Global Warming on the Road - THE CLIMATE IMPACT OF AMERICA'S AUTOMOBILES
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Global Warming on the Road THE CLIMATE IMPACT OF AMERICA’S AUTOMOBILES
Global Warming on the Road
THE CLIMATE IMPACT OF AMERICA’S AUTOMOBILES
AUTHORS
John DeCicco and Freda Fung
ENVIRONMENTAL DEFENSE
WITH THE ASSISTANCE OF
Feng An
ENERGY AND TRANSPORTATION TECHNOLOGIES, LLCCover image: Corbis. Our mission Environmental Defense is dedicated to protecting the environmental rights of all people, including the right to clean air, clean water, healthy food and flourishing ecosystems. Guided by science, we work to create practical solutions that win last- ing political, economic and social support because they are nonpartisan, cost- effective and fair. ©2006 Environmental Defense 100% recycled (100% post-consumer) totally chlorine free paper The complete report is available online at www.environmentaldefense.org.
Contents
Executive summary iv
Introduction 1
Methodology and assumptions 4
Carbon emissions from automobiles on the road 6
Beyond the carbon tally 13
Conclusions 21
Appendix A: Stock modeling methodology and assumptions 22
Notes 27
References 30
iiiExecutive summary
For most Americans, the automobile is portionate impact: U.S. cars are driven
an essential part of daily life. It has shaped further each year and burn more fuel
our culture and our landscape. The in- per mile than the international average.
dustries that build and serve cars form a The United States has 5% of the world’s
key part of our economy. The automobile population and 30% of the world’s auto-
is not without its faults, but they often mobiles, but it contributes 45% of the
are concealed by the styling, performance world’s automotive CO2 emissions.
and other features that make today’s In 2004, U.S. cars and light trucks
vehicles so desirable. Still, when a emitted 314 million metric tons of
product is so widely used, its faults can carbon-equivalent (MMTc). That equals
add up to massive unwanted side effects. the amount of carbon in a coal train
Consider global warming. Motor 50,000 miles long—enough to stretch 17
vehicles play a major part in what times between New York and San Fran-
scientists call the most serious environ- cisco. In fact, the amount of CO2 emitted
mental problem the world faces. The from oil used for transportation in the
automobile’s main contribution comes United States is similar to the amount
from the carbon dioxide (CO2) emitted from coal used to generate electricity.
as the engine burns fuel.
The greenhouse gas pollution that
causes global warming comes from America’s ‘rolling carbon’
numerous sources. Any single contribu- This report details, for the first time,
tion may seem small in proportion to the the global warming pollution emitted
world total, but collectively it becomes a in the course of America’s daily driving.
problem of vast scale. To address a prob- It represents a complete picture of the
lem of such vast scale requires interna- nation’s “rolling carbon,” from the latest
tional agreements and national policies. luxury SUV cruising through an upscale
But making good on such commitments suburb to the oldest pickup truck bump-
will require changes in how we manage ing along a rural lane.
every activity that contributes to the Many policy-related reports focus on
problem. How much should we cut, and emissions from new vehicles, since new
where? To answer this question, we need vehicle sales are regularly reported in
a clear picture of which sources con- detail. Here, using national statistics on
tribute most to global warming. how long vehicles last and how far they
are driven as they age, we examine the
CO2 emissions from all personal vehicles,
The disproportionate impact both new and used. This analysis allows us
of U.S. cars and light trucks to answer questions such as, “How much
Automobiles—by which we mean carbon is emitted by all the Ford-built cars
personal motor vehicles, including light now in use? From all the Hondas?” It also
trucks such as pickups, SUVs and vans enables us to estimate the CO2 emissions
as well as sedans and wagons—emit from all the sport-utility vehicles (SUVs)
roughly 10% of global CO2 emissions in use, from all the midsize cars, and so
from fossil fuels, which are the main on—that is, according to vehicle class.
form of greenhouse gas pollution. Table ES1 summarizes on-road car-
American automobiles have a dispro- bon emissions by vehicle class in 2004.
ivTABLE ES1
Rolling stock carbon emissions by vehicle class, 2004
Vehicle class Carbon emissions (MMTc) Carbon emissions share
Small cars 77 25%
SUVs 67 21%
Pickups 60 19%
Midsize cars 54 17%
Vans 29 9%
Large cars 26 8%
Cars 157 50%
Light trucks 157 50%
Overall 314 100%
Perhaps surprisingly, small cars (com- plants. Next were pickup trucks, which
pacts, subcompacts and two-seaters) collectively emitted 60 MMTc in 2004.
were responsible for the most carbon
emissions, amounting to 77 MMTc.
Small cars once had been the dominant Car companies vs. electric
segment by sales; given the longevity of companies: a comparison
vehicles, many of them remain on the Table ES2 gives the breakdown by car
road today. Thus, despite their higher company, which shows that automakers’
than average fuel economy, small cars shares of rolling carbon follow historical
still accounted for the largest share of market shares, led by GM. These results
rolling carbon emissions as of 2004. are highlighted in Figure ES1, which
This situation illustrates the relative shows the quantity of carbon emitted by
durability of automobiles: In terms of each automaker’s products compared to
usage, the U.S. light vehicle stock now the carbon emissions of major electric
has a “half-life” of roughly eight years; power companies. Car companies are
in other words, 50% of vehicles are on a par with—and some even higher
replaced within that time. It takes than—electric utilities in terms of the
16 years for the fleet to be 90% replaced carbon emissions associated with the
in terms of the carbon emitted during use of their products.
driving. In short, the choices made These estimates indicate that products
regarding new vehicles influence emis- made by each of the Big Three—GM,
sions for many years to come. Ford and DaimlerChrysler—emitted
SUVs represent the second largest more carbon in 2004 than the country’s
portion of rolling carbon. They soon largest electric utility, American Electric
will be the main source of automotive Power (AEP). GM’s products emitted
CO2 emissions, having overtaken small 99 MMTc, and Ford’s emitted 80
cars in terms of market share in 2002. MMTc, nearly twice AEP’s 41 MMTc.
