As a child I was a consumer of a fair amount of environmentalist alarmism. Not the standard stuff you see on the news, but books like The Population Bomb.
I also read the science fiction classic Stand on Zanzibar. Stand on Zanzibar is about an overpopulated Malthusian world. It is the world of 2010, and the population is 7 billion. The author, John Brunner, was writing in 1968. This was the beginning of the worries about population growth and sustainability.
Brunner was right about the world population in 2010…but it’s not quite the dystopia that he painted. In some places, like the Congo, it is quite hellish. But in much of the world there is a slow but steady advancement, much of it thanks to China.
Rather than the inevitability of a Malthusian crisis due to overpopulation (note that fertility rates peaked in the 1960s) slowly creeping up on us, I think we need to worry about our society’s ability to withstand shocks. Those shocks might destabilize the social matrix which our high productivity society needs to survive, and without that productivity, we will be a Malthusian crisis.