The concept of sustainable development (SD) has been a part of the global ecological dialogue among scientists and governmental leaders for more than two decades. One outcome of the 1992 United Nations Conference on Environment and Development (UNCED, or the Earth Summit) was The Earth Charter, a policy statement about the ethics of international SD. The Charter opens, "We must join together to bring forth a sustainable global society founded on respect for nature, universal human rights, economic justice, and a culture of peace" (Earth Charter International Secretariat 2000). This statement captures the ethical context in which policy-makers developed the SD concept.

The most commonly used definition of SD comes from the 1987 report prepared for the Earth Summit, Our Common Future (1987). SD is "Development that meets the needs of the present without compromising the ability of future generations to meet their own needs" (WCED...