Acid Rain Revisited Hubbard Brook Research Foundation Science Links Bridging the Gap between Science and Policy

Outline Patterns of Emissions and Deposition Forest Ecosystem Effects Ecosystem Response to Management Strategies Conclusions

Patterns of Emissions and Deposition

Time (years)

allowances allocated for that year all sources Phase I sources Phase II sources SO2 Emission Reductions under the Acid Rain Program

Source: Cantor Fitzgerald

SO 2 Emissions and the Allowance Bank, Allowances allocated that year Unused allowances from previous year (bank) Actual emissions from affected sources SO 2 Emissions (million tons)

1990 emissions Phase I ( ) average emissions Phase II ( ) average emissions scale: 1990 emissions in Ohio were 2.2 million tons SO 2 Emission Reductions, by State

projected emissions level in the absence of Title IV 8.1

1990 emissions Phase I ( ) average emissions Phase II ( ) average emissions scale: 1990 emissions in Ohio were 500,000 tons NO x Emission Reductions, by State

Source Area Includes: VT, MA, NY, NH, CT, RI, ME, OH, PA, DC, MD, NJ, DE, MI, VA, WV, QUE, ONT

Forest Ecosystem Effects

Soil Acid Rain Effects Soil S and N enrichment Nutrient cation (Ca 2+, Mg 2+) depletion Al mobilization

Aquatic Effects

Summary (n=1469) No. of Lakes(%)Surface area (ha)(%) pH < , ANC < 0 µeq/L388262,65011

Ecosystem Response to Management Strategies

Critical Chemical Indicators for Ecosystem Response to Acidic Deposition Terrestrial Soil and soil water Ca/Al < 1 Soil base saturation < 20% Aquatic Surface waters pH 2  mol/L

Ali (µmol/L) pH ANC (µeq/L) NO 3 (µeq/L) SO 4 (µeq/L)

Model Predictions of the Response of Soil and Water to Acidic Deposition: Past and Future

Climatic data Solar radiation Precipitation Temperature PnET Water balance Photosynthesis Living biomass Litterfall Net Mineralization BGC – Surface water Aqueous reactions Uptake Deep water flow Shallow water flow Weathering Wet Deposition Dry Deposition BGC Aqueous reactions Surface reactions Cation exchange Adsorption Humic binding Aluminum dissolution/precipitation

Policy or Proposal NO x (million short tons) SO 2 (million short tons) Deadline for Implementation 4 Pollutant? 1990 Clean Air Act No Jeffords Bill S.556 (as amended) % reduction from 1997 levels % reduction from Phase II levels of 1990 CAAAs 2008Yes Smith Bill S.2815 (Clear Skies) 2.1 by by % of current levels 4.5 by by % of current emissions 2010 and pollutant Carper Bill S.843 (Clean Air Planning Act of 2003) 1.87 by after by by after , 2013, pollutant Clinton Bill S.588Approx. 2.1 in % reduction from 1990 levels Approx % reduction from 1990 CAAAs levels Approx by % reduction from 1990 CAAAs levels : 2007 No

SO 2 Cap and Trade Program: Expected Annual Costs by 2010