The annoying thing about climate change is not that it is completely false, just mostly false.

Humans do have a measurable effect on temperature(specifically, by passively generating heat, and the only way to prevent that is literally genocide and/or eugenics), but the findings around carbon emissions increasing global temperature is dubious at best. More likely natural cycles, both geological as well as solar(such as sun spot activity), are more responsible for variations in climate trends. The entire earth is such a hard to measure and predict system that anyone making bold affirmative claims that they have something as complex as climate completely figured out can usually be dismissed unless they have a model with strong predictive power.

They don't have this model yet, so I don't believe them when they say they know how the climate is going to change.