Sunday, December 22, 2019

Ocean floor mining: What could possibly go wrong?

A recent article on undersea mining in The Atlantic brought back a detailed childhood memory. When I was in fifth grade, my class put on a sort of mini science fair and performance art program for parents. My project focused on the prospect of mining the oceans. I drew a large mural-like color illustration showing a submarine stationed just above the seabed where it hoovered up minerals with large hoses. 

The submarine had wide pipes running from it to the surface where a ship received the nodules of ore gathered by the hoses. During my presentation the classroom was dark, and my mural was illuminated using three small articulating lamps turned on and off by a classmate as I went through the distinct phases of the mining operations in a room meant to mimic the dark and foreboding deep.

It turns out these many years later that my cursory research into ocean mining as a fifth-grader yielded a roughly accurate portrayal of what is about to happen in the oceans starting early in the coming decade. The world's nations may conclude a treaty governing undersea mining through the auspices of the United Nations as early as next year. Once that is concluded, large scale mining of ocean bottoms is expected to begin.

One method—already in use in coastal waters controlled by individual countries—will be to suck up nodules of ore lying on the seabed with huge vacuums and filter out the sediment that comes with it. This method will move quickly to the deep ocean once the treaty is approved resulting in huge, dense clouds of particles suspended underwater for possibly hundreds of miles from underwater mining sites. Scientists are worried that both the vacuuming and the plumes will destroy entire ecosystems about which we know little.

I am reminded of the hydraulic mining employed in California in the late 19th century to recover gold from the mountains there. What looks like natural erosion today in those mountains is quite often the result of high-pressure washing of mountainsides with water to unearth specks of gold hidden in the soil.

Geologists estimate that this type of mining sent 13 billion cubic yards of the Sierra Nevadas hurtling down the mountains and into California's rivers. The river bottoms filled, rose and dumped their debris on adjacent land covering thousand of acres of farmland with the detritus from mining. When the water reached the ocean underneath San Francisco's Golden Gate bridge, it was still brown with silt.

Deep ocean mining will probably not affect shorelines because the mining will take place too far from land. But the affects are likely to be profound nonetheless. It turns that:

About a third of the carbon dioxide generated on land is absorbed by underwater organisms, including one species that was just discovered in the CCZ in 2018. [The Clarion-Clipperton Zone, located between Hawaii and Mexico, is 1.7 million square miles of prime underwater real estate for mining that is also teaming with life.] The researchers who found that bacterium have no idea how it removes carbon from the environment, but their findings show that it may account for up to 10 percent of the volume that is sequestered by oceans every year.

I have asked in a previous piece: "Which species are we sure we can survive without?" This little bacterium may be one of them. But, as it turns out, there are an untold number of species we know nothing about because no one has had the resources or equipment to go deep into the ocean to make a thorough-going catalog of living organisms there. Even so, we stand of the edge of eliminating many of them without even understanding whether we might need them to survive.

All of this will ironically be in service to the so-called "green economy." Minerals found on ocean seabeds—copper, cobalt, and manganese—are crucial to the move away from fossil fuels toward electricity as fuel for the world's transportation fleet. Will we end up devastating ocean organisms that absorb more carbon dioxide than we'll save by moving toward electrified transportation? In our blindness we can't see that our solutions lead to more problems, some of which merely compound our woes. The plumes resulting from undersea mining will contain in some cases mercury and lead liberated from the seabed that will poison the surrounding ocean and creatures large and small living there.

When I did my fifth-grade presentation, I wasn't thinking of consequences, only riches. I passed around samples of metals I had acquired from a high-school chemistry teacher who took an interest in my project. Small, irregular globules of manganese, copper, and iron—metals which the mining operations might capture in the form of polymetallic chunks—were circulated among the parents and students.

Someday somebody's going to get rich mining these minerals, I thought at the time. That someday seems to be arriving.

