The Natural Step (TNS) System Conditions

Sustainable development is economically progressive social betterment without growing beyond the ecological carrying capacity: achieving human well being without exceeding the Earth's twin capacities for natural resource regeneration (e.g., trees and water) and waste absorption (e.g., carbon dioxide and toxic chemicals). This is accomplished by the coming together of a community’s ecological, economic and social objectives.

The Natural Step recommends humans maintain the integrity of the ecological systems that support life. Using The Natural Step’s 4 System Conditions can provide a "compass" to guide organizations, communities, and individuals towards sustainable practices. The 4 Conditions are the following.

1. How can we reduce our dependence on mining and fossil fuels? In a sustainable society nature's functions and diversity are not systematically subject to increasing concentrations of substances extracted from the Earth's crust. There are thresholds beyond which living organisms and ecosystems are adversely affected by these increases. Human activities such as the burning of fossil fuels, and the mining of metals and minerals need not occur at a rate that causes them to systematically increase in the ecosphere.
2. How can we reduce our dependence on persistent, unnatural substances? In a sustainable society nature's functions and diversity are not systematically subject to increasing concentrations of substances produced by society. Synthetic organic compounds such as DDT, PCBs, and freon can remain in the environment for many years, concentrating in Earth's atmosphere or accumulating in the tissue of organisms, causing profound deleterious effects on predators in the upper levels of the food chain. Society needs to find ways to reduce economic dependence on persistent human made substances.
3. How can we reduce our dependence on nature consuming activities? In a sustainable society nature's functions and diversity are not systematically impoverished by physical displacement, over-harvesting, or other forms of ecosystem manipulation. Biodiversity, which includes the great variety of animals and plants found in nature, provides the foundation for ecosystem services which are necessary to sustain all life on this planet. Humans should avoid taking more from the biosphere than can be replenished by natural systems, or systematically encroaching upon nature by destroying the habitat of other species. Society's health and prosperity depends on the enduring capacity of nature to renew itself and rebuild waste into resources.
4. How can we do more with less? In a sustainable society resources are used fairly and efficiently in order to meet basic human needs globally. Humans need to be efficient and fair with regard to resource use and waste generation in order to be sustainable. Achieving greater fairness is essential for social stability and the cooperation needed for making large scale changes within the framework laid out by the first three conditions.