Deep-Sea Mining is Coming: Assessing the Potential Impacts

Numerous companies are moving ahead rapidly with plans to mine copper, gold, and other minerals near hydrothermal vents on the ocean floor. But in an interview with Yale Environment 360, marine biologist Cindy Lee Van Dover warns that without environmental safeguards the unique ecosystems of deep-sea vents could be severely damaged.

Deep-sea mining is attracting growing interest from mining companies and could begin in earnest in just a few years. Two firms — Canada’s Nautilus Minerals and Australia’s Bluewater Metals — have stepped up exploration of underwater mountain ranges in the South Pacific. China and Russia have expressed interest in mining the seabed below the Indian and Atlantic oceans, respectively. And a recent report by Nautilus suggests the deep ocean produces several billion tons of minerals each year, including vast amounts of copper.

As the prospect of undersea mining grows ever more likely, one major question looms: Can these valuable minerals be extracted on a large scale without causing significant environmental damage, particularly to the unique ecosystems near the deep hydrothermal vents where the minerals accumulate?

Cindy Lee Van Dover
Duke University
Cindy Lee Van Dover

One scientist seeking to address this question is Duke University marine biologist Cindy Lee Van Dover, who was one of the first researchers to explore hydrothermal vents, cataloguing numerous species of animals and microbes living in a part of the ocean that biologists once assumed was barren. Today, much of her work is focused on figuring out how drilling into the seabed might disrupt newly discovered life forms, such as the giant tubeworms that thrive near the vents.

In an interview with Yale Environment 360, Van Dover compared the deep sea to America’s Wild West and cautioned that wildlife losses could be similar if mining companies and the International Seabed Authority — the regulatory agency in charge of the ocean’s mineral resources — fail to establish environmentally sound mining practices before deep-sea exploitation begins. To this end, she has gone on research trips with Nautilus Minerals, the Canadian mining company, and is advising the company on conservation issues. But time is short, and Van Dover says she is continually surprised by how swiftly deep-sea mining is developing. “When I heard in 2005 that people were serious about wanting to mine hydrothermal vents, I just laughed,” said Van Dover. “Those of us in the biological community just didn’t think mining was going to happen for decades.”

Yale Environment 360: Let’s start with the basics of what hydrothermal vents are and why they produce these valuable mineral deposits.

Van Dover: Sure. So, hot springs on the seafloor are associated with volcanic venting centers, and they’re analogous to hot springs on land in the sense that water percolates down through the crust and reacts with hot rocks, except that on land it’s rainwater and in the ocean it’s seawater. If you just put rock and seawater together at room temperature, nothing happens, but at very high temperatures, the seawater and rock react chemically. The seawater picks up metals from the rocks, then when the hot vent water mixes with the cold seawater, there’s a pH change and a temperature change, and the combined effect causes the metals to fall back down to the seabed to form mineral deposits.

e360: Researchers have only known about hydrothermal vents since the late 1970s, correct?

“There used to be ore bodies on land as rich as what is found on the sea floor, but they are becoming exhausted.”

Van Dover: Yes, the first vents were recognized in 1976, then verified by a manned submersible vehicle in 1977, which collected samples. The geologists knew that there ought to be some kind of convective flow or hot spring because they were taking temperature measurements in the sediment on these mid-ocean ridges — the mountain ranges that girdle the globe — and they were finding that they were not as hot as they should be, given conductive cooling of the ocean floor. So they thought there ought to be hot springs on the seafloor just like on land. Then they found temperature anomalies in the water, which led them to the hot springs.

e360: When did the interest in deep-sea mining begin?

Van Dover: In the early 1980s. Very early on, geologists recognized that hot springs on the seafloor were the submarine version of what is on land. But on the seafloor you find copper, gold, and silver, which aren’t produced by hot springs on carbonate mounds like in Yellowstone National Park.

e360: Is that why there is so much interest in mining the seafloor?

Van Dover: Yes. My understanding is that ore quality is quite high for certain metals, copper in particular. There used to be ore bodies on land as rich as what is found on the sea floor, but they are becoming exhausted.

e360: So the desire to mine the seafloor was there from the beginning, but no one had the technology to do it.

Van Dover: Originally, when the vents were first discovered, there were only a few submersible, deep-water vehicles. But over the past couple of decades the capabilities of remotely operated vehicles and autonomous vehicles has really expanded. So mapping, sampling, plume prospecting — there are many different technologies that have developed that all help the mining companies explore and understand and map out the mineral deposits. I would say it’s very sophisticated.

The Russians have been interested for a long time, and the Chinese have been getting into it since their economic boom. Japan, China, the U.S., Russia and the EU all have big investments in exploration technology, for a multitude of reasons.

e360: How about the technology for extracting the minerals from the seafloor? Is it the same technology that researchers use to extract samples of the marine life?

Van Dover: The mining companies are using two physical tools and a variety of drilling technologies to explore and discover what the quality of the ore is and determine where it’s going to be the most economical to extract it. But the actual exploitation — I believe they’re working on technology that’s used in coal mining and maybe offshore diamond mining, and then trying to apply that to the deep sea so it’s adapted for the particular situation that they’re working in.

e360: You were one of the first researchers to discover the microbes and animals that live down near these vents.

hydrothermal vent
A deep-sea hydrothermal vent located in the East Pacific.

Van Dover: There is no light at the bottom of the ocean, and so no photosynthesis, but there are microbes that feed off the sulfides from the hot springs. Then, there are beautiful animals — giant tubeworms and clams — that feed off the microbes.

e360: How does conservation of these ecosystems factor into the regulations laid out by the International Seabed Authority, the organization the UN created to regulate the seafloor?

