When human numbers increase, human needs also increase. We meet those needs by consuming more resources. That consumption causes environmental damage, because the environment is the source of all our essential resources. The larger the population, the more resources we consume, and the more environmental damage we cause. When there are too many people for available resources, scarcity and poverty result.
Scarcity then drives migration, conflict, and greater environmental destruction .
As more resources are consumed, fewer are available. Resources also become more scarce as environmental damage increases, because the damaged environment can't produce as many resources. This resource scarcity causes a number of problems. If there isn't enough food, people go hungry. If there isn't enough water, people are thirsty.