Under changing political backgrounds ICP Forests carries out multifunctional long-term monitoring.
From the late 1970s on, the condition of tree crowns was observed to deteriorate in several forest areas of Europe. As a result of this decline being originally ascribed mainly to air pollution, the United Nations Economic Commission for Europe (UNECE) under its Convention on Long-range Transboundary Air Pollution (CLRTAP) established in 1985 the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests). Today, 40 European countries as well as Canada and the United States of America are participating. ICP Forests provides the Executive Body of CLRTAP with scientific knowledge of the effects of air pollution and other environmental factors on forest ecosystems. It does so in co-operation with other programmes under CLRTAP which aim at effects of air pollution on ecosystems, vegetation, fresh waters, materials and cultural heritages as well as human health, thus enabling the Executive Body to develop legally binding protocols on international air pollution abatement policies.
In 1986 the Member States of the European Union (EU) agreed upon the European Union Scheme on the Protection of Forests against Atmospheric Pollution. Since then ICP Forests and the EU have been closely co-operating in the monitoring of the effects of air pollution and other environmental factors on forests and have thus contributed together to the implementation of clean air policies at the European level. Co-financing of the Europe wide monitoring activities ended with the termination of the FutMon project in 2011.
The "Protocol to Abate Acidification, Eutrophication and Ground-level Ozone" signed by 27 parties under CLRTAP in December 1999 and the proposal for a "Directive on National Emission Ceilings for Certain Atmospheric Pollutants" adopted by the European Commission in June 2000 are two of the latest measures. Today, the collective monitoring of forest condition of UNECE and EU constitute one of the world's largest biomonitoring systems. The monitoring system and the results achieved by it are not only of relevance for clean air policies, but also for other processes of international environmental policies, such as those aimed at biodiversity, sustainable forest management and climate change.