_Fast
racts
U.S.Transportation Sector
Greenhouse Gas Emissions
1990-2015
United States
Environmental Protection
kl flAgency
Office of Transportation and Air Quality
EPA-420-F-17-013
July 2017

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Transportation Emissions of the United States
The transportation sector is one of the largest contributors to U.S. greenhouse gas (GHG)
emissions. According to the Inventory of US. Greenhouse Gas Emissions and Sinks 1990-2015
(the Inventory), the national inventory that the U.S. prepares annually under the United
Nations Framework Convention on Climate Change (UNFCCC), transportation represented
27% of total U.S. GHG emissions in 2015. Cars, trucks, commercial aircraft, and railroads,
among other sources, all contribute to transportation end-use sector emissions. Within the
sector, light-duty vehicles (including passenger cars and light-duty trucks) were by far the largest
category, with 60% of GHG emissions, while medium- and heavy-duty trucks made up the
second largest category, with 23% of emissions. Between 1990 and 2015, GHG emissions in the
transportation sector increased more in absolute terms than any other sector (i.e. electricity
generation, industry, agriculture, residential, or commercial) due in large part to increased
demand for travel.
Greenhouse gas emissions from transportation sources include carbon dioxide (C02), methane
(CH4), nitrous oxide (N20), and various hydrofluorocarbons (HFCs). C02, CH4, and N20 are
all emitted via the combustion of fuels, while HFC emissions are the result of leaks and end-of-
life disposal from air conditioners used to cool people and/or freight.2
Mobile Sources
Transportation
Non-Transportation Mobile
Highway Vehicles
Agricultural Equipment
Aircraft
Construction & Mining Equipment
Ships & Boats
Lawn & Garden Equipment
Rail
Logging Equipment
Lubricants
Recreational Equipment
Pipelines1

When including emissions from non-ttansportation mobile sources such as agricultural, lawn
and garden, and construction equipment, mobile sources constituted 31% of total U.S. GHG
emissions in 2015.
Medium- and
Heavy-Duty Trucks
23%
Electricity
29%
Transportation
27%
Share of U.S. Transportation Sector
GHG Emissions by Gas, 20154
Note: Totals may not add to 100% due to rounding.
Light-Duty
Vehicles
Share of U.S. Transportation Sector
GHG Emissions by Source, 20154'5
Note: Totals may not add to 100% due to rounding.
Other
4%
Rail
2%
Residential
6%
Commercial
Note: Totals may not add to 100% due to rounding.
Ships & Boats
2%v
Aircraft
9%
Share of U.S. GHG Emissions
by Sector, 20153'4
1	Pipeline emissions in the transportation sector include only C02 from the combustion of natural gas at compressor stations that power
natural gas pipelines, not emissions from electricity use, non-C02 gases, or other types of pipeline equipment. Note that natural gas pipe-
line compressor stations are stationary equipment that are included in the transportation sector, but are not considered mobile sources.
2	C02 emissions from the combustion of biofuels are not directly included in the energy sector contribution (which includes the contribution
of transportation and non-transportation mobile sources) to U.S. totals in the Inventory; instead, net carbon fluxes from changes in biogenic
carbon reservoirs are accounted in the estimates for Land Use, Land-Use Change, and Forestry in the Inventory. See page 4 for more
information on the Inventory.
3	For presentation purposes, emissions from territories which constitute less than 1% of the total U.S. GHG emissions, are not shown
in this chart although they are included in the total emissions used to calculate the percentage share of emissions from each sector.
See Table ES-6 in the Executive Summary of the Inventory for official data. See page 4 for more information on the Inventory.
4	"Transportation" emissions in these pie charts include C02, N20, CH4, and HFCs from transportation sources like highway vehicles,
aircraft, ships and boats, rail, pipelines and lubricants. They do not include emissions from non-transportation mobile sources such as
agriculture and construction equipment.
5	"Other" sources include buses, motorcycles, pipelines, and lubricants.

