1. Air Quality and Climate Change Co-authors: Amos Tai, Eric Leibensperger, and Xu Yue, Daniel Jacob, Jennifer Logan What U.S. city is this? Loretta Mickley Harvard University U.S. Air Quality Smog Blog, alg.umbc.edu/usaq Weather has a large effect on U.S. air quality.

2. Jan 23, 2013 Persistent temperature inversions this January over Northern Utah led to unhealthy air 11 out of 31 days. 2 Airnow; NASA Earth Observatory cooler warmer Salt Lake City

3. 3 Both emissions and weather have been changing over the United States. Thanks to Bryan Duncan OMI NO 2 data

4. 4 Temperatures have been increasing rapidly since the 1980s. NASA GISS temperature analysis, GISTEMP Contiguous US 1 0 Warming trend after 1980 Temperature anomaly ( o C) 1880 2000 What do these trends mean for surface air quality?

5. Number of ozone exceedances in Chicago and St. Louis looked promisingly low in recent years. Number of days MDA8 ozone > 75 ppb Chicago St. Louis www.epa.gov/airdata/ad_viz_ozcompare.html 5 Airnow

6. Drought + heat wave in 2012 ramped up number of ozone exceedances. Number of days MDA8 ozone > 75 ppb Chicago St. Louis www.epa.gov/airdata/ad_viz_ozcompare.html 6 Airnow

7. We know that surface ozone is sensitive to stagnation. Stagnant air covers East. Clear skies. High temperatures. Cold front moves through. Cool, clean air. 7 Leibensperger et al., 2010

8. Cold fronts clear away pollution in central and eastern United States. High ozone levels Clean air 8 Leibensperger et al., 2010

9. Cyclones passing through Great Lakes/ Southern Canada region are associated with cold fronts. Stagnant air.Cold front moves through. Cyclone 9 Leibensperger et al., 2010

10. Climate models predict decreasing trend in number of Great Lakes cyclones in warming atmosphere. Number of cyclones over Great Lakes region RCP 8.5 Turner et al., 2013 10 Climate model projection of JJA cyclone number over Great Lakes region. 30% decrease

11. 11 Climate models predict more persistent weather in future atmosphere over mid-latitudes. What are the implications for air quality? As high latitudes warm, slower eastward progression of Rossby waves in the upper-level flow. Francis et al., 2012

12. Climate penalty for ozone air quality: Increased stagnation + high temperatures will likely increase surface ozone. Climate generated by NASA GISS Model 3; Tai et al., 2013 -4 -2 0 2 4 2000-2050 change in JJA MDA8 ozone due to climate change. ppb  MDA8 JJA ozone 12 6 ppb

13. Response of PM 2.5 to changing meteorology is more complicated. Observed relationships with Temperature (% K -1 ) Observed sulfate correlates with temperature, but.... nitrate anti-correlates with temperature. Tai et al., 2010 13

14. Net effect of 2000-2050 climate change on PM 2.5 is small, at least when considering circulation changes. 2000-2050 change in annual mean PM 2.5 due to changing circulation.  annual mean PM 2.5 Tai et al., 2012 14 Increased maritime flow Increased stagnation Changes are small, on the order of 0.5  g m -3.

15. Wildfires may become the dominant player in changing PM 2.5 in future atmosphere. Tai et al., 2012; Yue et al., 2013 15 Modeled 2050s response of surface PM 2.5 to trends in circulation and in wildfires.

16. Doubling of wildfire activity in warmer and drier 2050s significantly increases PM 2.5 in the western U.S. 2000-2050 change in JJA mean organic carbon particles due to changing wildfires. 16 NASA GISS Model 3; Yue et al., 2013  organic PM 2.5

17. NASA GISS Model 3; Yue et al., 2013 Increase in organic PM 2.5 in 2050s is especially large during extreme wildfire events. Cumulative probability of daily mean concentrations of organic particles 2050s Present- day doubling 17 Projection shows doubling of organic particles during fire events over Rocky Mountains in May- October timeframe for the 2050s.

18. 18 Take home message 1 The response of air quality to climate change depends on trends in extreme events: stagnation, inversions, or wildfires. Persistent temperature inversions this January over Northern Utah led to unhealthy air 11 out of 31 days. cooler warmer Salt Lake City Airnow; NASA Earth Observatory

19. 19 Take home message 2: The climate penalty for ozone air quality could be large. -4 -2 0 2 4 2000-2050 change in MDA8 JJA ozone due to climate change. ppb  MDA8 JJA ozone NASA GISS Model 3; Tai et al., 2013

20. 20 Take home message 3: Air quality in the West is vulnerable to changing wildfire in a warmer, drier climate. Cumulative probability of daily mean concentrations of organic particles 2050s Present- day doubling Projection shows doubling of organic particles during wildfires over Rocky Mountains in 2050s. NASA GISS Model 3; Yue et al., 2013