1, virus outbreak
A virus is something that has always existed. Although it is too small for us to see, it is really fatal when it is fatal. There are countless kinds of viruses, many of which are harmless to us. Viruses have played a very important role in the evolution of human beings. But for some viruses, they will endanger human life. For example, the outbreak of novel coronavirus is highly contagious and harmful, and now it is harmful to all mankind. Besides novel coronavirus, there are many deadly viruses, such as Ebola virus, AIDS virus and dengue virus. The most terrible virus is smallpox virus, which killed 65.438+0.5 billion people.
2. Earth geomagnetic reversal
Our earth is actually a big magnet, and the magnetic field formed by this magnet can resist or weaken all kinds of dangers thrown by the sun and protect life on earth for hundreds of thousands of years. However, if the north and south magnetic poles deflect, the magnetic field will change, and the protection of the earth will be seriously weakened or even disappear directly. There have also been events in history that caused species extinction because of the deflection of the earth's magnetic pole.
3. Global warming
If the temperature of the earth is out of control, it will become as hot as summer and as cold as death as Venus. In several mass extinctions on the earth, the most fundamental reason is that the temperature is out of control. Most species have strict temperature requirements for their living environment, and few species can resist extreme weather. Now that the temperature of the earth has become higher than before, it is hard to say whether it will continue to heat up. And if the temperature gets higher, the sea level will also rise, and then a tsunami or something will happen together, then it will really be the end of the world.