On 5 June 1972, in the Swedish capital, they began to build their response, in the form of the United Nations Conference on the Human Environment - the first UN summit on the environment, and the event that really put the issue on the global political agenda.

BBC: Stockholm: Birth of the green generation

World Environment Day was established by the United Nations General Assembly in 1972 to mark the opening of the Stockholm Conference on the Human Environment.

BBC: NEWS | Science/Nature | Changing planet revealed in atlas