&ER&
  United States
  Environmental Protection
  Agency
                        The U.S. Greenhouse
                                Gas Inventory

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                                                nternational  Reporting
                                              In 1992, under the United Nations Framework Convention on Climate Change
                                              (UNFCCC), the United States, along with 185 other countries, agreed to develop and
                                              submit a national inventory of anthropogenic greenhouse gas emissions and sinks.
                                              To fulfill this obligation, each year the U.S. Environmental Protection Agency (EPA)
                                              prepares the official Inventory of U.S. Greenhouse Gas Emissions and Sinks in
                                              cooperation with the U.S. Department of State and other U.S. government agencies.

                                              Under the direction of the Intergovernmental Panel on Climate Change (IPCC),
                                              hundreds of scientists and national experts collaborated in developing a set of
                                              methodologies and guidelines to help countries create inventories that are compa-
                                              rable across international borders. The information presented in the Inventory of
                                              U.S. Greenhouse Gas Emissions and Sinks is in full compliance with these IPCC
                                              guidelines.
   he  U.S. Greenhouse Gas  Inventory Program
The U.S. Environmental Protection Agency's Clean Air Markets Division (CAMD) in the Office of Atmospheric Programs is responsible
for developing the annual Inventory of U.S. Greenhouse Gas Emissions and Sinks. EPA's Greenhouse Gas Inventory Program has
developed extensive technical expertise, internationally recognized analytical methodologies, and one of the most rigorous manage-
ment systems in the world for the estimation, documentation, and evaluation  of greenhouse gas emissions and sinks for all source
categories. To accomplish  its work, the Inventory Program collaborates with hundreds of experts representing  more than a dozen
federal agencies, many academic institutions, industry associations, consultants, and environmental organizations. The Program
also works directly with industries and other government agencies to develop high quality emissions data and is supported by
CAMD's experience with the U.S. emissions trading programs and its network of continuous emission monitors for C02 on most
electric power plants in the United States.
                                                    hat  is the Significance  of Emission Inventories?
                                              Greenhouse gas emission inventories are developed for a variety of reasons. Scientists
                                              use inventories of natural and anthropogenic  emissions as tools when developing
                                              atmospheric models. Policy makers use inventories to develop strategies and policies
                                              for emissions reductions and to track the progress of those policies. And, regulatory
                                              agencies and corporations rely on inventories to establish compliance records with
                                              allowable emission rates. Businesses, the public, and other interest groups  use inven-
                                              tories to better understand the  sources and trends in emissions.

                                              A well constructed inventory is consistently prepared, accurate, and thoroughly
                                              documented. Inventories typically include the following information:

                                                    Chemical and physical  identity of the pollutants
                                                    Types of activities that  cause emissions
                                                    Time period over which the emissions were estimated
                                                    Geographic area covered
                                                    Clear description of estimation methodologies  used and data collected

                                              The Inventory of U.S. Greenhouse Gas Emissions and Sinks provides important
                                              information about greenhouse gases,  quantifies how much of each gas was emitted
                                              into the atmosphere, and describes  some of the effects of these emissions on
                                              the environment.

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                                                     hat are Greenhouse  Gases?
                                               Many chemical compounds found in the earth's atmosphere act as greenhouse gases,
                                               trapping outgoing terrestrial radiation and warming the earth's atmosphere. Some
                                               emissions of greenhouse gases occur naturally, while others result from human
                                               activities. Carbon dioxide, methane, nitrous oxide, and ozone are greenhouse
                                               gases that have both natural and human-related emission sources. In addition,
                                               humans have created other greenhouse gases, such as hydrofluorocarbons (HFCs),
                                               perfluorocarbons (PFCs), and sulfur hexafluoride (SF6).
                                               The global warming potential (GWP) of a greenhouse gas is the ratio of global
                                               warming, or radiative forcing, from the emission of one unit mass of a greenhouse
                                               gas to that of one unit mass of carbon dioxide over a specified time horizon.
                                               Calculation of GWPs is based on the lifetime of the gas and how efficiently it
                                               traps heat in the atmosphere. See the Inventory Fast Facts  data card for a table
                                               of GWP values.
            Changes in Atmospheric Concentration
                  of CO2, CH4, and N2O
CD
o
I
      360
    „ 340
    §- 320
    ^300
    0 280
      260
  1750

