What are some likely scenarios for the long-term future of the Earth?
There are no solid proofs to how the earth is going to be like in the future. However, there are theories that are suggested based on hypothesis with proofs from evolutionary patterns, biochemical analysis and geographical references.
1. As the sun gets older, the size gets bigger. Consequently, the temperature of the earth will get hotter. It can remove the ozone layer totally that will allow the complete penetration of UV rays in the earth. This is theoretically assumed to start 1-2 millions years from now.
2. The life on earth is predicted to cease at the maximum of 2.8 billion years from now. At that point, the surface temperature is 147 degrees Celsius. Also, genetic components (DNA and RNA) are seen to disintegrate or decay.
3. There will be new volcanoes and islands to be formed. Polar caps will soon melt and the water current may change direction.
4. Humanity is seen to evolve 50,000 years from now and the genetic component will be completely different. The physical characteristic of human structure may vary. It is predicted that humans in those times were able to construct a self managing robots where they can store their genetic components to be used in the future. These robots can be able to dominate the world as predicted in some fiction films. Civilization will be completely different as compared to the present.
There's no for sure answer in what will happen in the future, but there is a chance that either humans will understand the danger we're in and start trying to help the world while they can, or a billion some years in the future, we will be forced to leave this earth because of the mass destruction we have caused.
1) Earth has a limited supply of fresh water. At some point the earth's population will excede the available amount of fresh water and only salt water oceans will remain. This will have a devastating effect, not just for humans but for all life on earth. Unless an effecient way of manufacturing fresh water is developed, life on earth will cease in this scenario.
2) Earth becomes depleted of its fossil fuels. This will not be nearly as catastrophic as running out of fresh water. We have already investigated energy alternatives that will suffice for fossil fuels. Eventually all energy will be from "green" sources, such as geothermal energy, solar and wind energy.
3) Humans run out of liveable space. Our poplulation is increasing rapidly and there is a limited amount of dry land on which to live and farm. Eventually, this may lead to alternavive farming techniques such as aquaponics. Even people may have to live over water when we run out of space.
In his book titled Ten Billion, Stephen Emmott predicts that our world population will reach 10 billion by the year 2100. Since the year 1998, we have had 10 of the hottest years on record, and he predicts that some of the coming years will break records as well. He says that our population directly effects the entire system of the world, and we are putting more and more stress on it as we continue to rapidly grow.
Emmott also predicts that the demand for food will double by the year 2050, which will mean more of our arable land will be used to meet this demand. He also predicts that, in 2025, we will be using 6,000 cubic kilometers of water per year globally. This rate was 600 a century ago and is currently 4,000. He predicts that by 2025, over 2.5 trillion acres of land will be cleared for food production, which is an area larger than the entire United States of America.
In short, Emmott predicts that, since we are currently going through our limited resources at an unsustainable rate, we will run this Earth dry in just a matter of time. If you are writing a paper on the topic, or simply interested in it, I definitely recommend this book, It is an interesting read that definitely gets you thinking about our world.