The Earth is more than just geology. Every world has its own ways of changing over time, and here on Earth, our environment is affected both by the physics of plate tectonics and the wear and tear of water; we also have life changing its environment through what it consumes, what it gives off, and what it moves around simply because it can.

This has been true for a long time.

2.4 billion years ago, a new kind of microbe evolved – the cyanobacteria – and these new critters used photosynthesis to process nutrients and produce oxygen, and it now appears that the slow rise of oxygen in our atmosphere may be due to the literal slow rise of cyanobacteria.

Researchers studying deepwater microbial mats in the Middle Island Sinkhole found that sulfur-eating microbes would coat the cyanobacteria from dusk to dawn and then retreat from the sunlight with the dawn. It would take time, but eventually, the cyanogens would be in sunlight and able to photosynthesize and produce oxygen. According to lead researcher Judith Klatt: It takes a few hours before they really get going, there is a long lag in the morning. The cyanobacteria are rather late risers than morning people, it seems. 

This has a lot of weird consequences. In the past, Earth’s days were much shorter; maybe even as short as six hours long! And with those shorter days, cyanobacteria may not have had enough time to produce a really useful amount of oxygen. According to a Max-Planck release on this work: The two major oxygenation events (jumps in oxygen concentration) in Earth’s history might be linked to increasing day length.

Now I really want to know what could cause those jumps in day length, but that is work for another day. This work you can find in Nature Geoscience.

More Information

MPG press release

“Possible link between Earth’s rotation rate and oxygenation,” J. M. Klatt et al., 2021 August 2, Nature Geoscience