Carbonaceous aerosols and climate change over Asia for the 1980-2030 time period

1. Carbonaceous aerosols and climate change over Asia for the 1980-2030 time period Surabi Menon Lawrence Berkeley Laboratory, Berkeley, CA, USA smenon@lbl.gov Dorothy Koch and Nadine Unger Columbia University/NASA GISS, NY, USA University of Vermont, VE, USA David Streets Argonne National Laboratory, Argonne, IL, USA Better Air Quality Workshop Yogyakarta, Indonesia, December 13-15, 2006

2. Outline  Aerosol-Climate/Air Quality Effects:1980, Present-day, 2030A1BA1B scenario: Balanced mix of technology and supply, no dominant single source of energy.Role of Black Carbon AerosolsRegional SignalsClimate Sensitivity, Radiative forcing, Surface mass, Temperature, PrecipitationSensitivity Study Increase carbonaceous emissions from transportation and biofuel to2x 2030A1Bfor Asia: 10S to 40 N and 58 to 120 E.

3. Why focus on Aerosol-Climate Effects? (Hansen et al. 2005, JGR) Aerosol climate effects: +0.8 to – 2.1 Wm-2 Greenhouse gas climate effects:+2.96Wm -2 (Menon 2004, Ann. Rev.)

4. Schematic of direct & indirect aerosol effects Aerosol indirect effect= Change in Cloud properties due to aerosol impacts on clouds Direct effect = Scattering/Absorption of radiation w/o clouds Modified from Lohmann (2005)

5. Regional measurements ofOC/BC over 4 cities in PDRC (Cao et al., 2004.) • ~ 1/3 of PM 2.5/10 mass were carbonaceous. • PM2.5: OC = 9.2 and BC = 4.1mg m-3 • PM10 : OC =12.3 and BC = 5.2mg m -3 • No strong seasonal fluctuations in OC and BC. • Motor vehicle emissions === major source. • Over India: Particulate matter more important than NOx or SO2. • Biofuels/fossil fuel combustionmajor contributor to deteriorating air quality. (Mitra and Sharma, 2002). • BC source ratio (biofuel/total) ~ 44% in India compared to 15% globally (Venkataraman et al. 2005). Aerosols and air quality over China and India OC=Organic CarbonBC =Black carbon

6. Black Carbon Sources and Distribution Burden(Tg) 1995 2030A1B Black carbon is a product of incomplete combustion. Fossil/bio-fuel = 0.08 0.07 Biomass = 0.07 0.06 Over Asia: 10S-40N, 58-122E Burden(Tg) 1995 2030A1B Fossil/bio-fuel = 0.22 0.17 Biomass = 0.04 0.05 Images: http://www.asthmacure.com, NASA GSFC

7. Forcing efficiencies: 2030A1B to 1995 Differences between 2030A1B and 1995 aerosol emissions *Forcing efficiency= Direct forcing Aerosol mass column burden (mg m-2)

8. Forcing efficiencies: 2030A1B to 1995 Differences between 2030A1B and 1995 aerosol emissions Differences between 2030A1B_A and 1995 aerosol emissions *Forcing efficiency= Direct forcing Aerosol mass column burden (mg m-2)

9. Climate Sensitivity: Black Carbon Calculate the ratio of surface temperature change to forcing for 2030 versus 1995 aerosol emissions. Ratio is a lower limit to climate sensitivity w/o a coupled ocean-atmosphere model. HadleyCenter climate model: 4 x fossil fuel Black Carbon: Climate sensitivity (Present day to 1850) = 0.56 K W-1m2 Climate sensitivity to doubled CO2 is ~ 0.91 K W-1m2. (Roberts and Jones, 2004, JGR).

10. China: Black Carbon and Summer Monsoon Trends Over the last few decades: • increased floods/droughts in the south/north; increased dust storms in the spring; • precipitation trends largest observed since 950 AD. We link increased emissions over China (since the late 1970’s) with observed climate. Assume a large proportion of aerosols are absorbing (black carbon). Changes in heating profile affects convective fluxes, stability and spatial redistribution of precipitation. With black carbon Without black carbon (Menon et al. 2002, Science)

