1) I believe that the climate is changing
2) Human activity is contributing to this
3) Even if we stopped all industrial and agricultural activity, it will not prevent the climate from changing.
Fact is, it is an article of faith among some environmentalists that mankind is a blight on thre face of Mother Earth, that we should all just disappear. This is the view of Anti-Christ.
I have seen this labelled the "Minimalist" position on global warming -- man does contribute, but it is such a miniscule amount, changing behavior would not have any meaningful impact.