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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

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slide1

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

slide2

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.

slide3

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.)

slide4

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)

aerosols and air quality over china and india

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

slide6

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

slide7

Forcing efficiencies: 2030A1B to 1995

Differences between 2030A1B and 1995 aerosol emissions

*Forcing efficiency= Direct forcing

Aerosol mass column burden (mg m-2)

slide8

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)

slide9

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).

slide10

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)

industrial pollution shenyang china and india nepal

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)

slide12

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

future climate 2030 1995
Future Climate (2030-1995)

Global annual amount and change in surface amount

1995 Surface Ozone

Change in Surface Ozone

26.42

3.43

(ppbv)

future climate 2030 19951
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

future climate 2030 19952
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

future climate air quality changes
Future climate/air quality changes

Average difference: 10S to 40N, 58 to 122E

Health effects from increase in ozone amount and particulate matter??

slide17

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)

slide18

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

summary
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.

slide20

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)