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UNECE-CLRTAP and EMEP Task Force on Integrated
Assessment Modelling
26th 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
26th 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
26th 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
26th 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
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
26th 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
26th 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
26th 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
26th 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 and 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
26th 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
26th 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
26th 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
26th 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
26th session, Brussels, 14-16 May 2001
Environmental effects of PM :
a possible way forward ?
• Concerning environmental effects, PM is not
a single pollutant :
Climate Climate Visibility
direct indirect
effect
effects
Elemental
carbon
(soot)
Organic
carbon
Sulphate
Nitrate
Hydrology
and local
climate
Tropospheric
Ozone
-
-
-
-
+?
+
?
-
-?
-
+
?
0
+
?
?
?
-?
?
?
?
+?
Mineral
dust
Table 1. A qualitative and tentative assessment of the effects of different types of particulate
matter relatively to various environmental effects.
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
26th session, Brussels, 14-16 May 2001