Deep-sea mining

New frontier: Only 0.0001% of the deep sea has been explored for minerals.

Miners are pushing hard to extract precious metals and rare minerals from the ocean floor. But there is mounting concern about what deep-sea mining might do to the marine environment.

  • What exactly is deep-sea mining?

    It is the process of retrieving mineral deposits from the deep sea – the area of the ocean below 200m.

    Around 90% of the ocean – and 50% of the Earth’s surface – is considered the deep sea. Since 1982, around 1.4m sq km have been explored, mostly in the Pacific Ocean. But this only amounts to 0.0001% of the area open to explore. Now, more companies are looking to expand into the deep sea to search for deposits.

  • Why are companies so keen to mine the deep sea?

    Companies have their eye on minerals deposited in three different parts of the ocean. Most exciting – and most popular – are polymetallic nodules. These are bundles of ore that look like potatoes. They litter the ground on abyssal plains – flat areas of the seafloor. The nodules are rich in manganese, nickel, cobalt and rare earths. Up to 10cm in diameter, they grow at a rate of just a few centimetres every one million years.

    Elsewhere, sulfide deposits rich with gold, silver, lead and zinc have been found on ridges near hydrothermal vents. And underwater mountains have rich cobalt crusts.

    As the price of rare earths and certain metals go up, it is becoming clear that companies and countries could make billions of dollars by setting up deep-sea mines.

  • What are all the minerals used for?

    Many of the minerals available underwater are used to make batteries as well as in renewable energy manufacture. Supporters of deep-sea mining argue that we need these metals and minerals to help with the green revolution.

    The lithium to be found under the sea could be used to create millions of electric vehicles, wind turbines or solar panels – as well as mobile phones.

  • Can’t we get these on dry land?

    We can – but current land mining is known to cause severe environmental problems including air and water pollution, soil erosion and loss of biodiversity. And the mining of some elements, such as cobalt, is centred in countries where children are known to carry out dangerous work.

    Plus, resources are running out. It’s calculated that by 2050, demand for cobalt and nickel will be four times greater than the available reserves on land. The answer, many mining companies argue, is in the oceans.

  • So what’s the problem?

    Some are concerned that the environmental impacts of underwater mining could be even worse than those on land. Duncan Currie, an international lawyer says: “You are talking about the destruction of the habitat. Any area you are mining will be destroyed.”

    And given the size and mystery of the ocean floor, many experts worry that the implications are completely unpredictable. The sediment and water returned to the ocean after the mining process will create almost constant plumes. “No one has any idea what it will do”, Currie warns, “It’s incredibly important and we know almost nothing.”

  • What’s next for the deep sea?

    It is down to regulation. International waters, known as the high seas, are controlled by the International Seabed Authority (ISA). Last month, the Pacific Island of Nauru, located in the Clarion-Clipperton Zone, triggered a clause in the law that gave the ISA two years to finalise rules. If they are not ready by then, companies will be able to start mining at will.

    But at the same time, more than 350 scientists from 44 countries signed a petition calling for a moratorium on deep-sea mining “until sufficient and robust scientific information has been obtained”.

You Decide

  1. Will humans ever be able to live within their means?


  1. Have a class debate: “Deep-sea mining should be banned internationally.”

Word Watch

The deepest point of the ocean is the bottom of the Mariana Trench, around 11km below sea level.
Abyssal plains
A flat area of the ocean floor, usually around 3,000m deep. They cover more than 50% of the Earth’s surface.
Rare earths
A set of 17 metallic elements found in the Earth’s crust.
Mobile phones
The average smartphone contains up to 16 rare earths, around 0.034g of gold and 0.34g of silver.
The variety of plant and animal life in the world or in a particular habitat.
International waters
If a country has minerals in the water it is responsible for, it is up to the government to decide whether to use them. Last year, Japan became the first country to demonstrate deep-sea mining in its waters.
International Seabed Authority
A United Nations body charged with regulating human activities on the deep sea floor. It has issued 30 contracts for mineral exploration since 1982.
Clarion-Clipperton Zone
An area in the Eastern Central Pacific Ocean estimated to contain three to six times more cobalt reserves than all known land reserves combined.
A temporary ban on a particular activity.

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