Kurt Cobb is a freelance writer and communications consultant who writes frequently about energy and environment. His work has appeared in The Christian Science Monitor, Resilience, Common Dreams, Naked Capitalism, Le Monde Diplomatique,, OilVoice, TalkMarkets,, Business Insider and many other places. He is the author of an oil-themed novel entitled Prelude and has a widely followed blog called Resource Insights. He is currently a fellow of the Arthur Morgan Institute for Community Solutions. He can be contacted at


sv koho said...

It remains to be seen what the cost in money and energy could be for this Hoover method of extraction. For iron: ridiculous. Copper or manganese seems unlikely unless they were very pure because these elements are still readily available as ores and easily recycled. Electric powered transport while feasible in dense urban environments will never be functional in the air or on the oceans. If we in fact are seeing the decline of the industrial revolution this century, such technology may be moot anyway.

Anonymous said...

Kurt, it amazes me that people are still writing articles like yours today. You need to do far more research into the subject before publishing as you (and others like you) are capable of doing real damage to the environment and to humanity with this message.

First, let's acknowledge that society will cease to exist as we know it without mining. Mining puts food on our tables, builds our homes, and provides heat for our homes. Recycling can help meet demand for metals, but it can't meet all needs and it is often prohibitively expensive.

If we've established that mining is required then we also need to acknowledge that all mining carries costs - impacts to the environment are real and consequential.

I think that if we have agreed to these first two points, we should also agree that our objective should be to mine in a manner that is designed to do as little environmental damage per ounce of mineral mined as possible. To that end, seabed mining for nodules and other surface ores, that is not located in extremely unique and sensitive environments is universally better for the environment than terrestrial mining and should be encouraged if our aim is truly to spare the environment.

It is true that there are attributes of ocean life that we haven't yet discovered - just as it is true that there are attributes of life deep within terrestrial mines that we haven't yet discovered. But sucking up nodules from a small section of ocean, while leaving 30% of the area set-aside to recolonize will not eliminate any species.

Seabed mining for nodules simply does much less damage than terrestrial mining for the same minerals. It uses far less land since the ores have high concentrations. It doesn't destroy the terrain because there is no overburden removal. The process emits fewer GHG emissions because of the combination of the two prior points. It doesn't create toxic wastelands post-mining, and it doesn't spoil fresh water. It doesn't displace humans, and it won't employ underage minors in dangerous slave-like operating conditions. It doesn't require permanent infrastructure built to support the operation, nor does it require dangerous tailing damns.

You are correct to cite the plume as the number one environmental impact of ocean mining. Look at recent studies done at MIT for background. The plume left by bottom operations extends no more than a few km, far fewer than what you mention in your article. It's true that mid-level ocean sediment disperal will create plumes that travel longer distances, but they also dilute to insignificant levels quickly. Regardless, mid-level disperal is not required in all systems, and it may be avoided all together.

The fact that we are discussing plume dispersion at all is a point in favor of seabed mining. Terrestrial mining causes massive plume dispersion also, but the plume is in the atmosphere and can travel around the entire world, causing damage to small organisms. It's certainly not a good thing, but it is a very small problem in comparison to the mountain top removal, fresh water poisoning, and ecosystem destruction experienced in terrestrial mining. Since we don't have any of those more serious consequences with seabed mining, we can focus our attention on plume dispersion in seabed mining, with an implicit understanding that these costs are far more manageable than those seen in terrestrial operations.

We won't have a green energy revolution without seabed nodules as there aren't enough terrestrial minerals to support it. It sounds like you're okay with this, but understand that the majority of society doesn't feel the same way.

Continue your education and write another article when you have become more knowledgeable on this subject. Thanks

Anonymous said...

Kurt, It's also important to understand that there are a variety of seabed mineral targets for mining. Nodules and sands are easy to extract and their removal imposes relatively little cost on the environment. When it comes to hydrothermal vents and rich mineral crusts, the environmental damage is more significant because extraction of these resources requires removal of the earth's crust. They also tend to be found in areas where there is more biodiversity and unique surroundings.

BTW, harvesting nodules is absolutely nothing like the hydraulic mining you cite in your piece. If anything, this comparison serves to underline the relative minor costs of harveting nodules.