Implications of current knowledge on nitrogen deposition and impacts for policy, management and capacity building needs: CLRTAP

The Convention on Long-range Transboundary Air Pollution (CLRTAP), linking North America, Europe, and large parts of Central Asia, has achieved considerable reductions in air pollution emissions and effects. In addition, CLRTAP has also facilitated political cooperation, international law development, and the use of science to develop and implement policy. For instance, regionalized emission reduction targets of the CLRTAP Gothenburg Protocol minimize environmental effects and abatement costs. However, reductions of nitrogen (N) emissions causing eutrophication effects have not been sufficient to prevent widespread critical load exceedances. CLRTAP has increasingly assessed links between N emissions/effects, climate change and biodiversity but more research is needed. To achieve enhanced capacity building and further emission reduction of N compounds challenges have to be overcome in science (e.g., regarding N effects on ecosystems and feedbacks with climate), policy (e.g., linking CLRTAP with other multilateral and global environmental agreements), and communication between science, policy and the public.