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EFFECT OF CLIMATE CHANGE ON AIR QUALITY

EFFECT OF CLIMATE CHANGE ON AIR QUALITY. Daniel J. Jacob. with Loretta J. Mickley, Shiliang Wu, Eric M. Leibensperger, Moeko Yoshitomi. and funding from, EPA, EPRI. CHEMISTRY-CLIMATE INTERACTIONS. CHEMISTRY-CLIMATE INTERACTIONS. FORCING. D Climate. D Emissions. Atmospheric chemistry.

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EFFECT OF CLIMATE CHANGE ON AIR QUALITY

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  1. EFFECT OF CLIMATE CHANGE ON AIR QUALITY Daniel J. Jacob with Loretta J. Mickley, Shiliang Wu, Eric M. Leibensperger, Moeko Yoshitomi and funding from, EPA, EPRI

  2. CHEMISTRY-CLIMATE INTERACTIONS

  3. CHEMISTRY-CLIMATE INTERACTIONS FORCING D Climate D Emissions • Atmospheric chemistry • Air pollution meteorology D Surface air quality

  4. AIR POLLUTION IN THE UNITED STATES # people in areas exceeding national ambient air quality standards (NAAQS) in 2006 84 ppbv 15 mg m-3 (day), 65 (annual)

  5. O2 hn O3 CHEMISTRY OF TROPOSPHERIC OZONE STRATOSPHERE 8-18 km TROPOSPHERE hn NO2 NO O3 hn, H2O OH HO2 H2O2 Deposition CO, VOC generally limiting Nitrogen oxide radicals; NOx = NO + NO2 combustion, soils, lightning Methane wetlands, livestock, natural gas Nonmethane volatile organic compounds (NMVOCs) vegetation, combustion, industry CO (carbon monoxide) combustion, VOC oxidation Tropospheric ozone precursors

  6. . . . . . . PARTICULATE MATTER (PM, AEROSOLS) SOURCES AND PROCESSES ultra-fine (<0.01 mm) fine (0.01-1 mm) cloud (1-100 mm) precursor gases oxidation nucleation cycling coagulation H2SO4 SO2 condensation RCO… VOCs coarse (1-10 mm) scavenging NOx HNO3 NH3 carbonaceous combustion particles combustion biosphere volcanoes agriculture biosphere soil dust sea salt

  7. OBSERVED DEPENDENCE OF AIR QUALITY ON WEATHER WARNS OF POTENTIALLY LARGE EFFECT OF CLIMATE CHANGE Interannual variability of exceedances of ozone standard in Northeast U.S. # summer days with 8-hour ozone > 84 ppbv, average for 257 northeast U.S. AIRS sites 1992, coldest on record (Pinatubo) 1988, hottest of record Lin et al. [AE 2001] Ozone is strongly correlated with temperature in observations; this is due to (1) chemistry, (2) biogenic VOC emissions, (3) joint association with stagnation

  8. USE OZONE-TEMPERATURE CORRELATION TO ESTIMATE EFFECT OF CLIMATE CHANGE ON AIR QUALITY Probability of max 8-h O3 > 84 ppbv vs. daily max. temperature Projected T change for northeast U.S. in 2000-2100 simulated with ensemble of GCMs for different scenarios [IPCC, 2007] Northeast Los Angeles Southeast Lin et al. [AE 2001] Probability of exceedance doubles Probability DT = 3K Temperature, K By 2025, DT = 1-3 K depending on model and scenario; use statistical approach at right to infer increased probability of ozone exceedance for a given region or city assume nothing else changes. Effect is large!

  9. IMPORTANCE OF MID-LATITUDES CYCLONES IN AIR POLLUTION METEOROLOGY Cold fronts from mid-latitude cyclones tracking across southern Canada are the principal process ventilating the U.S. Midwest and Northeast Clean air sweeps behind cold front

  10. INTERANNUAL CORRELATION BETWEEN CYCLONE FREQUENCY AND OZONE AIR QUALITY STANDARD EXCEEDANCES, 1980-1998 observed summer cyclone tracks (NCEP/NCAR reanalysis, NASA/GISS cyclone tracker) Correlation coefficient (R) in four reanalyses between # ozone AQS exceedances/summer and # 40-50o N cyclones (green box) -1 0.5 0 0.5 1 Leibensperger et al. , in prep.

  11. CLIMATOLOGICAL DATA SHOW DECREASE IN FREQUENCY OF MID-LATITUDE CYCLONES OVER PAST 50 YEARS 1000 Annual number of surface cyclones and anticylones over North America cyclones 500 Agee [1991] 100 anticyclones 1980 1950 Cyclone frequency at 30o-60oN McCabe et al. [2001]

  12. TREND IN SUMMERTIME CYCLONE FREQUENCY, 1950-2006 1980-2006 trend # cyclones/summer tracking through green box Both NCEP/NCAR and the GISS GCM show a decreasing trend starting in 1980; no trend is seen in a control GCM simulation in radiative equilibrium Leibensperger et al., in prep.

