Why does the amount of oxygen in the Earth's atmosphere need to maintain a level of 20.9%?

Humans and many other creatures are used to living in an atmosphere with an oxygen content of 20.9-21%. So what happens if oxygen levels rise or fall suddenly?

In the Earth's atmosphere, nitrogen accounts for up to 78%, the rest is CO2, CO, water vapor and trace elements. Therefore, the standard oxygen concentration in the air will be 20.9%-21%.

Where does Earth's oxygen come from?

Our Earth has existed for about 4.6 billion years. During such a long period of time, the Earth is constantly evolving and changing, so far, it has experienced 5 terrifying Mass Extinctions. Humans have been on Earth for about 200,000 years, maybe even longer. Deep down, humans are able to survive on Earth thanks to the planet's natural environment.

Human life and many other species on Earth cannot be separated from oxygen.

Human life and many other creatures on Earth cannot be separated from oxygen. In fact, during the first half of Earth's history, it was completely devoid of oxygen. Until the "Great Oxidation Event" occurs and produces oxygen globally, higher unicellular to multicellular organisms, as well as animals and even humans, have a chance to get started. life.

At the time of that event, the jump in oxygen levels was mainly caused by cyanobacteria, also known as cyanobacteria, which are photosynthetic bacteria that exhale oxygen. Living environment with abundant oxygen content has contributed to stimulate the growth of many species of animals and plants. The high oxygen uptake combined with the fresh air has made them much healthier and larger than they are today.

The proof is that in 2012, paleontologists Matthew Clappen and Jared Carr at the University of California, Santa Cruz published their research on changes in wing length as well as size of more than 10,500 insect fossils over the past 320 million years. They found that during the first 150 million years, their body size had a certain correlation with the oxygen concentration at that time. In environments with high oxygen content, insects tend to grow larger in body size. Not only insects, many creatures and animals and plants in that early age were enormous in size.

In the high-oxygen environment of the early Earth, many insects were very large.

However, this relationship also gradually disappeared over time and the species of organisms, animals and plants also became smaller. This has partly demonstrated that oxygen content has an effect on species. And we still know that, without oxygen on Earth, no living thing could exist. If the oxygen content becomes more dilute, the existence of organisms, as well as humans, will also be limited. That's why the oxygen content in the Earth's atmosphere needs to be controlled.

Why is the oxygen content on Earth 20.9%?

The oxygen content in the Earth's atmosphere is about 21%. In which, half of the oxygen is produced by trees and plants during photosynthesis. The other half is made by the ocean, microscopic marine organisms called plankton.

Humans and many types of creatures, animals and plants have completely adapted to the oxygen content of 20.9% in the Earth's atmosphere. Thanks to this adaptation, human civilization has had the stable development as it is now. Therefore, some scientists have questioned whether the high oxygen content on Earth is good or not? How would life on Earth change if the oxygen concentration was higher than 21%?

Pure oxygen is only really good for humans if used for a short time.

If the oxygen content in the Earth's atmosphere is pushed up to 100%, the human respiratory system will certainly benefit first of all. The proof is that in the world, there are many units that provide pure oxygen for customers. Many customers after using these services have had positive results such as: reducing symptoms of dizziness, headaches, healthier body.

However, pure oxygen is only really good when used for a short time. If humans breathe air of 100% pure oxygen for a long time, we can be poisoned. Specifically, after inhaling too much and too long of pure oxygen, people will feel chest tightness. After that, people will experience dizziness, headaches, lung and brain damage until they gradually lose consciousness and die.

Moreover, we need to remember that oxygen is the main element that occurs in fires. Therefore, too much oxygen in the Earth's atmosphere will make the fires more intense. Even someone lighting a match can cause a fire that has a serious impact on Earth.

The high oxygen content will turn insects into giants.

In addition, the oxygen content of 100% will have a great impact on insects. Because according to the research of two paleontologists Matthew Clappen and Jared Carr, insects used to be huge in size more than 300 million years ago. The reason for the large difference in their sizes was that the oxygen content at that time was up to 35%. So if the oxygen content is up to 100%, how big the insect's body can be and imagine what the world would be like if they became giant. It is certain that the danger of a new mass extinction will occur only a short time later.