J? 1500
Q.
Q.
~ 1250

O 1000

   750



   310


§ 290

O
 CM
Z  270


   250
            Carbon Dioxide
           Methane
          . Nitrous Oxide
1.5

1.0

0.5

0.0
0.5
0.4
0.3
0.2
0.1
0.0

0.15

0.10

0.05

0.0
        1000    1200    1400    1600   1800    2000
                         Year
           Source: IPCC Third Assessment Report (2001)
ra
S
a:
                hat is the Inventory of U.S.
          Greenhouse Gas Emissions and Sinks?
          The Inventory of U.S. Greenhouse Gas Emissions and Sinks is a cata-
          log of anthropogenic, or human-generated, greenhouse gas emissions
          in the United States. Carbon dioxide can also be sequestered (i.e.,
          stored) in "sinks" that result from forestry and other land-use prac-
          tices. Excluding all naturally occurring greenhouse gas emissions and
          sinks, the Inventory provides a detailed record of all emissions and
          sinks directly attributable to human activities. It does not address
          naturally occurring emissions or sinks.
                                                                           Trends in Atmospheric Concentrations and
                                                                           Anthropogenic Emissions of Carbon Dioxide
                                                                            Source: Oak Ridge National Laboratory (2001)

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The gases covered in the
U.S. Inventory include:

Carbon Dioxide (C02J
In nature, carbon is cycled between various atmospheric,
oceanic, biotic, and mineral reservoirs. In the atmosphere,
carbon mainly exists in its oxidized form as C02. Carbon
dioxide is released into the atmosphere primarily as a
result of the burning of fossil fuels (oil, natural gas, and
coal) for power generation and in transportation. It is also
emitted through various industrial processes, forest clear-
ing, natural gas flaring, and biomass burning. And, some
carbon is sequestered in forest  and agricultural soils.

Methane (CH4)
Methane is produced primarily through anaerobic
decomposition of organic matter in biological systems.
Specifically, methane is emitted as a result of the
decomposition of organic wastes in municipal solid
waste landfills and from agricultural and biological
processes related to wetland rice cultivation, livestock
digestion, and waste production. Methane emissions
also occur during the production  and distribution of fossil
fuels such as coal, natural gas, and petroleum. Methane's
overall contribution to global warming is significant
because it is estimated to be more than 20 times as
effective  at trapping heat in the atmosphere than  C02.

Nitrous Oxide (N20)
The microbial  processes of nitrification and denitrification
naturally produce nitrous oxide in soils. Anthropogenic
additions of nitrogen to soils during agricultural soil
management  activities increase  the amount of N20
emitted to the  atmosphere. Nitrous oxide is also emitted
during industrial production activities, solid waste  com-
bustion, and fossil fuel combustion. Nitrous oxide  is
approximately 300 times more powerful than C02 at
trapping heat  in the atmosphere.

MFCs, PFCs, and SF6
Hydrofluorocarbons (MFCs), perfluorocarbons (PFCs),
and sulfur hexafluoride (SF6) are powerful greenhouse
gases. MFCs are primarily used  as replacements for
ozone-depleting substances, but also are emitted as a
by-product of the HCFC-22 manufacturing process.
PFCs and SF6 are emitted by a variety of industrial
processes including aluminum smelting, electric power
transmission and distribution, magnesium processing,
and semiconductor manufacturing. Currently, MFCs,
PFCs, and SF6 have a relatively  small aggregate radia-
tive forcing impact; however, because some of them
have long atmospheric lifetimes, their concentrations
can irreversibly accumulate in the atmosphere.
     missions by Sector

Emissions of greenhouse gases  result from many  of the
industrial, transportation,  agricultural, and other activities that
take place in the United States.  The following  is a description
of the various sectors that emit greenhouse gases.


Energy
Historically, energy-related activities have accounted for more thai three-quirters
of GWP-weighted greenhouse gas emissions. Most of these arf carbp"- air,. -~
emissions; however, some emissions of methane and nitrous o:;ide also re?ut
from stationary and mobile combustion.  Almost all emissions  Tom  the energ r
sector result from fossil fuel combustion, which includes the birning of coal,
natural gas, and petroleum. Fossil fuel combustion from stationar> sources, such
as electricity generation, represents more than half of energy-relate 1 emissions,
while combustion of fossil fuels by mobile sources, such as automobiles, rep-
resents approximately one-third. In addition to fossil fuel combustion-relate J
activities, carbon dioxide is also emitted as a result of natural gas flaring and
biomass burning, and
methane is emitted
through coal mining
as well as the pro-
duction, processing,
transmission, and dis-
tribution of natural gas
and petroleum.

