As countries and regions around the world began to develop, it slowly became evident that industrialization and economic growth come hand in hand with environmental degradation. Eco-efficiency has been proposed as one of the main tools to promote a transformation from unsustainable development to one of sustainable development. It is based on the concept of creating more goods and services while using fewer resources and creating less waste and pollution. "It is measured as the ratio between the (added) value of what has been produced (e.g. GDP) and the (added) environment impacts of the product or service (e.g. SO₂ emissions)." The term was coined by the World Business Council for Sustainable Development (WBCSD) in its 1992 publication "Changing Course," and at the 1992 Earth Summit, eco-efficiency was endorsed as a new business concept and means for companies to implement Agenda 21 in the private sector. Ergo the term has become synonymous with a management philosophy geared towards sustainability, combining ecological and economic efficiency.