More Science Is Needed to Manage Deep-Seabed Mining and Minimize Its Impact

As nations consider mining the mineral-rich deposits found on the deep seabed, a new study reveals just how little experts know about these parts of the planet and how they might be affected by mining activities. The findings, which were published in the March 2022, issue of Marine Policy, show extensive gaps in scientific knowledge about deep-sea life and oceanographic, biological, and ecological linkages between deep-ocean habitats and the rest of the ocean and planet.

The authors report that, for regions with mining exploration areas, the scientific knowledge needed to enable evidence-based management exists for only two of the 180 scientific categories assessed. The study also outlines a potential path to address these information gaps and cites the United Nations Decade of Ocean Science for Sustainable Development (2021-2030) as an opportunity to foster the international collaboration and political will needed to meet this challenge.

Led by Diva Amon, Ph.D., a deep-sea biologist and the director and founder of the nonprofit organization SpeSeas, the study authors reviewed hundreds of scientific articles and consulted dozens of stakeholders to assess the state of scientific knowledge about the deep-sea areas targeted for mining. Amon was joined in this initiative by 30 experts, policymakers, and scientists from around the world.

The study authors conclude that experts’ understanding of these ecosystems is nascent at best and call into question whether it is currently possible to make evidence-based decisions about seabed mining that prevent “serious harm” and ensure the “effective protection of the marine environment from harmful effects,” in accordance with the U.N. Convention on the Law of the Sea.

The International Seabed Authority (ISA), an intergovernmental organization established to regulate all mineral activities in the international seabed, is developing regulations to govern this activity. But recent steps taken by the island nation of Nauru could force the ISA, which has 167 Member States, to fast-track this process and finalize its seabed mining regulations by July 2023. This study shows it would be impossible for the scientific gaps to be closed in that timeline.

Data gaps

The study authors framed their review of more than 300 articles published from 2010 to 2021 around two central questions:

1. What is known and unknown about the deep-sea environments and life where seabed mining may take place?
2. What is known and unknown about the impacts of deep-seabed mining and its management?

The answers to both questions were categorized by the three types of deep-sea mineral resources found in various geographic regions across the Pacific, Atlantic, and Indian oceans where deep-seabed mining exploration contracts have been granted by the ISA. Those resource types are:

• Polymetallic nodules are potato-size, rocklike deposits that form over millions of years and can be found on abyssal plains at depths of 3,000–6,500 metres.
• Polymetallic-sulfides are mineral deposits that form when the superheated solution released by hydrothermal vents cools and the minerals precipitate.
• Cobalt-rich ferromanganese crusts are concentrations of minerals that are often found on the sides and summits of underwater mountains.

The study found that even the Clarion-Clipperton Zone (CCZ), which spans 4.5 million square kilometres between Hawaii and Mexico and is arguably one of the most studied mining regions of the deep sea, is still largely unexplored and poorly understood. For example, the study found that in the CCZ, researchers have collected enough knowledge to enable evidence-based management for only one of the 20 scientific categories assessed. The CCZ tops the list of areas to be mined for polymetallic nodules.

For the parts of the CCZ that have been sampled, many species have only been collected once or twice, which is not enough to draw sound conclusions on species abundance, diversity, ranges, relationships with other species, contribution to overall ecosystem function, and vulnerability to and recovery from deep-sea mining. Biologists estimate that up to 75% of species have yet to be discovered in areas that have been sampled. And for 30% of the categories examined for the CCZ, experts have little to no scientific knowledge to inform evidence-based management, with many other regions and resources even less studied than the CCZ.

Experts offer their input  

Among the stakeholders consulted for the study, 88% agreed that scientific knowledge is too sparse to ensure the protection of the marine environment in the face of large-scale, deep-seabed mining. Stakeholders said the area where knowledge was most needed was on comprehensive environmental baseline information for the regions where mining may occur, followed by information on the direct and indirect impacts of mining.

Many stakeholders said they were unsure how long it would take to close these knowledge gaps. Those who answered that question said it would take six to more than 20 years to build the scientific knowledge needed to properly protect the marine environment from mining.

A potential way forward 

The study proposes a nine-stage pathway to gather the missing data as rapidly as possible. These stages include a series of workshops; greater coordination and data sharing among scientists studying the deep seabed and other stakeholders, including mining companies; and an enhanced focus on deep-sea research.      

This study offers decision-makers, including the ISA, a potential starting point to begin collecting the scientific information needed to inform policy decisions and ensure that deep-seabed mining activities, should they proceed, are effectively managed to minimize impacts to the environment. The monumental scale of this challenge will require the expertise of a well-supported globally collaborative scientific community working to build scientific capacity and develop new technologies that will expand what we know about the deep-sea environment.    

Peter Edwards is an officer with The Pew Charitable Trusts’ conservation science project, and Chris Pickens is a senior associate with Pew’s seabed mining project.