Factors that threaten Earth’s survival?

Will the Earth last forever? This is a difficult question to answer. However, a number of factors below can affect the existence of the Earth.

In what form could life on earth end in the end? Photo: Astronomy Some scientists point out that the earliest life on Earth was born about 4 billion years ago. At that time, the Earth was continuously bombarded by space meteors, but life continued strongly. Earth’s history has seen many catastrophes, and each one is like the end of the world. Supernova explosions, asteroid collisions, large-scale volcanic eruptions, sudden climate changes … these events have claimed countless lives. During a number of mass extinction events, most of the species at that time had been wiped out. In the end, however, life still goes on. There will always be new species on Earth, and a new cycle will begin again. Although human life may be unimaginably fragile, turning the entire Earth into a barren land is not so easy. Here are some events that have the potential to wip out all life on Earth (very low probability and not happening in the near future). The impact of asteroids When an asteroid hits Earth, it releases incredible energy. 66 million years ago, an asteroid the size of a city crashed into the Gulf of Mexico and led to the extinction of the dinosaurs. At that time, all other creatures on Earth were almost wiped out. Although human ancestors were not born at that time, it may be the most important event in human history. Without the asteroid impact, dinosaurs could always be the lord of Earth, and other mammals could only exist in their shadow. According to geological records assessment, the frequency of Earth being collided by large asteroids is about 100 million years. However, smaller asteroid effects occur more often. There is even evidence that some people have died from the effects of asteroids over the past few thousand years. In 1888, in Sulaymaniyah, now in Iraq, a meteor strike killed one person and injured another. This is the earliest recorded asteroid accident. But what is the probability that Earth will be hit by a large asteroid? A 2017 study published in Nature has shown that to cause this asteroid must be large enough. Only the largest asteroids in the solar system (like Pallas and Vesta) can do this. Richard Binzel, a professor of planetary science at MIT, said even though an asteroid might one day come and destroy us, the likelihood is very low. Oxygen depletion Fossil of trilobite, one of the earliest arthropods on Earth. Photo: Shutterstock The chances of the latter being slightly higher than the previous. First, let’s go back to long history. Nearly 2.5 billion years ago, Earth went through a period known as the “Great Oxidation Event” – creating oxygen on a global scale. The increase in cyanobacteria causes a huge increase in the amount of oxygen in the atmosphere. Without this event, no oxygen-breathing animals would exist and the biological world would not have been diverse, from low-order monocytes to higher multicellular flora and fauna, including humans. However, about 450 million years ago, one of the most serious extinction events on the planet – the Ordovic -Silur mass extinction occurred. It could be due to the sudden drop in oxygen levels at that time, which lasted for millions of years. But why is this happening? During the Ordovic period, all the continents on Earth were connected to form the supercontinent Gondwana. At that time, most life on Earth existed in the ocean, but plants began to appear on land. At the end of the Ordovic period, the Earth’s climate suddenly changed, causing this supercontinent to be covered with glaciers. The sudden drop in global temperature alone is enough to cause the disappearance of many species. Then, when global oxygen levels plummeted, life on Earth experienced a second wave of extinction. Scientists can find evidence of this drastic change in sediment samples on the seabed. Some researchers believe that glaciers at that time caused a fundamental change in ocean stratification, and that the temperature and oxygen concentration of each layer of seawater differ. However, the exact cause of this significant reduction in oxygen is still being debated. Whatever the reason, more than 80% of the species on Earth disappeared during the Ordovic mass extinction. Such events happened in the past, will history repeat in the future? In fact, a recent study published in Nature Communications has shown that climate change reduces oxygen levels in the ocean, which can cause the extinction of some marine life. Gamma-ray bursts Gamma-ray bursts can originate in binary star systems. Photo: University of Warwick Gamma-ray bursts occur when a giant star dies, explodes like a supernova, and collapses into a black hole. It spits out stream of rays at the speed of light in the universe. Any planet in the path of this stream would lose its atmosphere immediately and be burned. When the gamma rays in the explosion hit the blue planet’s atmosphere, they will cause oxygen and free nitrogen atoms to collide, and some will recombine into N2O compounds, the destroyer. ozone layer. N2O is long-lived in the atmosphere, and they continue to destroy ozone until it falls to the ground through rainfall. If there was a gamma-ray explosion in the Milky Way, it could potentially cause the extinction of a large number of species on Earth. If the gamma-ray burst was aimed in the direction of the Earth, even if it lasted only 10 seconds, it would destroy at least half of the Earth’s ozone layer. Scientific research in recent decades has shown that even a small fraction of the ozone layer is destroyed enough to weaken Earth’s “natural protective layer” and cause serious problems. And if the ozone layer is depleted to a certain extent, the Earth’s food chain will be severely damaged, leading to the extinction of a large number of species. Death of the Sun. As the sun continues to age, more and more energy is released, which could eventually wipe out the oxygen in Earth’s atmosphere. Photo: Nasa A study published in the journal Nature Geoscience in March this year showed that regardless of whether or not a gamma-ray explosion occurs, in about a billion years, most life on Earth will die from lack of oxygen. A team of scientists working with NASA believes that this oxygen-rich atmosphere will not last forever. In a billion years, the activity of the Sun will cause the Earth’s oxygen levels to drop back to the levels they were before the “Great Oxidation Event”. The team describes the last moment before the Earth’s inability to support life as follows: “We find that the deoxygenation of the future is an inevitable consequence of increased heat radiation from the Sun. The exact timing of this process will be governed by the redox flow that changes between the geological mantle and the ocean-atmosphere system and the Earth’s crust. ” Conclusions are made after modeling and running simulation based on the algorithm hundreds of thousands of times. The start time and duration of this process will depend on a variety of factors, and can be as short as 10,000 years. But researchers point out that for Earth, in the end, this fate is inevitable. Fortunately, humanity still has 1 billion years left to find another way out.