1. Intercontinental Transport and Climatic Effects of Air Pollutants Intercontinental Transport and Climatic Effects of Air Pollutants Workshop USEPA/OAQPS. October 21-22, 2004. Chapel Hill, NC REGIONAL ATTRIBUTION OF OZONE PRODUCTION AND ASSOCIATED RADIATIVE FORCING: A STEP TOWARDS CLIMATE CREDITS FOR OZONE REDUCTIONS V. Naik, Denise Mauzerall, L. Horowitz, D. Schwarzkopf, V. Ramaswamy, and M. Oppenheimer Woodrow Wilson School of Public & International Affairs, Princeton University Geophysical Fluid Dynamics Laboratory, Princeton With funding from the Carbon Mitigation Initiative, Princeton University

2. Overview Objectives Provide a mechanism by which countries can obtain climate credit for reductions in the emissions of O 3 precursors Quantify radiative forcing resulting from O 3 produced from NO x emissions from individual countries and continents of the world. Methodology Models (MOZART-2 & GFDL Radiation model) Simulations – base case and 9 regional cases Results O 3 distributions from perturbations of regional NO x emissions Radiative Forcing from O 3 perturbations Conclusions and Next Steps

3. Introduction – Air pollution and Climate Change Links Climate forcing due to tropospheric O 3 depends on the location of emissions of precursors (NO x, CO, NMHCs) and where O 3 is formed and transported 0.35 Wm -2 IPCC 2001

4. Objectives Quantify the contribution of anthropogenic emissions of ozone precursors (particularly NO x ) from individual continents to global O 3 distributions. Quantify regional radiative forcing resulting from regional emissions of O 3 precursors to improve understanding of the variability in the contribution of specific regions to climate change due to O 3 production. Potentially obtain involvement of developing countries in a climate agreement by providing a mechanism through which they can get credit for reducing emissions of O 3 precursors. This would simultaneously improve their local air quality and reduce their global climate impact.

5. Methodology – Models Global CTM – MOZART-2 (Horowitz, Walters, Mauzerall et al., 2003) Driven by MACCM3 meteorology at T42 resolution and 34 hybrid vertical levels (surface to 4 mb) with a time step of 20 minutes Chemistry: includes 63 chemical species and 168 chemical and photochemical reactions, anthropogenic, biogenic and biomass burning surface emissions of early 1990s Dynamics: advection, convective transport, boundary layer mixing and wet & dry deposition GFDL radiation model (Klein et al., 2004 in press) Driven by AM2 meteorology with 2 x 2.5 lat-lon resolution and 24 vertical levels (3 mb) Shortwave radiation code of Friedenreich and Ramaswamy (1997); longwave radiation code follows Simplified Exchange Approximation Schwarzkopf and Ramaswamy (1999) GG and aerosol concentrations typical of early 1990s Calculate instantaneous total sky radiative forcing

6. Methodology – Simulations Base run: standard configuration of MOZART-2 Perturbed runs: MOZART-2 with ANTHROPOGENIC NO x emissions reduced by 10% for each of 9 regions

7. Regional Anthropogenic NO x Emissions Region1990 Total Anthropogenic NO x (Tg N/yr) 10% NO x Reduction (Tg N/yr) Africa & Middle East (AF)2-0.2 Australia (AU)0.4-0.04 East Asia (EA)4-0.4 Europe (EU)5-0.5 Former Soviet Union (FSU)2.5-0.2 Indian Subcontinent (IN)1-0.1 North America (NA)8-0.8 South America (SA)1-0.1 South East Asia (SE)0.6-0.06

8. Results Chemistry Change in O 3 concentration resulting from 10% reduction in anthropogenic NO x emissions from each of 9 regions Radiative Forcing Global and seasonal instantaneous cloudy-sky radiative forcing due to perturbed O 3 distributions for each of 9 regions

9. Annual Tropospheric Ozone Column (Pert – Base) 10 -2 DU AFAUEA EUFSUIN NASASE

10. Change in Surface Temperature Resulting from 10DU O 3 Change at Different Altitudes Forster and Shine (1997)

11. Monthly variation in Global 12-Km O 3 Perturbations due to 10% NO x emissions reduction from each region Absolute O 3 Change (Pert–Base) Normalized O 3 Change (Pert–Base) / E NOx (Pert–Base)

12. Change in Annual Global O 3 Burden due to Regional 10% NO x reductions Normalized O 3 Change (Pert–Base) / E NOx (Pert–Base) Absolute O 3 Change (Pert–Base)

13. Radiative Forcing Results

14. Annual Average Radiative Forcing at the Tropopause mWm -2 AFAUEA EUFSUIN NASASE -0.92 -0.91 0.0 -0.72 -1.74 -0.09 -0.63 0.0 -0.50 0.0 -1.62 -0.22 -3.48 -0.42 -0.70 -1.72 -1.45 -2.10

15. Monthly Variation in Global Radiative Forcing due to Perturbed O 3 Absolute ΔF Normalized ΔF / Δ E NOx

16. Global Annual Radiative forcing due to Perturbed Tropospheric O 3 Absolute ΔF Normalized ΔF / Δ E NOx

17. Largest total O 3 reductions occur for regions with high-NO x emissions Global O 3 changes are most sensitive to NO x reductions from tropical low-NO x emitting regions (SE, SA, IN, AU) Reductions in radiative forcing from tropospheric O 3 due to 10% reduction of anthropogenic NO x emissions are: highest from North America followed by South East Asia lowest from Europe and Former Soviet Union Radiative forcing per molecule NO x reduction are highest for emission reductions from tropical regions particularly south- east Asia, South America and India Conclusions

18. Next Steps Evaluate the change in O 3 due to reductions in other precursors (CO, NMHCs) from these regions due to anthropogenic and biomass burning emissions. Calculate the change in CH 4 concentration as a result of NO x reductions Develop a policy tool by which radiative forcing from regionally attributed O 3 production can be included in a Kyoto Protocol type agreement. NO x O3O3 OHCH4

19. Monthly variation in Global Surface O 3 Perturbations due to 10% NO x emissions reduction from each region Normalized O 3 Change (Pert–Base) / E NOx (Pert–Base) Absolute O 3 Change (Pert–Base)