Control of Fossil-Fuel Particulate
Black Carbon and Organic Matter,
Possibly the Most Effective Method
of Slowing Global Warming
Mark Z. Jacobson
Dept. of Civil & Environmental Engineering
Stanford University
Coagulation among 16 size distributions
-3
dN (No. cm ) / d log 10 D p
105
A (Spray) Initial
B (Soil) Initial
D (Sulf) Initial
E (BC) Initial
F (OM) Initial
103
10
1
10-1
Number concentration
of each dis tribution
-3
10
10-5
-3
dN (No. cm ) / d log 10 D p
0.01
10
7
10
5
10
3
10
1
0.1
1
Particle diameter (m)
A (Spray) 12 hr
B (Soil) 12 hr
D (Sulf) 12 hr
E (BC) 12 hr
F (OM) 12 hr
AB (Spray-s oil) 12 hr
AD (Spray-sulf) 12 hr
AE (Spray-BC) 12 hr
10
100
AF (Spray-OM) 12 hr
BD (Soil-s ulf) 12 hr
BE (Soil-BC) 12 hr
BF (Soil-OM) 12 hr
DE (Sulf-BC) 12 hr
DF (Sulf-OM) 12 hr
EF (BC-OM) 12 hr
MX 12 hr
Number concentration
of each dis tribution
-1
10
10-3
-5
10
0.01
0.1
1
Particle diameter (m)
10
100
Feedbacks of aerosol-particles to
climate
1. "Self-feedback effect"
2. "Photochemistry effect"
3. "Smudge-pot-emission effect"
4. "Daytime stability-emission effect"
5. "Particle feedback to surface albedo"
6. "Particle feedback to large-scale meteorology"
7. "Indirect effect"
8. "Semidirect effect"
9. "BC-low-cloud positive feedback loop"
Cooling (K) after eliminating anth. emiss.
Modeled changes in temperature due
to elimination of all anthropogenic
emissions of CO2, CH4 and fossilfuel BC+OM
0.2
0
CO 2 (200y)
CH 4 (10y)
-0.2
f.f. BC+OM
-0.4
CO 2 (50y)
-0.6
-0.8
2000
2020
2040
2060
Year
2080
2100
Effects of Diesel on Global Warming
CO2 from gasoline car at 25 mpg
95.4 g-C/mi as CO2
CO2 from new diesel car w/ 30% better mileage
86.7 g-C/mi as CO2
Diesel BC+OM emiss. (U.S. & E.U. standard)
0.08 g-C/mi
CO2 savings of diesel over gasoline
8.7 g-C/mi
Ratio of CO2 saved to BC emitted by diesel
109:1
Ratio required for net cooling by diesel
5,000-21,000:1 for 1 yr.
220-500:1 for 100 yrs.
 Diesel cars enhance global warming
Ratio of CO2-C mass emission reduction
required per mass of f.f. BC+OM emitted
for diesel to cool climate
Ratio of CO2-C mass emission
reduction required per mass of f.f.
BC+OM emitted for diesel to cool
climate
4
10
200 years
1000
50 years
100
Current ratio
10
2000
2020
2040
2060
Year
2080
2100
Ratio of tax on gasoline to tax on
diesel by country
Belgium
Finland
Sweden
Netherlands
France
Germany
Denmark
Greece
Austria
Portugal
Spain
Italy
Luxembourg
Ireland
UK
European Commission (1997)
1.75:1
1.73:1
1.69:1
1.66:1
1.61:1
1.57:1
1.45:1
1.44:1
1.43:1
1.43:1
1.38:1
1.37:1
1.37:1
1.15:1
1.00:1
Summary
•
Control of fossil-fuel BC+OM appears to be
the most effective means of slowing global
warming during the next 20-90 years.
•
Global warming cannot be reversed unless
CO2 emissions are controlled as well.
•
Sulfate cooling masks much of BC+OM and
CO2 warming.
•
Diesel vehicles enhance global warming
more than do equivalent gasoline vehicles.
•
Control strategies for fossil-fuel BC+OM
include improving particle traps for diesel and
coal combustion sources and switching from
diesel to gasoline.
•
Aerosol-particles affect climate through at
least nine feedbacks.