good or bad is a subjective judgement. For me GW is a good thing.

To answer your listed questions
1. GW is a good thing for me, unfortunately I don't know if it is happenning
2. I don't know who caused GW, if at all. I think whoever cause it if it is true
3. I don't know human factor is negligible or not. I don't know if dinosaur factor is negligible to it extinction either. And I laugh at those religious people who believe they know
4. you probably should ask this question first. what a messed mind。