Carbonaceous aerosols and climate change

1
Carbonaceous aerosols and climate change over
Asia for the 1980-2030 time period
Surabi Menon Lawrence Berkeley Laboratory,
Berkeley, CA, USA smenon_at_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
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? Aerosol-Climate/Air Quality Effects
1980, Present-day, 2030A1B A1B
scenario Balanced mix of technology and
supply, no dominant single source of energy. ?
Role of Black Carbon Aerosols ? Regional
Signals Climate Sensitivity, Radiative
forcing, Surface mass, Temperature,
Precipitation ? Sensitivity Study
Increase carbonaceous emissions from
transportation and biofuel to 2x 2030A1B for
Asia 10S to 40 N and 58 to 120 E.
Outline
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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 2.96 Wm -2
(Menon 2004, Ann. Rev.)
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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)
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Aerosols and air quality over China and India

• Regional measurements of OC/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 4.1
  mg m-3
• PM10 OC 12.3 and BC 5.2 mg
  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 combustion major
  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).

OCOrganic Carbon BC Black carbon
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Black Carbon Sources and Distribution
1995
2030A1B
Burden(Tg)
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
1995
2030A1B
Burden(Tg)
Fossil/bio-fuel 0.22 0.17
Biomass 0.04 0.05

Images http//www.asthmacure.com, NASA GSFC
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Forcing efficiencies 2030A1B to 1995
Case Sulfate OC BC BC Total
(Total) (Fossil/biofuel/ biomass) (Fossil/bio-fuel) (Biomass)
Direct Forcing (Wm -2) -0.23 0.02 -0.03 -0.02 -0.26
Forcing efficiency (W g-1) -203 -77 882 1000
Differences between 2030A1B and 1995 aerosol
emissions
Forcing efficiency Direct forcing
Aerosol mass column
burden (mg m-2)
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Forcing efficiencies 2030A1B to 1995
Case Sulfate OC BC BC Total
(Total) (Fossil/biofuel/ biomass) (Fossil/bio-fuel) (Biomass)
Direct Forcing (Wm -2) -0.23 -0.24 0.02 0.00 -0.03 0.07 -0.02 -0.02 -0.26 -0.19
Forcing efficiency (W g-1) -203 -198 -77 - 882 1458 1000 1000
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)
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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.
Transportation biofuel black organic carbon Climate sensitivity (K W-1m2)
Standard -2.58 (0.67/-0.26)
2x (40?) -3.53 (0.67/-0.19)
Standard w/o BC/OC (10?) -2.37 (0.64/-0.27)
Standard Qflux (50?) -3.88 (0.97/-0.25)
Hadley Center 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).
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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 1970s) 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.

Without black carbon
With black carbon
(Menon et al. 2002, Science)
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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 Plumes

• Aerosol visible optical depths 0.6
• Aerosol single scattering albedo 0.78
• Inferred shortwave atmospheric forcing 25 W m-2

• Image courtesyImage Analysis Laboratory, NASA
  Johnson Space Center
• Astronaut photograph ISS010-E-13807, acquired
  January 18, 2005

(Ramana et al. 2004, GRL)
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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
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Future Climate (2030-1995)
Global annual amount and change in surface amount
1995 Surface Ozone
Change in Surface Ozone
26.42
3.43
(ppbv)
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Future Climate (2030-1995)
Global
Aerosol direct forcing -0.26 W m-2 Ozone
forcing 0.12 W m-2
1980 1995 2030A1B 2030A1BA
BC 0.33 0.32 0.27 0.37
OC -0.17 -0.17 -0.15 -0.17
Sulfate -0.68 -0.64 -0.87 -0.88
Total Ozone -0.52 -0.37 -0.49 -0.37 -0.75 -0.25 -0.68
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
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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 gt 20 increase in ozone forcing,
globally Over Asia, increase in ozone forcing is
4 gt 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
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Future climate/air quality changes
Average difference 10S to 40N, 58 to 122E
Time Period Ozone (ppbv) Aerosol Mass (?gm-3) Net Rad. Sfc/TOA (Wm-2) Ts (K)
2030A1B-1995 8.28 4.19 -2.5/-3.84 0.46
2030A1B_A - 1995 8.35 13.6 -3.25/-3.58 0.52
Health effects from increase in ozone amount and
particulate matter??
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Anthropogenic Aerosol Effects1960-2002
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)
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Surface Temperature Trends 1960-2002
0.52
Obs.
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
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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.
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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
(Koch et al. 2006, JGR)
(Hansen et al. 2004)