Seabed Mining

In the 1970s, it was widely believed that an era of seabed mining was about to begin. The targets were ‘manganese nodules’ – lumps rich in metals – lying on the ocean floor. A legal framework and mechanisms were established under UNCLOS1 both to regulate the industry and to ensure that benefits were shared between nations, with an emphasis on aiding development.

The industry did not develop because at the time, the economics of nodule collection turned out to be unattractive. But various enterprises, many of them state-owned, have been prospecting since 19842, and some are preparing to begin exploitation in earnest3 – initially in coastal waters, and eventually in the high seas.

In the main, mining companies are not now aiming for nodules, but for much larger deposits formed near hydrothermal vents, where hot, mineral-rich water gushes up through the ocean floor. These deposits, which can be up to 100 million tonnes in weight4, are rich in metals such as copper, zinc and lead. They have also been found to contain rare earth elements that are becoming increasingly important in in cutting-edge technologies such as high-density hard-drives, lasers and wind turbine generators5.

Hot, mineral-rich water pours into the ocean from hydrothermal vents, supporting unique ecosystems (AD Rogers, University of Oxford / NERC)

Hydrothermal vents also produce some of the ocean floor’s most spectacular features – black and white smokers, chimney-like structures formed from minerals in the scalding hot water. Smokers were discovered only in 19776, and the extraordinary life they support still amazes scientists. But science has not fully deciphered the importance of these features for the wider ocean; and UNCLOS was formulated when our understanding was less developed even than it is today. There is potential for mining to damage smokers, through direct contact or by kicking up sediment.

A separate issue is oil and gas exploration and exploitation. As onshore and near-shore deposits run down and the technology of extraction advances, companies are prospecting in deeper and deeper water. Eventually, notably in the Arctic, this could lead to exploration and extraction in high seas areas. The fossil fuel industry is also exploring the potential of methane hydrates – reserves of natural gas trapped in ice-like form on the seabed. Projects are initially likely to run in coastal waters7, but could extend into the high seas should the technology prove economic.

Modern technology and changing economics are making seabed mining feasible (Nautilus Minerals)

“We discovered a profusion of life, in a world that it should not exist in. Giant tube worms, 10 feet tall. I remember having to use vodka – my own vodka – to pickle it, because we don’t carry formaldehyde. We went and found these incredible clam beds… and when we cut them open, they didn’t have the anatomy of a clam; no mouth, no gut, no digestive system. Their bodies had been totally taken over by another organism, a bacterium, that had figured out how to replicate photosynthesis in the dark through a process we now call chemosynthesis. None of it in our textbooks; none of it in our textbooks.” Robert Ballard, ocean explorer, on discovering life around a Pacific ‘black smoker’ in the 1970s8.