Mining the Ocean Floor: Ecological Transition or Environmental Threat?

A sea cucumber swimming on nodules 5000 m west of the Clarion-Clipperton zone.

Deep seabed mining is on the verge of becoming a reality. As the world strives to achieve zero emissions, these large-scale projects would provide a supply of critical minerals. The possible destruction of thousand-year-old ecosystems and the lack of regulation, however, raise concerns among environmental groups and scientists.

What drives mining companies to dive 4,000 meters deep are polymetallic nodules. These nuggets are made of nickel, copper, cobalt and manganese: metals used to build batteries and electronic devices.

The Metals Company is one of the pioneer companies in this sector, as explained by Gerard Barron, the general manager of the Vancouver company. The company hopes to mine the Clarion-Clipperton area, which lies in the Pacific Ocean between Mexico and the Hawaiian archipelago, this year.

After ascending a 4 kilometer long riser to the surface in 12 minutes, the nodules harvested from the seabed are dried and sent on a conveyor to the ship's hold.

The majority of deepwater mining projects are concentrated there, because it is one of the richest places for these nodules in the world. We have identified 1.6 billion tons of these polymetallic nodules. That's enough to electrify the entire light transport fleet in North America, says Gerard Barron.

These nuggets are abundant on sea floors. It takes millions of years for the nodules to reach a size of a few centimeters and be large enough to be of interest for mining, however explains the oceanographer and professor emeritus at the University of Hawaii Craig Smith.

The oceanographer has led seven expeditions to this area, which in his experience is far from resembling a vast lunar desert. This is a hotspotof biodiversity. We have demonstrated in a study that it holds the greatest biodiversity of any studied abyssal site in the world.

The abyss is home to all kinds of organisms: corals, sponges, sea cucumbers and a large amount of bioluminescent beings. Hundreds of species live on these nodules and nowhere else, says Craig Smith.

A sea anemone in the Clarion-Clipperton area at 4200m depth.

The loss of this habitat is one of the concerns of Catherine Coumans, research and Asia and Pacific program coordinator at Mining Watch Canada. If you exploit these nodules, they generate a really huge dead zone, she says.

As the Clarion-Clipperton zone is located in international waters, it is the International Seabed Authority (AIFM) that regulates mining. This intergovernmental organization affiliated with the United Nations Organization has approved 19 exploration projects in this part of the globe.

If all the projects went into the exploitation phase, they would receive a area as large as British Columbia and the Yukon combined. It would be the largest mining area we have ever seen on Earth, says Catherine Coumans.

Sediment lifted up by mining operations to extract the nodules could affect an area three to five times larger than the mined area, according to oceanographer Craig Smith.

This is where the clearest bottom waters on the planet are found. […] The organisms are therefore adapted to clear water, they are probably very sensitive and intolerant of high levels of turbidity, he asserts.

Sea cucumber among polymetallic nodules in the eastern area Clarion-Clipperton fracture.

In an article co-authored by Craig Smith and published in the journal Sciencein 2022,one model predicts that mining noise from a single operation would exceed ambient noise levels up to 500 kilometers from site.

Seabed , accustomed to a low level of noise, will therefore have to withstand the noise of continuous mining equipment for the duration of their operation. I don't think we have a good understanding of the noise disturbance intensity of large-scale mining right now, he says.

Gerard Barron, the company's managing director, is however convinced that the data collected during an initial four-month pilot project will convince the regulators of the International Seabed Authority. We want strong regulations in place that protect the marine environment, he says.

However, an energy transition cannot take place without an increase in mining, he notes. The extractive industries will have to increase by about 500% by 2040.

The Pilot Nodule Collector Vehicle awaits launch from the side of The Metals Company's first production ship.

We must stop destroying our most biodiverse terrestrial ecosystems, such as our tropical forests, which is currently the case, he says.

An argument that does not convince the oceanographer Craig Smith. First, the footprint of deep-sea mining will be much larger in terms of area than any land-based mining operation. Second, deep-sea mining will not end land-based mining.

He urges caution and hopes the AIFM does not ;allow one or two mining operations until the cumulative environmental impacts of stressors are well documented.

By July 2023, the AIFM must produce the regulations that will allow companies to move from the exploration phase to the exploitation phase.