This brief reviews the climate-related implications of deep-sea mining, including associated environmental risks. It identifies multiple knowledge and governance gaps that must be closed to fully evaluate whether deep-sea mining offers an acceptable way to obtain critical minerals, and concludes that deep-sea mining should not be allowed unless and until these uncertainties are resolved. It is part of Ocean Conservancy’s “Ocean and Climate Discussion Series,” which provides science-based analysis to inform the global dialogue on integrating ocean issues into climate policy.
A global shift to renewable energy is central to solving the climate challenge. The batteries and digital technologies needed to support this shift require critical minerals including the chemical elements copper, silver, gold, zinc, manganese, cobalt, nickel, tin, and rare earth elements (REEs). Terrestrial mining currently satisfies the demand for cobalt, lithium, and REEs, but demand and supply chain risks are growing, increasing the interest in securing these materials elsewhere. Abundant stores of these elements have been discovered in specific seafloor environments. However, the full implications of deep-sea mining (DSM) for climate mitigation and adaptation, as well as its environmental costs, are insufficiently researched and highly uncertain.
This brief provides policymakers with an overview of the climate-related implications of DSM, including associated environmental risks. It reviews the state of knowledge concerning the mitigation and adaptation implications of mining in deep-sea environments, and highlights the current state of DSM governance and activity. Many uncertainties remain about the full consequences of DSM for ocean carbon storage and biodiversity, and about whether DSM offers an acceptable alternative to land-sourced or recycled materials. Industrial DSM should not be allowed unless and until these and other uncertainties are resolved.
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