Dark oxygen refers to oxygen produced in complete darkness, without photosynthesis. Traditionally, scientists believed that most oxygen on Earth was produced by photosynthetic organisms such as plants, algae and cyanobacteria. However, a 2024 study published in Nature Geoscience reported evidence of oxygen production on the deep seafloor, where sunlight does not reach. This discovery has made dark oxygen an important topic in science, environment and current affairs.
Meaning of dark oxygen
Dark oxygen means oxygen generated in an environment where there is no sunlight. It challenges the common understanding that oxygen production mainly depends on photosynthesis. In the deep ocean, sunlight cannot penetrate beyond a certain depth, yet researchers observed an increase in oxygen levels near the seafloor.
How is dark oxygen produced?
The 2024 study linked dark oxygen production with polymetallic nodules found on the ocean floor. These nodules are mineral-rich lumps containing metals such as manganese, nickel, cobalt and copper.
Researchers suggested that these nodules may act like natural “geobatteries”. They may create small electric charges that split seawater into hydrogen and oxygen through a process similar to electrolysis. In simple terms:
- Polymetallic nodules produce a small electric potential.
- This electrical energy may split water molecules.
- As a result, oxygen may form even without sunlight.
However, scientists have not fully settled the mechanism. Some experts have questioned the interpretation and demanded more experiments. Therefore, dark oxygen remains an exciting but debated scientific discovery.
Where is dark oxygen found?
Scientists reported dark oxygen from the abyssal seafloor of the Pacific Ocean, especially in areas covered with polymetallic nodules. The discovery came from deep-sea experiments in the Clarion-Clipperton Zone, a mineral-rich region of the Pacific Ocean. This zone lies around 4,000 metres below sea level, where sunlight does not reach.
Why is dark oxygen important?
Dark oxygen is important for many reasons:
- Challenges existing science: It questions the idea that oxygen production is possible only through photosynthesis.
- Deep-sea ecology: It may support oxygen-breathing organisms in dark, deep-sea ecosystems.
- Origin of life: It may change theories about how oxygen and life evolved on Earth.
- Astrobiology: It increases interest in life possibilities on icy worlds such as Europa and Enceladus, where sunlight is absent but oceans may exist.
- Deep-sea mining: Polymetallic nodules are targeted for metals used in batteries and clean energy technologies. If these nodules help produce oxygen, mining them may damage unknown ecological processes.
- Environmental governance: It strengthens the case for precautionary regulation under the International Seabed Authority before allowing commercial deep-sea mining.
Conclusion
Dark oxygen is oxygen produced in the absence of sunlight, possibly by polymetallic nodules on the deep-ocean floor. Although the discovery still needs further verification, it has major implications for marine ecology, the origin of life, astrobiology and deep-sea mining regulation. Therefore, policymakers must follow the precautionary principle before disturbing fragile deep-sea ecosystems.
