The climate impact of the household sector in China – backyard solutions to global problems?

1. 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?

2. 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

3. 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

4. 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?

5. Energy use Primary Energy Production by Source, 1949-2003 (Mtce) ?

6. Energy use Residential sector: 18% of energy consumption

7. Energy use Share of urban residents having access to gas for cooking (figure) and district heating is rapidly increasing Sinton, 2004

8. Energy use ...but biomass use in rural areas is stable

9. Emissions Numerous ways to measure and model particulate matter Health effects studiesSize; acidity; mutagenicity.. Global warming studiesSize and physiochemical properties (atm. lifetime;scattering/ absorption); ‘Particulate matter’: TSP PM10 PM2.5 PM1.0 Ultrafine particles (PM0.1) The fine fraction (PM2.5 orevenPM1.0) contains most of the acidity and mutagenicity ‘Aerosols’: BC OC Sulphates Nitrates Natural dust ...

10. Emissions Houshold sector’s share of emissions Products of incomplete combustion Streets et al

11. Concentrations, exposures and health risks Outdoor air pollution - Chinese cities among the worst

12. Concentrations, exposures and health risks Indoor air pollution adds to the exposure - especially for the poorer parts of the population

13. Concentrations, exposures and health risks 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

14. 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): 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

15. 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)

16. 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’

17. Radiative forcing and climate effects Total carbonaceous aerosols at the surface (mg/m3) Contribution from domestic fuel use to carbonaceous aerosol (mg/m3)

18. Radiative forcing and climate effects Monthly averaged contribution from domestic fuel use to troposheric column burden of BC (mg/m2)

19. 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

20. 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)

21. Radiative forcing and climate effects The contribution from domestic sources is largest in winter (i.e. probably not important for agricultural crop loss..)

22. Radiative forcing and climate effects Net positive radiative forcing of household sector (preliminary estimates) 2.4 % of global average RF from GHG Indirect effects of particles (via clouds) not included

23. 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 uncertaintiesare inescapable

24. 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,