It's sad seeing people without any respect to nature. Since Unabomber and Ellul were already mentioned I don't have much to say. Deforestation and economic use for one do not solve overcrowding problems, it only gives more space for more people and multiplies overpopulation, poverty and misery in the long run. Big cities will always be overcrowded because they are most economically successful. You can unload a chunk of people from big city and move it to the new area, but after some time both will end up being overcrowded or overused (in case it's a farming/industrial area).
This is the exact problem with civilization. A proper settlement self-regulated when dealing with overpopulation. Civilization on the other hands allows you to have overcrowded slums for several generations without dying out and in fact producing even more slums and more people. And this is a train you cannot stop, the more it runs the more troubles it creates, and any attempt at solution does exactly the opposite.
We in fact require less people, not more of them, and more nature, not less of it. There is much space, but all living creatures require their own space, you cannot keep stuffing them together or will have to deal with consequences.
Ideal system for me would be some kind of technologically advanced eco-Utopia with < 1 billion of population where technology is kept in symbiosis with nature, but it requires complex, portable and easy to deploy technology and will probably never happen. People have to seek for balance and symbiosis, because it is always the most successful form of life.
If you just keep going with multiplying population, suffering, poverty and pollution (in other words, scaling the industrial system) you will have to deal with consequences described by Kaczynski and Ellul, plus consequences such as shown in mouse utopia experiment.