The impacts of short lived ozone precursors on climate and air quality Meridith M. Fry JGCRI Seminar March 12, 2013

Transcription

1 The impacts of short lived ozone precursors on climate and air quality Meridith M. Fry JGCRI Seminar March 12, 2013 This research has been funded wholly or in part by the U.S. EPA under the Science to Achieve Results Graduate Fellowship Program. EPA has not officially endorsed this research, and the views expressed herein may not reflect the views of the EPA.

2 Climate Change and Air Pollution Climate Change Common sources & feedbacks Impacts: Regional to global, Near and long term Air Pollution Ozone, Particulates 2

3 Background: Air Pollution Short lived O 3 precursors: Carbon monoxide (CO) Nitrogen oxides (NO x ) Volatile organic compounds (VOCs) Secondary species: Ozone (O 3 ) Sulfate (SO 4 2 ) Nitrate (NO 3 ) Source: EPA 3

4 Background: Role of precursors in ozone chemistry Ozone (O 3 ): Secondary air pollutant & greenhouse gas h NO NO 2 O 3 (Adapted from J. West) HO 2 OH NMVOC, CO, CH 4 emissions Non methane volatile organic compound (NMVOC), Carbon monoxide (CO), Methane (CH 4 ), Nitric oxide (NO), Nitrogen dioxide (NO 2 ), Hydroxyl radical (OH), Hydroperoxyl radical (HO 2 ) 4

5 Background: Long range & Long term ozone effects Long range: by space O 3 lifetime ~22 days Intercontinental transport (5 10 days) Hemispheric to global effects due to O 3 precursors & transport Anthropogenic CO after 8 10 days of transport: Gray (<3km), Black (>3km) Long term: by time Long term O 3 CH 4 is longer lived (~10 yrs); O 3 responds more gradually NO x, NMVOC & CO also influence (via CH 4 ) Short term O 3 NO x, NMVOC & CO form O 3 within hours to weeks Steady state O 3 = Short term O 3 + Long term O 3 [TF HTAP, 2010] 5

6 Background: Role of precursors in methane chemistry Methane (CH 4 ): Primary & secondary species & greenhouse gas 90% of CH 4 loss via oxidation by the hydroxyl radical (OH) OH + CH 4 CH 3 + H 2 O Main sink for CH 4 h NO NO 2 O 3 O 3 precursor emissions influence OH, leading to CH 4 changes CO, NMVOC: OH decreases, CH 4 increases NO x : OH increases, CH 4 decreases HO 2 OH NMVOC, CO, CH 4 emissions 6

7 Background: Role of precursors in aerosol chemistry Aerosols: Primary & secondary pollutants & climate forcers Sulfate (SO 4 2 ) aerosols influenced by oxidant changes (OH, O 3, H 2 O 2 ) O 3 H 2 O h NO, O 3 h OH HO 2 RHCO Direct radiative effect of SO 4 2 : scatter radiation (cooling) NO 2 CO, VOC, O 3 RO 2 SO 4 2 & O 3 chemistry are coupled HNO 3 ROOH Sulfur dioxide (SO 2 ) Hydrogen peroxide (H 2 O 2 ) Nitric acid (HNO 3 ) Aldehydes (RHCO) Organic peroxides (ROOH) Organic peroxyl (RO 2 ) SO 2 SO 4 2 cloud H 2 O 2 HO 2 Adapted from Stein and Lamb [2002] 7

8 Background: How are air pollutants harmful? Impact health Respiratory, Cardiovascular (O 3, PM) Premature mortality (O 3, PM) Impact the environment Acid rain (NO x, SO x ) Eutrophication (NO x ) Damage to vegetation (O 3 ) Reduced visibility/haze (PM) Impact climate change Climate warming and cooling Increased frequency, intensity, and duration of heat waves 8

9 Background: Radiative forcing RF = Incoming Outgoing Irradiance at the Tropopause (W m 2 ) Atmosphere [Forster et al., 2007] 9

