Deep sea mining: the debate

What are the pros, and cons, of deep sea mining?
18 December 2020

Interview with 

Gerard Barron, DeepGreen, & Alex Rogers, Rev Ocean


The surface of the ocean.


Have you ever thought about where the metals in your phone come from? Or in electric cars? Cobalt is one of nature’s 118 chemical elements, and for centuries it’s been valued for its distinctive blue colour, but more recently it’s become a vital ingredient in the production of re-chargeable batteries. It’s mainly been extracted from ore quarried or mined on land, a process which can be environmentally damaging and disruptive for the communities who live nearby. But what if there was a different source of cobalt, and other metals, we need for electric car batteries? Well there is, but it’s deep down in the ocean and, as you might expect, plans to mine for it there are not without controversy. Some of the ocean reserves are in what’s known as the Clarion–Clipperton Fracture Zone - the CCZ - an area that’s about as big as Europe four thousand metres below sea level in the Pacific, as Eva Higginbotham heard earlier this year...

Eva - Despite being miles away from civilization, the CCZ has been an area of great interest for two key groups. Those who see it as a great resource opportunity, and those who feel it should be protected. Now, this is because the seabed in the CCZ is absolutely littered with polymetallic nodules, these strange potato-shaped lumps that are jam-packed with various metals, including cobalt, nickel, copper, and manganese. I spoke to Gerard Barron, the CEO of Deep Green, a deep sea mining company, focused on these nodules.

Gerard - A lot of people don't think about what goes into the battery that's in your mobile phone, or all the electric vehicle batteries that are going to be driving around our roads. But those batteries are made up of metals like cobalt. And in the case of cars, they're made up of nickel and cobalt and copper. And if you think about our desire to move away from fossil fuels, that means we're going to need hundreds, in fact billions, of tons of metals that are required for the green transition. So today all of these metals come from terrestrial known landmines, and a lot of people are shocked when they realise just what an environmentally unfriendly process mining has always been

Eva - Gerard's company Deep Green recently showed some research arguing that the damage we do to the environment by traditional land mining to get these metals was greater than the damage we would do to the deep ocean through the use of their machines, which they call gentle giants, essentially like plows that would run along the sea bed scooping up the nodules. The thing is, a lot of ocean conservation advocates and environmental scientists have disputed that conclusion. Here's Professor Alex Rogers of Rev Ocean.

Alex - The risk lies in the fact that we know so little about the deep ocean, both in terms of what lives down there, but also in terms of the way it actually works. What we understand so far, because of the relatively low supply of food into the deep ocean and the low temperatures, things happen very, very slowly. So animals grow and live for a very, very long time. If the ecosystems of which these animals are a part of are damaged, then recovery doesn't take place for decades or even hundreds or thousands of years, if it occurs at all

Eva - But what is living so far below sea level anyway? According to Gerard, not much.

Gerard - There's not much food down there, which means there's not much life down there. And in fact, most of the life that is in the area is very small organisms that live in the muck. So you don't find plants. You don't find coral reefs. You don't find lots of animals moving about.

Eva - On balance, companies like Deep Greens see the ecological impact of deep sea mining as the lesser of two evils when compared to terrestrial mining. But Alex and many other ocean scientists strongly disagree.

Alex - I think that's an incredibly dangerous argument to get into. You know, if you start to sort of toss up valuations of one form of life versus another, I think you get into very, very risky territory. I mean, this life is down there not doing nothing. It's very difficult to simply discard all that diversity of life that occurs in the deep ocean on the grounds that well, we don't see it every day. It's not an argument that I think is a valid one, particularly given our lack of knowledge of the deep ocean at the moment.

Eva - There's also the wider impact on life that lives above the seabed. Mining activities will stir up large plumes of sediment into the water, which will go several hundred metres above the sea floor. The wastewater and sediment produced from the mining will be dropped back in the ocean at an as yet undetermined depth, which is bound to interrupt life all the way down. There's also the fact that all this mining would be very noisy, which would throw off animals like whales that use echolocation to find their way around. It seems clear that deep sea mining for polymetallic nodules would be an absolute catastrophe for the deep sea ecosystem, but Gerard would argue, but that is a price we should be willing to pay.

Gerard - Waiting is not an option. It is irresponsible to suggest we should wait another 10 years while we learn more because climate change is real. One of the most impactful factors of climate change comes as a result of burning fossil fuels. And if, as our study found, that actually the increased metal production on land that will be necessary to meet the demands of the green transition releases gigatons more of CO2 emissions, then that's a really dumb thing to be doing. What we should be doing is continuing to research. We should be continuing to learn. And then we should be with the knowledge that we gather, make informed, intelligent decisions.

Eva - Many people I spoke to, including Alex, suggested that this was a bit of a false choice. That is to say, we don't have to choose either environmentally damaging land mining or environmentally damaging ocean mining. There's a lot of research at the moment trying to make batteries and other goods important for renewable energy without using these metals. Ultimately, most ocean conservationists are calling for a ban on deep sea mining of at least 10 years while research into impacts continue.


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