In a new study, scientists appear to have discovered a link between two phenomena on vastly different scales in order to learn how the Earth became an oxygen-rich planet capable of supporting life as we know it.
We’ve known for a long time that the Earth’s rotary speed has slowed and the days have grown longer. These changes are not visible on human time scales, but they can have a significant impact over millions and billions of years.
Examine this in greater depth. The Earth’s gravitational pull is to blame for the loss of rotational momentum. The Moon begins to pull away from Earth, slowing its momentum. The average day on Earth was 18 hours long 1.4 billion years ago, which is roughly one-third of an hour shorter than it is today. Taking this into consideration, the day lengthens by about 1.8 milliseconds every century.
Because of the massive emergence of cyanobacteria in the Earth’s atmosphere, oxygen levels skyrocketed. According to scientists, the existence of life on our planet would have been impossible without this event.
However, we don’t know much about this time period. A sinkhole in Michigan’s Lake Huron, on the other hand, may have provided the most crucial clues.
The two main sources of energy for these tiny, colourful microbes are sunlight and sulfur-rich water. White bacteria that consume sulphur to produce sulphate eat in tandem with purple cyanobacteria that seek sunlight and produce oxygen through photosynthesis.
Because sulfur-hungry bacteria rise to the surface of the microbial mat in the morning and evening, the purple cyanobacteria cannot get sunlight. When the sun is at its brightest, white bacteria migrate deeper into the sinkhole, allowing their purple counterparts to increase their photosynthesis rates and produce more oxygen.
As a result, it takes them several hours to get going in the morning. “The cyanobacteria appear to be early risers rather than early risers,” said geomicrobiologist Judith Klatt of the Max Planck Institute for Marine Microbiology in Germany. Arbic wondered if the lengthening of the Earth’s day had an effect on photosynthesis because of this narrow window of opportunity. Microbes were studied in both laboratory and natural settings, as well as in modelling studies that linked sunlight to microbial oxygen production.
They discovered that the changing length of Earth’s days was linked to increases in oxygen levels not only during the Great Oxidation Event, but also during the Neoproterozoic Oxygen Event, which occurred between 550 and 800 million years ago, when compared to global oxygen models.
“We have shown that there is a fundamental relationship between daily life and how oxygen can be released by ground-dwelling microbes,” said Arjun Chennu, a marine scientist at Germany’s Leibniz Center for Tropical Marine Research. “We connect physics legislation operating on vastly different scales, from molecular diffusion to planetary mechanics.”
It’s pretty awesome. “So, in the microbial mat, we are connected to our planet’s and moon’s dancing,” he added.