But what if the oxygen content in Earth's atmosphere drops below 20.9%? In the book "Oxygen Crisis" by author Roddy Newman (USA), compared to prehistoric times, the oxygen content in the Earth's atmosphere has decreased by one-third and stopped at 20.9%. The reason for the decrease in oxygen content is that 10,000 years ago, the area of ​​forest covered the Earth was twice as much as it is now. This also means that the amount of oxygen is only a quarter of what it was then.

The oxygen content in the sea is similarly reduced. According to a NASA report, the amount of oxygen-producing single-celled plants has decreased to only about 70% compared to 30 years ago. According to the United Nations, there are nearly 150 dead zones due to industrial and agricultural waste discharged into the sea. The waste in these areas causes the oxygen content in the sea to drop to the point where no marine life can survive. Lack of oxygen in the sea also causes gene mutations, affecting the fertility of marine organisms.

Whether the amount of oxygen in the atmosphere increases or decreases too much, the world is threatened.

Regarding the fact that if the oxygen content in the atmosphere is increasingly falling below 20.9%, Professor Ervin Laszlo, an American adviser to the United Nations on the systematic sciences and philosophy, thinks that human health will affected first. Because when the oxygen content is too low, the cells and organs will be deprived of oxygen, causing the immune system to weaken and function poorly. Physiological disorders occur when the percentage of oxygen in the air drops to 16-17%. When the oxygen content in the air is 7-8%, a fatal outcome can be caused.

If the oxygen content drops to 0%, concrete structures can collapse immediately. The reason is that oxygen acts as a special binder for concrete. The lack of oxygen also makes the sky pitch black. While all of the above was happening, the earth's crust also completely crumbled because it was made up of 45% oxygen. Therefore, this shell will continue to break until there is nothing left.

Thus, whether the air content is more or less than 20.9%, it is certain that our world, especially humanity, will be seriously affected.

How to maintain the oxygen content at 20.9%?

Over millions of years, the oxygen content in the air has paused at 20.9%. This oxygen content is ideal for life on Earth. The balance of oxygen and other gases is ensured by the natural cycle, that is: animals emit CO2, plants use it and release oxygen.

However, our vegetation is increasingly disappearing. An estimated 13 million hectares of forest (equivalent to the area of ​​Greece) disappear every year. It was people who cut down trees to meet their growing needs for agricultural and industrial production. And if the disappearance of trees cannot be prevented, in the future humanity will not be able to survive because the air is no longer suitable for breathing. To survive, the best that humanity can do is to bring an oxygen mask to filter the remaining oxygen in the air.

Furthermore, the balance of oxygen and other gases in the atmosphere created the ozone layer at an altitude of 8-30km above the ground. At the same time, it also protects life on Earth by absorbing the sun's ultraviolet radiation.

Unfortunately, a study by Princeton University, New Jersey, USA published in the journal Science showed that the amount of oxygen in the Earth's atmosphere has decreased by 0.7% over the past 800,000 years. The researchers measured the oxygen content of ice cores in Greenland and Antarctica. According to the team's assessment, these are areas that still store countless gas bubbles representing the Earth's atmosphere over the past millions of years. By analyzing the oxygen ratio of the nitrogen isotope in these ice cores, they were able to determine the rate of decrease of the specific oxygen concentration above.

To keep the oxygen content suitable for humans and other creatures on Earth to survive, we need to limit the cutting of trees, reduce the burning of fossil fuels.

Notably, Professor Daniel Stolper, who led the research team, added that, in the past 200 years, the industrialization period of human society was the period with the most irregularities. The oxygen content in the atmosphere has dropped rapidly by 0.1% due to the burning of fossil fuels, which consumes oxygen and produces carbon dioxide.

Every year, humanity burns 7 billion tons of fossil fuels, which affects the free oxygen content in the atmosphere. At current rates of photosynthesis, it would probably take about 2,000 years to produce the ideal oxygen content in Earth's atmosphere.

From here, it can be seen that the balance of oxygen content in the Earth's atmosphere will never be permanent. If humanity does not soon realize and change, the prospect of a mass extinction is the end that awaits us.