
Deep-sea Potatoes: Should We “Harvest” Them or Not?
There are valuable metals at the bottom of the sea that we could use for the transition to a greener economy. The most interesting “treasure” of all? Nodules of manganese, with nickel, copper and cobalt. However, mining them could be harmful to nature. So: should we harvest them?
More than four kilometres down in the deep ocean, there are a huge number of fist-sized rocks. These are manganese nodules – also called deep-sea potatoes due to their shape and the fact that they are found on the sea floor. They formed as metals dissolved in seawater precipitated in layers around a piece of stone, shell, bone or even a shark's tooth. These nodules contain a lot of manganese, as well as nickel, copper and cobalt. These valuable metals are the reason why many companies are very keen on "harvesting" the nodules.
Deep-sea mining
Manganese nodules could help us to green our economy. For example, cobalt is used in batteries, which we need for electric cars, and copper is widely used in wind turbines.
Demand for copper for green energy solutions alone is likely to exceed one million tons per year by 2050. It is getting more and more difficult to find good places to dig up more copper, which is why people are looking at the oceans and considering deep-sea mining.
Vulnerable ecosystems
Mining valuable metals on the ocean floor could avoid some of the environmental problems associated with land-based mining operations. But what about underwater ecosystems? In and around the "nodule fields" are corals, anemones, sea cucumbers, sponges and probably many other species we haven't discovered yet. Scientists are concerned that all this marine life could suffer if mining activities disturb its habitat.
An experiment in the 1980s showed how extensive this damage could be. In that study, mining operations in the Pacific Ocean were simulated by ploughing over an area of seabed. A few years ago, marine researchers dived down to assess the site. What did they find? The drastically disturbed ecosystem still had not returned to its original state. The damage that was done can still be seen decades later.
Resistance
As a result of this, there is a lot of opposition: many scientists and policy experts are calling for deep-sea mining to be delayed until its ecological consequences are clearer. This is despite the fact that many companies are already on the starting blocks, ready to start mining. So there is going to be an interesting battle over those "deep-sea potatoes”.