Malthusianism is the theory that population growth is potentially exponential, according to the Malthusian growth model, while the growth of the food supply or other resources is linear, which eventually reduces living standards to the point of triggering a population decline. This event, called a Malthusian catastrophe (also known as a Malthusian trap, population trap, Malthusian check, Malthusian crisis, Malthusian spectre, or Malthusian crunch) occurs when population growth outpaces agricultural production, causing famine or war, resulting in poverty and depopulation. Such a catastrophe inevitably has the effect of forcing the population to "correct" back to a lower, more easily sustainable level (quite rapidly, due to the potential severity and unpredictable results of the mitigating factors involved, as compared to the relatively slow time scales and well-understood processes governing unchecked growth or growth affected by preventive checks). Malthusianism has been linked to a variety of political and social movements, but almost always refers to advocates of population control.
For one thing, replacement births are going way, way down. As country after country goes from abject poverty to less poverty, women are having fewer babies. Modern medicine means fewer children die before 5 YO, which also leads to fewer babies born.
The world population should peak at about 11 million by 2100...
As far as resources go, look at the little European country known as the Netherlands. Given their extremely small size geographically, they are ranked the number three food exporter in the world, ranking only behind the USA, #1, and Brazil, #2. They Dutch are building and using multi-story buildings as greenhouses, with LEDs providing light to what would otherwise be dark floors shaded by ceilings and walls.
Pretty remarkable!
Smart!