Rapid population growth diminishes farm sizes and ultimately pushes people off the land to search for land and employment opportunities elsewhere. Landlessness is a growing problem in developing countries. Wars, social strife, and natural disasters such as drought also force people to become more mobile. As populations concentrate in areas not yet degraded, they invariably speed up the degradation process. Large-scale migration both within and between countries may not only cause environmental degradation, it may also result from it.
Property rights are particularly prone to externalities.
Resources with open access are vulnerable to exploitation because exploiters may benefit without paying the costs associated with reduced future productive capacity. While private landownership is often most effective in achieving food security and sustainability goals, it is not always superior to common ownership. The poor usually do not own resources or reap the benefits of conservation and thus have few incentives to conserve soil, protect groundwater, or preserve trees. Poverty need not lead to environmental degradation. It is the combination of poverty, population increases, land constraints, and lack of appropriate agricultural technology that usually results in environmental degradation.