Your are likely familiar with other feedback cycles without even knowing it. For example, in the 20^th century human population skyrocketed, following a near exponential growth pattern. A greater number of individuals in a population have the potential to produce an even greater number of individuals in the next generation, creating a positive feedback loop.

This positive feedback is limited by the availability of resources. From bacterial colonies to humans, every biological population on earth exhibits a carrying capacity. When this carrying capacity is exceeded, the environment can no longer sustain the size of the population, resulting in a population crash.

According to UN projections, the global population will reach 9 to 10 billion by the end of this century and remain at that level for the foreseeable future. Up until the mid-20^th century, global population was almost exclusively experiencing positive feedback. However, a slowing in the growth rate has been observed, indicating the possible presence of some negative feedback. At the moment we may approaching our carrying capacity, where the sheer number of humans on earth has a negative impact on our ability to keep increasing our numbers. Populations exhibit natural feedback cycles in which there are both positive and negative influences on the population as a result of the population.

Question: What do you think is the human carrying capacity of earth? When do you think we will reach that carrying capacity? What might happen if we exceed that carrying capacity?