Industrial  Processes

Industrial processes emit greenhouse gases as a by-product of various non-
energy related industrial activities. Manufacture of cement, lime, soda ash,
iron, steel, aluminum, ammonia, titanium dioxide, and ferroalloys produces
carbon dioxide as a by-product. The consumption of limestone, dolomite, and
carbon dioxide as raw materials in industrial applications also releases carbon
dioxide emissions. The production of petrochemicals and silicon carbide result
in small amounts of methane emissions, while producing nitric and adipic acid
generates nitrous oxide emissions. Emissions of HFCs, PFCs, and SF6 are
particularly important as substitutes for ozone-depleting substances such as
chlorofluorocarbons (CFCs). These gases may also be emitted as a result of
aluminum and HCFC-22 production, semiconductor manufacturing, electrical
transmission and distribution, and magnesium production and processing.

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Agriculture
Agricultural activities contribute directly to emissions of methane and nitrous
oxide. The majority of nitrous oxide emissions occur because cropping and
fertilizer practices increase the quantity of reactive nitrogen in the soils. This
occurs through application of commercial fertilizers, livestock manure, and sewage
sludge; production of nitrogen-fixing crops and forages; retention of crop residues
on the field; and the cultivation of soils high in organic matter. These activities
make more nitrogen available for the generation of nitrous oxide through micro-
bial activity. The normal digestive processes in ruminant livestock (known as
enteric fermentation) account for the largest portion of methane emissions. The
agriculture sector also emits  methane and nitrous oxide from managed and
unmanaged manure, rice cultivation, and the burning of agricultural residues.
                                                 Land-Use Change and Forestry
                                                 The natural carbon fluxes between biomass, soils, and the
                                                 atmosphere change when humans alter the terrestrial biosphere
                                                 through land-use, changes in land-use, and forest management
                                                 practices. Various forest, agricultural soil, and land management
                                                 practices can result in the uptake (i.e., sequestration) or emission
                                                 of carbon dioxide. If these activities result in a net removal of
                                                 carbon dioxide (versus net emission), they can offset a portion
                                                 of total greenhouse gas emissions each year. Forestlands con-
                                                 tribute the most to the net uptake of carbon dioxide, followed
                                                 by agricultural soils.
                                                                         .

                                                                                                      j ~
                                                                                                      i

                                                 Waste
                                                 Waste management and treatment activities are another source of greenhouse gas
                                                 emissions in the United States. Landfills are the nation's largest source of anthro-
                                                 pogenic methane emissions. Wastewater treatment systems, including human
                                                 sewage treatment, are sources of methane and nitrous oxide emissions.

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To download a free copy of the current edition of
the Inventory, to download emissions data, or for
more information, visit our Web site at
www.epa.gov/globalwarming/publications/emissions
or contact:
U.S. Greenhouse Gas Inventory Program
ghginventory@epa.gov
To order a free copy of the current edition of the Inventory, order online at
http://yosemite.epa.gov/ncepihom/nsCatalog.nsf/SearchPubs or call (800) 490-9198.
Other Useful Links
U.S. EPA's Global Warming site
www.epa.gov/globalwarming

Intergovernmental Panel on Climate Change Web site
www.ipcc.ch

United Nations Framework Convention on Climate Change Web site
www.unfccc.de
                                                                                 United States
                                                                                 Environmental Protection
                                                                                 Agency
                                                                                 EPA 430-F-02-008      April 2002
                                                                                 Office of Air and Radiation (6204N)
                                                                                 Washington, DC 20460
                                                                                 Recycled/Recyclable
                                                                                 Printed with Vegetable Oil Based Inks on Recycled Paper
                                                                                 (Minimum 50% Postconsumer) Process Chlorine Free

