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Ecosystem Modelling: Critical loads, dynamic modelling and bias

Explore the latest findings on critical loads of Cadmium, Lead, Mercury, acidity, and nutrient nitrogen with dynamic modelling progress reports. Understand the impact of bias and the focus on robustness in policy applications since 1998.

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Ecosystem Modelling: Critical loads, dynamic modelling and bias

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  1. Ecosystem Modelling:Critical loads, dynamic modelling and bias Jean-Paul Hettelingh Coordination Center for Effects (CCE) 30th Meeting of the Task Force on Integrated Assessment Modelling (TFIAM) Berlin, 25-27 May 2005

  2. Overview • Status of CCE work • Critical loads of Cadmium, Lead, mercury (progress report) • Critical loads for acidity, for nutrient nitrogen, and dynamic modelling of delay times (CCE Status Report 2005) • Possibilities for use in RAINS • On bias…: Robustness • Future • Nitrogen • Nitrogen-climate-biodiversity controversy (Bias ?)

  3. On bias… “….as we know, there are known unknowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns -- the ones we don’t know we don’t know…” (Secretary Donald Rumsfeld in a Dept.Of Defense briefing on 2 December 2002)

  4. On bias… We must be practical regarding the desire to quantify the sign and magnitude of the deviation of our scientific and technical knowledge of entities that are used to support European environmental policy (…precautionary principle and principle of preventive action should prevail*)Efforts to quantify uncertainty, sensitivity, error or bias of sub-entities should be traded off against their importance for the robustness of integrated assessment results compiled with scenario analysis including gap closure concepts on exceedances.*See Art. III-233, para 2 of the Treaty for the Establishment of a European Constitution

  5. On bias …Focus on robustness in policy applications Robustness of critical loads since 1998 Robustness of exceedances since 1998 Lagrangian vrs. Eulerian model 1998 vrs 2004 critical loads Average Accumulated Exceedances computed with the EMEP Eulerian model and critical loads from 1998-2004 known unknowns in the past and anticipated ones…

  6. Results on data forCritical loads for acidity, nutrient nitrogen and dynamic modelling Results are based on data that became available before the 15th CCE workshop, Berlin 25-27 April 2005 !

  7. 14 countries submitted data on critical loads 13 countries submitted Dynamic modelling Data in 2005 [25 countries (18 EU25) ever submitted CLO data; 18 EU25; 14 countries (10 EU25) ever submitted DM data)

  8. Ecosystem specific citical loads for acidity; CLmax(S) All Forests Semi-nat veg Surface waters

  9. Analysis of robustness of critical loads data since 1998

  10. On bias… Robustness of CLO’s 1998-2005: Change of CLmax(S) statistics Since 1998: Increase of median by more than 500 eq-1 ha-1 since 1998 in Austria and Italy Decrease of median by more than 500 eq-1 ha-1 since 1998 in Croatia

  11. Ecosystem specific critical loads for nutrient nitrogen; CLnut(N) All Forests Semi-nat vegetation Surface waters

  12. On bias … Robustness of CLO’s 1998-2005 Change of CLnut(N) statistics Since 1998: Increase of median by more than 500 eq-1 ha-1 since 1998 in Austria and The Netherlands Decrease of median by more than 500 eq-1 ha-1 since 1998 in Belarus and Ireland

  13. Use by RAINS • Critical load functions for acidity and nutrient nitrogen

  14. Exceedances

  15. On bias … % Area at risk of acidification: Influence of EMEP-model, landcover, emissions, critical loads Source: Tarrasón et al., EMEP Status Report 1-2004 pp. 139-154

  16. Average Accumulated Exceedance of critical load for acidity (2000) using Critical loads of 2005 and latest EMEP results provided to CCE 9.8% of the ECE-Ecosyst. NOT protected in 2000 (20.9 % in EU25) Forests Semi-nat veg Surface waters

  17. % Area at risk of eutrophication: Influence of EMEP-model, landcover, emissions, critical loads Source: Tarrasón et al., EMEP Status Report 1-2004 pp. 139-154

  18. Average Accumulated Exceedance of critical load of Nutrient-N (2000) 30.1 % of the ECE-Ecosyst. NOT protected in 2000 (71.2 % in EU25) Forests Semi-nat veg Surface waters

  19. On bias …known unknowns in the past In 1991 the concept of “filtering factors” was introduced (see also Hettelingh et al, CCE Status Report 1991, ch. 3) to modify “…present loads for the effects of throughfall…”. Filtering factors “corrected” depositions computed with the EMEP Lagrangian model upwards (…towards the levels now computed with the Eulerian model). However, the concept did ultimately not obtain consensus support and was not used to support the Oslo and Gothenburg protocol.

  20. Robustness of Average Accumulated Exceedances (AAE) for acidity, computed with the EMEP Unified Model usingcritical loads over 1998-2005.

