1. Air Quality and Climate Connections AQAST9 St. Louis University, St. Louis, MO June 3, 2015 Arlene M. Fiore Acknowledgments: V. Naik (GFDL), E. Leibensperger (SUNY Plattsburgh), J. Bachmann (Vision Air Consulting), M. Lin (Princeton/GFDL) O. Clifton, G. Correa, J. Guo, N. Mascioli, G. Milly, L. Murray, L. Valin (CU/LDEO) AQM Contacts: Pat Dolwick (EPA/OAR), Joe Pinto (EPA/NCEA), Terry Keating (EPA/OAR/OPAR), Gail Tonnesen (EPA Region 8) 83520601

2. Tropospheric ozone and precursors contribute to climate forcing from pre-industrial to present-day Adapted by E. Leibensperger (SUNY Plattsburgh) from IPCC, 2013 for Fiore, Naik, Leibensperger, in press Radiative Forcing components CO 2, CH 4, Strat. H 2 O, Trop. O 3

3. PM and precursors also contribute to climate forcing from pre-industrial to present-day Net impact of aerosols (-0.9 W m -2 ) opposes warming from GHGs Adapted by E. Leibensperger (SUNY Plattsburgh) from IPCC, 2013 for Fiore, Naik, Leibensperger, in press Radiative Forcing components CO 2, CH 4, Strat. H 2 O, Trop. O 3 sulfate, nitrate, dust BC (BF+FF; BB; snow albedo) OC (BF+FF; BB)

4. Air pollutants are Near-Term Climate Forcers (NTCFs); CO 2 dominates long-term climate (peak warming) Adapted by E. Leibensperger (SUNY Plattsburgh) from IPCC, 2013 for Fiore, Naik, Leibensperger, in press Short-Lived Climate Pollutants (SLCPs) = warming NTCFs Radiative Forcing components CO 2, CH 4, Strat. H 2 O, Trop. O 3 sulfate, nitrate, dust BC (BF+FF; BB; snow Albedo) OC (BF+FF; BB)

5. Reducing air pollutant SLCPs lessens near-term climate warming (and improves air quality by decreasing background O 3 ; PM 2.5 ) Adapted from Fig 12 Fiore et al. 2015  Target CH 4 and some BC-rich sources to offset near-term warming from health-motivated controls on SO 2 emissions Global mean surface temperature relative to 1890-1910 Shindell et al., 2012

6. Mitigate BOTH near-term AND long-term climate change by reducing SLCPs AND CO 2 Adapted from Fig 12 Fiore et al. 2015 CO 2 and SLCPs can induce other climate responses that affect pollution levels: Hydrologic cycle Circulation patterns (including “air pollution meteorology”) Shindell et al., 2012 Shoemaker & Schrag, 2013

7. Ozone and particulate matter build up during heat wave; cold fronts ventilate the polluted boundary layer Warmer climate  more heat waves  more pollution? Figure 7 of Fiore, Naik, Leibensperger, JAWMA, 2015

8.  Implies that changes in climate (via regional air pollution meteorology) will influence air quality  Downward trend in O 3 as EUS NO x emission controls are implemented Observations at U.S. EPA CASTNet site Penn State, PA 41N, 78W, 378m July mean MDA8 O 3 and July mean daily maximum temperature O 3 correlates with surface temperature on daily to inter- annual time scales in polluted regions [e.g., Bloomer et al., 2009; Camalier et al., 2007; Cardelino and Chameides, 1990; Clark and Karl, 1982; Korsog and Wolff, 1991] G. Milly Figure 6a of Fiore, Naik, Leibensperger, JAWMA, 2015

9. Decreasing NO x emissions reduces sensitivity of O 3 to temperature; helps to guard against any “climate penalty” [e.g., Bloomer et al., 2009; Rasmussen et al., 2012; Brown-Steiner et al., 2015] 1988-2001: 4.1 ppb/C 2002-2014: 2.4 ppb/C July mean MDA8 ozone (ppb) July mean maximum daily temperature (°C)  Historically observed relationships may not hold as emissions change  Meteorology may also change [e.g., Barnes & Fiore, 2013; Shen et al., 2015] G. Milly Figure 6b of Fiore, Naik, Leibensperger, JAWMA, 2015

10. Projected changes in U.S. surface ozone in summer (JJA) under climate and precursor emission scenarios: declines due to continued controls on precursor emissions Figure 10a of Fiore, Naik, Leibensperger, JAWMA, 2015 CMIP5 and ACCMIP models

11. Projected air quality changes over the Midwest mainly follow precursor emission trajectories CMIP5 and ACCMIP models Figure 10 of Fiore, Naik, Leibensperger, JAWMA, 2015 SUMMER (JJA) O 3 (ppb) WINTER (DJF) O 3 Annual mean PM 2.5 (μg m -3 ) Methane doubling in RCP8.5 raises background ozone all year, most pronounced in winter [see also Clifton et al., 2014]

12. Climate variability can modulate background ozone sources: e.g., frequency of deep stratospheric intrusions over WUS Meiyun Lin, Fiore AM, Horowitz LW, Langford AO, Oltmans SJ, Tarasick D, Rieder H, Nature Communications, May 2015 75 th 25 th 50 th O 3 Strat 1990 GFDL AM3 model Emissions held constant Nudged to “real” winds Stratospheric Contribution (ppb) April-May M. Lin (Princeton/GFDL) Median of daily MDA8 surface ozone (ppb)

13. Connection of frequent deep stratospheric intrusions over WUS to known mode of climate variability (La Niña)  May offer a few months lead time to aid WUS preparations for an active stratospheric intrusion season M. Lin et al., Nature Communications, May 2015 M. Lin (Princeton/GFDL) SST (C) Tropical SST cooling typically peaks in winter La Niña http://www.enr.gov.nt.ca/state- environment/22-pacific-decadal- oscillation-index-and-el-ninola-nina MDA8 O 3 (ppb) More frequent stratospheric intrusions the following spring over WUS? 1999 MDA8 O 3 (ppb)

14. Summary schematic of air quality-climate connections Figure 2, Fiore, Naik, Leibensperger, JAWMA, 2015 schematic c/o C. Raphael, GFDL Improved accuracy and trends in emission inventories are critical for accountability analyses of historical and projected air pollution and climate mitigation policies [AQAST!] Translating research into digestible products and training air managers in using data products and analysis tools [AQAST! Jacob et al., 2014; Duncan et al., 2014; Streets et al., 2014; Witman et al., 2014]

15. Summary schematic of air quality-climate connections Figure 2, Fiore, Naik, Leibensperger, JAWMA, 2015 schematic c/o C. Raphael, GFDL

17. Extra slides follow

18. Emission projections of NO and SO2 over the Midwest Tg SO 2 a -1 Tg NO a -1

19. Emission projections of NO over the U.S.A.

20. Emission projections of SO 2 over the U.S.A.