1970 - The firstEarth Day, on April 22, millions of people gather in the United States for the first Earth Day organized byGaylord Nelson, former senator of Wisconsin, andDenis Hayes, Harvard graduate student.
1972 -The Limits to Growth was published. The book is about the computer modelling of unchecked economic and population growth with finite resource supplies, and became both controversial and influential.
1993 - theConvention on Biological Diversity, known informally as the Biodiversity Convention, enters into force. It is an international legally binding treaty.
2002 - the World Summit on Sustainable Development, WSSD orEarth Summit 2002 took place in Johannesburg, South Africa, from 26 August to 4 September 2002. It was convened to discuss sustainable development by the United Nations.
