In 1992, the United Conference on Environment and Development, also known as the Earth Summit, was held in Rio de Janeiro. This Summit established linkages between economic and social development and environmental protection and adopted Agenda 21 and the Rio Principles. Follow-up is ensured through the setting up of the Commission for Sustainable Development (CSD), whose work is based on two-year cycles of review and policy years, organised around clusters of issues. The issues for 2008-2009 are: agriculture, rural development, land, drought, desertification and Africa; while the issues to be tackled in the following two-year cycle are: transport, chemicals, waste management, mining and 10-year framework of programmes on consumption and production patterns. In 1997, a special session of the General Assembly of the United Nations, called Earth Summit 5 adopted the Programme for Further Implementation of Agenda 21, including a programme of work for CSD for 1998-2002. The World Summit on Sustainable Development held in Johannesburg ten years after the Earth Summit evaluated progress since 1992 and adopted the Johannesburg Plan of Implementation.