  21. Possible use in RAINS (and extended CBA ?) of exceedance indicators • Marginal emission coefficients (Mec) of Ecosystem area Protected: • Mec of Accumulated Exceedance (already used for RAINS optimization): *Work in progress under EC-Service Contract 070501/2004/380217/MAR/C1

  22. Dynamic Modelling

  23. Dynamic modelling was applied by 14 countries on 683.237 km2 Convention-ECO area of which 168.661 km2 is NOT-safe (603.204 km2EU25-ECO area of which 153.828 is NOT-safe) Dynamic modelling revealed that more than 90% of the area which is NOT-safe in 2000 could become safe (i.e. critical loads not exceeded AND critical limit not violated) already in 2030 if acid deposition is sufficiently reduced. It is recommended to extend the analysis to the total area which is not safe from acidification in 2000 (≥ 345.000 km2 within the Convention and ≥ 580.000 km2 within EU25). …especially if knowledge on the risks of gap-closure concepts is considered useful…

  24. Target load maps in 2030, 2050 and 2100 in comparison to CLmax(S) 5% TLs 2050 5% TLs 2030 5% TLs 2100 5% CLmax(S)

  25. Robustness The 5th % of national target loads data (2030, 2050 and 2100) is lower than the 5th % of critical loads data in Switserland, the Czech Republic, Germany, France, Ireland,The Netherlands, Poland and Sweden.

  26. Possible use in RAINS (and Extended CBA) of dynamic modelling indicators ? • Marginal emission coefficients (Mec) of Accumulated Achievement failure (exceedance of target loads: • Mec of Delay Times (Damage or Recovery DT) *Work in progress under EC-Service Contract 070501/2004/380217/MAR/C1

  27. Future

  28. 6 focus issues regarding the modelling of N-effects The CCE organized a 1.5-Day nitrogen session during the 2005 CCE workshop of which the objective is to update knowledge on the effects of nitrogen, in support of European air pollution policies following the WGE work plan: • Establish what are harmful effects of nitrogen; present observation trends. • Review of currently used critical limits in the computation of critical loads (including proposals for a possible revision) • Establish whether other critical limits can be defined using material from experiments and observations. • How can new limits be used in steady state and dynamic models for the assessment of effects of air pollution? • How can new limits be used in the assessment of multiple effects (including e.g. changes of biodiversity)? • How can the interactions between air pollution and climate change (including e.g. long-term C and N sequestration, long-term N2O, CH4 etc. emissions) be assessed?

  29. Nitrogen supply Source: Vaclav Smill (1996) Cycles of Life, Scientific American Library, p. 188; Based on J.D Ader (1993) in: Donnell and Picket, Springer Verlag.

  30. On bias … On known unknowns in the future… Bias in future European environmentalpolicy support may be embedded in the requirement to deal with e.g. trade-off between Eutrophication, carbon-sequestration, and Change of biodiversity… …in a broad pan-European environmental policy context distinguishing between Natura 2000 and other areas …? …this may require a next generation of of (pan-) European multiple impact monitoring and assessment work within the Effect Programme Source of the Figure: Vaclav Smill (1996) Cycles of Life, Scientific American Library, p. 188;

  31. Preliminary conclusions • 14 parties under the Convention submitted updated data on critical loads of acidity and of nutrient-N, while 13 countries (10 EU countries) provided dynamic modelling data for acidification. • Trends between 1998-2005 of critical loads data and of their exceedances suggest that results are largely robust over time. • Dynamic modelling was applied to about 30% of the ecosystem area in Europe (about 40% in EU25) which is not safe from acidification in 2000 • Dynamic modelling revealed that more than 90% of that area could become safe in 2030 if acid deposition is sufficiently reduced. • This means that for the remaining unprotected European area dynamic modelling should be carried out to identify areas that can become protected in one of the target years (2030 or 2050) • This refers to countries that did not perform dynamic modelling on all exceeded ecosystems or countries where exceedances occur, but that did not submit dynamic modelling data. • The persisting high exceedances of critical loads for eutrophication point to the requirements of using dynamic models to improve knowledge on time delays of damage and recovery (…thus contributing to a knowledgeable application of exceedance gap-closure concepts) • There is a trade-off between efforts to reduce bias, uncertainty, sensitivity and error and their importance for robustness of integrated assessment results

  32. Proposal for 3 bullets for the TFIAM report • The Task Force took note of the presentation by J.-P. Hettelingh (CCE) on the preliminary 2005-set of European critical loads, target loads and proposals to derive marginal emission coefficients. • The Task Force took note of the CCE presentation on the robustness of national critical load distributions of data submitted over 1998-2005 and the limited influence on the explanation of the variability of exceedances since 1998. [It acknowledges a trade-off to be considered between efforts to assess possible causes of the variability of critical loads data and their importance for robustness of integrated assessment results.] • The Task Force welcomes the first results of dynamic modelling to improve understanding of time delays of recovery and damage caused by changes in exceedances of critical loads for acidification. It recommends the further exploration of the applicability of such methods with respect to eutrophication. It notes that dynamic modelling results could contribute to the further understanding of the risk of gap closure concepts when applied to critical load exceedances.

  33. As of 1 May 2005New Contact Address for the CCE:“RIVM” becomes “MNP”in E-contact extensions: www.mnp.nl/cce j.p.hettelingh@mnp.nl …located at RIVM.

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