It's hard to take any kind of wholesale prediction of population calamity seriously after The Population Bomb bombed in the early 1970s. But this article claims to be able to predict the future of civilization 100 years into the future. Assuming we even make it another 100 years, there is no way to know what our population will look like then, or whether we could pull another technological/logistical food revolution out of our asses, or whether global cultures would start to embrace a further explosion of population. WW2 resulted in unprecedented population growth in the USA. There's no way to know if a similar event, here or in other countries, might shake what we expect growth to be, or why. The biggest mistake we could make is to expect consistency.