Using Critical Loads to Protect Canadian Ecosystems from Damage due to Acid Deposition

1. WESTAR Council Understanding the Critical Loads Approach Denver, November 15-16, 2005 Using Critical Loads to Protect Canadian Ecosystems from Damage due to Acid Deposition Kerri Timoffee* Environment Canada Transboundary Air Issues Branch, Ottawa (* plus a many others, e.g., Silvina Carou, Dean Jeffries, Mike Moran, C.-H. Ro, R.J. Vet)

2. Outline • Post-2000 Acid Rain Strategy • How we got there • Scientific evidence of impacts, basis for 1982 deposition targets & decision process • control programs and anticipated ecological benefits • Current status • 2004 Canadian Acid Deposition Science Assessment • Current situation with respect to critical loads • Next Steps • Forecasting the future • Where to next

3. Canada’s current policy instrument is the 1998 Canada-Wide Acid Rain Strategy for Post-2000 • Signed by all Federal/Provincial/Territorial Energy and Environment Ministers • Main elements • Reduce acidifying emissions in eastern Canada and the United States • Prevent pollution and keep clean areas clean • Maintain an adequate science and monitoring program • Report annually • Long term goal is to reduce acid deposition to below critical loads across Canada

4. Early scientific evidence forecological impacts in Canada • acidic lakes, damage to terrestrial vegetation near smelters, Gorham and Gordon, 1960 • acidification damage in cottage country far from local emission sources, Dillon et al, 1977 • decrease in number and variety of fish species in lakes and rivers of Ontario and the Atlantic provinces, BRCG, 1979

6. Canada realised that controlling acid deposition would require an effects-based program • Large but local sources • Worlds’ tallest “superstack” was built • Air quality standard addresses local air pollution problem • missed the problem of damage downwind & cumulative exposures

7. Sulphate loadings and observed effects as basis for defining deposition targets

8. Canada adopted a critical load toprotect aquatic ecosystems in 1982 • aquatic evidence was sufficient • forest damage was, and still is, controversial • experimental cause-effect evidence of the chemical processes and sequence of biological changes as acidification progressed • targeted wet sulphate deposition • In 1982, Canada proposed a critical load of 20 kg/ha/yr to protect all but the most sensitive areas • In 1983 New England Governors and Eastern Canadian Premiers endorsed the 20kg/ha/yr target.

9. Projected impact of reducing SO2 emissions on the amount of wet sulphate deposited annually

10. Emission Reduction Control Programs • 1984 Sulphur Protocol • 30% reduction in SO2 emissions • national cap of 3.2 million tonnes beginning in 1993 • no particular environmental limit • 1985 Eastern Canada Acid Rain Program • plan to reduce total national emissions by 30% over the next ten years, about 50% of the emissions in Eastern Canada • Goal to protect moderately sensitive aquatic ecosystems • Committed to further science • 1991 Canada-US Air Quality Agreement reiterated the national cap

11. Reporting indicated that both countries would meet their targets for emission reductions, so the expectation was for ecosystems to improve • Expectation that aquatic and terrestrial ecosystems would recover significantly • Perhaps restore the most sensitive aquatic ecosystems

12. 20 < 16 < <=20 10 < <=16 8 < <=12 Canada developed new critical loads to fully protect all surface waters <=8 Critical load values (kg/ha/yr) of sulphate in precipitation

13. Even with full implementation of Canadian and US programs, almost 800,000 km2 in southeastern Canada would still receive harmful levels of acid deposition Area of eastern Canada expected to receive wet SO4 deposition above critical loads (in kilograms per hectare per year) in 2010, without further controls beyond provisions in the 1991 Canada-US Air Quality Agreement

14. These critical loads and exceedance estimateswere accepted by the scientific andpolitical communities as the basis for developingthe Post-2000 Acid Rain Strategy • Strategies goal is to achieve sulphate deposition levels that do not exceed “critical loads” • Scenario modelling predicted the changes in critical load exceedances resulting from further reductions in SO2 emissions in eastern Canada as well as the US • 25% cut in SO2 emissions → 34% reduction in area receiving harmful levels • 50% cut in SO2 emissions → 72% reduction • 75% cut → virtually all of eastern Canada would be protected from acid deposition

15. Current Status - Time SeriesCAPMoN and CASTNet Networks

16. Current status - Changes in nssSO4= Wet Deposition Patterns 1980-1984 Mean nssSO4= Wet Deposition (Kg/Ha/Yr) 1996-2001 Mean nssSO4= Wet Deposition (Kg/Ha/Yr)

20. Aquatic CLs • 5th percentile value for all lakes located within a grid square • Index map shows which model produced the grid value • 1983 target load (20 kg/ha/yr) covered by lowest four classes • 21% of eastern grid squares in lowest CL category

21. Area of Eastern Canada at Riskfrom Acid Deposition 0.5 million km2 1.8 million km2 • New science considers both sulphate and nitrate deposition and aquatic and terrestrial ecosystems.

22. Aquatic “N-leaching” Exceedances • 95th exceedance value for all lakes within a grid square • Current situation (note both positive and negative exceedance classes) • Largest (orange) exceedances occur in southern NS/NB and ON • Positive exceedance even occur in NW ON (but none in west)

23. Forecasting the Future Annual Effective Acidity Wet Deposition (combined annual SO4 and NO3 wet deposition) keq/ha/yr keq/ha/yr “First generation” Can-US SO2 and NOX emissions reductions Most realistic Can-US SO2 and NOX emissions reductions Implementation of current (e.g. Post-2000 Strategy) and proposed (e.g. U.S. Clear Skies) legislation is predicted to reduce the effective acidity of wet deposition by at least 30% over much of eastern North America by 2020.

24. Forecasting the Future • Implementation of current (e.g. Post-2000 Strategy) and proposed (e.g. U.S. Clear Skies) legislation, will reduce but not eliminate acid damage in eastern Canada. Draft Draft Aquatic Terrestrial • It is estimated that a further reduction in SO2 of ~75% will be required from Canada and the U.S. beyond those agreed to in the Canada-U.S. Air Quality Agreement to end acid rain.

25. Where to Next • New critical loads and preliminary exceedance estimates • Adjust our control control actions • Further domestic cuts • Decrease TB flows • Increase effort at KCAC/PP • Monitor and report on ecological benefits

26. Summary • Concept of working towards reducing deposition to below critical loads has long been central to Canada’s SO2 management program • There are still many regions of eastern Canada (and perhaps even small parts of western Canada) where present-day deposition levels exceed aquatic critical loads • Developing critical loads is an iterative process

27. Challenges • Concern that any sulphur dioxide control program would require large, and possibly expensive, reductions

28. Region ofConcern:Where Ecosystem EffectsLikely Occur(contains ~800000 water bodies) Environment Canada (1988)

29. Contact information Kerri Timoffee Manager, Acid Rain Program Transboundary Air Issues Branch Environment Canada Rm 1118, 351 St Joseph Blvd Gatineau, Quebec K1A 0H3 Email: kerri.timoffee@ec.gc.ca Telephone: (819) 994-9564 Fax: (819) 953-8963