Human population growth and impacts refers to those environmental, economic, and social impacts that result from human overpopulation on local, regional, and global scales. Such impacts include the environmental impacts of increasing demand from overpopulation for energy that exacerbates climate change, and of the degradation of natural resources from overfarming resulting in food scarcity.

Overpopulation has serious consequences for sustainabiity and the total environment.  A simple model has been used to sketch these consequences:

I = P x A x T

where I is environmental impact, P is the number of people, A is the affluence per person (a measure of consumption), and T is a measure of the effects of technologies on the extraction and use of resources.  Currently, all are increasing over time, thus increasing local and global impact, increasing environmental impact and thwarting sustainability.