The climate impact of the household sector
in China
– backyard solutions to global problems?
Kristin Aunan (CICERO)
Together with Terje K. Berntsen, Kristin Rypdal, Hans Martin Seip (all CICERO, Oslo, Norway); David G. Streets (Argonne
National Laboratory, Argonne IL, U.S.A.); Jung-Hun Woo (University of Iowa, Iowa City IA, U.S.A); and Kirk R. Smith
(University of California, Berkeley CA, U.S.A.)
• The relative importance of the household sector
for environmental burden in China
• Global benefits from abating indoor air pollution
in developing countries?
Background
 Increasing evidence that air pollutants play
an important role in the climate system
 Post-Kyoto treaties: Including radiative
forcing components that also have adverse
impacts on human health and environment
may increase participation
 Important pollutants in this context are
aerosols and tropospheric ozone precursors
Why the household sector?
• Indoor air pollution from solid fuel use ... the second
biggest environmental contributor to ill health, behind
unsafe water and sanitation (WHO, 2002)
• Indoor air pollution from solid fuel use is responsible for
more than 1.6 million annual deaths and 2.7% of the
global burden of disease (in Disability-Adjusted Life
Years) worldwide (WHO, 2002)
• 72% of the Chinese population live in rural or periurban
areas - areas where use of simple, low-efficiency
household stoves for coal or biomass is common
How important is residential cooking and
heating in a larger context?
• For energy use?
• For emissions?
• For concentrations, exposures and health
risks?
• For radiative forcing and climate effects?
Energy use
Primary Energy Production by Source, 1949-2003 (Mtce)
1800
1600
1400
Biomass
1200
Electricity
1000
Natural Gas
Crude Oil
800
?
Coal Raw
600
400
200
19
99
19
96
19
93
19
90
19
87
19
84
19
81
19
78
19
75
19
72
19
69
19
66
19
63
19
60
19
57
19
54
19
51
EB
Ye
ar
0
Energy use
Residential sector: 18% of energy consumption
Other
8%
Transportation
6%
Urban residential
RURAL
(commercial energy)
RESIDENTIAL
6%
(commercial energy)
4%
RURAL
RESIDENTIAL
(biomass)
14 %
Agriculture
4%
Industry
58 %
Energy use
Share of urban residents having access to gas for
cooking (figure) and district heating is rapidly increasing
Share of urban population using gas
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
1975
1980
1985
1990
1995
2000
2005
Sinton, 2004
Energy use
...but biomass use in rural areas is stable
1 200
Coal
Oil
Gas
1 000
electricity
Stalk
Biogas
Firewood
Mtce
800
600
400
200
0
1975
1980
1985
1990
1995
2000
2005
Emissions
Numerous ways to measure and model particulate matter
Health effects studies
Global warming studies
Size; acidity; mutagenicity..
Size and physiochemical properties
(atm. lifetime;scattering/ absorption);
‘Particulate matter’:
‘Aerosols’:
TSP
BC
PM10
OC
PM2.5
Sulphates
PM1.0
Nitrates
Ultrafine particles (PM0.1)
Natural dust
...
The fine fraction (PM2.5 or even PM1.0)
contains most of the acidity and
mutagenicity
Emissions
Houshold sector’s share of emissions
Products of
incomplete
combustion
CO2
CH4
NOx
SO2
nmVOC
CO
BC
OC
PM10, PAH..
31% (9%)
30%
9%
11%
44%
49%
72%
96%
??
