Effects-based integrated assessment modelling for the support of European air pollution abatement policies

Critical load and exceedance based indicators for effects of air pollution are used to define and compare air pollution abatement scenarios, thus assisting in the framing of policies and strategies, of emission abatement options. In this chapter the effects-based support of European air pollution abatement policies since the early 1990s is described. The systematic use of computed as well as empirical critical loads and other impact assessment methodologies, such as dynamic modelling, are addressed. Computed impacts of policy alternatives that have been considered to alleviate acidification and eutrophication are compared, including the relative robustness of the magnitude and location of these impacts in Europe. It is concluded that policies have led to significant reductions in the acidification over the whole of Europe, such that expected impacts are currently minimal. With respect to eutrophication it is concluded that the excessive atmospheric deposition of nitrogen compounds will continue to have detrimental impacts on plant biodiversity and ecosystems, unless emissions of oxidized and reduced nitrogen are further reduced.