Their impact will be all the greater due DaimlerChrysler’s cars and light trucks
to their lower than average fuel economy. in use emitted 51 MMTc. The total
As of 2004, all the SUVs on the road in CO2 emissions from Big Three auto-
the United States emitted 67 MMTc, mobiles in 2004 was comparable to the
an amount equivalent to the CO2 total from the top 11 electric companies.
spewed by 55 large coal-fired power And the global warming pollution from
vvehicles made by Toyota (the fourth both cases, their carbon emissions
among automakers) edges out that from include the impacts of long-lived
the Tennessee Valley Authority (the products and equipment. The quantity
third among electric companies). of each sector’s emissions also is deter-
Electric utilities and automakers may mined by a number of actors, including
seem like apples and oranges, but in fact end-users such as consumers and busi-
they make a suitable comparison. In nesses. For example, AEP’s CO2 emis-
TABLE ES2
Rolling stock carbon emissions by automaker, 2004
Manufacturer Carbon emissions (MMTc) Carbon emissions share
GM 99 31%
Ford 80 25%
DaimlerChrysler 51 16%
Toyota 27 9%
Honda 17 6%
Nissan 15 5%
Volkswagen 5 2%
Hyundai 4 1%
Mitsubishi 4 1%
BMW 3 1%
Kia 2 1%
Subaru 3 1%
Others 4 1%
Big Three 230 73%
Overall 314 100%
FIGURE ES1
Carbon emissions of major automakers’ products vs. major electric
producers in the United States, 2004
General Motors 99
Ford 80
DaimlerChrysler 51
American Electric Power 41
Southern Company 37
Toyota 27
Tennessee Valley Authority 26
Major automakers’ products
Honda 17 Major electric producers
Xcel 17
Ameren 17
Cinergy 16
Dominion 15
Edison International 15
Progress Energy 15
Nissan 15
0 20 40 60 80 100 120
Carbon emissions (MMTc)
Source: Table 1 and CERES et al. (2006).
visions are the result of the electricity Total U.S. car and light truck VMT in
consumed in homes, offices, schools 2004 amounted to 2.6 trillion miles.
and other power-using facilities in their • Fuel use rate, or the amount of fuel
service area. Decisions by state and local consumed per mile, which is the
officials are also important in both cases, inverse of fuel economy. The fuel
through regulation of electric utility economy of the U.S. automobile stock
services and rates on one hand, and averaged 19.6 mpg in 2004, implying
through transportation infrastructure and an average fuel use rate of 51 gallons
land use planning on the other. More- per 1,000 miles of driving.
over, greenhouse gas pollution from both
sectors is influenced by the carbon in- • Fuel carbon content, or the amount of
tensity of their fuel supply. While each greenhouse gases emitted per gallon of
utility has its own mix of fuels, overall fuel consumed. Counting only the CO2
utility emissions reflect the fact that 54% directly released when fuel is burned,
of U.S. electricity comes from coal. Auto- this factor amounts to 5.3 pounds of
mobile fuel essentially all comes from oil. carbon per gallon of gasoline.
These three factors combined result in
The three-legged stool propping the 314 MMTc emitted by U.S. auto-
up emissions mobiles in 2004.
Because automotive CO2 emissions are Among these factors, only decreases
influenced by many different decision in fuel use rate (achieved by increasing
makers, finding opportunities to cut car- fuel economy) have served to partially
bon entails looking at the factors behind limit CO2 emissions. Fuel carbon con-
emissions. Figure ES2 illustrates the three tent has not significantly changed,
main factors propping up rolling carbon: reflecting the tenacity of oil as a useful
resource and the barriers facing alterna-
• Travel demand, or the amount of driv-
tive fuels. And many forces drive travel
ing, which is commonly measured as
demand, all of them serving to push
annual vehicle miles of travel (VMT).
auto sector CO2 emissions upward.
FIGURE ES2
Three main factors behind rolling
carbon Managing automotive rolling
carbon
Ultimately, cutting auto sector CO2 emis-
Vehicle CO2 emissions sions will require attention to all three
legs of the stool. Thus, policy discussions
regarding transportation and climate are
typically framed around the question of
how to change travel demand, fuel econ-
omy or fuel type. A key challenge, how-
ever, is that each factor is the product of
decisions made by many actors. In addi-
tion to consumers, automakers and others
involved in the auto market, total auto
Travel Fuel sector CO2 emissions are influenced by
demand Fuel use rate carbon the energy industry as well as by the
content
many interests and levels of government
viithat shape land use, infrastructure and zero. Better information on emissions,
other parts of the transportation system. new evaluation tools and education are
The magnitude of the automotive needed to enable all actors to understand
global warming problem and the com- how their decisions impact emissions.
plexities of the associated decision making This report seeks to aid that process.
suggest a need to recast the question. By underscoring the magnitude of auto-
Instead of asking “What policies are motive CO2 emissions, it highlights the
required to address the factors that prop need to break the problem down into
up automobile carbon emissions?” deci- manageable pieces. Consideration can
sion makers can ask “What policies can then be given to opportunities to reduce
motivate each actor to address the aspects carbon by tackling each piece of the
of emissions that they can influence?” larger problem. Such a carbon manage-
Such a view shifts the focus from tech- ment paradigm would enable each actor
nical factors and how they are deter- to address the emissions each influences,
mined to individual actors and the parts complementing existing policy strategies
of the problem they each can control. defined around the technical factors that
For some major actors, such as auto- characterize total emissions. A city
makers, how much they can address emis- government, for example, can change
sions is limited by other players. The the emissions associated with its trans-
ability to increase fuel economy by re- portation operations. It might do this
designing vehicles depends in part on by carrying out its functions with less
the extent to which consumers make driving, increasing the efficiency of its
fuel economy a priority. Nevertheless, it vehicles or using low-carbon fuels.
is implausible that automakers (or other Exactly how to define a set of carbon
actors) have no ability to lower carbon management policies appropriate for
emissions. Similarly, while individual the auto sector is a subject for future
consumers cannot themselves redesign research as well as an important topic
cars (or develop new fuels or reshape for discussion by everyone who holds a
land use), their scope of influence is not stake in the car-climate problem.
viiiIntroduction
America’s cars are one of the world’s enable us to answer questions such as
largest sources of global warming pollu- “What portion of CO2 emissions is
tion. Our personal vehicles—from the associated with pickup trucks?” or
Mini Cooper to the Hummer and every- “What portion of CO2 emissions is
thing in between—emitted 314 million represented by all Toyota vehicles on
metric tons of carbon-equivalent U.S. roads?” The results also underscore
(MMTc) annually as of 2004.1 That the scope of the car-carbon problem and
equals the amount of carbon in a coal show how long it takes for changes in
train 50,000 miles long, enough to the characteristics of new car sales to
stretch 17 times between New York influence the overall carbon emissions
and San Francisco.2 In the United from the auto sector.
States, in fact, the amount of global The approach taken here is similar
warming pollution from oil used for to that of our previous reports4 on auto-
transportation is similar to that from motive carbon burdens, referring to the
coal used for electric power generation.3 annual CO2 emissions associated with a
Such comparisons can help Ameri- given population of vehicles. However,
cans understand the extent of our car- while our Automakers’ Corporate Carbon
bon problem, and they also help us Burdens reports calculated CO2 emis-
think about how to solve it. Emissions sions as annual averages over the ex-
from power plants depend on decisions pected lifetime of a series of new model
by power companies, but also on deci- year vehicles, this report addresses the
sions made by businesses and consumers emissions from all vehicles (new and
who choose and use electrical equip- used) on the road in a given year. This
ment and appliances. Similarly, auto- particular analysis has never been done
mobile emissions depend not only on before. We present the results for 2004,
automakers and fuel suppliers, but also the most recent year for which sufficient
on decisions by businesses and con- data are available.5 The results depend
sumers who choose vehicles, and by not only on vehicle characteristics (such
local, state and federal officials who as fuel economy) but also on the extent
oversee America’s transportation system of driving. Thus, these “rolling carbon”
and land use. Whether it is an issue of estimates reflect both the number of
primary energy resources (fossil or vehicles in use and how many miles they
otherwise), how the fuels are converted are driven each year. The carbon emis-
and distributed to consumers, or how sions from model year 2004 new auto
efficiently the fuels are used through sales represent 10% of the emissions
choices of technology and infrastruc- from all automobiles on the road.