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The U.S.  Inventory of Greenhouse
Gas Emissions and Sinks:
U.S. Greenhouse Gas Emissions and Sinks (Tg CO2 Equivalents)
^^^^^^^^^^^^^^•^^•^^•^^•^^•^1
C02 4,998.5 ; 4,943.2 ; 5,045.9 ; 5,157.3 ; 5,261.0 ; 5,305.9 ; 5,483.7 ;
Fossil Fuel Combustion 4,779.8 ; 4,733.0 ; 4,836.0 ; 4,950.9 ; 5,047.2 ; 5,085.0 ; 5,266.6 ;
Iron and Steel Production 85.4 ! 76.2 ! 75.0 ! 69.9 ! 73.6 ! 74.4 ! 68.3 !
Cement Manufacture 33.3 \ 32.5 \ 32.8 \ 34.6 \ 36.1 \ 36.8 \ 37.1 \
Indirect C02 Emissions 30.9 ! 30.7 ! 30.5 ! 29.5 ! 29.3 ! 29.5 ! 28.9 !
Waste Combustion 14.1 i 15.8 i 16.3 i 17.2 i 17.9 \ 18.6 i 19.6 \
Ammonia Manufacture 18.5 ; 18.7 ; 19.5 ; 18.7 ; 19.5 ; 18.9 ; 19.5 ;
Lime Manufacture 11.2 ; 11.0 ; 11.4 ; 11.6 ; 12.1 ; 12.8 ; 13.5 ;
Limestone and Dolomite Use 5.2 j 5.0 j 4.5 j 4.1 i 5.2 i 7.0 i 7.4 i
Natural Gas Flaring 5.5 \ 5.6 \ 5.1 \ 6.5 \ 6.6 \ 8.7 \ 8.2 \
Aluminum Production 6.3 ; 6.4 ; 6.3 ; 5.8 ; 5.1 ; 5.3 ; 5.6 ;
Soda Ash Manufacture and Consumption 4.1 i 4.0 i 4.1 i 4.0 i 4.0 i 4.3 i 4.2 i
Titanium Dioxide Production 1.3 ; 1.3 ; 1.5 ; 1.6 ; 1.7 ; 1.7 ; 1.7 ;
Ferroalloys 2.0 i 2.0 i 2.0 i 2.0 i 1.8 I 1.9 i 2.0 i
Carbon Dioxide Consumption 0.8 ; 0.8 ; 0.9 ; 0.9 j 0.9 i 1.0 i 1.1 i
Land-Use Change and Forestry (Sink)> (1,097.7) \ (1,085.6) \ (1,091.1) \ (1,113.8) \ (1,117.8) \ (1,110.0) \ (1,108.1) \
International Bunker Fuelsb 113.9 ! 119.9 ! 109.9 ! 99.8 ! 98.0 ! 101.0 ! 102.3 !
CH4 651.3 i 651.0 i 656.7 i 648.9 i 653.3 i 657.6 i 643.7 i
Landfills 213.4 i 213.2 i 215.8 i 217.8 i 217.8 i 216.6 i 211.5 i
Enteric Fermentation 127.9 i 127.2 i 130.2 i 128.5 i 130.1 i 133.2 i 129.6 i
Natural Gas Systems 121.2 ; 122.7 ; 124.5 ; 129.0 ; 127.3 ; 125.7 ; 126.6 ;
Coal Mining 87.1 ; 83.7 ; 81.4 ; 69.7 ; 70.3 ; 73.5 ; 68.4 ;
Manure Management 29.2 ; 31.1 j 30.7 ; 31.6 j 33.8 ; 34.8 ; 34.2 ;
Wastewater Treatment 24.3 \ 24.6 \ 25.2 \ 25.6 \ 26.2 \ 26.8 \ 27.0 \
Petroleum Systems 26.4 ; 26.8 ; 25.9 i 25.0 i 24.6 i 24.2 i 24.0 i
Stationary Sources 7.9 i 8.0 i 8.3 i 7.8 i 7.8 i 8.2 i 8.4 i
Rice Cultivation 7.1 ; 7.0 ; 7.9 ; 7.0 ; 8.2 ; 7.6 ; 7.0 ;
Mobile Sources 4.9 ; 4.9 ; 4.9 ; 4.9 ; 4.8 ; 4.8 ; 4.7 ;
Petrochemical Production 1.2 ; 1.2 ; 1.3 ; 1.4 ; 1.5 ; 1.5 ; 1.6 ;
