■ For nonrenewable resources, there should be an equivalent development
of renewable substitutes.
■ Waste generation should not exceed the assimilative capacity of the
environment.Ecological Footprint
The “ecological footprint” is a measure of human demand on Earth’s
ecosystems. It is a standardized measure of demand for natural capital (world’s
stocks of natural assets, which include air, geology, soil, water, and all living
things) that may be contrasted with the planet’s ecological capacity to
regenerate. It represents the amount of biologically productive land and sea area
that is necessary to supply the resources a human population consumes, and to
assimilate associated waste.
Figure 10.5 below shows the ecological footprints of various countries on
Earth measured in global hectares per person. One global hectare represents the
average productivity of all biologically productive areas measured in hectares on
Earth in a given year.
1 ha = 2.5 acres = 10,000 m^2