1. Climate-Air Quality: Linkages and OAQPS Strategy National Tribal Forum April 2007

2. 2 Presentation Overview Climate-Air Quality Linkages –Key terms and definitions –How the global climate impacts air quality –How air pollution impacts regional climate OAQPS Climate-Air Quality Strategy –Global climate impacts on U.S. air quality –Air pollution impacts on U.S. regional climate –Climate-related impacts of OAQPS programs

3. 3 OAQPS Priorities Where Climate and Air Quality Converge Global climate impacts on U.S. air quality –For example increasing temperature may affect concentrations of ozone Air pollution impacts on U.S. regional climate –Aerosols may affect precipitation patterns Climate-related impacts of OAQPS programs –Possible energy penalties of control technologies

4. 4 Global climate impacts on U.S. air quality Preliminary policy-relevant findings reported in Feb. 2007, amid large uncertainties, suggest: –Climate change makes it harder to attain ozone NAAQS: Increased temperature is associated with increases ozone –More biogenic emissions, faster reaction rates, and increased frequency and duration of stagnation events Potential for 10% climate penalty –Climate change has mixed impacts for PM NAAQS and Visibility In the West, more droughts and wildfires increase PM In other areas more precipitation decreases PM For many areas there may be a mix of PM benefits and disbenefits; the net impact of climate on PM is not clear. Continuing work to reduce uncertainties –2007/2010 Assessments –STAR grant process Green = Current Activities

5. 5 Evolution of a typical pollution episode over 6 days. Box 1: Weak winds as pollution builds Box 4: Stronger winds with cold front from Canada bring cleaner air Modeling: Shows a 20% decrease in cold fronts in future summers (2000- 2050). [Adapted from Loretta Mickley, Harvard] Implication: Higher ozone concentrations from increases in duration and severity of summer episodes.

6. 6 Is there a Climate Change Penalty?

7. 7 Air pollution impacts on regional climate Effects of existing PM policies and strategies –Light/energy absorbing characteristics of PM –Precipitation effects, as well as warming and cooling Enhance understanding of direct and indirect aerosol effects –Next generation models to capture climate system feedbacks and complexities –Characterize and minimize uncertainties –Impacts from long range transport Ozone –Contributor to Arctic warming –Quantify climate benefits of domestic ozone reductions Green = Current Activities Yellow = Future Opportunities

8. 8 Wildfire and climate OC / BC aerosols GHGs CO Increasing Temperature Increasing Rainfall Air Quality Visibility Climate Change Longer fire seasons, more fires…. Less fires….. [From Spracklen at 2006 AGU]

9. 9 Air pollution impacts on regional climate  Tropospheric ozone is the 3 rd most important Greenhouse Gas  Not covered by Kyoto since ozone is a short-lived GHG.  PM may have offset most of the GHG warming  Modeling studies suggest that PM may have offset as much as 50 to 75 percent of the greenhouse gas forcing (NAS 10-05).  PM directly scatters and absorbs radiation; PM also interacts with clouds in several ways that can have indirect effects on climate.  The indirect effects have a low level of scientific understanding.  PM also influences cloud lifetime and precipitation.

10. 10 From the IPCC Summary for Policy Makers (2007) CO 2 : + 1.66 Ozone: + 0.35 PM (ambient): - 0.5 PM (cloud effect): - 0.7 Note: PM effects have a low level of scientific understanding

11. 11 PM affects solar radiation:smaller cloud droplets reflect more and have a longer life. PM Affects Clouds

12. 12 PM Affects Rainfall: Smaller cloud droplets can decrease precipitation efficiency

13. 13 Climate Related Impacts of OAQPS Programs Investigate unintended consequences of OAQPS programs –Either positive or negative Past Implementation rules and policies Future rules and policies –NAAQS reviews, secondary standards –Modeling guidelines Green = Current Activities Yellow = Future Opportunities

14. 14 Cross-Cutting Activities Populate existing analytical tools to be “climate capable” (e.g., Control Strategy Tool - CoST) Communicate –Explain complex climate-air quality linkages emerging from CCSP, GCAQ, and IPCC. –Internally and externally re: climate – air quality activities Collaborate with OAR, ORD, Regions, States, RPOs, NASA, NOAA, and DOE Integrate with other OAQPS programs and Initiatives

15. 15 Summary OAQPS has focused our niche to where climate and air quality converge Activities designed to further three priority areas AND meet domestic air quality objectives Our strategy is tied to the science and will evolve as the science evolves