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, (Mtce) ? Energy use

Residential sector: 18% of energy consumption Energy use

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 Energy use

Health effects studies Size; acidity; mutagenicity.. ‘Particulate matter’: TSP PM 10 PM 2.5 PM 1.0 Ultrafine particles (PM 0.1 ) The fine fraction (PM 2.5 or even PM 1.0 ) contains most of the acidity and mutagenicity ‘Aerosols’: BC OC Sulphates Nitrates Natural dust... Global warming studies Size and physiochemical properties (atm. lifetime;scattering/ absorption); Numerous ways to measure and model particulate matter Emissions

Houshold sector’s share of emissions Streets et al CO 2 31% (9%) CH 4 30% NO x 9% SO 2 11% nmVOC44% CO49% BC72% OC96% PM 10, PAH..?? Emissions Products of incomplete combustion

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

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

Assuming only coal i rural areas (cheap and abundant in Shanxi): PWE winter = 475  g/m 3 PWE summer = 215  g/m 3 (PWE: Population weighted exposure) Assuming only biomass i rural areas: PWE winter = 615  g/m 3 PWE summer = 315  g/m 3 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

Total carbonaceous aerosols at the surface (  g/m 3 ) Contribution from domestic fuel use to carbonaceous aerosol (  g/m 3 )

Monthly averaged contribution from domestic fuel use to troposheric column burden of BC (  g/m 2 ) Radiative forcing and climate effects

Jan., Dom. fossil fuel, RF=0.008Febr., Dom. fossil fuel, RF=0.010 Jan., Dom. biofuel, RF=0.025Febr., 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)

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) 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 CO 2 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