10 Background: How do emissions affect radiative forcing? Short lived Climate Forcers (SLCFs) RF CO+VOC 16% of CO 2 RF [Shindell et al., 2009] O 3 precursor emissions influence RF due to effects on O 3, CH 4, & aerosols 10

11 Background: Current standards and agreements National Ambient Air Quality Standards (NAAQS): CO, Lead, NO 2, O 3, PM, SO 2 Primary Air standards quality protect focus public local, health short term Secondary standards protect public welfare Gothenburg Protocol (UNECE CLRTAP, 2012): NO x, VOCs, SO Air 2 quality, and NHfocus 3 emission long range, reduction long term commitments for EU member states by 2020 Kyoto Protocol (UNFCCC): CH 4 among 6 greenhouse gases targeted Climate change by participating focus global, partieslong term What s missing? Coordinated air quality & climate policies; Climate agreement/policy for SLCFs

12 Background: Opportunity for SLCFs Many have suggested that short lived climate forcers and their precursors be considered in climate mitigation strategies [Fuglestvedt et al., 1999; Rypdal et al., 2005, 2009; Naik et al., 2005] Opportunity to address near term climate change, and to complement long term CO 2 mitigation efforts But they impact RF non uniformly and may require geographically varying metrics (i.e. Global Warming Potential) 12

13 Background: Modeling tools Chemical Transport Mathematical estimate of ambient air pollutant concentrations in 4D based on measured inputs Supplements monitoring Global Chemical Transport Model (CTM) Radiative Transfer Calculation of solar and terrestrial radiative transfer in 4D Supplements satellites A component of global atmosphere/land surface models, or general circulation models (GCM) Radiative Transfer Model (RTM) Image Source: 13

14 Research Concepts Air quality and radiative forcing impacts of short lived ozone precursors (CO, NMVOC, NO x ) are non uniform and more sensitive to particular regions emissions. Regionally variable climate metrics for shortlived ozone precursors may be appropriate in future climate agreements and emissions trading schemes. 14

15 Three Studies 1) The influence of ozone precursor emissions from 4 regions on tropospheric composition and radiative climate forcing 2) Net radiative forcing and air quality responses to regional CO emissions (10 regions) 3) Air quality and radiative forcing impacts of volatile organic compound emissions from ten world regions 15

16 Study 1 The influence of ozone precursor emissions from four world regions on tropospheric composition and radiative climate forcing Fry, M. M., V. Naik, J. J. West, M. D. Schwarzkopf, A. M. Fiore, W. J. Collins, F. J. Dentener, D. T. Shindell, C. Atherton, D. Bergmann, B. N. Duncan, P. Hess, I. A. MacKenzie, E. Marmer, M. G. Schultz, S. Szopa, O. Wild, and G. Zeng (2012), Journal of Geophysical Research, 117, D07306, doi: /2011jd

17 Study 1: Motivation Task Force on Hemispheric Transport of Air Pollution (TF HTAP) Multimodel assessment of air pollution transport for 20% reductions in global CH 4 & anthropogenic NO x, NMVOC, and CO emissions from 4 regions Assessment of model uncertainty Gridded results improve understanding of how impacts vary by emission location Objective: Estimate tropospheric and RF impacts, which may support development of future climate policies or agreements 17

18 Study 1: Research Methods Using ensemble of 11 global chemical transport models, we calculate multimodel mean ±1 standard deviation O 3, CH 4, SO 4 2 1) Analyze tropospheric composition changes of O 3, CH 4, SO 4 2 2) Simulate net RF using GFDL radiative transfer model (RTM) NA: North America EU: Europe SA: South Asia EA: East Asia [Fiore et al., 2009] TF HTAP Simulations (year 2001): Simulation Description SR1 Base SR2 20% CH 4 (global) SR3 20% NO x SR4 20% NMVOCs SR5 20% CO SR6 20% Combined REGIONAL *GFDL: NOAA Geophysical Fluid Dynamics Laboratory

