In an exclusive interview with Guardian Seascape last Saturday, James Cameron argued that it is “less wrong” to mine the deep sea than mining on land. “I’ve seen an awful lot of seafloor,” said the Titanic director and accomplished deep-sea explorer. “And while there are some amazing creatures, they tend to be clustered in small habitats. What you mostly have is miles and miles of nothing but clay.”
His view, which he conceded made him “something of an outlier”, is disputed by scientists and environmentalists who claim the opposite: that the ocean floor is a richer and more biodiverse place than previously thought, with new species uncovered each time they look. Deep-sea mining, said one, would result in “extinction on a vast timescale”.
Who is right? That is a key issue at this week’s assembly meeting of the International Seabed Authority (ISA), a quasi-UN body of 168 member states tasked with regulating deep-sea mining.
Last week, the ISA council – a smaller group of 36 nations that develops the mining rules – set itself the goal of allowing mining to proceed within two years. But this week, a growing number of countries, led by France, Chile, Costa Rica, Palau and Vanuatu, is urging the larger assembly to discuss a long term “precautionary pause” on mining, with a key argument being a lack of knowledge.
For many decades, the abyssal plain – where sunlight cannot penetrate and organisms must adapt to cope with extreme pressure – was considered an underwater desert. The main target of deep sea-mining firms is a particular area of the Pacific between Hawaii and Mexico called the Clarion-Clipperton Zone (CCZ), which is scattered with rocks called polymetallic nodules. They are estimated to contain more cobalt and nickel – key ingredients in electric batteries – than all known land deposits.
Mining firms such as the Metals Company argue that there is a global benefit to making these minerals available more cheaply, to hasten the transition to green energy and mitigate the climate emergency.
In the past three months, however, researchers have discovered the CCZ contains far greater biodiversity than previously thought. One recent paper suggested there were more than 5,000 species new to science. Scientists say not enough is known about them to gauge the effect of mining – or whether it might even wipe them out for ever.
“What we know is the tip of the iceberg,” says Muriel Rabone, a data researcher at the Natural History Museum, who found evidence of the 5,000 species. Only six of the species, which includes a sea cucumber, nematode worm and carnivorous sponge, have been seen elsewhere. “We only know a fraction of what we need to know about these species – their life, their ecosystem functioning, their traits, their reproductive status – to be able to predict what the impacts will be.”
The nodules that mining companies want to bring to the surface take millions of years to form. More than half the species found in the CCZ, which is mainly soft sediment, depend on the rocks as a hard substrate on which to survive. As a result, much of the biodiversity and habitat loss by mining would be permanent. The scientific consensus is that deep-sea mining would cause significant permanent damage to ocean ecosystems.
Lack of knowledge is the problem. So far, exploration and research trips have been made only by mining companies, and scientists tend to rely on their surveys in this hard-to-reach zone.
Nevertheless, they have made strides in understanding the deep. Following Rabone’s paper, a study this month found that, due to the impact of ocean warming on tropical tuna populations, some of the world’s most valuable fisheries may increasingly overlap with deep-sea mining operations in the CCZ.
There are also potential new discoveries. Bacteria from corals and sponges on the ocean floor can beat superbugs and cancer, and scientists fear losing the vast potential of organisms that are not yet known.
Rabone says there is “massive potential in terms of not just the biodiversity but the value of the biodiversity”. She adds: “What we might lose if we mine is an important part of the discussion.”
Cameron – who has discovered several new species on his own, self-funded expeditions – sees deep-sea mining as the lesser of two evils. He notes that mining on land not only affects “highly diverse rainforest ecosystems” but also Indigenous populations. “Society,” he says, “has a weird habit of blowing the wrong thing out of proportion.”
His opinion echoes a recent editorial in the Economist, arguing that deep sea-mining is a less invasive way to get the minerals needed for a green economy. Opponents counter that while Cameron is right about the impact of mining in rainforests, deep-sea mining is highly unlikely to reduce any mining on land.
“Saying it’s better to mine the seafloor than the rainforest is a straw-man argument,” says Rabone. “In terms of what we don’t know, it’s not just the species that live in the habitat, it is the ecology, and [potential future] uses in terms of socioeconomic value.”
Nor is the deep sea a flat, homogeneous plain. Recent topographical maps show it is punctuated by at least 14 undersea mountains, known as seamounts, between 200–500m in height.
”There is biology there,” says Dr Adrian Glover, a deep-sea biologist at the Natural History Museum and co-author of Rabone’s paper. “If you look at macrofauna, the diversity is remarkably high. Abyssal plains are high in diversity even if they are low in abundance.”
While we have “massively increased” our knowledge of the CCZ, a lot remains undescribed, he says. “We don’t know their biology. It’s hard to predict the extinction rate without knowing where things live.”
Scientists fear that noise pollution from mining equipment may affect larger marine life too. Noise from mining equipment could radiate up to 500km (more than 300 miles), harming deep-diving marine mammals as well as ecosystems.
The latest research is published this week by a team of researchers from 13 institutions led by the UK’s National Oceanography Centre (NOC), which spent a decade examining data. They reveal two distinct zones of deep-sea fauna. Using autonomous underwater cameras, they found a surprising increase in diversity with depth, challenging a long-held belief that biodiversity is limited by harsher living conditions in deeper areas.
“Muddy abyssal seafloors were initially considered almost ‘marine deserts’,” says Dr Erik Simon-Lledó, a deep-sea ecologist at the NOC, because of “the extreme conditions for life there – a lack of food, high pressure, and extremely low temperature.
“But as deep exploration and technology progressed, these ecosystems keep unveiling a large biodiversity, comparable to that in shallow water ecosystems, only found on a much wider spatial spread.”
Deeper areas of the plain were dominated by soft anemones and sea cucumbers, they found, while the shallower area was full of soft corals, molluscs and brittle stars. Any future mining regulations will have to take into account that the spread of animals across the area is “more complex than we thought”, says Simon-Lledó
Above all, scientists warn that new discoveries are constantly being made, which means that the true impact of mining has been understated, particularly given the millions of years it has taken the seabed to evolve into its current form.
“This is a habitat that has been stable for millennia,” says Rabone. “We know there’s likely to be extinction on a vast timescale.”
