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The Great Oxidation Event: Mass Extinction Caused By Too Much Oxygen

by hridika ahire
The Great Oxidation Event: Mass Extinction Caused By Too Much Oxygen

April 1, 2021

What do you think will happen if there is no oxygen left for us to breathe? Of course, we will all die. So what do you think will happen if there is more oxygen in the atmosphere than a human or any organism can take? The answer is Mass Extinction.

Do you know the rule of threes (survival)? First, you can go three weeks without food, Second, you can go three days without water and third, you can go three hours in extreme climate and lastly, you can survive three minutes without breathable air. Pretty cool, right?  Maybe you’ll remember these rules if you find yourself in a mass extinction situation. We hope that situation never arrives.

Mass extinctions aren’t unknown to us. We’ve heard about it all. We know about the mass extinction between the Cretaceous and Paleogene periods where we lost the dinosaurs, but it made way for various mammals and birds—over 99.9% of the organisms that lived on this Earth. But there was a time when oxygen, the oxygen that keeps us and many other microorganisms alive, caused the first mass extinction!

oxygen-scoolbuzz
There was a time when oxygen, the oxygen that keeps us and many other microorganisms alive, caused the first mass extinction!

Too Much Of Oxygen

The Great Oxidation Event, also known as Oxygen Catastrophe, Oxygen Crisis, oxygen Holocaust, Great Oxygenation Event, or Oxygen Revolution. Too much, right? Ironically, the oxygen was indeed too much. We all know that the Earth was way different two billion years ago or so. There were no beautiful plants or animals or even insects. It was just a big ball of bacteria. A lot of these bacteria which was living on Earth was anaerobic. Meaning they would metabolize their food without any oxygen.

But a new type of bacteria appeared. The Cyanobacteria. This was a blue-green alga that would reside in the water. Cyanobacteria would photosynthesize. This meant that the alae would convert sunlight into energy and release oxygen. We learned about this process in school. The oxygen levels in the atmosphere experienced a sudden rise in oxygen, approximately 2.4-2.0 Ga, during the Paleoproterozoic era.

cyanobacteria-scoolbuzz
Cyanobacteria are a group of photosynthetic bacteria, some of which are nitrogen-fixing, that live in a wide variety of moist soils and water either freely or in a symbiotic relationship with plants or lichen-forming fungi

The Escalation

As the algae produced more oxygen, iron present in the water would bond with it, and the environment would try to accommodate the sudden increase in the oxygen levels. Eventually, the oxygen became too much. The other organisms which were anaerobic could not take in oxygen. It was poison to them. This is how extinction started. A lot of this bacteria was killed due to over oxidization.

Soon enough, the atmosphere started reacting to the rise in oxygen levels. Some of the oxygen, combined with methane, was available in the Earth’s atmosphere and made carbon dioxide. Methane was responsible for keeping the Earth warm as it is a much stronger gas than CO2. As Methane got combined with oxygen and started creating carbon dioxide, the carbon dioxide levels increased, and as a result, the nice warm Earth started cooling down. This caused the Huronian glaciation. This event lasted from 2.4 billion years to 2.1 billion years and was one of the most severe and longest-lasting ice-ages in history. This was similar to the snowball earth situation that happened in the Neoproterozoic era.

huronian-glaciation-scoolbuzz
The Huronian glaciation was a glaciation that extended from 2.4 billion years ago to 2.1 Gya, during the Siderian and Rhyacian periods of the Paleoproterozoic era.

The Conditions That Stayed

Cyanobacteria, which was responsible for this hike in oxygen levels, was also engendered due to the glaciation event. Their numbers dropped as well as almost all of the life which was thriving on the Earth.

A team of researchers published their findings on this Great Oxidation Event in Proceedings of the Nation Academy of Sciences. They said that the oxygen levels in Earth’s atmosphere faced a tremendous increase due to algae formation. Suddenly the oxygen level fell and caused one of the “most transformative events in all of Earth’s history” and also caused famine condition that stayed for the next 1 billion years.

An Evident Shift in Earth's Nutrients

These researchers found a barite piece, which is a sulphate mineral found in the Belcher Islands, Canada. On analyzing the substance, it was found negative values, which are said to have occurred after the Great Oxidation Event. This also implied that the event caused a shift in the number of nutrients that were available. “The fact that this geochemical signature was preserved was very surprising. What was especially unusual about these barites is that they clearly had a complex history.” Malcolm Hodgskiss, co-author.

Due to the rise in oxygen levels, new species got the chance to be born, and it also causes changes in the chemical interactions between sand, clay, rock and other such geological substances. Despite such a big extinction, some life managed to survive. For example, mitochondria. It evolved after the event and gave the organisms the energy to explore the brand new and complex morphology.

The Birth Of 2,500 Minerals

This mass extinction also gave birth to around 2,500 of the total minerals found on Earth. Since the growth in oxygen levels was toxic to ancient microenvironments, only the toughest survived and an evolutionary transformation in single-celled organisms.

Don’t you think that we are in a similar situation? The CO2 levels rising could cause our Earth to freeze, and the Earth would once again go through a mass extinction. The other theory would be overheating due to methane. It is safe to say that if the climate change that we are facing every year does not stop, we are all going to die, and there will be no future for our kids and grandkids. Just like the previous extinctions, we would all become history. 

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