Environmentalists have massive concerns about deep-sea mining. In the meantime, companies are increasingly turning their attention to shallow sea areas in order to mine minerals and metals there. The consequences are hardly foreseeable.
At the end of 2021, the company Scandinavian Ocean Minerals (SOM) approached the Swedish environmental authorities. The mining company applied for a permit to drill test holes in the Bottensee – a part of the Baltic Sea between Sweden and Finland. The ultimate goal is to mine manganese nodules at a depth of 60 to 150 meters, i.e. in a relatively shallow area of ??the sea. To do this, the company would also need an exemption from the general ban in Sweden on discharging mined bottom sediments back into the sea.
A decision has not yet been made in Sweden, but the case illustrates two things: The world is thirsty for raw materials. And the mining of mineral resources from the seabed is increasingly coming into focus.
So far, public attention has been focused primarily on deep-sea mining, which is only gradually developing, i.e. the extraction of raw materials such as manganese nodules or massive sulphides from water depths of up to 5000 meters. The International Seabed Authority (ISA), based in Kingston, Jamaica, had already issued exploration licenses for an area in the central Pacific – the Clarion Clipperton Zone (CCZ) – to Germany at the beginning of the millennium. But deep-sea mining still seems to be a long way off – technically complex, expensive and extremely risky for the still partially unknown environment.
With rising commodity prices and deepening geopolitical conflicts, this form of mining could be closer. The ISA is currently preparing an international framework for the exploitation of deep-sea mineral resources in international waters.
It would be easier to extract mineral resources from the continental shelf, i.e. those areas of the sea that lie in front of the coasts. With water depths of mostly up to 200 meters, raw materials are not only much easier to mine than in the deep sea, they also have to be transported less far. In addition, up to a maximum distance of 200 nautical miles – a good 370 kilometers – from the coast, areas are considered exclusive economic zones, so national authorities decide on mining.
However, according to some experts, this shallow-water mining – also known as shelf mining – is ecologically even more questionable than deep-sea mining, which has only been partially researched in terms of environmental consequences. “In contrast to deep-sea mining, the biomass of organisms is much higher in this area,” says Annemiek Vink from the Federal Institute for Geosciences and Natural Resources (BGR) in Hanover. “Furthermore, the phytoplankton, which are very important for storing carbon dioxide from the atmosphere, will be affected.”
Raw materials have been mined on the continental shelves for well over 100 years: On the one hand, there are oil and gas platforms all over the world. The two fossil fuels are also mined in German territorial waters: in the North Sea in the Mittelplate oil field off the coast of Dithmarschen and in the Doggerbank natural gas field. Added to this is the global mining of sand and gravel for construction purposes – also in the German North Sea and Baltic Sea.
But now other mineral resources in the shallow water are attracting the attention of mining companies: minerals and metals. This is what the researchers Laura Kaikkonen and Elina Virtanen from Helsinki write in the journal “Trends in Ecology and Evolution”. Diamonds have been mined off the coast of Namibia to a depth of around 130 meters since 2002. The authors locate the world’s largest metal mining in the sea off the coast of Indonesia: Tin is mined there on a large scale.
And off the Mexican Pacific coast, phosphorites – i.e. phosphorus-containing sediments, for example for the production of fertilizer – are to be lifted from a depth of 50 to 100 meters. Mexican environmental authorities are currently examining a corresponding application.
“The offshore industry started with oil and gas,” says BGR expert Carsten Rühlemann. However, this would tap into oil or gas deposits under the sea floor. “When mining mineral raw materials, on the other hand, large areas are excavated extensively.”
Such large-scale mining not only puts companies in conflict with local residents and environmental organizations, but also with other potential users of a sea area – such as fishing, tourism and shipping.
Researchers from the Geomar Helmholtz Center for Ocean Research Kiel wrote in 2017 that the search for raw materials in the sea was shifting closer to the coast. Mark Hannington, Sven emphasized that a huge area of ??around one third of the entire terrestrial landmass lies below sea level on the continental shelf Petersen and Anna Kratschell in “Nature Geoscience”.
Because these vast shelf areas are largely geological extensions of the rocks on land, mineral resources mined on land could also be developed in the offshore shelf, they said. “When you consider the number of ore deposits that are known on land near the coast, the potential of the offshore continental shelf is staggering.”
But an example from New Zealand shows how sensitive the public in industrialized countries can be to marine mining. There, an application to promote iron-rich sands off the North Island was recently rejected. For 20 years, the company Trans-Tasman Resources Limited (TTR) wanted to extract up to 50 million tons of such sand annually off the west coast of the island – against the opposition of fishing associations, environmentalists and organizations of the Maori indigenous people.
The environmental agency EPA had already approved the license, but the Supreme Court overruled it in October 2021. The Supreme Court referred the request back to the EPA on the condition that it respect historical treaties with the indigenous peoples.
TTR continues to fight for a license. The mining offers New Zealand an unprecedented economic opportunity, the company finances accompanying scientific research and the damage to the environment is only short-term and manageable anyway, wrote TTR Managing Director Alan Eggers in the daily newspaper “New Zealand Herald” in August.
Tim Packeiser from the environmental organization WWF doubts that: “If sediments are removed over a large area, the habitat disappears, along with the organisms living there.” In addition, the marine ecologist emphasizes that excess substrate will probably be dumped back into the sea. This is a “death sentence” for sensitive ecosystems, especially coral reefs.
“Since shallow water mining has not been considered in many places, environmental regulation is insufficiently addressed in many national legislations,” write Kaikkonen and Virtanen. This gray area creates the opportunity to circumvent rules and poses significant risks to the environment.
The duo write that mining removes the sediments and thus the basis of life for the inhabitants of the seabed, which means that species could become extinct locally. In addition, the clouds of sediment thrown up during dredging or suction would cloud the water and suffocate organisms. “In addition, there is a possible release of hazardous substances from the sediment and the disturbance of marine life through noise, light and vibration from the work.”
The Swedish company Scandinavian Ocean Minerals mentioned at the beginning takes a different view: Basically, the mining of manganese nodules in the Baltic Sea offers the chance for a “transition to a society without fossil fuels,” according to the website. After all, the minerals extracted from it could be used for batteries, solar cells and semiconductors, for example.
The consequences of mining on the Baltic Sea are also limited: the ecosystem there is relatively species-poor, and because no light reaches the sea floor anyway, there is no photosynthesis there. “Therefore, a local sediment plume on the bottom does not affect the primary production of algae,” emphasizes the company, which speaks of a “green offshore industry”.