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U.S.Transportation GHG Emissions
(Tg C02 Equivalent)
Change from
1990 to 2015s
Source

1990
1995
2000
2005
2010
2014
20156
Absolute
Percent
On-Road Vehicles6,7
1,233.5
1,370.4
1,572.6
1,673.4
1,541.3
1,553.8
1,522.0
288.5
23.4
Light-Duty Vehicles
991.9
1,083.1
1,212.1
1,260.9
1,132.0
1,122.1
1,083.5
91.7
9.2
Passenger Cars
656.7
646.6
697.2
708.7
783.4
778.4
758.4
101.8
15.5
Light-Duty Trucks
335.2
436.5
514.9
552.2
348.7
343.7
325.1
-10.1
-3.0
Motorcycles
1.8
1.8
1.9
1.7
3.7
3.9
3.7
2.0
110.2
Buses
8.5
9.2
11.0
12.0
15.9
19.5
19.8
11.3
134.0
Medium- and Heavy-
Duty Trucks
231.4
276.2
347.7
398.9
389.7
408.3
415.0
183.6
79.3
Aircraft
189.2
176.7
199.4
193.6
154.8
151.5
160.7
-28.5
-15.1
Commercial Aviation
110.9
116.3
140.6
134.0
114.4
116.3
120.1
9.2
8.3
Military Aircraft
35.3
24.5
22.9
19.5
13.7
15.5
14.9
-20.5
-57.9
General Aviation
42.9
35.8
35.9
40.1
26.7
19.7
25.7
-17.2
-40.1
Ships and Boats
44.9
58.5
61.3
45.0
44.9
17.6
33.1
-11.8
-26.4
Rail
35.8
40.0
42.7
46.4
40.2
44.4
42.9
7.1
19.8
Pipelines8
36.0
38.4
35.4
32.4
37.3
39.4
38.0
1.9
5.4
Lubricants
11.8
11.3
12.1
10.2
9.5
9.1
10.0
-1.9
-15.8
Transportation Total
1,551.2
1,695.2
1,923.5
2,001.0
1,827.9
1,815.8
1,806.6
255.4
16.5
U.S. Non-Transportation Mobile GHG Emissions
Non-Transportation
Mobile6,9
128.8
146.7
159.5
191.8
203.1
213.9
208.1
79.3
61.6
Agricultural
Equipment
31.4
37.0
39.7
47.9
48.4
51.3
48.0
16.6
52.9
Construction
Equipment
42.4
49.3
56.6
67.4
74.0
80.4
78.8
36.4
85.9
Other Non-
Transportation Mobile
55.0
60.4
63.2
76.5
80.7
82.2
81.3
26.3
47.8
Non-Transportation +
Transportation Total
1,680.0
1,841.9
2,083.0
2,192.8
2,031.0
2,029.7
2,014.7
334.7
19.9
U.S.Transportation GHG Emissions by Gas, 2015
(Tg C02 Equivalent)
Source
o
o
ch4
n2o
HFCs
Total
Percent
On-Road Vehicles7
1,467.0
1.5
11.2
42.3
1,522.0
75.5
Light-Duty Vehicles
1,033.7
1.3
10.3
38.3
1,083.5
53.8
Passenger Cars
735.7
1.0
6.9
14.9
758.4
37.6
Light-Duty Trucks
298.0
0.3
3.4
23.4
325.1
16.1
Motorcycles
3.7
0.0
0.0
0.0
3.7
0.2
Buses
19.3
0.0
0.1
0.4
19.8
1.0
Medium- and Heavy-
Duty Trucks
410.4
0.1
0.8
3.6
415.0
20.6
Aircraft
159.2
0.0
1.5
0.0
160.7
8.0
Commercial Aviation
119.0
0.0
1.1
0.0
120.1
6.0
Military Aircraft
14.7
0.0
0.1
0.0
14.9
0.7
General Aviation
25.5
0.0
0.2
0.0
25.7
1.3
Ships and Boats
32.3
0.0
0.6
0.1
33.1
1.6
Rail
39.9
0.1
0.3
2.7
42.9
2.1
Pipelines8
38.0
0.0
0.0
0.0
38.0
1.9
Lubricants
10.0
0.0
0.0
0.0
10.0
0.5
Transportation Total
1,746.3
1.6
13.6
45.1
1,806.6
89.7
Rail Electricity
3.72
0.00
0.04
0.00
3.76
NA
U.S. Non-Transportation Mobile GHG Emissions by Gas, 2015
Change in GHG Emissions by Sector: 1990-2015
¦ Light- Duty Vehicles ¦ Medium- and Heavy-Duty Trucks ¦Aircraft ¦ Rail ¦ Non Transportation Mobile Sources ¦ All Other Transportation Sources ¦ Ships and Boats
Non-Transportation
Mobile9
206.1
0.4
1.6
0.0
208.1
10.3
Agricultural
Equipment
47.5
0.2
0.4
0.0
48.0
2.4
Construction
Equipment
78.1
0.1
0.6
0.0
78.8
3.9
Other Non-
Transportation Mobile
80.6
0.1
0.6
0.0
81.3
4.0
Non-Transportation +
Transportation Total
1,952.5
2.0
15.1
45.1
2,014.7
100.0
1990 1991 1992
1994 1995
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015
The methodology for estimating the share of gasoline used in on-road and non-road applications was updated in
2016, resulting in a break in the time series between 2015 and previous years. See page 4 for more details.
GHG emissions and vehicle miles traveled (VMT) estimates for on-road vehicles presented in the Inventory
are based on FHWA data. FHWA changed its methods for estimating (VMT) and related data in 2011. These
methodological changes included how vehicles are classified, moving from a system based on body-type to one
that is based on wheelbase. These changes were first incorporated for the 2010 Inventory and apply to the 2007—
14 time period. This resulted in large changes in VMT and fuel consumption data by vehicle class, thus leading to
a shift in emissions among on-road vehicle classes. For instance, "passenger car" has been replaced by "light-duty
vehicles short WB" and "other 2-axle 4-tire vehicles" has been replaced by "light-duty vehicles long WB."
Includes only C02 from natural gas used to power natural gas pipelines, does not include emissions from electricity
use or non-C02 gases.
Note: non-transportation C02 emissions estimates are presented here and in Annex 3.2 of the Inventory for
informational purposes, but these emissions are officially accounted for in other energy sectors in the Inventory
(i.e., industrial, residential, commercial sectors) using a different method. See Annex 3.2, Supplemental Inform^n
on Transportation-Related GHG Emissions, of the Inventory for more information.

