Space junk also "bullies" the ozone layer? It's too difficult to open the "Pandora's box" of life on Earth!

On March 5, scientists from the Chemical Sciences Laboratory of the National Oceanic and Atmospheric Administration of the United States found that cleaning up space debris and retired satellites, allowing them to return to Earth and burn after friction with the atmosphere will generate metal particles. These metal particles will form polar stratospheric clouds and may destroy the ozone layer.

Schematic diagram of space junk (Source: Wikipedia)

The ozone layer is the protective umbrella for life on Earth. The standard equipment for geologists in the field is sun protection clothing and sun hats to protect against ultraviolet radiation. In fact, the ultraviolet rays that reach the ground are less than 5% of the solar radiation released. If all the ultraviolet rays were absorbed, life would probably cease to exist.

However, just last September, the European Space Agency released the latest data showing that the ozone hole over Antarctica has reached an area of ​​26 million square kilometers, which is larger than the entire North America. Humanity is facing a dangerous situation of "broken umbrella and leaking roof".

Schematic diagram of the formation of the ozone hole (copyright image of the library, reprinting and use may cause copyright disputes)

What should we do now? To find out, we must trace back to the origin of the ozone layer and understand how it was formed.

Ozone and oxygen are like two brothers. If you want to know the secret of ozone, you have to look for the answer from the two most important "storms" of oxygen in the history of the Earth, which geologists call the "Great Oxidation Event."

In the Hadean Eon, the atmosphere was filled with methane, carbon dioxide and other gases. There was no ozone, not even oxygen, and no ozone layer. In the Paleoproterozoic Eon, the prosperity of a certain kind of organism made the gears of life on Earth start turning. That was cyanobacteria, which relied on photosynthesis to set off a world-shaking revolution and became the oxygen-producing factory of the Earth. This was the first "surge" of oxygen, and the ozone layer was gradually formed.

In the Neoproterozoic Era, a violent geological activity rewrote the original script. At this time, all the land on the earth merged to form a supercontinent, and sent minerals to the ocean. Microorganisms in the ocean consumed a large amount of organic matter in the ocean and produced oxygen, thus becoming the earth's new oxygen-producing factory. This was the second "surge" of oxygen. The oxygen content was far ahead, which further strengthened the ozone layer and directly opened the "Pandora's Box" of the earth's creatures. This was the famous Cambrian explosion of life.

It can be seen that the "rush" of oxygen created the ozone layer, providing a guarantee for the reproduction of life.

250 million years ago, violent volcanic activity punctured the ozone layer of this period, followed by the largest biological extinction event in the history of the Earth, with more than 70% of land life and more than 90% of marine life becoming extinct.

Since the 1970s, humans have released a large amount of chemical products used in refrigerators, air conditioners, and fire extinguishers, such as Freon and Halon. When they enter the atmosphere and encounter ozone, they capture the oxygen atoms of ozone, and then continuously consume ozone in the atmosphere, forming a large area of ​​ozone hole.

The evolutionary history of the earth tells us that the destruction of the ozone layer will bring about huge disasters. Only by stopping the use of chemical products that harm the ozone layer and protecting the protective umbrella of life on earth can the flower of life continue to bloom on this planet.

(The author is a PhD student at China University of Geosciences and the second prize winner of the 10th National Science Popularization Explanation Competition)