ture, the interlocking nature and sheer As the statistics assembled in this
magnitude of carbon emissions implies report show, the carbon emissions
a shared task. from all General Motors’ vehicles on
This report provides a detailed snap- the road as of 2004 were more than
shot of carbon emissions from the “roll- double those from America’s largest
ing stock” of all U.S. cars and light electric generating company, American
trucks on the road in 2004. We report Electric Power (AEP). In fact, the
results both by automaker and market CO2 emissions of the Big Three—
segment. The statistics compiled here GM, Ford, DaimlerChrysler—each
1exceeded those of AEP, and the emis- magnified because of their lower than
sions associated with most major auto- average fuel economy.
makers are comparable to or larger than Figure 1 places these estimates in
those from the largest electric utilities a global context. Figure 1(a) breaks
in the country. down global fossil fuel CO2 emissions
Perhaps even more surprising, the by major energy end-use in 2003.
small car market segment (including Worldwide, automobiles (cars and
compacts, subcompacts and two-seat other light-duty vehicles) emitted 680
sports cars) produced the most global MMTc in 2003, about 10% of global
warming pollution in 2004, simply CO2 emissions from fossil fuels.6 Oil,
because so many of them remain on the coal, natural gas and related fossil
road. The small-car carbon tally reflects resources account for 84% of all human-
the longevity of vehicles, underscoring caused CO2 emissions (including other
how decisions about the CO2 emissions major sources such as deforestation).
rate of new vehicles will affect the CO2 is the dominant greenhouse gas
amount of global warming pollution for (GHG, the term for any form of air
years to come. SUVs had the second pollution that contributes to global
largest share of CO2 emissions. While warming). It accounts for 72% of all
their sales grew rapidly over the past 15 human-caused GHG emissions. Thus,
years, SUVs only overtook small cars in the light duty vehicle slice in Figure 1(a)
terms of new car market share in 2002. represents an estimated 6% of all global
SUVs soon will become the dominant warming pollution.7
source of global warming pollution on Figure 1(b) breaks down global light
America’s roads, and their impact will be vehicle CO2 emissions by country or
FIGURE 1
Global fossil carbon emissions by economic sector
1(a). Global carbon emissions by sector 1(b). Light duty vehicle carbon emissions
(6,814 MMTc in 2003a) by regionb
(680 MMTc in 2003a)
Other sectorsc
9%
OECD OECD
Residential Industry Pacific
18% Europe
8% 21% 9%
Former Soviet Union
and Eastern Europe
6%
China
2%
Canada Other Asia
and Mexico 2%
Electricity Light duty India
vehicles 7%
and heat 1%
10% Middle East
production
1%
41%
Latin America
5%
Africa
Other 2%
transportation United States
14% 45%
These estimates include only CO2 emissions from fossil fuel use, and so exclude emissions from biofuel use or deforestation.
a
Global emissions by sector are estimates for 2003 from IEA (2005). Global light-duty vehicle CO2 emissions for 2003 are projections from WBCSD (2004).
b
Light duty vehicle emission shares by region are estimates for 2000 from WBCSD (2004).
c
Other sectors include commercial, public services, agriculture and energy industries other than electricity and heat production.
2major region as of 2000. U.S. cars and because our vehicles are driven more
light trucks—the subject of this than those in the rest of the world; the
report—are 45% of this total. The 202 11,000 miles per year average for U.S.
million automobiles on America’s roads automobiles is about 29% greater than
in 2000 represent 30% of the estimated the global average of 8,500 miles per
683 million automobiles (light duty year.9 U.S. automobiles also consume
vehicles) in use worldwide that year.8 more fuel, emitting about 15% more
The U.S. share of automotive CO2 CO2 per mile than the average light
emissions is disproportionately high duty vehicle globally.10
3Methodology and assumptions
Characterizing rolling stock CO2 (g/mi) prior to 2000, corresponding
emissions involves data on new vehicle to an average on-road fuel economy of
sales plus statistics on how long vehicles 20 mpg (similar to the actual on-road
last and how much they are driven as average in recent years). If the CO2
they age. To perform this analysis, we emissions rate of new vehicles were
use what is termed a stock model: a halved, down to 220 g/mi (correspond-
computer-based accounting framework ing to a doubling of on-road fuel econ-
that calculates fuel consumption and omy to 40 mpg) in 2000, the effect would
CO2 emissions for various groupings of not be fully reflected in the rolling stock
vehicles. Given the sales volumes and until 2025. The gradual change in the
fuel economy of a group of new vehicles stock average CO2 emissions rate
in a given year and previous years, the reflects the slow turnover of vehicles;
