Human overpopulation occurs if the number of people in a group exceeds the carrying capacity of a region occupied by that group. Overpopulation can further be viewed, in a long term perspective, as existing when a population cannot be maintained without the rapid depletion of non-renewable resources or without the degradation of the capacity of the environment to give support to the population.The term often 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 meager or non-existent capability to sustain life (e.g., a desert). Advocates of population moderation cite issues like quality of life, carrying capacity and risk of starvation as being a basis to argue against continuing high human population growth.