11. Snow cover change between urban and rural areas Aerosol optical depth from satellite (MODIS), Dec 2002 Hun River Industrial Pollution: Shenyang, China, and India/Nepal Image courtesy:Image Analysis Laboratory, NASA Johnson Space Center Astronaut photograph ISS010-E-13807, acquired January 18, 2005 Industrial Plumes • Aerosol visible optical depths ~ 0.6 • Aerosol single scattering albedo ~ 0.78 • Inferred shortwave atmospheric forcing ~ 25 W m-2 (Ramana et al. 2004, GRL)

12. Future Emission Trends: A cause for concern • SO2 emissions in China and Korea for an A1B scenario for 2020 exceed targets. • BC emissions in China for 2000 are very large (2.3 Tg/yr) compared to Japan (0.053 Tg/yr) • Every 1 mg m-3 increase in BC causes a 3.5 mg m-3 reduction in O3 • -----Surface reactions on soot. (Latha and Badarinath, 2004.) • Based on Jan 2004 data over Hyderabad, India. • NOx emissions are rising in Asia Also confirmed by recent satellite estimates from Schiamachy that show high NO2 columns over major cities. Annual mean radiative forcing over China : Anthropogenic BC: 5.0 W m-2 Anthropogenic O3: 0.5 W m-2 25 ppm increase in CO2: 0.1 W m-2 (Chung and Seinfeld, 2005) Street et al. 2002, Akimoto 2003, Image source from D. Alles

13. Future Climate (2030-1995) Global annual amount and change in surface amount 1995 Surface Ozone Change in Surface Ozone 26.42 3.43 (ppbv)

14. Future Climate (2030-1995) Global Aerosol direct forcing = -0.26 W m-2 Ozone forcing = 0.12 W m-2 Average: 10S to 40N, 58 to 122E Aerosol direct forcing = -0.50 W m-2 2x BC/OC = -0.48 W m-2 Ozone forcing = 0.24 W m-2 = 0.25 W m-2

15. Future Climate (2030-1995) Global Aerosol direct forcing = -0.26 W m-2 Ozone forcing = 0.12 W m-2 Without carbonaceous aerosols, Ozone forcing = 0.15 W m-2 ===> 20% increase in ozone forcing, globally Over Asia, increase in ozone forcing is ~4% ==> no net benefit from BC/OC Average: 10S to 40N, 58 to 122E Aerosol direct forcing = -0.50 W m-2 2x BC/OC = -0.48 W m-2 Ozone forcing = 0.23 W m-2 = 0.25 W m-2

16. Future climate/air quality changes Average difference: 10S to 40N, 58 to 122E Health effects from increase in ozone amount and particulate matter??

17. Anthropogenic Aerosol Effects:1960-2002 “Global dimming: 1960-1990; Reversal after 1990” Calculate linear trend in absorbed solar radiation for 1960 to 2002: Exp A: All forcings (ozone, land-use, snow/ice albedo change, solar, GHG, water vapor, aerosols) Exp B: Similar to Exp A but no anthropogenic aerosols Exp A Exp B -0.91 0.23 Units (W m-2); Global means: r.h.s of graph (Nazarenko and Menon 2005, GRL)

18. Surface Temperature Trends: 1960-2002 Obs. 0.52 With anthropogenic aerosols, temperature trends (Exp A) match observed trends. Policy Implications: Without mitigating both GHGs and aerosols, sfc. temp. reduction due to aerosols may no longer mask GHG effects in some regions if only aerosols are reduced, as in Europe & U.S. 0.50 0.77 Units in K; Global means: r.h.s. of graph

19. Summary • Carbonaceous aerosols from industrial/biofuel sources have important regional climate effects especially over Asia: • Ratio of change in surface temperature to radiative forcing increase by 40% if biofuel/transportation black carbon increases by a factor of 2. • Black carbon induced heating within the atmospheric column changes spatial pattern of precipitation. • Future air quality change: 2000 to 2030 • Ozone and aerosol effects over Asia is twice the global average and especially strong over tropical regions such as India. • With addition of carbonaceous aerosols, ozone forcing  ~ 20% for 2030, but • not much benefit for Asia. Health and air quality issues will becoming increasingly important for Asia! Large unknown in climate change: Emission sources, Interactions and feedbacks of the climate system.

20. Future Predictions and link to climate Based on CO2 and temperature response, emission pathways may change: • Industrial aerosol emissions are linked to technological change and economic projections, • If future emissions change, climate response is going to depend on regional changes and the impact on distant climate. US CO2 Emissions Global emissions (Hansen et al. 2004) (Koch et al. 2006, JGR)