Real scientists, through the eyes of physics, biology and astronomy, will see the dramatic future of the world actually portrayed by movies. The term does not convey the end of the world in the sense of destruction and complete obliteration of the planet, but more so, usually, the end of human civilization. Fortunately, for much of this, no or even very few millions/billions of years would have to pass before the event happens.
The Death of the Sun
By far the surest end of Earth is from the Sun. In another 5 billion years, hydrogen fuel would run out in the Sun and it would become a “Red Giant.” While it expands up to the orbital radius of this planet, maybe the inner planets including Earth get swallowed by it. The heat will still be so intense that even if it does not physically swallow Earth, it would scorch to cinders.
Rising Solar Heat
Long before it dies, the Sun will gradually become much brighter and hotter, and in about a billion years, scientists predict, by that time the intense heat will bring the oceans evaporated. Then the world returns to the carbon cycle of breathing and surely plunges the earth into a lifeless hellish and desert of Venus.
Asteroid Near Misses
Huge space rocks float around, and the history of our planet tells us how tremendous asteroids have been instrumental in devastating Earth (the more famous of them all is that which took all the dinosaurs below). It is a pattern a little belated for the “planet killer” to show up and the sun-to-visit always results in a cloud of dust that blinds the food change.
Super Volcanic Eruptions
Super-volcanoes are very many around the world, under Yellowstone, for example. A Supervolcano eruption would not only inflict damage in the particular country where it would happen, but it would also draw so much ash into the atmosphere that sunlight, for several years, would be completely pervaded everywhere. A volcanic winter would produce similar effects on all varieties of crops and discard millions into starvation, millions of people.
Loss of Biodiversity
It is, however, a rather complex web involving plants, insects, and animals which are required for human survival. As per the scientists, humans stand a big chance of future biodiversity collapse when keystone species numbers are reduced too much-all those, for example, like bees which help in pollination, or a certain section of ocean life. Anthropocentric survival will be difficult without these services from nature feeding human civilization.
Climatic Change and the Tipping Points
Such a temperature could really trigger irreversible changes when exceeded; the most obvious are huge ice caps melting, and should gigantic areas of frozen ground suddenly release large amounts of methane. Extreme weathers will be caused to permeate with polluted coasts, rendering the larger part of this beautiful planet unliveable.
The Global Pandemic
Fast spreading and lethal viruses can never be a much bigger threat to civilization with the ever-closer intertwining of worlds. For all of the advancements in science that have made possible effective vaccines, there remains the risk of some “Pathogen X” that could have a higher rate of spread than our ability to treat it, one of the major issues of concern in global health research today.
The Fading Magnetic Field
Earth is protected from poisonous solar radiation through a magnetic field. If the core of the Earth cools down and stops spinning, just like Mars, we are going to lose this shield. Oxygen cannot support life for a long time because all the solar wind would eventually blow it away and leave the surface cold and radiation-soaked.
Gamma Ray Burst
This is the only wild card coming from very deep space. If a gigantic star within our galaxy implodes and shoots a beam of gamma towards the earth, this would result in catastrophe by instantaneously stripping the ozone layer off the earth, allowing the most intense UV rays of the sun to penetrate through the atmosphere to reach the surface, exterminating most life forms in record time.
