Discover How Earth’s Slowing Rotation May Hold the Key to Our Oxygen Supply

Earth has changed a lot since it formed about 4.5 billion years ago, especially when it comes to how quickly it spins. This slowing rotation means our days are getting longer, and surprisingly, this has big effects on our atmosphere.

As days stretched out, blue-green algae, or cyanobacteria, thrived. They began producing more oxygen about 2.4 billion years ago. A 2021 study pointed to this connection, linking Earth’s slower spin with oxygen levels in the atmosphere. Microbiologist Gregory Dick from the University of Michigan explained, “Our research suggests that day length may have influenced when and how much oxygen was released into the atmosphere.”

This slowdown happens because the Moon pulls on Earth. As it drifts away, it affects how fast our planet spins. The fossil record shows that around 1.4 billion years ago, days were only 18 hours long. Now, we’re adding about 1.8 milliseconds to our day every century.

One major event in history that highlights this change is the Great Oxidation Event. This is when the cyanobacteria produced enough oxygen to transform the atmosphere. Without this increase, complex life as we know it might not have been able to develop. So even if cyanobacteria seem unimportant today, they played a crucial role in our existence.

There’s still much we don’t fully understand about why this oxygen surge happened when it did. Recent studies explored microbial mats found in the Middle Island Sinkhole in Lake Huron. These mats are like the ancient cyanobacteria, with purple algae producing oxygen and white microbes consuming sulfur. At night, the white microbes surface, but when the sun rises, the purple ones come to life, ready to photosynthesize.

Geomicrobiologist Judith Klatt noted that these cyanobacteria start slowly in the morning: “They’re late risers, which creates a limited window for oxygen production.” This delay might have affected how much oxygen reached the atmosphere during early Earth’s history.

Oceanographer Brian Arbic wondered if historical changes in day length played a role in photosynthesis rates. Researchers conducted experiments and built models to explore this, linking sunlight to oxygen production and tying it to the planet’s history.

The findings were surprising. They discovered that not only the Great Oxidation Event but also another rise in atmospheric oxygen known as the Neoproterozoic Oxygenation Event were influenced by the lengthening of days.

Marine scientist Arjun Chennu emphasized the importance of these connections: “We show that the physics governing these processes at different scales is intertwined, showing a fundamental link between day length and oxygen release from microbes.”

This research tells us the fascinating story of how the dance of our planet and its Moon shaped the life we see today. The findings are published in Nature Geoscience.

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