I think most of us agree on the fact that the human is one of the main cause of earth's destruction.
I would say that the human factor that have made the earth go wrong the most is overpopulation.
Remember that each human needs maintenance and earth has limited resources. If there is more humans, there
needs to be a broader distribution of the limited resources what means, less food/water, more poverty and more contamination.
There's a terence mckenna talk about this topic which is very insightful and eye-opening about the importance of this problem, here's the link:
https://www.youtube.com/watch?v=gdQaBd6dHAE