Oxygen on Earth has surged twice before, what would happen if it happened again?

Oxygen is not an "innate" substance to the earth. In the past 4.55 billion years, the oxygen on the earth has undergone a process of "from nothing, from less to more", and in this process, Oxygen does not increase linearly, in fact, oxygen on Earth has exploded twice.

Two oxygen surge events on Earth

The first started about 2.6 billion years ago and ended about 1.8 billion years ago, and its "initiator" was a simple single-celled organism - cyanobacteria, which were also the first on Earth to evolve photosynthesis creature.

Cyanobacteria first appeared about 3.4 billion years ago. At that time, the oxygen content in the earth's atmosphere was negligible and completely negligible. The whole earth was in a reducing environment. Therefore, at the beginning, the oxygen released by cyanobacteria through photosynthesis It will quickly combine with other elements to form various oxides, which will be consumed.

With the proliferation of cyanobacteria, more and more oxygen is released, and it constantly changes the reducing environment on the earth. In this case, oxygen accumulates in the atmosphere in large quantities, and eventually the oxygen on the earth appears. The explosion brought the oxygen concentration of the atmosphere to about 2%, which is also known as the "Great Oxidation Event".

The second oxygen surge event on Earth began about 580 million years ago, and in a short period of about 60 million years (relative to the age of the Earth), the oxygen concentration of the atmosphere rapidly increased to about 60% of modern levels .

Scientists speculate that the main reason for this event is that large-scale geological movements continuously weathered and denuded a large amount of sulfate and input it into the ocean, and a series of reactions occurred in this process, which released a large amount of oxygen (as shown above). shown). So the question is, what will happen if there is another oxygen surge event like this?

What would happen if oxygen on Earth exploded again?

Today, the oxygen concentration in the earth's atmosphere is 21%. In fact, this is not the best oxygen concentration for human survival. Research shows that the most suitable oxygen concentration for human survival is 24%-30%. In this environment, human actions are more Agility, the mind is more flexible, and stamina is improved.

That is to say, if the oxygen on the earth does not increase a lot (no more than 30%), humans can adapt completely. Since humans can, so can other creatures on the earth. However, the increase of oxygen concentration from 21% to 30% does not seem to be a "surge". I secretly think that it has to be doubled to be called a "surge". So what will happen in this case?

21% is doubled to 42%. In such a high-oxygen environment, humans will experience the phenomenon of "oxygen drunk", which is manifested as dizziness, weakness, chest tightness, drowsiness, etc. In addition, high concentrations of oxygen will A large number of oxygen free radicals are produced in the human body, which will cause unpredictable damage to human cells, lysosomes, mitochondria and various non-cellular structures, thus affecting human health.

Humans don't feel well, as do many other animals (especially those that breathe with their lungs), but humans can still find livable places. Because the atmospheric pressure will decrease as the altitude increases, the air density will also decrease, and the oxygen content per unit volume of air will also be less, so in this case, the high-altitude areas on the earth will become human beings. Habitable Zones on Earth.

Since oxygen is only slightly soluble in water, high concentrations of oxygen in the atmosphere basically have no direct effect on organisms such as fish in the water, and most plants on land are not much affected.

It should be noted that some animals on land will also benefit from the increase in oxygen concentration, especially insects, because insects do not breathe with lungs, they exchange gases with the outside world by gas diffusion through their body walls, so high concentrations The oxygen instead helps them grow in size.

That is to say, if the oxygen on the earth surges again and maintains a high concentration for a long time, the size of the insect will gradually become larger. In fact, in the Carboniferous period about 290 million years ago, the average oxygen in the earth's atmosphere was The concentration was as high as 35%, and the insects at that time were very huge. For example, there was a giant dragonfly with a wingspan of nearly 1 meter.

So what if the oxygen concentration doubled from 42%?

If this is the case, we don't need to discuss whether biological organisms can adapt to this oxygen concentration at all, because in this case, everything combustible on earth will become very easy to burn, just a little bit of Mars, Or a flash of lightning, or even just a little longer in direct sunlight, is enough to start an unstoppable blaze.