So what would the world look like with roughly four billion fewer people on the planet? Well, I'm assuming that it would still be a rocky planet, and I assume it would still have lots of water on it too. However, if there were only two billion people on the planet, it would ease a lot of the stresses that the inhabitants of the planet face, and it wouldn't just be the people who benefit. The entire planet would benefit if there were fewer people, and the world could actually be a better place to live.
If there were two billion people on the Earth, it would not be much different in terms of how we got along. There would still be war, and there would still be famine, disease, and other plagues of the Earth. These things have been around since man first came into being, and will be with us for the rest of our existence. Remember that the population of the world was much smaller during the earlier days of man, and warfare was still prevalent. The black plague spread across Europe at a time when the population of Europe was just a few million at most.
However, if there were two billion people on the planet, we would be fighting over fewer resources. The land masses that humans inhabit would be more than sufficient to provide everything that we would ever need. We wouldn't have to cut down the rain forests to have access to more farmland, and we wouldn't have to worry about water shortages in places like Arizona, and other desert areas. We would have that water available because there wouldn't be as many people so spread out.
The effects of pollution wouldn't be as significant because we wouldn't have nearly the carbon footprint that we have today. There would be fewer cars, and industry wouldn't have to put out as much in order to provide for the population. With roughly two thirds of the population gone, we wouldn't need nearly as much energy either, which means that we wouldn't be using so much fossil fuels, and we wouldn't be putting nearly as many emissions into the air. The greenhouse effect would be significantly lower, and maybe global warming wouldn't be nearly the issue that it is.
Animals would probably enjoy it if there were fewer humans. With fewer humans around, it would provide animals with more space to roam. The oceans would be teeming with more life since humans wouldn't need to fish them as much. Animals in places where the habitat is threatened would have more space in which to roam, and the populations of certain species would be allowed to expand. Wolves, and other animals that humans have put in danger would be able to expand once again if left alone.
If there were two billion people on the Earth, it would probably be a good thing in a lot of ways. There would be less need for humans to take resources from the Earth, and we wouldn't need as much land. There would be less of a carbon footprint, and it would be possible for us to live in harmony with nature, or at least do so more than we do now. The Earth would belong to everything that lives on it, and not just for the survival of the human race.