Overpopulation can result from an increase in births, a decline in mortality rates, an increase in immigration, or a depletion of resources.
Scientists suggest that the Human impact on the environment as a result of overpopulation, profligate consumption and proliferation of technology has pushed the planet into a new geological era known as the Anthropocene.
Most contemporary estimates for the carrying capacity of the Earth under existing conditions are between 4 billion and 16 billion.
Depending on which estimate is used, Human overpopulation may or may not have already occurred.
The population is expected to reach between 8 and 10.5 billion between the years 2040 and 2050 and 11.2 billion for 2100.
The recent rapid increase in Human population over the past three centuries has raised concerns that the planet may not be able to sustain present or future numbers of inhabitants.
Many environmental problems, such as rising levels of atmospheric carbon dioxide, global warming, and pollution, are aggravated by the population expansion.
Other problems associated with Overpopulation include the increased demand for resources such as fresh water and food, starvation and malnutrition, consumption of natural resources faster than the rate of regeneration, and a deterioration in living conditions.