Streets et al
Concentrations, exposures and health risks
Outdoor air pollution - Chinese cities among the worst
Delhi
Mexico City
Rio de Janeiro
NO2
Los Angeles
SO2
New York
TSP
Tokyo
Shanghai
Lanzhou
Taiyuan
Guangzhou
Beijing
0
100
200
300
400
mg/m 3
500
600
700
800
Concentrations, exposures and health risks
Indoor air pollution adds to the exposure - especially for
the poorer parts of the population
Indoor trad. cookstove (rural Yunnan, China)
Delhi
Mexico City
Rio de Janeiro
NO2
Los Angeles
SO2
New York
TSP
Tokyo
Shanghai
Lanzhou
Taiyuan
Guangzhou
Beijing
0
500
1000
1500
mg/m 3
2000
2500
Concentrations, exposures and health risks
Average PM10 exposure for different population groups
(given present outdoor PM10 levels in urban and rural areas in
Taiyuan, Shanxi)
1200
urban coal users
1000
rural coal users
urban gas users
800
m g/m
3
rural biomass users
600
400
200
0
winter
summer
Estimates of indoor air pollution taken from ’Database on
Indoor Air Pollution’ (K. Smith and J. Sinton);
Time activity pattern from study in Hong Kong
Preliminary estimates
Concentrations, exposures and health risks
Using data from Taiyuan, Shanxi, on population and access to
town gas and district heating (preliminary estimates)
Assuming only coal i rural areas
(cheap and abundant in Shanxi):
Assuming only biomass i rural
areas:
PWEwinter = 475 mg/m3
PWEwinter = 615 mg/m3
PWEsummer= 215 mg/m3
PWEsummer= 315 mg/m3
(PWE: Population weighted exposure)
Radiative forcing and climate effects
Effects of BC on the input of energy to the system
 Direct: Absorption of shortwave solar radiation
+ heating of the atmosphere
(- reduction of incoming solar radiation at Earth’s surface)
 Semidirect: ‘Cloud burning’
+ Reduction of lower clouds increase solar radiation
+ Red. of high-level clouds increase solar radiation, but
- also reduce the trapping of heat (greenhouse effect of the clouds)
 Indirect:
- Cloud enhancing (act as cloud condensation nuclei →
optically thicker and more reflective clouds)
+ Reduce the albedo of the Earths surface (dirty snow
and ice)
Radiative forcing and climate effects
Some preliminary model results
• Modelled RF for BC – only the direct effect
(radiative transfer model at Institute for Geophysics)
• RF for OC, sulfates, and ozone are estimated
(scaled) from ’Does location matter’
Radiative forcing and climate effects
Total carbonaceous aerosols at the surface (mg/m3)
Contribution from domestic fuel use to carbonaceous aerosol (mg/m3)
Radiative forcing and climate effects
Monthly averaged contribution from domestic fuel use
to troposheric column burden of BC (mg/m2)
Radiative forcing and climate effects
Jan., Dom. fossil fuel, RF=0.008
Jan., Dom. biofuel, RF=0.025
Febr., Dom. fossil fuel, RF=0.010
Febr., Dom. biofuel, RF=0.033
Radiative forcing and climate effects
Montly averaged enhancement of surface concentrations of ozone (ppbv) due to
emissions of NOx, CO and VOCs from domestic fuel use (fossil and biofuel)
Radiative forcing and climate effects
The contribution from domestic sources is largest in
winter (i.e. probably not important for agricultural crop loss..)
Seasonal cycle of surface ozone in Beijing
25
Ozone (ppbv)
Contribution
from DF
Ozone (ppbv)
80
20
60
15
40
10
20
5
0
0
450
0
50
100
150
200
250
300
350
400
Ozone from domestic fuels (ppbv)
100
Radiative forcing and climate effects
Net positive radiative forcing of household sector
(preliminary estimates)
2.4 % of global average RF from GHG
70
60
50
Total (low and high)
mW/m 2
40
30
Domestic (fossil and
biomass)
20
Domestic fossil fuels
10
Domestic biomass
0
-10
CO2 SO2 SO2 BC
(low) (high)
OC
O3
CH4
-20
-30
Indirect effects of particles (via clouds) not included
Radiative forcing and climate effects
Climate sensitivity to BC radiative forcing?
• Indications that lBC is higher than lCO2 due to the
multitude of feedbacks to the climate system
triggered by BC;
– large uncertainties are inescapable
Summary
• Living standards in rural areas can be significantly
improved by promoting a shift from direct combustion of
biomass fuels and coal in inefficient and polluting stoves
to clean, efficient liquid or gaseous fuels and electricity
• An increased focus on energy use in the household
sector in China will likely also have significant beneficial
global effects in terms of reduced global warming,