Deep-Sea Polymetallic Nodules: Resources, Risks, and Controversies

Polymetallic nodules, found across the abyssal plains of the ocean floor, are rich in critical minerals but pose major environmental, legal, and economic challenges.
Data: ISA, Nature, Metals Co., MDPI, GEOMAR, SETAC, DeepSeaMining.ac (2025)

Key Metals

Mn, Ni, Co, Cu

Manganese, Nickel, Cobalt, Copper[2][3][5][6]

Major Region

CCZ

Clarion-Clipperton Zone (Pacific)[1][2][3][4]

Potential Cobalt Supply

20%+

of global demand if commercialized[3]

Nodule Growth Rate

2-10 mm/Myr

2-5 mm/Myr (hydrogenetic), 10 mm/Myr (diagenetic)[2][4]

Estimated Value

$233T

Total global nodule value (gross)[3]

Average Metal Content of CCZ Nodules (wt%)

Nodules: ~27-30% Mn, 1.25–1.5% Ni, 1-1.4% Cu, 0.2-0.25% Co[2][3][5][6]

Projected Global Supply Share if Commercialized

Nodules could supply 20%+ cobalt, 10%+ nickel, plus significant Mn and Cu[3]

Key Deep-Sea Nodule Regions

Most nodule resources are in the Pacific (CCZ, Peru Basin), Indian Ocean[1][2][3][4]

Environmental and Social Risk Matrix

Risk	Severity	Scientific Certainty
Ecosystem Disruption	Very High	Low-Medium
Carbon Cycle Impact	Medium-High	Low
Species Loss	High	Low
Regulatory Gaps	High	Medium
Geopolitical Tension	Medium	High

Risks rated by severity and certainty (ISA, Nature, GEOMAR, SETAC)[1][6][7][8]

Global Policy Stance (2025)

Moratorium/support/neutral by country (est.)

Legal, Market, and Scientific Context

Aspect	Current Status	Key Details
International Governance	ISA	International Seabed Authority regulates mining beyond national EEZs[1]
National Policy	Fragmented	Norway, Cook Islands moving to approve; France, Germany, Pacific Island states support moratorium[1][3]
Market Readiness	Unproven	Commercial-scale economics remain uncertain; land mining interests may resist[3]
Scientific Baseline	Incomplete	Deep-sea biodiversity, recovery rates, and carbon impacts not fully understood[7][8]

[1] ISA, [3] Metals Co., [4] DeepSeaMining.ac, [5] MDPI, [6] GEOMAR, [7] Nature, [8] SETAC (2025)
All values are latest available estimates; scientific uncertainty remains high.

Deep-Sea Polymetallic Nodules

Deep-sea polymetallic nodules are rich mineral deposits scattered across the abyssal plains of the ocean floor, particularly in regions like the Clarion-Clipperton Zone (CCZ) of the Pacific Ocean. These nodules, composed primarily of manganese, nickel, cobalt, and copper, offer a potential alternative to terrestrial mining for critical minerals essential to the global energy transition. However, deep-sea mining poses significant environmental risks to fragile and poorly understood marine ecosystems, sparking major international controversy over whether and how these resources should be exploited.

Key resources: Manganese, nickel, cobalt, copper
Physical properties: Dense metal-rich nodules formed over millions of years through the slow precipitation of minerals from seawater
Projected importance: Potential to supply over 20% of global cobalt, 10% of global nickel, and substantial amounts of manganese and copper if commercialized
Key regions: Clarion-Clipperton Zone (Pacific Ocean), Peru Basin (Pacific), Indian Ocean Nodule Field

Environmental and Social Criticisms:

Ecosystem disruption: Mining nodules would involve large-scale disturbance of seafloor sediments, potentially destroying habitats for unknown or endemic species and altering deep-ocean biodiversity permanently.
Carbon cycle risks: Stirring up deep-sea sediments could release long-sequestered carbon and methane, disrupting natural carbon sinks critical for climate regulation.
Scientific uncertainty: Deep-sea ecosystems are poorly understood, and baseline studies are incomplete. Recovery times for disturbed habitats could span centuries or longer.
Legal and governance gaps: The International Seabed Authority (ISA) governs seabed mining beyond national jurisdictions but has been criticized for insufficient transparency, environmental standards, and enforcement capability.

Geopolitical and Market Risks:

Race for licenses: Countries and private companies are competing aggressively for exploration contracts, raising concerns about geopolitical tensions and uneven benefit distribution.
Regulatory fragmentation: Some nations, like Norway, are moving toward approving deep-sea mining within their own jurisdictions, while others, like France, advocate for a moratorium until environmental impacts are better understood.
Market uncertainty: The economics of deep-sea mining remain unproven at commercial scale. Land-based mining interests may seek to obstruct or slow deep-sea development to protect existing investments.