19 Research Methods: Radiative Transfer Modeling INPUTS: O 3, CH 4, and SO 4 2 concentrations (CTM) In each grid cell (3D) and month NOAA GFDL Radiative Transfer Model (RTM) OUTPUTS: Monthly mean net radiation fluxes (solar, infrared), stratospheric adjusted Note: Uncertainty from omitted RFs Nitrate & secondary organic aerosols Carbon cycle feedbacks Stratospheric ozone Water vapor NET RF CALCULATION: Net RF = Net fluxes (solar minus infrared) at Tropopause for Perturbed Base In each grid cell (3D) and month 19

20 Results Study 1: Tropospheric Changes Tropospheric O 3 Full & upper troposphere changes (blue, yellow) Greater O 3 sensitivity to SA NO x & NMVOCs EA: East Asia, EU: Europe, NA: North America, SA: South Asia Tropospheric CH 4 NO x reductions increase CH 4, while NMVOC & CO decrease CH 4 Tropospheric SO 4 2 Uncertainty in oxidant changes & SO 2 oxidation pathways

21 Results Study 1: Net RF Distributions -20% NO x NA -20% CO NA Contributions: SO 4 2 = local; O 3 = regional/ hemispheric; CH 4 = global NO x : Long term O 3 (via CH 4 ) in SH & O 3 in NH NMVOC & CO: O 3 & CH 4 in NH & SH EA: East Asia EU: Europe NA: North America SA: South Asia NH = Northern Hemisphere SH = Southern Hemisphere 21

22 Results Study 1: Global Net RF & GWP O 3 CO 2 uptake RF -20% NO x -20% NMVOC -20% CO 22

23 Results Study 1: Global Net RF & GWP -20% NO x -20% NMVOC -20% CO EA: East Asia, EU: Europe, NA: North America, SA: South Asia O 3 RF & CH 4 RF: same sign as tropospheric changes SO 2 4 RF: opposite sign Net RF/ emissions greatest for SA NO x & NMVOC CO 2 RF: Influence of O 3 on CO 2 uptake by vegetation CO 2 uptake O 3 RF -20% NO x -20% NMVOC -20% CO Global Warming Potential (GWP H ) RF integrated to time horizon, H, following 1 year pulse emission: H RF CO / emissions / H RF CO2 / emissions Patterns of GWP 100 similar to normalized net RFs 23-20% NO x -20% NMVOC -20% CO

24 Study 1: Key Findings & Implications NMVOC and CO emission reductions most effectively mitigate climate warming NO x may as well, if we consider CO 2 uptake influence Regionally specific GWPs may support future agreements and policies Especially for NO x and NMVOCs (SA > other regions) Regional to global RF patterns reflect distributions of O 3, CH 4, and SO 4 2 changes 24

25 Study 2 Net radiative forcing and air quality responses to regional CO emission reductions Fry, M. M., M. D. Schwarzkopf, Z. Adelman, V. Naik, W. J. Collins, and J. J. West (2012), Atmospheric Chemistry and Physics Discussion, 12, , doi: /acpd

26 Study 2: Motivation Reduction regions Few studies evaluate global scale air quality & climate impacts of regional CO emissions Contribution of CO + VOC emissions to global annual net RF ( ): 0.25 ±0.04 W m 2 [Shindell et al., 2009] CO has longer lifetime than other short lived precursors, so impacts may be more widespread Objective: Air quality & RF of 50% reductions in anthropogenic CO from 10 regions (& globally) 26

27 Study 2: Research Methods MOZART 4 global chemical transport model (CTM) IPCC AR5 RCP anthropogenic & biomass burning emissions GEOS 5 global meteorology ( ) Base simulation, comparison to observations Jul 2004 Dec 2006 at 1.9 x 2.5 x 56 vertical levels Fixed global CH 4 (1783 ppbv) GFDL radiative transfer model (RTM) Anthropogenic CO Emissions 27

28 Results Study 2: Surface CO and Tropospheric CH 4 NA: North America SA: South America EU: Europe FSU: Former Soviet Union AF: Africa IN: India EA: East Asia SE: Southeast Asia AU: Australia ME: Middle East CO Largest Greatest decreases changes in global surface CHCO 4 : occur EA ( 19.4 within ppbv), reduction IN ( 11.5 region ppbv) EA Global contributes CH 4 per 39% unit change of US surface CO emissions CO change varies from little that among of NAregions 28

