Carrying capacity
Human ecologist William Rees made me familiar with the distinction between K-selected species (K for maximum carrying capacity) and R-selected species (R for maximum reproductive capacity). Humans are K-selected, which means they will expand as long as the carrying capacity allows. That’s what happened with the green revolution and will indeed probably happen again if we are able to increase yields.
World estimate - 2B. Source: TW
Haber process
Nearly 50% of the nitrogen found in human tissues originated from the Haber–Bosch process. Thus, the Haber process serves as the “detonator of the population explosion”, enabling the global population to increase from 1.6 billion in 1900 to 7.7 billion by November 2018.