Biodiversity: Deep-sea mining will be 25 times as bad as mining on land

Extracting minerals from the ocean floor could negatively impact biodiversity on a scale of up to 25 times greater than land-based mining

Extracting minerals from the ocean floor could negatively impact biodiversity on a scale of up to 25 times greater than land-based mining, and fixing the damage would cost twice as much as extraction, a new report said on Thursday.

A search for alternatives to fossil fuels has driven demand for materials that go into batteries, some of which can be found on the seabed where ecosystems have yet to be fully explored.

Deep-sea mining would extract cobalt, copper, nickel, and manganese from potato-sized nodules which pepper the sea floor at depths of 4-6 kilometres. The nodules are an essential habitat for many species.

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The total biosphere impacted by this mining in international waters alone would be up to 75 million cubic kilometres, a greater volume than all the freshwater in the world, according to the report by non-profit Planet Tracker.

"Sadly, the nodules... take millions of years to form," said François Mosnier, head of Oceans Programme at Planet Tracker, which warned resulting biodiversity loss could be permanent.

Advocates say deep sea ecosystem restoration, such as installing artificial clay nodules to replace those lost, could mitigate these impacts.