A key issue in ecological and environmental economics is the relationship between
private behaviour and social goods, such as clean air and water. The social problems of
over-use and pollution arises from the use of inadequately regulated common resources,
i.e. open resources such as the atmosphere, rivers, seas, or public land or infrastructure,
such as parks or roads. Suppose that each individual, social group or country is free to
consume and produce within the framework of national or international law and social
custom. Suppose also that the consumption or production also entails damaging use of
the common resources, e.g. burning of fossil fuels and emissions of waste gases, smoke
and other pollutants into the air. The benefits accrue in the form of private or marketed
use or acquisition of goods and services, such as transportation. The costs are not only
the direct private or marketed costs of the activity, e.g. the cost of the fuel, but the social
costs of the pollution. The costs of pollution are generally social because they are borne
by society as a whole rather than by the private individual, group or the country who
generates them.