Just for giggles, let’s say that once-upon-a-time some powerful people, who were already suppressing working non-polluting energy sources, decided that there were too many people on the planet for them to control. They had already tried to convince people that reproduction needed to be controlled for the good of “the gene stock,” but because a nasty group over in Germany adopted their program of Eugenics a little too enthusiastically and gave it a bad name, they had to find other approaches. So they decided they needed to convince everyone that “…the real problem then, is Humanity itself.”
So they founded think tanks, funded universities and professorships, gave out generous grants for research proving their idea was true, used the media that they controlled entirely, held international conferences, changed the historical data while saying the new “facts” were science that needed to be worshiped, marginalizing anyone who disagreed with their new fable to justify the solutions they had already decided on.
The new story, which marched to their massive propaganda drumbeat was: PEOPLE WERE BREATHING TOO MUCH and causing the imminent collapse of the Earth’s biosphere, and the number of breathers must be reduced OR ELSE!!!
Of course, anyone who suggested that the problem was not real would now be denounced as pariahs with vehement emotion and executed before outraged crowds in the public square, thereby eliminating both their deluded ramblings and the damage their breathing caused. And the Earth was saved.