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Deep Sea Mining not essential for renewables revolution

Nuku'alofa, Tonga

Editor, We write to you about the story appearing in your issue “Seabed mining environmental study underway” of 22 February, which contains a number of misconceptions which need correcting:

“DeepGreen aims to use the metals (nickel, copper, cobalt and manganese) found in polymetallic rocks, to power electric cars.”

Deep Sea Mining (DSM) is not essential for a renewables revolution. Research indicates that better managed land based mines, circular economies based on smart product and urban design, recycling and reducing demand are more than enough to meet the mineral needs into the future. Research from the University of Technology in Sydney demonstrates that a transition to 100% renewable energy worldwide by 2050 would still not require deep sea mining.

New technologies are also being developed such as batteries which do not rely on rare and expensive metals requiring the mining of deep seabed DSM bears all the same hallmarks of terrestrial mining, including but not limited to, massive environmental destruction of which the greatest risks being shouldered by poor countries and subsistence communities much like ourselves here in the Pacific.

DSM is a relic, left over from the extractive economic approaches of the ’60s and ’70s. It has no place in this modern age of a sustainable blue economy. Post-COVID we can do things better and reduce pressures on our much stressed natural systems to the benefit of all of us. "The seafloor is like a desert and all you can see are these rocks laying unattached on the seafloor."

The deep sea was once thought of as an ecological desert, and mining companies still present it that way. Only a tiny fraction of the millions of square kilometers of deep seabed, which is already under exploration licenses, has been studied. However, research shows that it is brimming with wonderfully diverse and unique life forms. Nodules themselves provide a unique habitat and have their own ecology, about which we know very little. At this point it is understood that the nodule surfaces houses unique organisms that grow, forage on these nodules. The nodules are also the spawning grounds for others organisms. Nodules take millions of years to form, not only is it not ‘sustainable’ in any sense to mine but the loss of the habitats will result in irreversible damages to the surrounding ecosystem of area they mine and the whole balance of ocean health.

“There is no solid waste when processed unlike land based mining.”

There would be massive amounts of waste produced and discharged to the ocean. The removal of nodules involves scouring of the sea floor sucking up large quantities of biologically rich soft sediments, surrounding nodules, will go up the riser pipe and will be dumped back through the waste pipe, causing sediment plume. It is not the sanitized vacuuming depicted by DeepGreen. Sediment plumes will be generated via machinery movement, mining activity, leakage from riser pipes, accidental spillage and disposal of mine waste. Estimates of the spread of plumes vary from 200 km to thousands km for fine grains.

The disposal of mine waste will produce a constant plume for the lifetime of the mining operation. With virtually no information on the machinery and methods to be used, researchers predict the volumes of sediment discharged could be in the hundreds of thousands to millions of tons of sediment per year per operation. DeepGreen and other seabed miners are planning to discharge sediment returned from processing nodules into the water column, thousands of meters above the seabed. The plumes may also be quite toxic, with metals and processing agents. The plumes will spread into the upper water layers, potentially affecting many other species. Metals could bio-accumulate in marine food chains, into tuna and eventually reaching humans.

As Pacific Islanders already know – and science is just starting to learn – the deep ocean is connected to shallower waters and the coral reefs and lagoons. What happens in the deep doesn't stay in the deep.

References and more details can be found at a recent report “Predicting the impacts of mining of deep sea polymetallic nodules in the Pacific Ocean” available at

Best Regards
Pelenatita Kara
National DSM Campaign Coordinator
Civil Society Forum of Tonga