model computes the CO2 emissions rate lower-emitting new vehicles gradually
of all such vehicles remaining on the replace older vehicles as they are driven
road in the given year. less and then retired. However, progress
Figure 2 illustrates how a stock model is more rapid at first; 90% of the lower
works, showing what would happen if CO2 emissions rate is achieved within
the CO2 emissions rate of new cars sud- 16 years, even though it takes approxi-
denly were cut in half as of model year mately another decade for the oldest
2000. The left graph shows the CO2 vehicles to be completely replaced.
emissions rate of the new fleet; the right For our stock model, new vehicle
graph shows the resulting impact on characteristics are obtained from federal
the rolling stock emissions rate. In sales and fuel economy data, covering cars
this simplified example, we assume an and light trucks of up to 8,500 pounds
initially constant new fleet average CO2 gross vehicle weight (GVW). The
emissions rate of 440 grams per mile stock turnover parameters, including
FIGURE 2
How the rolling stock responds to a cut in the new fleet CO2 emissions rate
500 500
New fleet CO2 emissions rate (grams/mile)
Stock CO2 emissions rate (grams/mile)
Stock CO2 emissions
400 400 rate drops gradually
over 25 years
300 New fleet CO2 300
emissions rate
halved in 2000
200 200
100 100
0 0
1970 1980 1990 2000 2010 2020 2030 1970 1980 1990 2000 2010 2020 2030
4age-dependent vehicle survival proba- the roughly 6 pounds of CO2 and other
bilities and usage rates, are also based greenhouse gases emitted upstream
on government statistics. We calibrated would bring the total, full fuel cycle emis-
our fuel use (and therefore CO2 emis- sions to 25.3 pounds per gallon.13
sions) calculation to the most recently While developing our vehicle stock
available data on total light duty vehicle model, we reviewed the models used by
fuel use, ensuring that our total rolling several government agencies and research
carbon estimate matches national institutes, including the Department of
statistics on the auto sector’s share of Energy’s VISION and NEMS (Energy
U.S. CO2 emissions. We performed Information Administration) models,
sensitivity analyses to examine the the Stockholm Environment Institute’s
effects of different vehicle survival and LEAP model and EPA’s MOVES
usage parameters, confirming that our model. VISION, LEAP and NEMS
estimates of manufacturer and vehicle use approaches similar to the one we
segment shares are insensitive to changes adopted, estimating stock carbon emis-
in such parameters. sions based on vehicle sales, fuel econ-
We report the CO2 emissions (given omy and stock turnover rate. They are
on a carbon-mass equivalent basis) more complex, however, in that they are
released directly from fuel combustion designed to calculate future stock changes
by the car—in other words, only the that reflect numerous hypothetical alter-
CO2 coming from the tailpipe. How- natives and couple the calculations to
ever, the tailpipe is not the only source a broader energy modeling framework,
of greenhouse gases associated with each neither of which are needed for our pur-
gallon of motor fuel consumed. Addi- poses. EPA’s MOVES model combines
tional CO2 and other greenhouse gases vehicle-specific, second-by-second emis-
are released when crude oil is extracted sions calculations with travel activity
and shipped, when it is refined into data to project stock fuel consumption,
gasoline or diesel fuel, and when these allowing users to generate results for
motor fuels are distributed through smaller geographic areas (e.g., at the
pipelines, barges and tanker trucks, even county level) and in smaller temporal
before they go into a vehicle’s fuel tank. units (e.g., by time of day). Although we
These upstream emissions add about did not run these other models, we con-
31% to the global warming impact of firmed the consistency of our stock
each gallon of gasoline burned in the modeling results by comparing them
United States and about 23% to each to published results from NEMS and
gallon of diesel fuel.11 The CO2 directly MOVES. Appendix A provides further
released when burning gasoline amounts detail on our stock model and the
to 19.4 pounds per gallon.12 Counting assumptions behind it.
5Carbon emissions from automobiles on the road
Our stock model tallies enable us to (model year 2004) vehicles.15 In other
break down, by automaker and vehicle words, the average older vehicle on the
class, the 314 MMTc emitted by all of road actually burns less fuel and emits
the passenger cars and light trucks up to less carbon than the average new
8,500 lbs gross vehicle weight (GVW) vehicle. This situation reflects the fact
on U.S. roads in 2004. that new fleet fuel economy has been
falling since 1988 due to the market
shift from cars to light trucks. A com-
Rolling stock impacts of major parison of rolling stock vs. new fleet
automakers carbon burden shares by automaker is
Table 1 lists our rolling stock results by given in Figure 3. It shows that the
automaker, including estimates of the distribution of CO2 emissions has
number of vehicles in service, their been shifting away from the Big Three
average on-road fuel economy, average toward other firms who are gaining
CO2 emissions rate, and contribution to market share.
overall carbon emissions.14 These values Vehicles built by the “Big Six”—
for the 2004 on-road stock can be com- General Motors (GM), Ford,
pared to those for model year 2004 new DaimlerChrysler, Toyota, Honda and
sales to illustrate the trends as older Nissan—made up an estimated 92%
vehicles are replaced by newer ones. For of the on-road light vehicle stock as
example, the overall stock on-road fuel of 2004. With their historically leading
economy of 19.6 mpg is greater than market shares, the Big Three (GM,
the 19.3 mpg overall average for new Ford and DaimlerChrysler) alone
TABLE 1
Light vehicle stock, fuel consumption, and carbon emissions by automaker, 2004
ROLLING STOCK AS OF 2004 (ALL VEHICLES NEW AND USED) MY2004 (NEW FLEET ONLY)
Vehicle On-road Fuel Carbon Vehicle Carbon On-road Carbon
population fuel economy consumption emissions population emissions fuel economy Market burden
Manufacturer (millions) (mpg) (Mbd) (MMTc) share share (mpg) share share
GM 64.4 19.2 2.68 98.6 31.6% 31.4% 18.9 27.5% 28.0%
Ford 49.8 18.6 2.17 80.0 24.4% 25.5% 17.4 18.6% 20.6%
DaimlerChrysler 30.4 18.0 1.39 51.3 14.9% 16.3% 17.8 14.4% 15.6%
Toyota 18.6 21.6 0.74 27.1 9.1% 8.6% 21.3 13.2% 11.9%
Honda 13.3 24.2 0.47 17.3 6.5% 5.5% 23.2 8.7% 7.2%
Nissan 10.0 20.8 0.40 14.6 4.9% 4.6% 19.3 6.1% 6.1%
Volkswagen 3.7 22.7 0.14 5.1 1.8% 1.6% 21.6 2.3% 2.0%
Hyundai 2.8 23.8 0.10 3.8 1.4% 1.2% 22.0 2.7% 2.4%
Mitsubishi 3.0 21.8 0.12 4.3 1.5% 1.4% 22.4 0.9% 0.8%
BMW 2.0 19.7 0.09 3.3 1.0% 1.0% 20.0 1.9% 1.8%
Kia 1.3 21.0 0.06 2.2 0.6% 0.7% 20.0 1.7% 1.6%
Subaru 2.0 22.4 0.07 2.7 1.0% 0.9% 21.6 1.0% 0.9%
Others 2.5 19.1 0.10 3.8 1.2% 1.2% 19.0 0.9% 1.0%
Big Three 144.6 18.7 6.24 229.9 71.0% 73.2% 18.1 60.5% 64.2%
Overall 203.7 19.6 8.53 314.2 100.0% 100.0% 19.3 100.0% 100.0%
6FIGURE 3
Stock vs. new fleet carbon burden shares by automaker, 2004
General Motors
Ford
DaimlerChrysler
Toyota
Honda
Nissan
On-road stock
Volkswagen New fleet
Mitsubishi
Hyundai
Others
BMW
Subaru
Kia
0% 5% 10% 15% 20% 25% 30% 35%
Carbon burden share
accounted for 71% of the stock, com- Ford has the second largest share of
pared to their 60% share of the 2004 carbon emissions. Its vehicles comprise
new vehicle market. Automakers’ shares 24.4% of the rolling stock and 25.5% of
of rolling stock carbon emissions closely the stock carbon burden, amounting to
track their respective shares of the on- 80 MMTc in 2004. In Ford’s case, the
road vehicle population, with differences shift to SUVs during the 1990s pulled
due to different average fuel economy down their overall average fuel economy
levels and different mixes of older and more than GM’s. Ford’s own reporting
newer vehicles on the road. of CO2 emissions from its vehicles is
GM, which for many years has given on a global, rather than U.S. basis,
been the biggest automaker both in and Ford did not provide an estimate in
the United States and globally, had an its report to DOE’s Voluntary Report-
estimated stock share of 31.6%, with ing of GHG Program, so direct com-
64 million light vehicles in 2004. The parison is difficult. In its Corporate
average fuel economy of all GM cars Citizenship Report 2003–04, Ford
and light trucks on the road was estimated that all the greenhouse gases
19.2 mpg, slightly lower than the over- (CO2 and other GHGs, including
all average of 19.6 mpg.16 As seen in refrigerants) emitted by Ford vehicles
Table 1, however, GM’s estimated share on the road worldwide, including light
of overall rolling CO2 emissions, 31.4%, and heavy duty vehicles, amounted to
is slightly lower than its share of the 109 MMTc in 2000.19
vehicle population.17 Thus, GM’s rolling DaimlerChrysler follows in third
carbon amounted to 99 MMTc in 2004. place, accounting for 14.9% of the roll-
This estimate compares well with the ing stock and for 16.3% of stock carbon
93 MMTc estimate for 1999 based on burden. That amounts to 51 MMTc,
information that GM supplied for the a level greater than that from any U.S.
