I think this started with a discussion about global warming predictions that turned out to be inaccurate.
Why don't people accept the accurate predictions? It was predicted that increasing atmospheric CO2 levels would cause an increase in global temps, and that has indeed happened. Why do people dispute it?
For example, Svante Arrhenius did the first crude calculations for how much global temperatures would rise with a given amount of CO2. He predicted a 5-6C increase in temperatures if the amount of CO2 doubled. This was clear back in 1898.
Right now, we are about 1.1C above 1880 levels with a ~50% increase in CO2 levels, and we really haven't hit temperature equilibrium yet. Even given Arrhenius' crude calculations back in 1898, we are about where we would expect to be.
We have known about the risks of CO2 for over 100 years. It isn't a mystery. The real question is why people want to deny the basic science?