The document provides background information on several United Nations environmental summits held between 1972 and 2012, including key outcomes and issues discussed. It summarizes the United Nations Conference on the Human Environment held in Stockholm in 1972 which established the UN Environment Programme. It also describes the 1987 Brundtland Commission report and the 1992 Earth Summit in Rio de Janeiro which resulted in agreements on climate change, biodiversity, and forests. The document further discusses the Rio+5, Rio+10, and Rio+20 summits and their focus on advancing sustainable development goals.