U.S. voluntary GHG reporting initiative electric company as of 2004. To our
(EIA 2001).18 knowledge, neither DaimlerChrysler
7nor other automakers (besides GM and market share had dipped to 60% by
Ford) have publicly reported estimates model year 2004, the Big Three still
of GHG emissions from their vehicles accounted for more than 70% of the
in use. Vehicles of the Big Three taken vehicle stock. This lag reflects the
together accounted for nearly three lifetime usage and slow turnover of
quarters (73%) of U.S. light vehicle cars and light trucks, and also implies
carbon emissions in 2004. a similar persistence of rolling carbon
Toyota, Honda and Nissan have impacts. According to Davis and Diegel
the fourth, fifth and sixth largest shares (2004), the expected median lifetime
of the stock respectively. Since their for a 1990 model year (MY ) car is
fuel economy levels are higher than 16.9 years, while that for a MY1990
average, these three firms have rolling light truck is 15.5 years,20 and lifetimes
stock carbon shares (8.6%, 5.5% and have been continuing to lengthen. It
4.6% respectively) that are lower than should be noted, however, that light
their shares of the on-road vehicle pop- vehicle lifetimes are still shorter than
ulation. Other players in the U.S. those of many other energy-consuming
market, including Volkswagen, Mitsu- items; freight trucks and aircraft last
bishi, Hyundai, BMW and Subaru, longer than cars, and buildings last
each accounted for about 1%–2% stock much longer (although appliances and
share. Kia, though it still has a small equipment may not).
market share, is an example of another
company where mix differences lead
to a stock carbon share slightly greater Rolling stock carbon burdens by
than the population share of their market segment
vehicles (see Table 1), even though Another way to examine carbon
their fleet has been more fuel efficient emissions is by major market segment
than average. (vehicle class): small cars, midsize cars,
Another interesting note: Even large cars, pickups, vans and SUVs.21
though the market share of the Big Table 2 shows the stock share, carbon
Three has been generally declining since emissions and average fuel efficiency
the mid 1970s, and their combined of these six vehicle segments. This
TABLE 2
Light vehicle stock, fuel consumption, and carbon emissions by vehicle class, 2004
ROLLING STOCK AS OF 2004 (ALL VEHICLES NEW AND USED) MY2004 (NEW FLEET ONLY)
Vehicle On-road Fuel Carbon Vehicle Carbon On-road Carbon
population fuel economy consumption emissions population emissions fuel economy Market burden
Vehicle class (millions) (mpg) (Mbd) (MMTc) share share (mpg) share share
Small cars 65.1 24.3 2.10 77.2 32.0% 25% 24.6 23% 18%
Midsize cars 38.5 21.4 1.46 53.7 18.9% 17% 23.2 17% 17%
Large cars 17.6 19.7 0.72 26.5 8.6% 8% 20.8 7% 8%
Pickups 32.2 16.3 1.63 59.9 15.8% 19% 15.6 16% 15%
Vans 17.3 17.9 0.80 29.5 8.5% 9% 19.1 5% 7%
SUVs 33.1 16.3 1.83 67.5 16.2% 21% 16.9 31% 34%
Cars 121.2 22.6 4.27 157.3 59.5% 50% 23.4 47% 43%
Light trucks 82.5 16.6 4.26 156.9 40.5% 50% 16.7 53% 57%
Overall 203.7 19.6 8.53 314.2 100.0% 100% 19.3 100% 100%
8FIGURE 4
Stock vs. new fleet carbon burden shares by vehicle class, 2004
Small cars
SUVs
Pickups
Midsize cars
On-road stock
Vans New fleet
Large cars
0% 10% 20% 30% 40%
Carbon burden share
breakdown of carbon emissions share by sions, putting them in fourth place in
vehicle class is also depicted in Figure 4. terms of carbon share.
Despite falling sales since 1987, SUVs and pickups comprised the
small cars remained the largest segment third and fourth largest segments, with
of the on-road stock. The 65 million 16.2% and 15.8% of the in-use vehicle
small cars (including small wagons) in population respectively. However, SUVs
use accounted for 32% of the total U.S. and pickups were in second and third
light duty vehicle stock in 2004, in place, respectively, in terms of carbon
contrast to their 23% share of new emissions in 2004. Each of these two
vehicle sales. Small cars still accounted segments contributed about one-fifth
for the largest share of rolling stock of total rolling stock emissions. SUV
carbon emissions, emitting 77 MMTc carbon emissions in 2004 amounted to
in 2004, or about one-fourth of total 67 MMTc and pickup trucks emitted
light vehicle carbon emissions. The 60 MMTc. The disproportionate share
segment’s 25% carbon share is sub- of SUV and pickup emissions results
stantially less than its 32% stock share from their below-par fuel economy,
because of its higher than average fuel averaging 16.3 mpg for both segments.
economy. U.S. small cars averaged 24.3 This fuel economy level is 17% lower
mpg on-road in 2004, 24% better than than the stock average and corresponds
the overall average, for an average emis- to an average emissions rate of about
sions rate of 4.3 tons CO2-equivalent 6.5 tons of CO2-equivalent per year.
per year.22 The 67 MMTc emitted by all the SUVs
Midsize cars were the second largest on the road in 2004 is comparable to
segment of vehicle population, com- the carbon emissions from 55 large coal-
prising 19% of the 2004 light vehicle fired power plants.23
stock. Averaging 21.4 mpg on the road, The remaining segments, vans
midsize cars accounted for 54 MMTc, (mainly minivans) and large cars,
or 17% of rolling stock carbon emis- accounted for smaller portions of the
9stock and contributed 9% and 8% of vehicles that each contribute to more
2004 stock carbon emissions than 5% of stock carbon emissions
respectively. Overall, the 2004 vehicle include four segments of General
stock composition was 59% cars and Motor’s products (small cars, midsize
41% light trucks. But the rolling carbon cars, pickups, SUVs) and two segments
shares were roughly 50% each for cars of Ford’s products (pickups and SUVs).
