The problem is that there are too many people on Earth. Our impact on Earth is much too high. We would already need 2 Earths. Overpopulation causes a lot of problems, not just deforestation, mass extinction of animals and climate change, but also lack of food, human mass migrations, elevating crime rates, and so on. However if we could reduce the world population to 3 or 4 billion people, than all mentioned problems should be solved and Earth should be able to re-establish a natural balance.
I am ready to help.