Ecosystems are highly sensitive to air pollution. To sharpen emissions reductions measures under the UNECE Convention on Long-Range Transboundary Air Pollution, expert groups have started scientific and technical work to support decision-making in the context of the process to revise the Protocol to Abate Acidification, Eutrophication and Ground-Level Ozone (Gothenburg Protocol).
To support this objective, the International Cooperative Programme on Modelling and Mapping of Critical Levels and Loads and Air Pollution Effects, Risks and Trends (ICP Modelling and Mapping), its Coordination Centre for Effects (CCE) and its Centre for Dynamic Modelling (CDM) have recently initiated technical and scientific work to improve modelling and mapping tools to assess the risks of nitrogen and sulphur exceedances, two pollutants the Gothenburg Protocol sets targets for.
The ICP Modelling and Mapping Task Force and its centres meet once a year to gather biogeochemistry and modelling experts around the most up-to-date science to advance work on pollutant thresholds for various receptors (critical loads and levels). This year’s annual meeting (Oslo, 23- 25 April) gathered some 20 Parties to the Convention.
The receptor-specific critical loads are powerful tools to assess the likelihood of indirect effects of the long-term deposition of various air pollutants. Similarly, critical levels serve as tools to assess direct effects of gaseous air pollutants. Both are intended to evaluate risks for protection of biodiversity or ecosystem functions. The predominant work of ICP Modelling and Mapping is dealing with the calculation and collection of ecosystem specific critical loads data to model and map the exceedance of critical nitrogen and sulphur pollution loads.
In its aim to improve methods and tools for this assessment, CCE provided new region-wide applications of the empirical critical loads for nitrogen and the critical levels for ammonia. In addition to that, a number of national focal points provided empirical critical loads data for their territories. Empirical critical loads are expected to reflect risks for biodiversity resulting from air pollution. The updated and improved data will be delivered to the Centre for Integrated Assessment Modelling (CIAM) for optimization calculations in 2025 and thus contribute to the effects-based approach of the Convention and to the policy recommendations in the Gothenburg Protocol revision process.
Working together with the International Cooperative Programme on Assessment and Monitoring of the Effects of Air Pollution on Rivers and Lakes (ICP Waters), experts also focused discussions on work on critical loads methods developed for assessing the risks in surface waters, confirming the importance of including these into the optimization calculations for the Gothenburg Protocol revision.