and light trucks, reflecting the higher GM’s and Ford’s pickups are the two
CO2 emissions rates of trucks compared groups with the largest emissions over-
to cars. all, accounting for 6.8% and 6.6% of
Tables 3 and 4 cross-tabulate stock carbon share, respectively. Since our data
share and carbon share, respectively, by exclude Class 2b trucks (8,501–10,000
segment and automaker. Groups of lb GVW), which are mostly three-
TABLE 3
Vehicle population cross-tabulation by automaker and vehicle class, 2004
Manufacturer Small cars Midsize cars Large cars Pickups Vans SUVs Overall
GM 8.2% 6.9% 4.4% 5.6% 2.1% 4.4% 31.6%
Ford 6.3% 4.0% 2.7% 5.6% 2.1% 3.8% 24.4%
DaimlerChrysler 2.9% 2.0% 1.2% 2.2% 3.2% 3.5% 14.9%
Toyota 3.2% 2.2% 0.4% 1.5% 0.4% 1.5% 9.1%
Honda 3.9% 1.5% 0.4% 0.8% 6.5%
Nissan 2.1% 1.1% 0.8% 0.2% 0.7% 4.9%
Volkswagen 1.4% 0.4%quarter- and one-ton pickups, the actual from the Big Three’s automobiles in
carbon emissions share of pickups over- 2004 were comparable to the total from
all is greater still.24 the top 11 electric companies. Next
down the list, the CO2 emissions from
Toyota vehicles were slightly higher
Comparing automobile and than those from the Tennessee Valley
electric sector carbon emissions Authority, the nation’s third largest
Accounting for roughly 20% of U.S. power producer.
energy-related CO2 emissions, cars and Comparing CO2 emissions from on-
light trucks are a key source of the road stocks (rather than just new sales)
nation’s global warming emissions. to those from electric utilities is appro-
Viewed in a corporate impact context, priate in that both include the emissions
GM, Ford and DaimlerChrysler of long-lived products and equipment
vehicles are the first, second and third (automobiles and appliances or other
largest CO2 emitters in the United electrical devices). Both are influenced
States, all ahead of country’s largest by the actions of end-users, that is,
electricity producer, American Electric consumers and businesses. For example,
Power (AEP). Such comparisons are a power company’s CO2 emissions are
illustrated in Figure 5. the result of the electricity consumed in
The 99 MMTc from GM vehicles homes, offices, schools and other power-
in 2004 was more than double the using facilities in its service area. Both
41 MMTc from AEP. Ford’s cars and are influenced by the carbon intensity of
trucks emitted 80 MMTc, essentially their fuel supply. For example, coal
double AEP’s emissions that year, and accounts for 54% of energy consumed
DaimlerChrysler’s products emitted by U.S. power generation25 and 83% of
51 MMTc. The total CO2 emissions carbon emissions from the electric
FIGURE 5
Carbon emissions of major automakers’ products vs. major electric
producers in the United States, 2004
General Motors 99
Ford 80
DaimlerChrysler 51
American Electric Power 41
Southern Company 37
Toyota 27
Tennessee Valley Authority 26
Major automakers’ products
Honda 17 Major electric producers
Xcel 17
Ameren 17
Cinergy 16
Dominion 15
Edison International 15
Progress Energy 15
Nissan 15
0 20 40 60 80 100 120
Carbon emissions (MMTc)
Source: Table 1 and CERES et al. (2006).
11sector.26 Government decisions and ways, particularly in the nature of the
policies are also important in both cases. markets and the specific roles played by
State and local regulators oversee elec- the other actors who influence usage.
tric utility services and rates for the Another way to view corporate CO2
power sector, and multiple levels of emissions impacts would be to tally
government oversee transportation those associated with the motor fuel
infrastructure, finance and land use sales by major oil companies, but we
planning for automobiles. The sectors have not attempted such an analysis
are, of course, different in many other due to lack of data.27
12Beyond the carbon tally
The rolling stock snapshot for 2004 is quantifiable and can be tracked through
the product of many forces. Key factors time, and examining them forms a
include the amount of travel, the level of common basis for analyzing the car-
fuel economy and the carbon content of climate problem.
motor fuel. Among these factors, only For the 2004 rolling carbon snapshot
fuel economy has served to partially discussed in this report, total U.S. auto
control CO2 emissions. Fuel carbon sector CO2 emissions can be viewed as
intensity has not significantly changed, the product of:
reflecting the tenacity of oil as a source
of motor fuel and the fact that no sys- • Travel demand (2.6 × 1012 miles/year)
tematic effort has been made to reduce • Fuel use rate (51 gallons/1000 miles)
or offset GHG emissions associated • Fuel carbon content (5.3 pounds of
with petroleum fuels. Many forces drive carbon/gallon)
travel demand, and all of them have had
a combined effect of pushing auto sector The result rounds out to the 314 MMTc
CO2 emissions upward. total of rolling stock carbon emissions
given in Tables 1 and 2.
The first factor, known as vehicle
Factors determining auto sector miles traveled (VMT), represents the
CO2 emissions total amount of driving in cars and light
As illustrated in Figure 6, auto sector trucks.28 The second factor, average
CO2 emissions can be depicted as a fuel use per mile, is based on the stock
three-legged stool, with the overall level average fuel economy of 19.6 mpg.
propped up by the three major factors The third factor, fuel carbon content
noted. These factors are generally of 5.3 pounds/gallon, represents the
carbon in gasoline.29
A look at what’s behind each of the
FIGURE 6 three legs of the car-carbon stool sheds
Three main factors behind rolling
light on the multifaceted nature of auto
carbon
sector carbon emissions and puts into
perspective the challenge of addressing
Vehicle CO2 emissions a problem of this magnitude.
TRAVEL DEMAND
Demographic and economic factors,
urban and regional development, changes
in transportation infrastructure and
evolving land-use patterns all influence
the amount of driving. The travel demand
factor, however, is often given but passing
attention in U.S. climate policy, and dis-
cussions frequently focus on the politically
Travel Fuel charged issue of raising fuel taxes.
demand Fuel use rate carbon In the United States, road building,
content
automaking and the supply of petroleum
13fuels form a three-way symbiosis that pounding population growth are
has served to sustain steady increases in increases in vehicle ownership rates and
driving. The public appreciates the average VMT per capita, as shown in
benefits of automobiles enough to Figure 7. Both have grown steadily over
support fuel taxes that help pay for the second half of the 20th century.
roads. Yet taxes receive great scrutiny, VMT per capita has increased 82%
and taxes on fuel generally have been since 1970—double the population
limited to the minimum needed to cover growth over this period—rising from
basic highway costs. roughly 5,400 miles per year to 9,900 by
The personal value of the car is high 2002. Car ownership (vehicles per
enough that this major part of the trans- capita) has risen essentially in parallel.
