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?

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

Background

• 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

Why the household sector?

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?

Primary Energy Production by Source, 1949-2003 (Mtce)

?

0

200

400

600

800

1000

1200

1400

1600

1800

Biomass

Electricity

Natural Gas

Crude Oil

Coal Raw

Energy use

Residential sector: 18% of energy consumption Urban residential

(commercial energy)6 %

Industry58 %

Agriculture4 %

Transportation6 %

Other8 %

RURAL RESIDENTIAL

(commercial energy)4 %

RURAL RESIDENTIAL

(biomass)14 %

Energy use

0.000.050.100.150.200.250.300.350.400.450.50

1975 1980 1985 1990 1995 2000 2005

Sinton, 2004

Share of urban residents having access to gas for cooking (figure) and district heating is rapidly increasing

Energy use

...but biomass use in rural areas is stable

0

200

400

600

800

1 000

1 200

1975 1980 1985 1990 1995 2000 2005

Mtc

e

Coal

Oil

Gas

electricity

Stalk

Biogas

Firewood

Energy use

Health effects studiesSize; acidity; mutagenicity..

‘Particulate matter’:

TSP

PM10

PM2.5

PM1.0

Ultrafine particles (PM0.1)

The fine fraction (PM2.5 or even PM1.0) contains most of the acidity and mutagenicity

‘Aerosols’:

BC

OC

Sulphates

Nitrates

Natural dust

...

Global warming studiesSize and physiochemical properties (atm. lifetime;scattering/ absorption);

Numerous ways to measure and model particulate matter Numerous ways to measure and model particulate matter

Emissions

Houshold sector’s share of emissions

Streets et al

CO2 31% (9%)

CH4 30%

NOx 9%

SO2 11%

nmVOC 44%

CO 49%

BC 72%

OC 96%

PM10, PAH.. ??

Emissions

Products of incomplete combustion

0 100 200 300 400 500 600 700 800

Beijing

Guangzhou

Taiyuan

Lanzhou

Shanghai

Tokyo

New York

Los Angeles

Rio de Janeiro

Mexico City

Delhi

NO2

SO2

TSP

mg/m 3

Outdoor air pollution - Chinese cities among the worstOutdoor air pollution - Chinese cities among the worst

Concentrations, exposures and health risks

0 500 1000 1500 2000 2500

Beijing

Guangzhou

Taiyuan

Lanzhou

Shanghai

Tokyo

New York

Los Angeles

Rio de Janeiro

Mexico City

Delhi

Indoor trad. cookstove (rural Yunnan, China)

NO2

SO2

TSP

mg/m3

Indoor air pollution adds to the exposure - especially for Indoor air pollution adds to the exposure - especially for the poorer parts of the populationthe poorer parts of the population

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)

0

200

400

600

800

1000

1200

winter summer

mg

/m3

urban coal users

rural coal users

urban gas users

rural biomass users

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

Assuming only coal i rural areas (cheap and abundant in Shanxi):

PWEwinter = 475 mg/m3

PWEsummer= 215 mg/m3

(PWE: Population weighted exposure)

Assuming only biomass i rural areas:

PWEwinter = 615 mg/m3

PWEsummer= 315 mg/m3

Using data from Taiyuan, Shanxi, on population and access to town gas and district heating (preliminary estimates)

Concentrations, exposures and health risks

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

Radiative forcing and climate effects

Total carbonaceous aerosols at the surface (mg/m3)

Contribution from domestic fuel use to carbonaceous aerosol (mg/m3)

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 Febr., Dom. fossil fuel, RF=0.010

Jan., Dom. biofuel, RF=0.025 Febr., Dom. biofuel, RF=0.033

Radiative forcing and climate effects

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)

Seasonal cycle of surface ozone in Beijing

0

20

40

60

80

100

0 50 100 150 200 250 300 350 400 450

Ozo

ne

(pp

bv)

0

5

10

15

20

25

Ozo

ne

fro

m d

om

esti

c fu

els

(p

pb

v)

Ozone (ppbv)

Contributionfrom DF

The contribution from domestic sources is largest in winter (i.e. probably not important for agricultural crop loss..)

Radiative forcing and climate effects

Net positive radiative forcing of household sector (preliminary estimates)

-30

-20

-10

0

10

20

30

40

50

60

70

CO2 SO2(low)

SO2(high)

BC OC O3 CH4

Total (low and high)

Domestic (fossil andbiomass)

Domestic fossil fuels

Domestic biomass

mW

/m2

2.4 % of global average RF from GHG

Indirect effects of particles (via clouds) not included

Radiative forcing and climate effects

Climate sensitivity to BC radiative forcing?

• Indications that BC is higher than CO2 due to the

multitude of feedbacks to the climate system triggered by BC;

– large uncertainties are inescapable

Radiative forcing and climate effects

• 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,

Summary