Interconnections Between Air Pollution, Climate Change and Health: Promoting Sino U.S. Cooperation

Transcription

1 Interconnections Between Air Pollution, Climate Change and Health: Promoting Sino U.S. Cooperation Denise L. Mauzerall Woodrow Wilson School of Public and International Affairs & Civil and Environmental Engineering Department Princeton University Woodrow Wilson International Center Washington D.C. May 12, 2009

2 Air Pollution and Climate Change are Interconnected Air pollution levels are highly sensitive to weather, and it follows that climate change will likely have air quality implications. Conversely, Some air pollutants increase radiative forcing (RF) eg. ozone (O 3 ), black carbon (soot) resulting in warming; Some air pollutants decrease RF eg. sulfate and organic aerosols resulting in cooling. Hence, reductions in the emission of air pollutants can either warm or cool the climate. Integration of air quality and climate stabilization goals in environmental policy design would be highly beneficial.

3 Air Pollution Adversely Impacts Health The World Health Organization identified ambient air pollution as a high public health priority. Both long and short term exposure to aerosols (fine particulate matter PM2.5) can result in premature mortality and cardio pulmonary disease. (Dockery et al., 1993; Pope et al., 2002; Laden et al., 2006) PM2.5 includes sulfate, black carbon (BC), organic carbon (OC) and other aerosols Ozone is associated with premature mortalities and respiratory ailments. (Bell et al., 2004, 2005; Levy et al., 2005; Ito et al., 2005). Elevated O 3 concentrations reduce agricultural yields of many crops. Ozone will likely have an increasingly adverse impact on East Asian (Wang and Mauzerall, 2004) and global production of soybeans, corn and wheat. Reduced yields may have an adverse impact on global nutrition and hence health.

4 Global radiative forcings due to emission changes from Important contributions of air pollutants Tropospheric ozone (O 3 T) and black carbon have positive radiative forcing Sulfate and organic carbon have negative radiative forcing both directly and indirectly by making clouds whiter (increasing cloud albedo). IPCC, 2007

5 Co Benefits Concept Strategic reductions in the emissions of some GHG (e.g. methane) can improve air quality. Strategic reductions in the emissions of some air pollutants (e.g. black carbon) can benefit climate; reductions of others (e.g. sulfate and SO 2 ) will increase warming. GOAL: Identify emission reduction strategies which simultaneously improve air quality and reduce climate warming.

6 Global Emission Projections for SO 2 and Black Carbon (BC) for various IPCC SRES scenarios. SO 2 BC Policies to reduce aerosol loadings could thus have considerable impact on climate change. IPCC, 2001

7 Types of Combustion Emitting Black Carbon (BC) Contained BC emission sources Dominated by fossil fuel combustion, especially diesel engines. Organic carbon (OC), which cools, is co emitted in small quantities Strong warming effect Uncontained BC emission sources Dominated by agricultural waste, forest and savanna burning High OC co emissions Negligible or negative warming effect from aerosols

8 Global Annual Emissions of BC by Region and Source Type in 1995 Note: China has more contained combustion than any other region [WWS report, 2009; Adapted from Bond et al., 2004]

9 Breakdown of Global BC Emissions by Source weighted by radiative forcing contribution [WWS report, 2009]

10 Why is it hard to reduce Black Carbon emissions? Scientific uncertainty, complexity, and chemical variability of Black Carbon Large Proportion of Emissions from Developing Countries Dispersion of Emissions Sources High Cost of Replacement Technologies Administrative Challenges of Black Carbon Emissions Reduction

11 Opportunities Presented by BC Mitigation Short Lifetime and High Radiative Forcing of BC means Reductions Yield Rapid Climate Benefits Immediate Availability of Solutions Health Benefits of Emission Reductions Energy Efficiency and Service Quality Gains Infrastructure Development Political Advantages and Funding Sources Chasing Co Benefits Arctic Protection

12 Because lifetimes are very different, the relative RF over time of one ton each of BC and CO 2 emitted over the course of one year differ Hence, there is an immediate benefit for reducing BC emissions! Black Carbon CO 2 12

