Sustainability, in a general sense, is the capacity to maintain a certain process or state indefinitely.similarly the absence of certainty in terms climate change, global warming has rasied the profile of sustainability . In recent years the concept has been applied more specifically to living organisms and systems. As applied to the human community, sustainability has been expressed as meeting the needs of the present without compromising the ability of future generations to meet their own needs.

The term has its roots in ecology as the ability of an ecosystem to maintain ecological processes, functions, biodiversity and productivity into the future. To be sustainable, nature's resources must only be used at a rate at which they can be replenished naturally. There is now clear scientific evidence, (environmental science), that humanity is living in an unsustainable way, by consuming the Earth's limited natural resources more rapidly than they are being replaced by nature.1 Millennium Ecosystem Assessment web site – the full range of reports are available here. Consequently, a collective human effort to keep human use of natural resources within the sustainable development aspect of the Earth's finite resource limits is now an issue of utmost importance to the present and future of humanity.

Sustainability has become a controversial and complex term that is applied in many different ways: to different levels of biological organization (e.g. wetlands, prairies, forests), human organization (e.g. ecovillages, eco-municipalities, sustainable cities) and human activities and disciplines (e.g. sustainable agriculture, sustainable architecture).

Definition

Sustainability is many things to many people. It can simultaneously be an idea, a property of living systems, a manufacturing method, or a way of life. For some people it is little more than a hollow buzz word. Although the definition of sustainable development given by the Brundtland Commission (used above), is the most frequently quoted, it is not universally accepted and has undergone various interpretations. Difficulty in defining sustainability stems in part from the fact that it may be seen to encompass all human activity. It is a very general concept like "liberty" or "justice", which is accepted as important, but a "dialogue of values" that defies consensual definition. It is also a call to action and therefore open to political interpretation concerning the nature of the current situation and the most appropriate way forward. A further practical difficulty with a universal definition is that the strategies needed to address "sustainability" will vary according to the particular circumstances under consideration