One doesn't need 'credentials' to have an opinion on a subject. We all have our own areas of expertise and disciplines but those don't exclude other things that interest us.
I have been fascinated with science with a particular interest in weather, environment, Earth phenomena for honestly as long as I can remember. Certainly since I was in grade school.
I didn't choose that as a vocation as my heart (and circumstances) took me in a different direction, but all my life I have read extensively on volcanoes, earthquakes, hurricanes, tornadoes, mega storms and their over all affect short term and long term. And in recent decades I read a lot about climate, especially paleontological climate trends and the current 'climate change' issues.
Does that make me an expert or a scientist? Not by any stretch of the imagination. But because I am not a climate change 'religionist' pushing one scientific theory to the exclusion of all others--I call that 'religion' and not science--and also because I recognize when money is most likely a primary driving force behind a so-called 'scientific' trend, I also am not ignorant on the subject either.
So when I am trolled by somebody who is a climate 'religionist' unwilling to even think about anything other than AGW as the primary force in current climate change, most especially one who debates via ad hominem and personal insults, I don't have any respect for that person's position and feel pretty reinforced in mine.