It's like the "anti-vaxxer" thing. Anyone who questions "climate science" is dubbed a "denier" and is therefore, according to some, stupid. The problem is that the last ice age is estimated to have ended some 20,000 years ago. Since then, the earth has been in a warming period, save for interruptions caused by massive volcano eruptions. The current ICE age (see what I did there) is only a little over 120 years old, and is concurrent with technological developments in measuring temperatures in the earth's atmosphere and taking accurate ice core samples. Add to this the fact that ice core samples cannot be construed as completely accurate, because the top layers of ice are and have been melting, and you have some problems with extrapolation that should start to be pretty obvious. For some reason, if you admit that the earth is getting warmer but question the need to drastically alter our way of life, you get labelled a "denier".
The thing is, people who consistently argue about how they listen to the science hide behind that word as if it somehow magically makes them correct. Science is the process of searching for truth by testing hypotheses and trying to prove them incorrect. Science is not in itself a truth. The big problem with climate science is there is no control. There is no other Earth that is exactly the same size, has the exact same atmosphere, and is the exact same distance from the same size star putting out the exact same amount of heat but without industrial humans on it. (As far as we know or can measure) So there is no real way to prove that human industrial waste is the cause of all of our climate woes. It's a pretty good hypothesis, and there is definitely merit to being good stewards of the environment, but when a person points this out, they get called a "climate science denier" as if that makes them the one who is stupid.
Ultimately, we're all going to die and it probably doesn't matter anyway, but much like climate science, I have no way to prove my hypothesis.
Patiently waiting for the anger mob.