Before global warming, their "solution" to the idea of a supposed overpopulation problem in their heads was ideally war, or just straight up starvation of the working class. But it was mainly war, because it established a pecking order among the rich, and did the job of killing poor people well enough.
Also overpopulation has been a "problem" to these fucks for a really long time.

You better not lose a children's card game to it, or else you may be sent to the shadow realm.