29 Results Study 2: Surface and Tropospheric O 3 Largest decreases in annual average steady state surface O 3 occur within reduction region, with lesser decreases hemispherically. Decreases Steady state in global tropospheric surface surface O 3 responses O 3 are 3 changes more are greatest are widespread 40 to within 83% across greater hemisphere hemisphere than of short term of reduction, reduction. changes, but the long term suggesting component long term impacts influence air of quality CO is relevant globally for air quality 29

30 Results Study 2: Surface O 3 Annual average steady state surface O 3 changes (pptv) for each regional perturbation: Largest changes in bold Some regional reductions strongly influence air quality in other regions EA has impact on US surface O 3 : 93% of that from NA NA reduction strongly impacts EU and ME surface O 3 : 77% and 75% of impacts from domestic emissions

31 Results Study 2: Long range transport Downwind production of O 3 more important for long range transport than formation and export of O 3 from each region >70% of O 3 burden and production outside reduction region 50 59% of O 3 production in UT (SE, SA, AF, and IN) 31

32 Results Study 2: Surface and Tropospheric SO 4 2 Surface SO 4 2- Trop. SO 4 2- Near equator: Gas phase SO 2 oxidation by OH dominates Northern mid latitudes: Decreased aqueous phase SO 2 oxidation by O 3 and H 2 O 2 32

33 Results Study 2: Net Radiative Forcing of Anthropogenic CO For combined change in tropospheric O 3 (steady state), CH 4, and SO 4 2 (direct effect only) for the regional and global CO reduction simulations. Ozone Ozone Estimated present day RF of CO: 128 mw m 2 8.2% of global net RF of CO 2 and 8.2% of total RF of positive Sulfate short lived climate forcers Net RF (CO, CH 4, NMVOCs, BC) mw m 2 (Tg CO yr 1 ) 1 Sulfate Net RF Global annual net RF: to mw m 2 (Tg CO yr 1 ) 1 [Fry et al., ACPD, 2012] 33

34 Results Study 2: CO Global Warming Potentials Using methods from Fry et al. [2012] and Collins et al. [2013] 20 yr GWP 100 yr GWP 1.57 (CO 2 ) Fry et al. (2012): GWP 20 : 4.6 ±1.3 to 5.3 ±1.2 GWP 100 : 1.5 ±0.4 to 1.7 ± (CO 2 ) 4.07 [3.71 to 4.37] All regional GWP 20 within 8.8% of Global GWP 20 O 3 + CH 4 O 3 + SO [1.26 to 1.44] All regional GWP 100 within 7.5% of Global GWP 100 [Fry et al., ACPD, 2012] 34

35 Study 2: Key Findings & Implications Present day global net RF of CO: 128 mw m 2 RF among 10 regions: to mw m 2 (Tg CO yr 1 ) Little variability in RF & GWPs among 10 regions suggests a globally uniform GWP for CO RF distributions: Widespread cooling globally (O 3 and CH 4 ), localized warming/cooling (SO 4 2 ) Largest CO emitters (EA, IN, AF, NA) have greatest impacts on surface CO and O 3 regionally to globally Long range O 3 impacts influenced substantially by transport of CO and production of O 3 downwind 35

36 Study 3 Air quality and radiative forcing impacts of volatile organic compound emissions from ten world regions Fry, M. M., M. D. Schwarzkopf, Z. Adelman, V. Naik, and J. J. West (In preparation for Atmospheric Chemistry and Physics) 36

37 Study 3: Research Methods Motivation Anthropogenic NMVOC Emissions NMVOCs impact air quality and climate [Collins et al., 2002] Lack of global 3 D modeling of chemistry & climate influence Objective: Air quality & RF impacts of anthropogenic NMVOC reductions (50%) from 10 regions and globally 10 Reduction regions Research Methods MOZART 4: Same inputs and base, new perturbation simulations GFDL RTM 37