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2015 Fuel Consumption

Volume
(billion gallons unless
otherwise specified)
Energy (Tbtu)
C02 (Tg)
MOTOR GASOLINE
127.1
15,779.0
1,125.5
Transportation10
Light-Duty Vehicles
114.4
14,220.9
1,014.5
Passenger Cars
82.4
10,251.0
731.3
Light-Duty Trucks
31.9
3,969.9
283.2
Medium- and Heavy-Duty Trucks
4.4
550.6
39.3
Motorcycles
0.4
51.3
3.7
Buses
0.1
12.5
0.9
Recreational Boats
1.4
170.4
12.2
Non-Transportation"
Agricultural Equipment
0.2
19.1
1.4
Construction Equipment
0.4
44.3
3.2
Other Non-Transportation Mobile
5.9
710.0
50.5
DISTILLATE FUEL
60.2
8,272.7
611.8
Transportation10
Light-Duty Vehicles
1.8
246.4
18.2
Passenger Cars
0.4
58.1
4.3
Light-Duty Trucks
1.4
188.3
13.9
Buses
1.7
234.0
17.3
Medium- and Heavy-Duty Trucks
36.3
4,994.4
369.4
Recreational Boats
0.4
52.8
3.9
Ships and Boats
1.2
162.7
12.0
Rail
3.9
539.1
39.9
Non-Transportation11
Agricultural Equipment
4.5
623.2
46.1
Construction Equipment
7.4
1,013.2
74.9
Other Non-Transportation Mobile
3.0
406.9
30.1
RESIDUAL FUEL OIL
0.4
56.6
4.2
Ships and Boats
0.4
56.6
4.2
JET FUEL
16.2
2,183.8
157.7
Commercial Aircraft
12.5
1,692.1
119.0
General Aviation Aircraft
2.3
304.8
24.0
Military Aircraft
1.4
186.9
14.7