Van Dover: The International Seabed Authority does have regulatory authority over the mineral resources on the seabed beneath international waters, and they are responsible for environmental management during the extraction of those resources. Their job is to make sure those resources are exploited in a way that is fair to all countries, all people, that it’s a common heritage of mankind. That’s environment management, but conservation is different from environmental management. Right now nations and mining companies can apply for exploration leases, and down the road they’ll be able to apply for mining leases. And they can choose to mine where they want without thinking about conservation needs.

We need to see if the International Seabed Authority will in fact accept conservation as part of their mandate. We’re all optimistic that they will want to do so. I think there’s no doubt that mining is going to happen. What we want to make sure is that the stakeholders are all talking to one another. The conservation community is a stakeholder, science research is a stakeholder, and mining is a stakeholder. There may be others that come along — tourism, I don’t know what else. The stakeholders need to work together and right now it’s been a mining-dominated philosophy, with environmental management associated with that, but not so much thinking about conservation.

e360: Why wasn’t conservation a priority from the beginning? After all, it was scientists, such as yourself, who first discovered the vents.

Van Dover: When I heard in 2005 that people were serious about wanting to mine hydrothermal vents I just laughed. The International Seabed Authority came to me and asked, “What will we need to care about for hydrothermal vents?” And those of us in the biology community working on hydrothermal vents agreed to do it, but we just didn’t think mining was going to happen for decades. It just didn’t even occur to me that it was feasible.

“It never occurred to me that anyone would want to take away the sulfide that my beautiful animals lived on.”

Right after the vents were discovered, I joined in as a submersible pilot, and it was like the Wild West. We just had a great time. And then I was totally naïve. It never occurred to me that anyone would want to take away the sulfide that my beautiful animals lived on. I had my head in the sand I guess. So, shame on us. In the ‘60s when I was growing up, the deep sea was where we threw trash. Ammunition, munitions waste, chemical waste was all thrown in the deep sea. It was infinitely large — that’s what I grew up on. Of course, I got to realize it wasn’t that infinite and large, but it takes a while to have that really sink into your brain that what we’re doing now is impacting the seabed incredibly. I just thought it would be like the Wild West forever, but I didn’t think about the lessons coming from our own Wild West.

e360: What efforts are there to incorporate conservation into the ISA deep-sea mining guidelines?

Van Dover: A colleague of mine, Craig Smith, has been working with the ISA regarding conservation in areas where there is interest in hydro-manganese mining. It has been welcomed input. They don’t shy away from the issue at all. I think what the conservation community and the scientific community would like to do is have policies in place before the exploitation takes place. I mean, that’s kind of a novel idea, right? Unlike in fisheries, where we’re trying to catch up with all the damage we’ve done.

e360: So conservation practices would be included in the mining permits from the beginning.

Van Dover: That’s right. The explorers in other sites can really help us understand the systems. That would be an ideal situation. But some of this is kind of exciting. I don’t want to see vents mined, but if they’re going to be mined, wouldn’t it be cool to do it in a way that is wise?

e360: What preventative measures could the mining operations take? Would there be spatial restrictions, for example, preserving certain areas?

I don’t want to see vents mined, but if they’re going to be mined, wouldn’t it be cool to do it in a way that is wise?”

Van Dover: I think it could be a combination of things. We would like to set aside some spatial reserves. Especially to begin with, we’d rather err conservatively and have more than we need and then be able to open them up as we understand more about what the impacts are. If it’s not so severe, then maybe we could agree on an acceptable amount of diversity loss. It might be that you’d say, ‘Well, mine this half of the site in these five years and lay the other half undisturbed.’ Maybe if it’s a five-year mine, we’ll just do two and a half years of the extraction and then stop and wait and see what happens, go somewhere else.

There might also be restoration strategies. If the animals are easily moved, one might move them to another area. That’s one idea. Nautilus Minerals has been very active in thinking about these kinds of out-of-the-box ideas, and they do it by engaging the scientists as well. They come to the scientific community and say, ‘Well, what do you guys think we should do? How do we do this well?’ And I think that’s the attitude that they approach this with, and it’s a very interesting thing to challenge the scientists and say, ‘Well, okay, you want us to take care of your environment, tell us how to do it.’

e360: Do you have a sense of how long you have before they would want to start having exploitation?

Van Dover: That’s a good question. I think it’s probably about three, four, or five years down the road.

e360: So you have about 3 to 5 years to get these conservation policies in place.

Van Dover: Yeah, although they may take much longer. My personal view is that these deep-sea vents are exquisite, extraordinary places, and conveying that is important to me. The animals there have adapted in fabulous ways for the environment. And there are still many, many strange animals out there to discover. We haven’t begun to see all the specialized environments there are in the deep sea.

e360: What are your main concerns regarding the ecosystems around the hydrothermal vents?

Van Dover: In some cases these vents have been around for, you know 5,000 years or more, and there’s one example in the mid-Atlantic Ridge of a vent that has built up over 100,000 years. And what we don’t yet understand is, if you were to mine a site like that how quickly will the animals that live there come back? Until we understand the impacts of both a single mining event and a cumulative mining event on one of these older sites, we’re going to wonder how the animals will respond.

We’d also want to know what the genetic diversity is. When you mine you’re going to kill all those animals. You’re going to take away their habitat. But it’s a big area, the size of a couple of football fields. If the mining event is slow, if it takes five years to remove the whole deposit, once you get to the back end, the front end should perhaps already be habitable, so you could have the animals recolonize. But we’re in nursery school when it comes to thinking about this kind of thing.