The Clarion-Clipperton Zone^[1] (CCZ) or Clarion-Clipperton Fracture Zone^[2] is an environmental management area of the Pacific Ocean, administered by the International Seabed Authority (ISA).^[3] It includes the Clarion Fracture Zone and the Clipperton Fracture Zone, geological submarine fracture zones. Clarion and Clipperton are two of the five major lineations of the northern Pacific floor, and were discovered by the Scripps Institution of Oceanography in 1954. The CCZ is regularly considered for deep-sea mining due to the abundant presence of manganese nodules.

The CCZ extendes around 4,500 miles (7,240 km) East to West^[4] and spans approximately 4,500,000 square kilometres (1,700,000 sq mi).^[5] The fractures themselves are unusually mountainous topographical features.

In 2016, investigation of the seafloor in the zone was found to contain an abundance and diversity of life – more than half of the species collected were new to science.

The fractures can be divided into four parts:

• The first, 127°–113° W, is a broad, low welt of some 900 miles (1,400 km), with a central trough 10 to 30 miles (16 to 48 km) wide;
• The second, 113°-107° W, is a volcano enriched ridge, 60 miles (97 km) wide and 330 miles (530 km) long;
• The third, 107°-101° W, is a low welt with a central trough 1,200–2,400 feet (370–730 m) deep which transects the Albatross Plateau; and
• The fourth, 101°-96° W, contains the Tehuantepec Ridge which extends 400 miles (640 km) northeast to the continental margin.^[6]

The Nova-Canton Trough is often seen as an extension of the fractures.^[7]

The zone contains nodules made up of valuable rare-earth and other minerals. Some of these play an essential role for the energy transition to a low carbon economy.^[8] These nodules form around bone fragments or shark teeth. Micronodules then further aggregate and accrete into the clumps targeted for harvesting.^[9]

The CCZ has been divided into 16 mining claims spanning approximately 1,000,000 square kilometres (390,000 sq mi). A further nine areas, each covering 160,000 square kilometres (62,000 sq mi), have been set aside for conservation.^[1] The International Seabed Authority (ISA) estimates that the total amount of nodules in the Clarion Clipperton Zone exceeds 21 billion tons (Bt), containing about 5.95 Bt of manganese, 0.27 Bt of nickel, 0.23 Bt of copper and 0.05 Bt of cobalt.^[12] The ISA has issued 19 licences for mining exploration within this area.^[13] Exploratory full-scale extraction operations were set to begin in late 2021.^[2] ISA aimed to publish the deep sea mining code in July 2023. Commercial license applications were to be accepted for review thereafter.^[14]

The so-called two-year rule states that before regulations are passed, a member nation has the authority to notify ISA that it wants to mine. This starts a two-year clock during which the ISA can come up with rules. If it fails to do so, the mining is implicitly approved. Nauru gave notice in July 2021, creating a deadline of July 9, 2023. ISA's next meeting, however, begins a day later, on July 10.^[9]

Areas of the fracture zone that have been licensed for mining are home to a diversity of deep-sea xenophyophores. A 2017 study found 34 novel species in the area. Xenophyophores are highly sensitive to human disturbances, such that mining may adversely affect them. They play a keystone role in benthic ecosystems such that their removal could amplify ecological consequences.^[15] The nodules are considered "critical for food web integrity".^[16] The zone hosts corals, sea cucumbers, worms, dumbo octopuses and many other species.^[9]

Massachusetts Institute of Technology and TU Delft use their ISA observer status to investigate the potential impact of collecting these minerals and compare it to the environmental and human impact of terrestrial mining.^[17][18] In April 2021, scientists from JPI oceans project carried out in depth studies into mining technology and its possible effect on the seabed.^[19]

Mining has the potential for large environmental impacts. The impact of the release of tailings from nodule processing into the water column on pelagic organisms or the detrimental effects they may have on the benthic communities below are unknown.^[20]

Along with the xenophyophores, many types of species reside in the Clarion-Clipperton Zone: protists, microbial prokaryotes, and various fauna including megafauna, macrofauna, and meiofauna, each distinguished by size.^[21] Due to the lack of historical research in the region—in large part because of the inaccessibility, monetary, and physical cost without modern technology—very little is known about life in the CCZ. The increasing tests in the region have led to the discovery of many new species, suggesting both a high species richness and high species rarity within the CCZ. It seems that polymetallic nodules in the region, the target of much deep-sea mining, are crucial for fostering a high level of biodiversity on the sea floor. Even so, there are many gaps in the current understanding of the ecosystem roles played, life history traits, sensitivities, spatial or temporal variabilities, and resilience of these species.^[22]

Much of what is known about the potential environmental impact is a result of a dredging pilot test conducted in 1978. In the years since the tests, the region has been monitored. Many species here are more susceptible to the negative effects of environmental shifts as change at these depths is atypical. Specifically looking at nematodes, it has been determined that there is a lower species richness and lower total biomass in the area where the dredging occurred as compared to the neighboring spaces. Additionally, the composition of species and the frequencies at which they are found change with human interference. The removal of polymetallic nodules, as proposed through deep-sea mining, would decrease suitable habitat as many species of nematodes reside within the upper five centimeters where nodules exist, too. Even those species that do remain will face changes to their habitat conditions as the new top layer of sediment after the removal of the nodules will be significantly denser. The low sedimentation levels and minimal currents show that disruption in the CCZ would have long-lasting effects on the environment; the upturned sediment remains unsettled even decades later.^[23] Additionally, nodules form for millions of years; as such their removal would fundamentally alter the ecosystem for millennia to come. The species directly dependent on them, and all of their subsequent linkages or environmental functions would see vast changes that could not be quickly restored after the damage is complete.^[24]

The vast majority of relevant spheres are still lacking adequate research. What is known makes clear that many aspects of deep-sea mining activity would endanger species in the Clarion-Clipperton Zone; they face threats of being crushed by machinery, dispelled in sediment plumes, smothered by unsettled sediment, the loss of resources and habitat, etc. This does not include the threats posed by noise and light pollution—the effects of which are still largely unknown.^[25]

NGOs and governments have called for a moratorium until more is known about potential environmental impacts.^[26]