portation system is privately financed Figure 7 shows ownership over the
by consumers themselves. Even during entire population, including children,
price spikes, fuel cost is generally a small the very old and others who do not
fraction of the total cost of owning and drive. The intensity of auto use is
operating a car.30 Thus, U.S. fuel prices highlighted by the fact that there are
provide little restraint on VMT. Absent now more cars than drivers, with the
effective policies to manage transporta- latest statistics showing that the United
tion demand at the national scale, VMT States has 1.06 personal vehicles per
has increased steadily for many years. licensed driver.33
Net VMT growth was 158% between Surveys of how Americans use their
1970 and 2004, for an average growth cars are commonly reported on a house-
rate of 2.8% per year.31 hold basis, as shown in Figure 8. The
A key factor driving travel demand is average household drove roughly
population. The U.S. population in 2002 21,000 miles in 2001, 17% more than
was 288 million, representing an the household average in 1990. While
increase of 41% since 1970, and an commuting trips still had the largest
increase of 90% since 1950.32 Com- share of driving, American households
FIGURE 7
U.S. vehicle ownership and VMT per capita (1950–2002)
0.9 12,000
0.8
Vehicles per capita 10,000
0.7
VMT per capita
VMT per capita (miles)
Vehicles per capita
0.6 8,000
0.5
6,000
0.4
0.3 4,000
0.2
2,000
0.1
0.0 0
1950 1960 1970 1980 1990 2000
Source: Davis and Diegel (2004), Table 8.2
14FIGURE 8
VMT trend by travel purpose
25,000
I Other
I Social and recreation
20,000 I Misc. family and personal business
I Shopping
I To and from work
Miles per year
15,000
10,000
5,000
0
1969 1977 1983 1990 1990a* 1995 2001
Year of survey
Source: Hu and Reuscher (2004), Table 6.
*The survey methodology changed in 1995 and so the 1990 results are shown in two forms: using original survey
definitions (labeled "1990") and adjusted for comparison to the 1995 and 2001 surveys (labeled "1990a").
are using their vehicles more often reductions have not been enough to
for shopping. The number of miles achieve healthy air in many regions
for shopping trips steadily increased (Scott et al. 2005). Thus, in addition
since 1969, and grew by 40% from to ongoing efforts to improve tech-
1990 to 2001, as a result of increased nology, renewed attention is being
shopping trips and extended trip placed on improved land use, trans-
lengths.34 These statistics highlight the portation alternatives and rationalized
trend of Americans’ increasing reliance pricing to achieve a more efficient
on personal vehicles, a natural conse- transportation system that is less reliant
quence of burgeoning auto-oriented on motor vehicles.
development that has been the norm
in most parts of the United States over FUEL ECONOMY
the past several decades. The 1970s oil crises—with gasoline
The issue of how to manage travel lines, fears of shortages and suddenly
demand, which is intimately linked to higher fuel prices, plus the policy
land use and many other factors, is quite response of Corporate Average Fuel
involved. However, a growing sense of Economy (CAFE) standards—drove a
the limitations of traditional transporta- leap in new light vehicle fuel economy
tion priorities reveals many reasons between 1975 and 1981. Fuel economy
to pursue policies that would serve to continued to slowly increase between
dampen VMT growth (TRB 2005). 1981 and 1988 but then began declining
As noted in the next section, catalytic due to the rising popularity of light
converters have succeeded in cutting trucks and largely unchanged CAFE
air pollution in spite of VMT growth; standards. Nevertheless, the EPA-rated
nevertheless, such technology-based fuel economy of the new automobile
15fleet saw a net 78% increase from health-harming pollution from cars and
1974–2004. Adjusting for increased light trucks.36 This drop in total emis-
shortfall, average on-road fuel economy sions was achieved by cutting stock-
improved by roughly 50% over that average per-mile emission rates to
period.35 This efficiency gain implies a roughly 15% of their pre-control levels.
33% reduction in CO2 emissions per In short, catalyst-based emissions
mile from today’s vehicles compared to control—incorporating computerized
those of a generation ago. engine management, reformulated low-
It is instructive to compare the fuel- sulfur gasoline and related devices—has
economy driven reductions in CO2 been a potent enough technological fix
emissions with the reductions in the to achieve net pollution reductions in
emissions of other forms of vehicle spite of increased driving.
pollution. Efforts to seriously control The difference between the effective-
smog-forming automobile emissions ness of tailpipe emissions controls and
also began in the 1970s. The Clean Air fuel economy improvement over this
Act limited tailpipe emissions of period is illustrated in Figure 9. The
hydrocarbons (HC), nitrogen oxides backdrop for both air pollution and CO2
(NOx) and carbon monoxide (CO) by emissions from cars and light trucks is
model year 1975 to levels that most VMT growth, which, as described
vehicles could attain only through the earlier, rose by more than a factor of
use of catalytic converters (Mondt 2.5 since 1970. Yet total health-damaging
2000). Today, after an ongoing air pollution from U.S. automobiles
tightening of tailpipe standards and a dropped by nearly 10 million tons of
generation of effort, the United States NOx-equivalent,37 corresponding to
has achieved over a 60% reduction in the 60% reduction noted. Reductions
automotive “rolling smog,” that is, will continue as even tighter tailpipe
FIGURE 9
Trends in carbon dioxide emissions and other air pollution from U.S.
automobiles
2.0
1.8 Carbon dioxide
Other air pollutants Up by 70% (+114 million tons)
1.6
1.4
Index (1970 = 1)
1.2
1.0
0.8
0.6
0.4
Down by 63% (–10 million tons)
0.2
0.0
1970 1975 1980 1985 1990 1995 2000 2005
Source: Authors’ analysis of EPA (2005b), FHWA (2006) and historical editions of Highway Statistics. The “other air
pollutants” trend is based on a health-damage-weighted composite for tailpipe emissions of nitrogen oxides (NOx),
volatile organic compounds (VOC), particulates (PM10), carbon monoxide (CO) and sulfur dioxide (SO2).
16standards are phased in. Automotive However, by the mid-1990s it became
CO2 emissions, on the other hand, have clear that all standards short of the zero-
increased by 70% since 1970 and are emission vehicle (ZEV) mandate could
continuing to rise. Although many tech- be met with improved catalytic controls
nologies are available to cut CO2 emis- and reformulated gasoline.
sions rates, none of the options (not even Most alternative fuels are now pro-
hybrid powertrains) are as effective as the moted as offering low GHG emissions.
catalytic converter has been for cutting An ongoing debate plays out in numer-
conventional pollutants. Lacking such a ous paper studies (“full fuel cycle”
technological fix, vehicle design changes analyses) of which fuels might have low
will need to be complemented by other or zero GHG emissions under various
strategies, such as low-carbon fuels and assumptions. However, requirements to
reductions in travel demand, to see major control GHG emissions throughout a
progress in reducing rolling carbon. fuel’s life cycle are yet to be developed.