Volume
(billion gallons unless
otherwise specified)
Energy (Tbtu)
C02 (Tg)
AVIATION GASOLINE
0.2
21.1
1.5
General Aviation Aircraft
0.2
21.1
1.5
NATURAL GAS (million cubic feet)
705,593.1
731.7
38.8
Passenger Cars
68.5
0.1
0.0
Light-Duty Trucks
218.1
0.2
0.0
Medium- and Heavy-Duty Trucks
517.9
0.5
0.0
Buses
13,925.9
14.4
0.8
Pipelines
690,862.5
716.4
38.0
LPG
0.6
48.3
3.0
Passenger Cars
0.0
1.1
0.1
Light-Duty Trucks
0.2
14.2
0.9
Medium- and Heavy-Duty Trucks
0.3
28.0
1.7
Buses
0.1
5.1
0.3
LUBRICANTS
1.0
148.1
10.0
Total12
211.7
27,241.4
1,952.5

BIOFUELS



Transportation
BiodieseP3
1.5
190.6
14.1
EthanoP
13.1
1,109.4
75.9
10	Fuel consumption, energy, and C02 emissions from transportation sources using motor gasoline and distillate fuel exclude
contributions from biofuels.
11	Non-transportation mobile fuel consumption, energy, and C02 are estimated based on the N ON ROAD component of EPA's
MOVES model (see www.epa.gov/moves/nonroad-model-nonroad-engines-equipment-and-vehicles). Because the fuel compo-
sition in the NONROAD model is intended to reflect real-world usage, these estimates may include low-level ethanol blends.
Note that these estimates are presented here and in Annex 3.2 of the Inventory for informational purposes, but that non-
transportation mobile source C02 emissions are officially accounted for in other energy sectors in the Inventory (e.g., the
industrial sector) using a different method and do not include emissions from biofuels.
12	Total Volume is the sum of physical (billion) gallons of fuel; because natural gas volumes are reported as million cubic feet,
natural gas volumes are converted to billion gallons of gasoline equivalent for the Total Volume (billion gallons) sum in
this table.
13	Biofuels are presented as line items below the total for informational purposes only, in line with IPCC methodological guidance
and UNFCCC reporting obligations. Biofuel estimates only reflect transportation sources and do not include biofuels used in
non-transportation mobile sources, e.g., ethanol used in commercial or industrial applications. C02 emissions from the
combustion of biofuels are not directly included in the energy sector contribution (which includes the contribution of transpor-
tation sources) to U.S. totals in the Inventory; instead, net carbon fluxes from changes in biogenic carbon reservoirs are
accounted in the estimates for Land Use, Land-Use Change, and Forestry in the Inventory. See page 4 for more information
on the Inventory.
3

