"Human overpopulation occurs when the ecological footprint of a human population in a specific geographical location exceeds the carrying capacity of the place occupied by that group. Overpopulation can further be viewed, in a long-term perspective, as existing when a population cannot be maintained given the rapid depletion of non-renewable resources or given the degradation of the capacity of the environment to give support to the population. The term human overpopulation refers to the relationship between the entire human population and its environment: the Earth, or to smaller geographical areas such as countries. Overpopulation can result from an increase in births, a decline in mortality rates, an increase in immigration, or an unsustainable biome and depletion of resources. It is possible for very sparsely populated areas to be overpopulated if the area has a non-existent capability to sustain life, such as a desert."