The approach is simple, and has been tested over and over again throughout history.
If you can convince a significant segment of the population that there is evil which threatens their existence, you can get them to engage in almost any atrocity.
The particular evil is irrelevant. Hitler convinced many people in Germany that Jews were evil, and threatened their existence. Hansen has convinced many people that CO2 and climate deniers are evil, and threaten their existence. The same story has repeated itself over and over again – Infidels, Muslims, Hindus, witches, blacks, whites, alcohol, Chinese, Japanese, immigrants … etc.
History is full of atrocities committed by imbeciles – who were motivated by irrational fear and believed that they were doing something good.