Air Quality in a Changing Climate

Transcription

1 Air Quality in a Changing Climate Allen L. Robinson Carnegie Mellon University Funding: US EPA Presented at 2018 BC Lung Association Air Quality and Health Workshop: The Future of Air Quality Management for Improved Public Health Vancouver, Canada February 5, 2018.

2 Many linkages between air quality and climate Climate Change Air Pollution Meteorology Natural Emissions Anthropogenic Emissions Air Pollution Concentrations Replace with better ima

3 Climate Change and Air Pollution Meteorology Temperature Increase Precipitation No Change Not just temperature Spatial heterogeneity Models don t always agree on details (esp. spatial patterns) Decrease BL Height (Val Martin et al. ACP 2015) RCP = Representation Concentration Pathway RCP4.5 is an intermediate scenario

4 O 3 Climate Penalty almost all studies predict an increase Δ MDA8 O 3 (ppb) Climate penalty = increase in pollution from climate change assuming constant emissions Met Factors & O 3 : Temperature Absolute humidity Mixing / dilution Wind speed Mixing height Clouds Precipitation Effect of a T of 2.5 on July MDA8 O 3 using constant 2001 emissions. (Dawson et al. AE 2006)

5 PM 2.5 Climate Penalty more variability among studies January (-0.6 μg m -3 ) July (+2.2 μg m -3 ) Winter decrease mainly driven by increasing T and nitrate partitioning. Increase over Northeast due to decreased precipitation. Summer increase mainly oxidant driven. Δ PM 2.5 (μg m -3 ) (Dawson et al. JGR 2009)

6 Biogenic emissions depend strongly on Climate US VOC Emissions Strong temperature dependence of BV Anthro. Biogenic (Baghi et al. Biogeo Disc 2012

7 Increased T Increased Biogenic VOC Emissions Increased Pollution 24 hr ave secondary PM 2.5 (BSOA) increased by up to 1 µg m -3 Cumulative Distribution of MDA 8hr O 3 (Chen et al. AE 2009)

8 Effects of Changes in Land Use and Land Cover Land Use Changes in BVOC Emissions Higher Current Lower Future Changes in O 3 Changes in PM 2.5 (Chen et al. AE 2009)

9 Wildfires GOES-16 satellite visible image from September 4,

10 Increases in wildfires driven by changes in climate r 2 = 0.48 p < Westerling, Increasing western US forest wildfire activity: sensitivity to changes in the timing of spring, Phil. Trans. R. Soc. B, 2016.

11 What might smoke be like in the future? What impact on mortality might it have? r 2 = 0.48 p < Future: % increase in fires? Westerling, Increasing western US forest wildfire activity: sensitivity to changes in the timing of spring, Phil. Trans. R. Soc. B, 2016.

12 Predicted PM 2.5 from fire smoke greatly increases Jeff CSU Annual-mean PM 2.5 from wildfire smoke only Unpublished results from Jeff Colorado State Univ.

13 Anthropogenic emissions are falling RCP scenarios for traditional pollutants CH 4 SO 2 NO BC NH 3 Fiore et al. Chem Soc Rev 2012

14 PM changes in anthropogenic emissions generally swamp climate and land use effects (Val Martin et al. ACP 2015)

15 Will fires offset PM 2.5 reductions from anthropogenic emissions? (Val Martin et al. ACP 2015) Summertime levels?

16 Ozone: Emissions more important than meteorology factors Climate change penalty Emissions cuts (SRES B1) (Racherla and Adams EST 2008)

17 Linkages between climate and air pollution policies Policy costs covered by health (%) CO2 reduction (%) (Thompson al. Nat Climate Change 2014) 50,000 people per year dying the US from air quality. VSL 100s of billions per year. Few percent of GDP. Health benefits, from e.g. increased natural gas use, can cover 10-30% climate change mitigation for free

18 Linkages between climate and air pollution policies Policy costs covered by health (%) CO2 reduction (%) 50,000 people per year dying the US from air quality. VSL 100s of billions per year. Few percent of GDP. Health benefits, from e.g. increased natural gas use, can cover 10-30% climate change mitigation for free Challenges: Could you get air quality benefits other ways? E.g. cheaper end of pipe in short term Private versus social costs Very different time scales We are already doing many of these things. (Thompson al. Nat Climate Change 2014)

19 Natural Gas & US Electricity Production Fraction of US Electricity Generation US Electricity Generation % 50% Renewable Hydro Nuclear Natural Gas Coal 33% 30% Air Pollutant Emissions CO 2 (g CO 2 /kwh) NO x (g NO 2 /kwh) coal gas coal gas (de Gouw et al. Earth s Future, 2014) DOE EIA

20 What about local impacts? Natural gas drill rigs in Hopewell Township, news.nationalgeographic.com

21 Gasoline Direct Injection (GDI) vehicles are being rapidly adopted to meet fuel economy standards Port Fuel Injection (PFI) GDI = Gasoline Direct Injection GDI Benefits: (1) Higher compression ratio due to evaporative cooling effect reducing compression temperature and knock onset (2) Greater flexibility in valve operations ~5% higher fuel economy (Zimmerman et al. EST 2016)

22 Gasoline (PFI) vehicle PM emissions falling ~10x LEV ULEV SULEV (Saliba et al. EST 2017)

23 GDI vehicles have higher PM emissions GDI ~ 2xPFI GDI ~ 3xPFI LEV ULEV SULEV (Saliba et al. EST 2017)

24 GDI: Health costs > climate benefits Analysis for Los Angeles Area using EMFAC emissions and EASIUR social cost of PM Social cost of carbon: $37/ton

25 GDI: Health costs > climatebenefits Analysis for Los Angeles Area using EMFAC emissions and EASIUR social cost of PM Social cost of carbon: $37/ton

26 Carbon Capture and Sequestration (CCS)

27 CCS Ammonia Slip and Air Quality Social cost of CCS ammonia: $31-$68/t-CO 2 Social cost of carbon: $28-$102/t-CO 2 Ammonia emissions not too difficult to control PM 2.5 increase from capturing 2 Gt-CO 2 (~ current coal emissions) in 2050 (Heo et al. EST 2015)

28 Conclusions Complex interplay of climate change and air pollution Meteorology Natural Emissions Large reductions in anthropogenic emissions will likely win! But Climate penalties degrade benefits Lots of interesting technology scenarios Health benefits of some mitigation options can cover some climate mitigation cost