When discussing the prospect of commercial-scale polymetallic nodule collection, one of the first questions that arises is: what proportion of the ocean floor will be impacted? This is not only a technical question, but also one that informs public debate and policymaking.
The ocean in perspective
The Earth’s surface covers about 510 million square kilometers. Roughly 70% of that is ocean, meaning the seabed extends across 357 million square kilometers.
Of this, almost all – about 337 million square kilometers – lies in the deep ocean, at depths below 200 meters. Within these vast areas, the abyssal plains stretch across roughly 107 million square kilometers, or about one-third of the entire ocean floor. These are the regions where polymetallic nodules are found.
The Clarion Clipperton Zone (CCZ)
The CCZ in the Pacific Ocean is one of the most intensively studied polymetallic nodule regions of the world. It spans around 6 million square kilometers – equivalent to approximately 1.2% of the ocean floor.
However, not all this area is under consideration for commercial-scale polymetallic nodule collection. Around one-third of the CCZ has been designated as protected. Exploration contracts currently cover about 1.3 million square kilometers, or 0.25% of the ocean floor.
Estimates of minable area
ISA Contractors estimate that between 18-50% of each polymetallic nodule exploration contract area would be mined. There are a number of reasons for this, including geological conditions such as the seafloor’s characteristics including slope, the capabilities of available technology, the metal grade and density of nodules, and environmental management factors including measures designed to maintain biodiversity and ecosystem integrity, such as establishing set-aside areas.
As mentioned above, assessments suggest the maximum potential minable area of the total current exploration contracts is about 50%, or 650,000 square kilometers.
In proportional terms that’s:
- About 11% of the CCZ
- About 0.18% of the ocean floor
- About 0.13% of the Earth’s total surface
These figures are important because they help situate the debate about deep-sea minerals within a global context. Although the numbers are substantial in absolute terms, they constitute a small portion of the overall ocean environment. Understanding scale and proportionality are important for scientists, policymakers, and stakeholders to evaluate the potential footprint of nodule collection and consider it in relation to ecological, technological, and societal factors.