38 Results Study 3: Surface and Tropospheric O3 Overall Largest decreases in tropospheric annual average O3steady state across hemisphere surfaceoforeduction, 3 occur yet within regional reduction to intercontinental region, with lesser increases decreases from SA, hemispherically. AF, SE, and AU. 38

39 Results Study 3: Tropospheric O 3 NO x VOC Sensitivity NO x Photochemical indicator ratios (Sillman et al., 1995; 1997; 1999) 39

40 Results Study 3: Surface PM 2.5 Surface PM 2.5 PM 2.5 = (NH 4 ) 2 SO 4 + NH 4 NO 3 + SOA + BC + OC 40

41 Results Study 3: Net Radiative Forcing of Anthropogenic NMVOCs For combined change in tropospheric O 3 (steady state), CH 4, and SO 4 2 (direct effect only) for the regional NMVOC reduction simulations. Ozone Ozone Estimated present day RF of NMVOCs: 27.7 mw m 2 1.8% of global net RF of CO 2 and 1.8% of total RF of positive short lived climate forcers Sulfate Net RF Sulfate Net RF 0.21 mw m 2 (Tg C yr 1 ) 1 [Fry et al., in prep] Global annual net RF: to 0.55 mw m 2 (Tg C yr 1 ) 1 41

42 Results Study 3: NMVOC Global Warming Potentials Using methods from Collins et al. [2012] and Fry et al. [2012] 20 yr GWP 3.7 (CO 2 ) 5.83 [ 1.13 to 18.9] Regional GWP 20 are 0.2 to 3.2 times Global GWP 20 Fry et al. (2012): GWP 20 : 15.5 ±6.8 to 26.5 ±5.3 GWP 100 : 4.8 ±2.4 to 8.3 ±1.9 SO 4 2, O 3 O 3 + CH 4 O 3 + SO yr GWP 3.7 (CO 2 ) 2.36 [0.079 to 6.05] Regional GWP 100 are 0.03 to 2.6 times Global GWP 100 [Fry et al., in prep] 42

43 Study 3: Key Findings & Implications Present day global net RF of NMVOCs: 27.7 mw m 2 RF among 10 regions: to 0.55 mw m 2 (Tg C yr 1 ) Variability in RF and GWPs suggests regionallyspecific GWPs may be necessary Accounting for fuller set of RFs may change magnitude of each region s impacts Greatest O 3 changes within each reduction region Several regions increase tropospheric O 3 (NO x sensitivity) Generally small impacts on PM 2.5 air quality 43

44 Main Contributions 3 studies Opportunity to reduce O 3 precursors for near term climate benefits, where NMVOC and CO reductions most promising among short lived O 3 precursors Including these gases in an agreement provides greater incentive to reduce; may lower costs of meeting climate goals Regionally variable climate metric: NO x, NMVOCs Globally uniform climate metric: CO Emissions from the tropics and SH generally produce the greatest RF and air quality impacts (per unit emission) RF patterns correspond to the distributions of secondary species (O 3, CH 4, and SO 4 2 ) 44

45 Future Research Directions Model realistic scenarios/policies aimed at improving air quality, health, and climate in the near term [UNEP, 2011; Shindell et al., 2012] Investigate regional impacts of emission control measures Provide stakeholders with air quality and RF benefits of priority measures in particular regions Evaluate costs of control measures and policies Update standalone RTM to account for greater number of forcings; improve CTM emissions Analyze full climate responses (e.g. surface temperature, precipitation) 45

46 Acknowledgements Advisor & Committee Chair: Jason West (UNC ESE) Committee: Will Vizuete (UNC ESE) Jason Surratt (UNC ESE) Adel Hanna (UNC Institute for the Environment) Vaishali Naik (UCAR GFDL) Collaborators: Dan Schwarzkopf (NOAA GFDL) Arlene Fiore (Columbia University) Bill Collins (University of Reading) TF HTAP modelers UNC Climate, Health, & Air Quality Lab (CHAQ) Susan Anenberg (EPA), Zac Adelman, Raquel Silva, Yuqiang Zhang 46

47 Questions and Comments Contact Information: Meridith Fry 47