| > It is not possible for there to be more people than there are resources to create them People can have different daily-intake requirements as children versus adults, plus a growing populations consummation can temporarily exceed food production by burning trough food stores. Also, local food production can vary, place to place, season to season - what's sustainable during a good year, might not be during a bad one. Plants and animals can eat and drink things humans can't; e.g. a plant is fine with muddy, faeces-contaminated water, it would even thrive on it. Livestock may happily eat grass/straw long-term. The killing of one cow won't feed a human for the rest of their lives - multiple cows are needed to provide constant food, and the cow population may as such increase along with the human population. When the rate at which the cows are eating grass is faster than the rate at which the grass grows, your population is unsustainable, and you will eventually not be able to feed everyone. The only sense in which it's "impossible to exceed the carrying capacity of the earth" is that when you do, people will die. |
So I should elaborate, global overpopulation is impossible. Local overpopulation and resource shortages are possible, but this is not due to too many people (as the resources exist somewhere on earth to support them) but due to inefficient resource management.
Local shock increases in population are due to migration, not birth rate explosion, since birth rate follows resource availability. And again, a sudden migration from one place to another of large numbers of people (which we see in urbanization) is another example of inefficient resource allocation.
The increase in resource demand from a person as they grow into adulthood is a consideration, but an indicator that resources are strained is child mortality. The fact that it is decreasing worldwide tells us that we are not at the edge of carrying capacity. Even if we were, the result would be either decreased standard of living or increased child mortality, and thus the problem self corrects. My assertion again is that human population cannot exceeded carrying capacity globally.
Some creatures can consume resources that humans need to process before consuming, but in aggregate the amount of biomass stays the same and so the resources are always available. It is a question of production, not availability. An increase in livestock that depletes the food store of the herd is essentially the same scenario as a local increase in population of humans that strains locally available resources. And like I pointed out talking about that scenario, the issue is inefficient resource allocation, not overpopulation.