Overpopulation is indeed a concerning issue, that if not controlled soon, will have a major impact on Earth. When population levels reach a critical threshold, we then see both a decline in the resource base, and damage to the environment, which supplies all those resources. These trends reinforce each other - the damaged environment provides fewer resources, and the shortage of resources causes us to further damage the environment. World energy needs are projected to double in the next several decades, but no credible geologist foresees a doubling of world oil production, which is projected to peak within the next few decades. Many `growth' advocates will argue that the natural ingenuity of people will overcome any problems that population growth creates. Advocates of `sustainability' argue that increasing population and consumption are already causing massive damage to the planet and that soil erosion, extinction of species, pollution of air and water, and deforestation are all indicators of exceeding carrying capacity. Deforestation is driven by a wide range of social and economic forces, but underlying them all is the severe growth of human population and the rising demand for land and forest products such growth creates. Due to overpopulation, and hence over-exploitation, the world's oceans are being pushed beyond their breaking point. Eleven of the fifteen most important oceanic fisheries and seventy percent of the major fish species are now fully or over-exploited, according to. It is impossible for people to live without forests, food, and water. Yet the world's supply of these necessities is gravely threatened by thriving population growth.
Another issue concerning population is employment. Some growth advocates argue that their economies will suffer as the citizens age if populations do not continue to grow. Some industrialized nations with stable populations already face shortages of younger workers.