13 Black Carbon Summary BC is not like GHGs 2ºC target is very difficult without tackling BC BC has strong regional effects BC has costly impacts on human health BC Science BC Science Target transportation sector Diesel retrofits cost effective for health reasons Improve fuel efficiency Locate super emitters Reduce off road vehicle emissions Fuel switching Developing nations: Major growing contributors Developing nations are more vulnerable to climate and health effects Focus on transport fleet (new vehicles and retrofits) and stoves BC Abroad BC Abroad International Policy Promote Awareness Need IPCC Special Report on BC Hot Spot treaties Global Technical Standards Multilateral funds No trading of BC with GHG 13

14 Strong sensitivity of 21 st century climate to projected changes in short lived air pollutants Reductions in SO 2 emissions and hence sulfate aerosols plus continued increases in black carbon (BC) and ozone will likely result in substantial warming [US Climate Change Science Program, 2008]. A large and growing fraction of BC emissions comes from developing countries in Asia. Reductions in BC emissions would be advantageous for both air quality, public health and climate change. Reductions in methane emissions (a GHG and a precursor of ozone) would also be advantageous for both air quality, public health and climate change.

15 [US Climate Change Science Program, Product 3.2, 2008]

16 Linking Changes in Aerosol Emissions from China to Global Public Health and Radiative Forcing Objective: For 2000 and for three 2030 scenarios evaluate the impact of emissions of SO 2 (sulfate precursor), OC & BC from China on: Premature mortalities globally, Radiative forcing. E. Saikawa, V. Naik, L. W. Horowitz, J. Liu, D. L. Mauzerall E. Saikawa, V. Naik, L. W. Horowitz, J. Liu, D. L. Mauzerall. Present and potential future contributions of sulfate, black and organic carbon aerosols from China to global air quality, premature mortality and radiative forcing, Atmospheric Environment, 2009.

17 Emission Scenarios Unit: Tg/yr 2030 BAU = Business as usual emission growth 2030 CLE = Full implementation of current air quality legislation by MFR = Maximum feasible reduction using technology existing today

18 Results Effect of sulfate, OC and BC aerosols originating from China on annual premature mortality in each region

19 Results Radiative Forcing (RF) from sulfate, OC and BC from China China s s aerosol emissions currently create net NEGATIVE radiative forcing, offsetting global warming, but at large costs to health. Unit: mwm 2 However, the negative forcing will decrease in the future as SO 2 emissions decrease and BC emissions rise. Reductions in BC emissions provide opportunity to reduce positive RF with simultaneous health benefits.

20 Evaluating the Impacts of Air Pollution on Human Health in China on the local scale: Implications for future air pollution and energy policies Questions: How severe was air pollution in eastern China in 2000? How large were the resulting health impacts? What was the monetary value of these health impacts? How severe will air pollution and health impacts be in 2020 if energy demand increases but: No additional pollution controls are implemented (BAU)? Best available control technology (BACT) is used? Advanced Coal Gasification Technology (ACGT) is used? ACGT eliminates most air pollutant emissions, and permits sequestration of CO2 while continuing use of coal. What is the monetary value of these health damages? Wang, Xiaoping, Mauzerall, Denise L., Atmospheric Environment, 2006.

21 Study Region Beijing Shanghai Zaozhuang Population: 3.5 million (37% urban) Per capita GDP: 2000US$ 842 Area: 4550 km 2 Coal production: 20 mil tons Coal consumption: 3.1 mil tons Zaozhuang in Shandong Province used for case study Population in model domain: 281 million - Rich in coal, particularly high sulfur coal - 85% of energy services provided by coal with substantial coal export - Region of particularly poor air quality that is likely to worsen - Region with potential to use high-sulfur coal cleanly - A medium-sized municipality with potential to be replicated

22 Integrated Assessment Structure Intermediate Outcome Method 1) Energy consumption and technology scenarios Collect energy consumption and technology data for base year 2000, project energy demand for 2020, and develop pollution control and alternative energy scenarios for ) Emission inventory Estimate anthropogenic emissions based on levels of energy consumption and emission factors 3) Ambient air pollution concentrations Use CMAQ regional model to simulate hourly concentrations of pollutants for four seasons of 2000, 2020 and for future alternative scenarios. 4) Human exposure Calculate exposure based on calculated ambient concentrations and population distributions. 5) Health Impacts Estimate number of deaths, years of life lost and illness based on concentration-response functions from literature. 6) Economic costs Estimate economic value of health impacts.