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Additional Information
Data Sources for This Document
The source for all data in this document is the Inventory of US. Greenhouse Gas Emissions
and Sinks 1990-2015 (the Inventory) (EPA 2017). The U.S. Environmental Protection
Agency prepares the inventory annually to fulfill the U.S. commitment under the United
Nations Framework Convention on Climate Change (UNFCCC), using calculation methods
that are consistent with guidelines from the Intergovernmental Panel on Climate Change
(IPCC). Complete information on the inventory is available at: www.epa.gov/ghgemissions/
inventory-us-greenhouse-gas-emissions-and-sinks. The inventory methods and assumptions
related to transportation and non-transportation mobile sources are available in the main
body of the Inventory as well as Annex 3.2 of the Inventory.
Inventory Definitions of Selected Transportation Categories14
Light-Duty Vehicles: passenger cars and light-duty trucks
Passenger Cars:15 automobiles used primarily to transport 12 people or less. In
2015, passenger cars traveled a total of 2,147,840 million vehicle miles.
Light-Duty Trucks:15 vehicles used primarily for transporting light-weight
cargo or which are equipped with special features such as four-wheel drive
for off-road operation. In the U.S., this category also includes many vehicles
that primarily transport passengers such as sport utility vehicles (SUVs) and
minivans. The gross vehicle weight rating (GVWR) normally ranges around
8,500 pounds or less. GVWR is the maximum weight a vehicle is designed to
carry when passengers, fuel, cargo, and any other additions to the vehicle are
accounted for. In 2015, light-duty trucks traveled a total of 631,852 million
vehicle miles.
Medium- and Heavy-Duty Trucks:15 vehicles with GVWR of more than
around 8,500 pounds. In the Inventory, single unit trucks and combination
trucks represent the medium- and heavy-duty truck category, including tractor-
trailers and box trucks used for freight transportation. In addition, this category
includes some vehicles that are not typically used for freight movement such as
service and utility trucks. In 2015, medium- and heavy-duty trucks traveled a
total of 296,073 million vehicle miles.
Pipelines: systems that transport liquids, gases, or slurries through either
above or below ground pipes. In the Inventory, the pipelines category includes
emissions from the combustion of natural gas used to power pumps and other
distribution equipment, while leaks and other emission sources from pipelines
are assigned to the natural gas systems category.
Emissions Metrics
A teragram (Tg) is equal to 1 million metric tons.
Greenhouse gas (GHG) emissions are measured in this document in terms of teragrams
of "carbon dioxide equivalent" (C02 Eq); an "equivalent" refers to the Global Warming
Potential (GWP) of a greenhouse gas. GWP values are determined based on the chosen time
horizon and properties of the gas, such as its ability to absorb radiation and its atmospheric
lifetime. C02 has a GWP of "1"; all other greenhouse gases have GWP values relative to
that of COr For example, methane (CH4) has a radiative forcing value or GWP of 25, which
means that releasing one ton of CH4 is equivalent to releasing 25 tons of C02.
The data in this document is based on the 100-year time horizon GWP values from the Inter-
governmental Panel on Climate Change's (IPCC's) Fourth Assessment Report16, in accordance
with UNFCCC reporting guidelines for national GHG inventories. More information on
greenhouse gases and GWP is available at: www.epa.gov/ghgemissions/overview-greenhouse-gases.
Gasoline Method Update for 2015
In 2016, the Federal Highway Administration (FHWA) updated its methods for estimating
the share of gasoline used in on-road and non-road applications. While these methodology
updates did not impact total U.S. gasoline consumption estimates in the Inventory, they did
create a time-series inconsistency between 2015 and previous years in gasoline consumption
estimates for transportation, as well as agricultural, construction, commercial, and industrial
non-transportation mobile sources. The method updates are discussed further in the Planned
Improvements sections of Chapter 3.1 of the Inventory under C02 from Fossil Fuel Combus-
tion and CH4 and N20 from Mobile Combustion.
14	The data used to estimate emissions for specific transportation categories may not directly align with the Inventory's
definition of the categories; both the data and Inventory definitions may also differ from EPA's regulatory definitions
for the same categories.
15	GHG emissions and vehicle miles traveled (VMT) estimates for on-road vehicles presented in the Inventory
are based on FHWA data. FHWA changed its methods for estimating (VMT) and related data in 2011. These
methodological changes included how vehicles are classified, moving from a system based on body-type to one
that is based on wheelbase. These changes were first incorporated for the 2010 Inventory and apply to the 2007—
15 time period. This resulted in large changes in VMT and fuel consumption data by vehicle class, thus leading to
a shift in emissions among on-road vehicle classes. For instance, "passenger car" has been replaced by "light duty
vehicles short WB" and "other 2-axle 4-tire vehicles" has been replaced by "light duty vehicles long WB."
16	See www.ipcc.ch/pdf/assessment-report/ar4/syr/ar4_syr.pdf.
4

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