Since little work has been done to
LOW-CARBON FUELS systematically measure and track the
The 1970s energy crisis also prompted actual fuel-cycle impacts of commer-
efforts to develop and commercialize cially produced fuels, the real-world
alternatives to petroleum-based trans- greenhouse gas implications of alter-
portation fuels. Since then, the U.S. native fuels remain uncertain. Moreover,
economy has seen major shifts in the one major U.S. policy to promote alter-
structure of oil use; sectors that could native fuels, giving automakers CAFE
switch to other fuels have largely done credits for selling flexible-fuel vehicles
so. Non-transportation oil use is now (FFVs), is counterproductive. The
lower in absolute terms than it was in resulting trade-off in vehicle efficiency
1970, even after three decades of eco- has increased oil consumption and
nomic growth. Transportation, however, carbon emissions over what they would
remains 96% petroleum dependent, and have been without the FFV policy
the sector now accounts for two-thirds (DOT 2002).
of U.S. oil use, compared to one-half One alternative fuel that has seen
in 1970.38 consistent backing is ethanol. Ethanol
Throughout this time a variety of can be readily blended with gasoline in
fuels have been promoted by federal low concentrations and such “gasohol”
and state policies. Alternatives that have has long been available in the Midwest.
seen support include synthetic fuels U.S. fuel ethanol use is now increasing
(synfuels) from coal and oil shales, rapidly toward the renewable fuel man-
natural gas, methanol (derived from date of 7.5 billion gallons by 2012.40
natural gas or coal), various biofuels, That level would amount to about 3% of
electricity and hydrogen.39 U.S. light vehicle fuel consumption.41
Although nearly all alternative fuels However, because the energy use and
are advertised as “clean,” policies to emissions associated with agricultural
promote them have had few if any and ethanol production processes are
stipulations regarding environmental not tracked, it is difficult to ascertain
performance beyond those already the net carbon impact of ethanol use.
required for gasoline. California’s 1990 A recent meta-study found that replac-
low-emission vehicle (LEV) program ing gasoline with corn ethanol has an
was partly premised on levels of strin- ambiguous effect on GHG emissions
gency that would favor alternative fuels. (Farrell et al. 2006). Like most commercial
17and agricultural activity in the United suppliers and consumers, as well as by
States, ethanol production is now pur- regional planning bodies and other
sued without a need to manage carbon. transportation policy forums.
To ensure reductions in GHG emissions For example, consider fuel economy,
through fuel substitution, protocols will a tangible and easy-to-track factor
need to be established for tracking fuel- behind automotive CO2 emissions.42
cycle impacts and certifying that the net Consumers influence fuel economy
GHG emissions from ethanol or other through their selection of vehicles as
fuels are measurably lower than those well as their driving and maintenance
from gasoline. habits. Automakers influence fuel
Fuel supply infrastructure is long- economy through their product strategies
lived, with large-scale investments and design choices. But the decisions
needed to develop new fuel production made by consumers and automakers
facilities, so shifting to alternative fuels are not independent; moreover, the net
requires longer lead times than modi- carbon impact of fuel economy depends
fying vehicles. Although the past few on the broader influences that shape
years have seen high oil prices, and the vehicle use.
U.S. Department of Energy revised its
oil price outlook significantly upward RECASTING THE DISCUSSION
(EIA 2005), the competitive environ- The complex, market- and policy-
ment for petroleum alternatives remains mediated nature of decisions that
speculative. This uncertainty in com- influence CO2 emissions is not unique
mercial outlook compounds the uncer- to the auto sector, of course. But our
tainty in the carbon impacts of any given rolling stock tally underscores the mag-
fuel due to the lack of policies for man- nitude of automotive CO2 emissions
aging GHG emissions associated with and spotlights the roles of the many
fuel production. Therefore, while shift- actors whose decisions are behind the
ing to low-carbon fuels is an essential 314 MMTc from U.S. cars and light
complement to cutting travel demand trucks. Such a view suggests a need to
and raising fuel economy, how well new recast the discussion of what to do about
fuels will serve to reduce GHG emis- the car-carbon problem from
sions depends on programs and policies
that largely remain to be developed. What policies are needed to address
each factor behind automotive CO2
emissions?
Managing auto sector carbon
While the major factors that determine to
emissions—the three-legged stool of
travel demand, fuel economy and type of What policies can motivate each actor
fuel—provide a convenient snapshot of to address the aspects of CO2 emissions
the sector, such an analysis has limitations under each actor’s control?
when considering how to cut emissions.
Multiple decision makers (“actors”) in- In a market-based framework, only
fluence each leg of the stool. In other individual decision makers can deter-
words, the factors that technically deter- mine the actual, perceived costs and
mine emissions are the product of benefits to themselves resulting from
choices made by many players in the the decisions they make. Developing
marketplace, such as automakers, fuel an actor-based carbon management
18framework can clarify the roles of all regional governments as well as state
players and enable cost-effective deci- officials to explicitly manage carbon
sions about carbon reduction. Under impacts in all aspects of transportation
this framework, policies can be designed and land use planning. Such decisions
to motivate actors to consider and are the clear area in which local govern-
reduce carbon impacts of every decision ments can affect the “rolling carbon”
they can control. Such an approach impacts of their jurisdiction. Challenges
would be a step beyond factor-based and costs are likely be associated with
analysis, which rests on assumptions any of the actions a city might consider
about the costs and benefits to particular for cutting carbon from transportation,
actors presumed to hold the most influ- but there might also be cost savings.
ence over a given factor. A city is just one actor, but the above
example illustrates how any entity in-
A NEED FOR NEW TOOLS fluencing auto sector CO2 emissions can
Exactly how to define a set of auto- approach the problem under a carbon
sector specific carbon management management paradigm. A private com-
policies is a subject for future work. We pany or institution that uses vehicles in
can, however, illustrate the value of such the course of business also has a measure
an approach by considering the example of control over the associated CO2 emis-
of a city as an actor who can influence sions, and opportunities to reduce emis-
the CO2 emissions associated with its sions can be found once an effort is
transportation operations. The vehicles made to look for them. Right now,
a city operates are, in fact, a microcosm however, most cities (as well as most
of the larger rolling carbon situation. other entities who influence auto sector
To cut the carbon from a city’s CO2 emissions) have little way of know-
transportation operations, its agencies ing how their day-to-day or year-by-
might consider ways to carry out their year transportation decisions impact
functions with less driving; they might CO2 emissions. Thus, a starting point
change the number, type and efficiency for finding ways to cut emissions is
of the vehicles they operate; or they developing new evaluation tools that
might use low-carbon fuels.43 Changes make the carbon impacts and costs of
in vehicle purchases would influence the decision options explicit. Sector-specific
demand side of the market to which carbon impact evaluation tools will
automakers respond. Moreover, under facilitate “carbon-sensitive decision
such a fleet carbon management ap- making,” enabling each actor to make
proach, decisions about vehicle choice the decisions that most affordably
would no longer be made in isolation reduce their portion of emissions. A
from looking at other (and sometimes broader question is how to motivate
more accessible) ways for the city to cut carbon-sensitive decision-making. Ulti-
carbon from its vehicles. mately, those who reduce emissions
Of course, a municipality’s vehicle might be able to realize a financial value
fleet is just a small fraction of all the from their actions in the market for car-
vehicles within a community. In fact, bon reductions that will emerge under
beyond its own fleet, city officials have a national and international climate
measure of control over land-use, zoning protection regimes.
and development decisions, parking and In short, many different entities have
the availability of non-auto modes of some measure of control over auto sector
transportation. A city can help lead other CO2 emissions. Opportunities to cut
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