23 Cost of Health Damages Caused by Air Pollutant Emissions from Zaozhuang % Equivalent GDP BAU 2020 BACT 2020 ACGT

24 Tropospheric ozone (O 3 ) is a critical link between air pollution and climate change O 3 is a GHG. O 3 is a component of photochemical smog. O 3 is a precursor for OH which removes air pollutants and reactive GHG from the atmosphere. O 3 is a criteria air pollutant associated with adverse effects on health (including premature mortality), agriculture and ecosystems. Methane (CH 4 ) contributes to the formation of O 3. CH 4 + NO x + sunlight O 3 Background concentrations of O 3 are increasing globally due in part to increasing methane.

25 Background Ozone is Growing and Will Continue to Grow! Future increases in ozone due to increasing emissions of methane, NO X and VOCs are projected to be large (Prather et al., 2003) (IPCC A2) Ozone trend at European mountain sites, (Marenco et al., 1994).

26 Can methane emission reductions be justified for ozone air quality purposes? Objective: Estimate the global benefits to human health (lives saved) by controlling methane emissions and hence reducing background O 3 concentrations. Jason West, Arlene Fiore, Larry Horowitz & Denise Mauzerall Global Health Benefits of Mitigating Ozone Pollution with Methane Emission Controls, Proceedings of the National Academy of Science, vol. 103, no. 11, pp , March 14, 2006

27 Global Methane Emissions Natural: 180 Mton CH 4 yr 1 Wetlands Termites Ocean Coal Oil Gas Biofuel Rice Other Wastewater Landfills Biomass burning Animals Anthropogenic: 300 Mton CH 4 yr 1 * USA is ~9% of global anthropogenic emissions. EDGAR3.2 & Houweling et al., 1999

28 Co Benefits of Reducing Methane Reducing ~20% of anthropogenic methane emissions will: Reduce 8 hr. average ozone globally by ~1 ppb. Reduce global radiative forcing by ~0.14 W m 2. Provide ~2% of global natural gas production. Prevent ~30,000 premature deaths globally in 2030, ~370,000 from [West et al., PNAS, 2006]

29 Surface Ozone Distributions and Their Impact on Grain Production in China, Japan and South Korea: 1990 and 2020 Wang, X and DL Mauzerall, Characterizing Distributions of Surface Ozone and its Impact on Grain Production in China, Japan and South Korea: 1990 and 2020, Atmospheric Environment, 38, pp , Mauzerall, D. L. and X Wang Mauzerall, D. L. and X Wang, Protecting Agricultural Crops from the Effects of Tropospheric Ozone Exposure: Reconciling Science and Standard Setting in the United States, Europe and Asia, Annual Review of Energy and the Environment, 26, pp , 2001.

30 Crop Yield Reductions Resulting from Exposure to Ozone Data from the US NCLAN study. Plots use median of Weibull parameters obtained from all cultivars studied W126 (ppmh) [Wang and Mauzerall, 2004]

31 Mean O 3 concentrations over various crop growing seasons Legend (ppb) Zero or No Data M7/M12, M7/M12, 2020 Winter wheat, M7 Single rice, M7 Spring corn, M12 Soybeans, M12

32 Relative Yield Loss (RYL) in 1990 and Legend (%) < RYL, RYL, Zero or No Data 2020 Winter wheat, SUM06 Single rice, M7 RYL = 1 Y/Y base Spring corn, SUM06 Y = actual yield Y base = mean yield at reference O 3 level Soybeans, SUM06

33 Conclusions Air pollutants play a major role in climate change and should be viewed as a short term lever in climate stabilization strategies. Opportunities for co benefits: BC emission reductions from contained combustion have clear co benefits for both health and climate. Methane emission reductions would decrease climate warming and surface O 3 concentrations globally providing co benefits for climate, human health and agricultural yields. Increases in efficiency and the use of renewable energy reduce emissions of both reactive air pollutants and CO 2. Win win option. Reducing methane and BC emissions should be viewed as a companion rather than an alternative to reducing CO 2 emissions, as the latter is essential for long term stabilization of climate.

34 Papers are available at the web site of Denise Mauzerall: Woodrow Wilson School report Black Carbon: A review and policy recommendations is available at: S591E.Black.Carbon.report.2009.pdf