The document provides a historical timeline of global action taken to address environmental damages and sustainability from 1900 to 2100. It summarizes key events and documents that increased awareness of environmental issues and led to strategic approaches to build healthy societies and economies while protecting the environment, including the London Smog, Rachel Carson's Silent Spring, the UN Conference on the Human Environment in 1972 that established the UN Environment Programme, and the Rio Summit in 1992 that resulted in agreements like Agenda 21.