Answer: a reduction in oxygen as trees would be cut and an increase in poverty as no much resources to sustain the population
Step-by-step explanation:
As humans increase in population, there are some events that will likely happen as a result of that, One of them would be a reduction in oxygen, these would be effective due to humans would begin dominating more environment; building houses and would take down trees which contribute to oxygen intake.
Another would be a rise in poverty and lack of resources. These is already effective in china and India. The rates of humans there have pushed people into poverty as there is not enough resources to sustain the environment. China has to adopt measures to ensure a family is not more than four so they can control the population growth.