In 2024, researchers claimed to find something mysterious at the bottom of the ocean. It was “dark oxygen”—oxygen produced where there’s no chance of photosynthesis. So what could possibly be producing it?

Natural batteries—at least according to the scientists. This bizarre discovery seemed to upend everything we knew about the abyssal floor, had big implications for deep sea mining, and might even have helped explain the origin of aerobic life. But (and look, you know what we’re going to say here) could there have been something a little more mundane explaining the findings?

The Science Fictions podcast is brought to you by Works in Progress magazine. On this week’s episode we talked about the new article on the genetics of cabbages, and how the wild cabbage has been selected into so many of the familiar vegetables we know today. Find this and so many more articles, all for free, at worksinprogress.co.

Show notes

* The 2024 dark oxygen paper in Nature Geosciences

* Media coverage: BBC, Guardian, New Scientist

* Andrew Sweetman’s piece in The Conversation discussing his research

* On the deep seas of Enceladus and Europa

* The UN and Greenpeace discussing the implications of dark oxygen

* The “extraordinary claims” critical paper in Frontiers in Marine Science from 2025

* Huge European investigation into marine mining from 2023

* Critical EarthArXiv preprint from 2025

* Norwegian interview with Andrew Sweetman, addressing some criticisms

* PubPeer discussion of the paper; Wikipedia page with some rather harsh language

* Paper on the expected amount of oxygen on the ocean floor, and on how the process itself needs oxygen to get started

* Reanalysis of Sweetman’s raw data in another EarthArXiv preprint

Credits

The Science Fictions podcast is produced by Julian Mayers at Yada Yada Productions.

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Episode 98: Dark oxygen

Science Fictions