Ancient Volcanoes May Have Helped Create Perfect Balance For Life On Earth

For billions of years, the Earth's atmosphere was nothing like it is now. There was no oxygen, no air to breathe, just a barren land shrouded in mystery. Then something changed and came the oxygenation, which paved the way for life as we know it.

The origin of oxygen has long been a matter of debate among scientists. A recent study suggests that volcanoes may have a much larger role in the process than previously thought. A team of scientists at the University of Tokyo discovered that oxygenation events, or "whiffs," that predicted the upcoming Great Oxygenation Event (GOE), were influenced by volcanic eruptions.

With the GOE, atmospheric oxygen levels significantly increased, enabling the rise of complex life. The standard explanation is that an increase in photosynthesis-capable microbes transformed the carbon dioxide-rich atmosphere into an oxygen-dominated one.

However, smaller oxygenation episodes took place before the GOE, suggesting it was made possible by previous environmental changes.

In a study published in Communications Earth & Environment, scientists mentioned early microorganisms were supported by nutrient recycling caused by volcanic activity. 

Massive volumes of carbon dioxide were emitted during these massive eruptions, warming the earth. This warming increased the rate of continental rock breakup, releasing phosphorus into the oceans. With the help of this phosphorus, photosynthetic microorganisms were able to produce oxygen as a byproduct.

“Activity of microorganisms in the ocean played a central role in the evolution of atmospheric oxygen. However, we think this would not have immediately led to atmospheric oxygenation because the amount of nutrients such as phosphate in the ocean at that time was limited,” said Professor Eiichi Tajika from the Department of Earth and Planetary Science at the University of Tokyo.

He added, "It likely took some massive geological events to seed the oceans with nutrients, including the growth of the continents and, as we suggest in our paper, intense volcanic activity, which we know to have occurred." 

These findings suggest that the Earth's atmosphere went through a sequence of oxygenation episodes fueled by geological and biological interactions rather than a single event.

The emergence of oxygen-consuming enzymes prior to the GOE lends credence to the notion that life was already adjusting to these transient oxygen-rich periods.