UNECE-CLRTAP and EMEP Task Force on Integrated Assessment

UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 26 th session, Brussels, 14 -16 May 2001 Integrating the environmental effects of Particulate Matter in emission control strategies Jean-Marc BRIGNON Guy LANDRIEU

Presentation outline • Environmental effects of PM : *climate change * hydrology * visibility * air quality (tropospheric ozone) • why and how integrate those effects in the integrated assessment ? UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 26 th session, Brussels, 14 -16 May 2001

Environmental effects of PM : climate change

Environmental effects of PM : climate change (direct effect) • The direct effect on climate change : * backscattering of incident UV, absorption of infrared radiation * sulphates, nitrates, organic carbon aerosol have a direct cooling effect * soot aerosol has a warming effect : stronger when internally mixed with other aerosol (sulphates) [Jacobson M. Z. , 2001] * mineral dust : warming and cooling UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 26 th session, Brussels, 14 -16 May 2001

Environmental effects of PM : climate change (indirect effects) • Interaction radiation/clouds/PM * First indirect effect : sulphates, nitrates(? ), organic carbon (? ) aerosol enhance incident UV backscattering by clouds => cooling effect. * Second indirect effect : sulphates, nitrates(? ), organic carbon (? ) aerosol extend cloud cover and lifetime => cooling effect. UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 26 th session, Brussels, 14 -16 May 2001

Environmental effects of PM : climate change (indirect effect) I n c i d e n t U V FIRST INDIRECT EFFECT Adapted from Haywood and Boucher, 2000 SECOND INDIRECT EFFECT

Environmental effects of PM : climate change (semi-direct effect) • Absorption of solar radiation by soot aerosol => reduces cloud cover (evaporation of cloud droplets) => lower reflection of incident UV by clouds => warming effect [Ackerman, 2000]. UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 26 th session, Brussels, 14 -16 May 2001

Environmental effects of PM : climate change : is the picture changing for Black Carbon ? IPCC, 2001

Environmental effects of PM : climate change : is the picture changing for Black Carbon ?

Environmental effects of PM - Climate change : Relevance of sulphate and black carbon (BC) for Europe • Direct positive forcing of carbonaceous aerosols from fossil fuel burning [quoted in Haywood and Boucher, 2000] => control of BC emissions from fossil fuel burning could be of particular importance in Europe. • Negative forcing by sulphate aerosol : partially offset by BC in Europe.

Environmental effects of PM : impact on hydrology aerosol Rain suppression Adapted from Haywood and Boucher, 2000

Environmental effects of PM : hydrological cycles • Observational evidence of rain suppression by industrial and urban air pollution (especially ash particles) [Rosenfeld, 2000] • Regional effects of the semi-direct effect of soot aerosol (industrial/urban/biomass burning) : decreases the intensity of the hydrological cycle (Indian Ocean [Sateesh and Ramanathan, 2000] , ? Europe ? ) UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 26 th session, Brussels, 14 -16 May 2001

Environmental effects of PM : visibility impairment (picture from USEPA website) • Visibility reduces the distances how far we can see, degrades the colours, clarity and contrast of the scenes. • Expressed in terms of visual range (human measurement) or light extinction (measurable and linked to visual range) UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 26 th session, Brussels, 14 -16 May 2001

Environmental effects of PM : visibility impairment • Visibility reduction is mainly caused by particulate matter that scatters visible light. • In the USA, the main contributors to visibility reduction are : - sulphate (especially in humid conditions) - organic carbon - nitrate, black carbon, (mineral dust) • US Regional Haze program • Benefits from Clean Air Act estimated to be higher for visibility reduction than avoided crop damage. UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 26 th session, Brussels, 14 -16 May 2001

Environmental effects of PM : visibility impairment Global map of the light extinction coefficient between 1994 and 1998 Picture from [Husar, 2000]

Environmental effects of PM : visibility impairment • Visibility reduction is higher in Europe than in the USA, during the period 1994 -1998. • But, contrary to the USA, only one study [Holland King, 1999] seems available, concerning the economic evaluation of the benefits from improved visibility. This study concerning the NEC Directive, used US benefit estimates. The benefits were comparable to the US case, but benefit transfer from US studies is questionable. UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 26 th session, Brussels, 14 -16 May 2001

Environmental effects of PM : air quality : general • Absorption and scattering of UV radiation by aerosol modify the kinetics of photochemical reactions • Temperatures modification by aerosols modify the kinetics of chemical reactions UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 26 th session, Brussels, 14 -16 May 2001

Environmental effects of PM : air quality : general • Interactions in ozone and PM photochemistry (coupled pathways, cloud chemistry, secondary formation of PM from VOCs, heterogeneous chemistry. . . )

Environmental effects of PM : air quality : urban / regional scale • Urban scale : Effects on ground-level ozone concentrations are either modest or pronounced, either positive or negative according to local conditions and local aerosol composition (+33% and -8% in two different studies in the USA). • Regional effects : several studies (see [Jacob, 2000]), found that decreases in ozone concentrations up to 25% are encountered due to the take-up of ozone precursors by aerosols. UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 26 th session, Brussels, 14 -16 May 2001

Environmental effects of PM : implications for the integrated assessment ? • If confirmed, the fact that black carbon aerosol could be the second Green House “Gas” should be taken into account. • Visibility impairment is not a great concern in Europe, (even if visibility seems to be more impaired in Europe than in the USA). This might change, and knowing that PM control strategies could improve or deteriorate visibility, it should be taken into account. UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 26 th session, Brussels, 14 -16 May 2001

Environmental effects of PM : implications for the integrated assessment • Efforts could be made to illustrate and evaluate ozone responses to PM strategies and conversely, because opposite responses could be found according to differing strategies. This is the way the PM scientific assessment of PM is planned in the North American Research Strategy for Tropospheric Ozone. UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 26 th session, Brussels, 14 -16 May 2001

Environmental effects of PM : a possible way forward ? • Concerning environmental effects, PM is not a single pollutant :

Environmental effects of PM : a possible way forward ? • 1° Evaluate, for each emitting sector, the chemical speciation and size distribution of particulate matter emissions ? • 2° Assess the impact of control measures in each sector, in terms of environmental effects associated with each class of particulate matter ? • 3° Incorporate this analysis to the integrated assessment ? UNECE-CLRTAP and EMEP Task Force on Integrated Assessment Modelling 26 th session, Brussels, 14 -16 May 2001