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More recently, a team of scientists at the University of Oxford, who evaluated the chances that humanity was on the brink of mass extinction from some non-human cause, had estimated the probability to be less than one in 14,000 and possibly less than one. at 87,000. Modern man, Homo sapiens, is estimated to have existed on Earth for at least 200,000 years.
Viruses that pre-existed life
This period of time is like a drop in the ocean when you consider when viruses appeared on Earth. They are considered to be older than life itself. After all, the family of viruses, some 400 arias known to man today, move between decomposition and incorruption, that is, they are and are not living structures. Viruses are essentially genetic material enclosed in a bag of proteins, they can have an extra layer of lipids but do not show the slightest trace of life until they enter an organism. They will then invade your cells and use their mechanisms to reproduce your genetic material with devastating consequences for the devoured organism.
Obviously, the virus, whose existence became known to man as soon as the electron microscope was discovered, was not the only chance in 87,000 that it could cause human extinction.
But scientists seem to have disproved it, and the advanced coronavirus continues to decimate lives in every country in the world. The pandemic has always been considered one of the most feared causes of extinction for much of the world’s population. But not the only one. For tens of millions of years, objects that pass close to our planet, as well as huge geological formations on Earth such as volcanoes, have been considered the main causes of mass extinction on Earth, although there are many who claim that in the distant past, contributed or caused one of them.
So far, in the last 541 million years, there have been five major mass extinctions on our planet and another 13 smaller ones, according to the “fossil record.” The eruption of a volcano, like Yellowstone in the United States, can be the catalyst for life on Earth.
The volcanoes
The Yellowstone volcano is estimated to have erupted more than 140 times. The last eruption 600,000 years ago is believed to have released 1,000 cubic kilometers of lava and ash. Until now, scientists believed that it took 100,000 to 200,000 years to fill the magma reservoirs that supply these volcanoes and create the pressure that would cause them to erupt. But now they have realized that even a few hundred years is enough.
A typical volcano, one of the few on Earth, is Yellowstone, where huge deposits of magma exist underground, at a depth of nine kilometers.
The accumulation of magma begins at a depth of 600 kilometers and rises to the surface of the Earth. Since 2004, magma has risen at record speeds.
The Yellowstone Caldera looks like a pot lid and was formed 600,000 years ago, when the last giant eruption in the area took place. Scientists believe that the time when it will explode again is much closer than they thought. When it does, it will be the fourth eruption in a period of 2.1 million years.
What will happen, experts say, is something similar, but on a much larger scale, to the Santorini volcano eruption 3,600 years ago. There will be a great loss of life, great areas will be destroyed, the global climate will change and the global economy will take a great blow if it does not collapse.
Scientists rank a volcano eruption second only to a massive catastrophe after an asteroid collided with Earth.
When the Yellowstone volcano last erupted 640,000 years ago, a large ash cloud covered North America, affecting the climate. However, if an eruption were to occur today, with its magma chamber even larger than it was then, the volcanic material ejected into the atmosphere would orbit Earth, affecting the planet’s climate.
Asteroids
Throughout its geological evolution, our planet has been systematically bombarded by falling asteroids and comets, often with disastrous results. It is obvious that the danger posed by these space intruders is real.
It was only in February 2013 that the explosion of a space missile over Russia, which released at least 20 times more energy than that released by the Hiroshima atomic bomb, reminded us more clearly how real this danger is. Furthermore, as the comet Shoemaker-Levy that crashed on Jupiter in July 1994 demonstrated, the bombardment of the planets of the Solar System by such space invaders is not something that happened only during the first period of their evolution, but with significant frequency. less. you can continue today.
On the Moon, in particular, a completely arid and geologically “dead” world, more than 300,000 craters with a size equal to or greater than 1 km have been recorded. On our planet, on the other hand, the really large craters, with a diameter greater than 20 km that we have more than 45, while the total number of craters does not exceed 175. It has been estimated that the asteroids and comets that crashed into the Earth’s surface must have been at least ten times more than those that fell on the Moon, that is, more than 3 million impact craters with a diameter of 1 km or more!
However, the continuous erosion of surface rocks by the elements of Nature and the unstoppable tectonic activity that constantly reshapes the earth’s surface through the displacement of tectonic plates and volcanic eruptions, erase its previous characteristics and the “scars” that occurred. from the fall of space invaders “become extinct” with the passage of geological time.
Such collisions, capable of causing mass extinction of species, are extremely rare, occurring every 100 million years or so. In fact, there is no doubt that the frequency of an asteroid colliding with Earth is inversely proportional to its size. Space projectiles with a diameter of 50 meters enter the Earth’s atmosphere with a frequency that generally does not exceed once every few hundred or thousands of years. On the other hand, asteroids with a diameter of 1-2 km bombard our planet on average every 1 million years, while asteroids with a diameter of 5 km every 10 million years.
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