The problem is our ecological footprint. There are too many people on Earth. We would already need 2 Earths. Overpopulation causes so many problems. Not just air pollution and climate change, but also deforestation, mass extinction of animal species, lack of food, human mass migrations, elevating crime rates, and so on. Human impact on Earth is so profound that scientists have already declared a new epoch: the Anthropocene. That's really terrible. Everything is out of balance. I think we should try to reduce the world population. I think, it's not enough to stop the growth. If we could reduce it to 3 or 4 billion, Earth should be able to reestablish a natural balance. Then all the mentioned problems should be solved. I am ready to help.