The environmental impacts of deep-sea mining

Area of Science:

• Marine biology
• Deep-sea ecology
• Environmental science

Background:

• Deep-sea mineral resources, including polymetallic nodules, seafloor massive sulphides, and cobalt-rich crusts, are under investigation for commercial exploitation.
• Environmental research has focused on biodiversity baselines and disturbance impacts from experimental mining in key areas like the Clarion-Clipperton Zone (CCZ).

Purpose of the Study:

• To review decades of environmental research on deep-sea mining impacts.
• To assess biodiversity baselines and recovery from experimental mining disturbances.
• To differentiate ecological resilience from biodiversity loss risks.

Main Methods:

• Review of environmental research data spanning several decades.
• Analysis of biodiversity baselines in deep-sea environments.
• Evaluation of experimental mining and disturbance test results.

Main Results:

• The CCZ seafloor is biodiverse but has low biomass; nodule mining impacts are persistent for decades, with slow recolonisation.
• Limited data exists for sulphide and seamount mining, with unknown recovery timescales and likely different disturbance responses.
• Deep-sea mining may generate plumes affecting pelagic ecosystems; biodiversity loss is a significant risk, especially at vents and seamounts.

Conclusions:

• Deep-sea mining poses persistent environmental challenges, particularly concerning biodiversity persistence and recovery.
• Significant biodiversity loss and species extinction are likely at hydrothermal vents and seamounts.
• Mining in areas designated as 'high biodiversity importance' is incompatible with current Convention on Biological Diversity policies.