I think experts are given credence because they can do a deep analysis. I expect a civil engineer to do calculations instead of just saying "I'm the expert trust me"

Is this whole trust the expert thing some new phenomenon? Because I feel confident scientists were very keen to provide the reason and evidence for their beliefs. Saying someone should be trusted just because they are an expert seems against the spirit of science

So is there reasons to believe in man made global warming? Is there is lots of reliable evidence. We should focus in that instead of who is making the claims.

You and the parent are making different versions of a similar fallacy - his is ad hominem and yours is appeal to authority. The flaw in both is they focus on the identity of the speaker rather than evaluating the validity of what is said