> What nonsense.

What rudeness.

> That’s rarely the opinion of those who hold that view.

I've tracked climate science deniers for decades and that simply isn't true.

> If climate change has any non-human causes, then to what extent are we humans able to have an affect on those non-human causes?

Of course climate change has some non-human causes, but most of them aren't the ones that we humans are able to have an effect on, so the question is off base. It's the human causes that we humans are able to have an extensive effect on, obviously.

Your question can possibly be read as implying that the causes are either non-human or they are human, rather than there being both types of factors ... if that's the case then it reflects an extraordinary lack of knowledge about the subject.