The Deep Ocean Is Essential for Life on Earth—but It Is Under Threat
Seabed mining could destroy biodiversity and habitats, and sacrifice benefits not yet understood, marine biologist says
As a small handful of private companies and countries push for the international community to allow commercial-scale mining on the ocean floor, deep-sea biologist Diva Amon and colleagues are urging that decisions be grounded in science. There’s just one problem. Scientists don’t yet know enough about the deep ocean to ensure its protection.
That’s why Amon led a study—just published in Marine Policy and co-authored with two researchers from The Pew Charitable Trusts—designed to identify the gaps in environmental knowledge for areas where deep-sea mining might take place. The article also proposes a path for filling those gaps to help ensure that the necessary scientific information is available for evidence-based decision-making.
This interview with Amon, director and founder of the nonprofit group SpeSeas, has been edited for clarity and length.
Q: Why is the deep ocean so important?
A: The deep ocean is not only incredible and huge, but it’s a vast reservoir of biodiversity, from glowing sharks to armoured snails, with new species being discovered every year. And the deep ocean and its inhabitants are absolutely essential to keeping our planet healthy and keeping us alive by sequestering carbon and forming the basis of food chains that sustain billions of people.
Q: And yet there’s a “but,” isn’t there?
A: Yes. The deep ocean provides critical benefits to humanity—but unprecedented changes are already happening due to human-caused stressors such as climate change, habitat destruction, and overfishing. And the exploitation of the deep ocean could grow even worse if seabed mining moves forward. If we continue to proceed on this path blindly and irresponsibly, we will likely lose parts of our planet before we truly know them. The deep ocean includes places that could be as iconic as the Okavango Delta, the Himalayas, and the Grand Canyon, and potentially as important as the Amazon rainforest. When we find these places, we need to protect them. But we can’t effectively manage and protect what we don’t know, understand, and value.
Q: Your paper seeks to identify gaps in the world’s scientific knowledge about the deep sea. Where does that knowledge stand?
A: Although we know more than we ever have, we still have a long way to go. Our team of scientific and policy experts synthesized the peer-reviewed literature and consulted with deep-sea mining stakeholders and found that, despite an increase in deep-sea research, there are few categories of publicly available scientific knowledge that are comprehensive enough to enable evidence-based decision-making on whether to proceed with deep-sea mining in regions where exploration contracts have already been granted by the International Seabed Authority (ISA).
Q: Can you say more about these existing contracts for deep-sea mining?
A: The International Seabed Authority has granted exploration contracts in 31 areas. I was really struck that even in these regions, there’s not enough data available to even answer our most fundamental questions—such as, “What lives there?” How could it be OK to move forward with this new extractive industry, on the scale and in the time frame that the ISA is pushing, if we’re missing comprehensive information that’s essential to guide environmental management?
Q: How long do you think it will take to close this knowledge gap?
Q: How many?
A: We estimate at least three decades. There’s no way we’ll have the critical scientific information we need to prevent serious harm and ensure effective protection of the deep ocean in the next two years, or even the next 10 years. There is still a lot left to understand about how deep-sea environments will cope with the impacts of mining because there have been very few tests done, and none of them on the scale or intensity of proposed commercial deep-sea mining operations. We simply don’t know enough yet about the deep sea.
Q: What does that mean for the prospect of seabed mining?
A: Our findings support pressing pause on the commencement of exploitation. The potential dangers of deep-sea mining may far outweigh the benefits.
Q: What kinds of dangers?
A: Deep-sea mining will have direct impacts that we can easily predict as well as possible indirect impacts that may be much harder to forecast. We know that mining machines would remove and destroy the habitat in their direct path, killing most life. Sediment plumes from seafloor disturbance kicked up by the machines and the wastewater returned to the sea from onsite processing could travel tens to hundreds of kilometers vertically and horizontally. There could also be changes to geochemical and physical properties of the seafloor and water column, and the release of pollutants, including noise and light that would impact sensitive animals who otherwise live in a very stable environment. Overall, given the connected nature of the ocean, the footprint of deep-sea mining could extend way beyond the actual mining operation.
Q: Are there specific qualities of the deep ocean that make seabed mining particularly problematic?
A: Because most of the deep ocean is slow and stable, with time scales completely different from what you and I are familiar with, deep-sea ecosystems don’t cope well with change. Recovery will be slow, if it happens at all, given that deep-ocean formations—such as polymetallic nodules, potato-sized rocks on the seafloor that contain metals considered valuable by potential miners—develop over millions of years.
Q: What role does science play—or should it play—in policymaking, especially concerning the deep ocean?
A: Robust independent science must underpin policymaking, and the deep ocean is no different. The challenges we face are growing more and more complex and the need for sustainable solutions for the future more and more urgent. Scientific research plays a key role in solving these challenges, helping us to protect lives and the environment, and raise awareness. But scientific research conducted in a vacuum, without the results and lessons learned being shared broadly, will lead to significantly limited societal benefits. As scientists, we have a responsibility to make sure that policymakers understand the value of our science—and have access to the best available scientific knowledge.