery represent zones of significant ecological loss, where the delicate balance of the seafloor is fundamentally altered.
Surprises from the Abyss: Life at 4,000 Metres
Perhaps the most startling discovery was the sheer amount of life thriving in one of Earth’s most inhospitable environments. At 4,000 metres below the surface, where sunlight never reaches and food is incredibly scarce, researchers found a thriving, albeit sparsely populated, ecosystem.
The study identified 788 different species from a collection of 4,350 animals. Notably, hundreds of these species were previously unknown to science. The majority of these creatures belong to groups such as:
- Marine bristle worms
- Crustaceans
- Mollusks (including snails and mussels)
- A newly identified species of solitaire coral
A Fragile Balance: The Deep Sea vs. The North Sea
To illustrate the unique nature of this environment, the researchers compared the deep Pacific seabed to the North Sea. While a single seafloor sample from the North Sea might contain 20,000 individual animals, a similar sample from the deep Pacific contains only about 200 individuals. However, the Pacific sample contains roughly the same number of species as its shallower counterpart.
This high level of diversity combined with low individual density makes the ecosystem exceptionally fragile. Furthermore, the sediment layer in this region grows at a rate of just one-thousandth of a millimetre per year, meaning any disturbance could take centuries, or even millennia, to recover.
Questions & Answers: The Future of Deep-Sea Mining
Why is the Clarion-Clipperton Zone so important?
This region is considered one of the most mineral-rich areas on the planet, containing vast quantities of the “critical metals” required for batteries and green infrastructure.
What is the role of the International Seabed Authority (ISA)?
The ISA is the intergovernmental body that regulates mineral-related activities in international waters. This new study provides the ISA with essential data to help formulate future mining regulations.
Does the study mean deep-sea mining is safe?
Not necessarily. While the “overall” impact might be less than some worst-case scenarios, the 32 percent drop in species diversity along mining paths shows that local ecosystems suffer heavy damage.
Frequently Asked Questions (FAQ)
1. How long did this research project take? The project spanned five years and included 160 days of active research at sea.
2. What kind of animals live 4,000 metres below the surface? Most of the animals found were small (larger than 0.3 mm), including worms, crustaceans, and mollusks. The team also discovered a brand-new type of solitaire coral.
3. Why do we need metals from the ocean? Metals like nickel and cobalt are vital for the “green transition,” specifically for manufacturing the batteries used in electric vehicles and renewable energy storage.
4. How fast does the deep-sea floor recover? Recovery is likely to be extremely slow. Because the sediment grows at only 0.001 mm per year, the “scars” left by mining equipment may remain visible and biologically depleted for a very long time.
