Environmental indicators are essential tools for tracking environmental progress, supporting policy evaluation and informing the public. Since the early 1990s, such indicators have gained in importance in many countries and in international fora. As part of their commitment to transparency and to better information of the public, OECD countries increasingly use a reduced number of indicators, so-called “key indicators”, selected from larger sets to report on major environmental issues. The OECD pioneered the development of international environmental indicators and has long supported its member countries' efforts in this field. Its work has led to several sets of environmental.
