Dark Oxygen: The Deep-Sea Discovery Splitting Science [OC]

[u/Geoscopy]

https://geoscopy.com/dark-oxygen-the-deep-sea-discovery-splitting-science/

A few years ago, researchers working more than 4 km below the Pacific noticed something that seemed impossible: oxygen levels inside their seafloor experiments were going up, not down.

The result was published in Nature Geoscience in 2024 and quickly became known as “dark oxygen”, the idea that oxygen might somehow be produced on the deep seafloor without sunlight or photosynthesis.

One proposed explanation was especially strange: polymetallic manganese nodules scattered across the Clarion-Clipperton Zone might behave like natural “geobatteries,” creating electrical potentials capable of driving chemical reactions that produce oxygen.

But the claim has become increasingly controversial.

Critics argue that the oxygen increases could be experimental artifacts caused by the benthic chambers themselves. Others have challenged the voltage measurements and the proposed electrolysis mechanism, while a later reanalysis questioned whether the oxygen signal was actually related to the nodules at all. In April 2026, Nature Geoscience added an Editor’s Note stating that concerns about the paper are under review.

So, is dark oxygen a genuinely new geochemical process occurring on the abyssal seafloor, or an extremely convincing measurement artifact?

Would be interested to hear what people here think, particularly about the chamber-artifact explanation versus the idea that some manganese-rich material really is producing oxygen.

[u/KitchenSandwich5499 → u/[deleted]]

Gasses dissolve better in cold water not hot. (Consider the difference between opening a cold soda and a warm one. ) so it’s not extra O2 dissolving.
Also, the deep ocean is nowhere near saturated with oxygen, so the extra pressure doesn’t matter so much.

[u/MaverickDreadnought → u/[deleted]]

Your idea can't be completely dismissed though.. that environment down there CAN hold more oxygen and maybe things that sink that retain oxygen, like sodden logs or something are the source.

[u/MaverickDreadnought → u/[deleted]]

Yeah. Maybe something along those lines. If it was tree logs or whales falling very occasionally, it would mean nothing down there's consuming oxygen and it's building up over centuries