  13. CYCLONE TREND FROM NCEP/NCAR REANALYSIS WOULD IMPLY LARGE EFFECT ON OZONE TRENDS # 80 ppb exceedance days in Northeast dropped from 38 in 1980 to 19 in 1998, but would have dropped to 5 in absence of cyclone trend Observed 1980-1998 JJA trends in daily # 40-50N cyclones # 80 ppb O3 AQS exceedances Interannual variability in the two is highly anticorrelated (r = - 0.64) Black: observed AQS exceedances Red: AQS exceedances predicted from trend in cyclone frequency Green: AQS exceedances predicted in absence of trend in cyclone frequency # AQS exceedances # cyclones Leibensperger et al., in prep. 1980 1985 1990 1995 2000 1980 1985 1990 1995 2000

  14. …BUT OTHER REANALYSES SHOW NO 1980-2005 TREND – THOUGH LARGE INTERANNUAL VARIABILITY Leibensperger et al., in prep.

  15. D.J. Jacob and L.J. Mickley (Harvard), J.H. Seinfeld (Caltech), D. Rind (NASA/GISS), D.G. Streets (ANL), J. Fu (U. Tenn.) , D. Byun (U. Houston) EPA-STAR GLOBAL CHANGE AND AIR POLLUTION (GCAP) PROJECT 2000-2050 IPCC emission scenario ozone-PM precursors greenhouse gases input meteorology boundary conditions GEOS-Chem global CTM CMAQ regional CTM GISS GCM 3 MM-5 RCM input meteorology boundary conditions Applied to 2000-2050 global change simulations with IPCC SRES A1 scenario; compare 2050 climate (GCM 2049-2051, 3-y averages) to 2000 (1999-2001)

  16. 2000-2050 PROJECTED EMISSION TRENDS • Global increase in anthropogenic emissions but large decreases in U.S. • Climate-driven increases in natural NOx, NMVOC emissions Wu et al. [JGR, in press]

  17. EFFECT OF 2000-2050 CLIMATE CHANGE ON GLOBAL TROPOSPHERIC OZONE Tropospheric ozone in year 2000 (ppb) 2050/2000 ratio Zonal annual mean concentrations • Ozone increases in tropical upper troposphere because of increased lightning; • …but decreases in background surface air because of higher water vapor Wu et al., submitted

  18. CHANGES IN SUMMER MEAN 8-h AVG. DAILY MAXIMUM OZONE FROM 2000-2050 CLIMATE CHANGE (NO CHANGE IN EMISSIONS) Effect of changing climate ppb • Different models agree that 2000-2050 climate change will decrease background ozone but increase surface ozone in U.S. by generally 1-10 ppb • Most but not all models find maximum effect during pollution episodes (up to 10 ppb in ours) • All models find significant effect in Northeast but disagree in other regions • Differences in Southeast partly due to different mechanisms for oxidation of biogenic isoprene (the dominant VOC precursor) Wu et al. [JGR in press]

  19. 1999-2001 2049-2051 2000-2050 DECREASE OF CYCLONE FREQUENCY Summertime cyclone frequency decreases by 17% in 2050 climate (GISS GCM A1 scenario) Wu et al. [iJGR n press]

  20. correlation coefficient R -1 -.5 0 .5 1 OZONE-TEMPERATURE CORRELATION AS TEST OF MODEL SENSITIVITY TO CLIMATE CHANGE Correlate daily max-8h-avg ozone with daily max temperature in Jun-Aug GCAP/GEOS-Chem model present-day climate (3 years) Observations (1980-1998) Yoshitomi et al. [in progress]

  21. COMPARING THE EFFECTS OF CHANGING CLIMATE AND EMISSIONS ON SUMMER MEAN 8-h AVG. DAILY MAXIMUM OZONE (2000-2050) 2000 2050 climate - 2000 2050 emissions – 2000 2050 – 2000 Wu et al. [in press]

  22. CLIMATE CHANGE PENALTY: MEETING A GIVEN AIR QUALITY GOALWILL REQUIRE GREATER EMISSION REDUCTIONS IN FUTURE CLIMATE NOx emission - 40% (2050 climate) 2000 conditions NOx emission - 40% (2000 climate) NOx emissions - 50% (2050 climate) In this example, 2000–2050 climate change implies an additional 25% reduction in NOx emissions (from 40% to 50%) to achieve the same ozone air quality. Wu et al. [JGR in press]

  23. 2000-2050 CHANGE OF ANNUAL MEAN PM2.5 (mg m-3) Effect of climate change is small (at most 0.3 mg m-3), in part because of compensating factors; but this doesn’t include fires… 2000 2050 climate - 2000 2050 emissions – 2000 2050 - 2000 Shiliang Wu, Harvard

  24. WILDFIRES: A SIGNIFICANT PM2.5 SOURCE Total carbonaceous (TC) aerosol averaged over all contiguous U.S. IMPROVE sites S. California fire plumes, Oct. 25 2004 ~100 IMPROVE sites nationwide • Interannual variability in annual mean carbonaceous PM2.5. is largely determined by wildfires • Open fires contribute about 25% of annual mean PM2.5 in the western U.S., 10% in the east • Dominant contributions from western U.S. fires (in the west), Canadian fires (in the northeast), prescribed fires (in the southeast) Park et al. [AE 2007]

  25. INCREASING WILDFIRE FREQUENCY IN PAST DECADES Westerling et al. [2006] Temperature and drought index can explain 50-60% of interannual variability in fires Canadian fires [Gillet et al., 2004] 1920 1940 1960 1980 2000

  26. INTERCONTINENTAL DUST INFLUENCE April 16, 2001: Asian dust! clear day Glen Canyon, Arizona Annual mean PM2.5 dust (mg m-3), 2001 Asia Sahara Fairlie et al. [AE 2007] Most fine dust in the U.S. (except in southwest) is of intercontinental origin

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