Agricultural Residue Burning 0.7 j 0.6 j 0.8 j 0.6 j 0.8 j 0.7 j 0.7 j
Silicon Carbide Production +; +; +; +; +; + ; + ;
International Bunker Fuelsb 0.2 i 0.2 i 0.2 i 0.1 i 0.1 i 0.1 i 0.1 i
N20 387.3 ; 392.8 ; 402.7 ; 402.0 ; 428.7 ; 419.8 ; 430.5 ;
Agricultural Soil Management 267.1 ; 270.1 ; 278.0 ; 273.0 ; 295.1 ; 283.4 ; 292.6 ;
Mobile Sources 50.9 ! 53.2 ! 56.4 ! 58.5 ! 60.0 ! 60.4 ! 60.1 !
NitricAcid 17.8 j 17.8 j 18.3 j 18.6 j 19.6 j 19.9 j 20.7 j
Manure Management 16.0 ; 16.5 ; 16.3 ; 16.7 ; 16.7 ; 16.4 ; 16.8 ;
Stationary Sources 12.8 i 12.7 i 12.9 I 13.1 i 13.4 i 13.5 i 14.1 i
Human Sewage 7.0 ; 7.2 ; 7.3 ; 7.5 ; 7.7 ; 7.7 ; 7.8 ;
AdipicAcid 14.9 ; 14.7 ; 12.6 ; 13.9 ; 15.4 ; 17.9 ; 17.8 ;
Agricultural Residue Burning 0.4 ; 0.4 ; 0.4 ; 0.3 ; 0.5 ; 0.4 ; 0.4 ;
Waste Combustion 0.3 j 0.2 j 0.3 j 0.3 j 0.3 j 0.3 j 0.3 j
International Bunker Fuelsb 1.0 i 1.0 i 0.9 i 0.9 i 0.9 i 0.9 i 0.9 i
MFCs, PFCs, and SF6 93.6 i 88.1 i 89.4 i 94.0 i 92.8 i 98.5 i 111.9 i
Substitution of Ozone Depleting Subs 0.9 ; 0.8 i 1.5 i 5.2 ; 8.4 ; 21.8 i 30.6 ;
HCFC-22 Production 35.0 ; 30.8 ; 34.9 ; 31.8 ; 31.6 ; 27.0 ; 31.1 ;
Electrical Transmission and Distribution 31.2 j 32.5 j 30.2 j 34.1 i 31.4 i 26.5 i 26.8 i
Aluminum Production 18.1 \ 15.7 i 14.5 \ 13.9 i 12.2 i 11.8 j 12.5 i
Semiconductor Manufacture 2.9 i 2.9 i 2.9 i 3.6 i 3.9 i 5.9 ; 5.4 ;
Magnesium Production and Processing 5.5 ; 5.5 ; 5.5 ; 5.4 ; 5.2 ; 5.5 ; 5.5 ;
Total 6,130.7 i 6,075.2 i 6,194.8 i 6,302.2 i 6,435.7 i 6,481.8 i 6,669.8 i
Net Emission (Sources and Sinks) 5,033.0 i 4,989.6 i 5,103.6 i 5,188.4 i 5,317.9 i 5,371.8 i 5,561.7 i
^^m
5,568.0
5,339.6
76.1
38.3
28.4
21.3
19.5
13.7
8.4
7.6
5.6
4.4
1.8
2.0
1.3
(887.5)
109.9
633.3
206.4
126.8
122.7
68.1
35.8
27.5
24.0
7.5
7.5
4.6
1.6
0.8
+
0.1
429.8
297.5
59.7
21.2
17.1
14.2
7.9
11.5
0.4
0.3
1.0
116.9
38.0
30.0
24.5
11.0
6.5
6.9
6,748.1
5.860.5
^^M
5,575.1 ;
5,356.2 ;
67.4 !
39.2 j
28.2 !
20.3 i
20.1 ;
13.9 ;
8.2 !
6.3 j
5.8 !
4.3 i
1.8 !
2.0 j
1.4 i
(885.9) \
112.9 !
627.1 j
201.0 !
124.9 i
122.2 ;
67.9 ;
38.0 !
27.8 j
23.4 !
7.0 i
7.9 ;
4.5 ;
1.6 !
0.8 j
+ i
0.1 i
426.3 ;
298.4 ;
59.1 !
20.9 j
17.1 !
14.3 i
8.1 ;
7.7 ;
0.5 !
0.2 j
1.0 !
127.7 i
44.9 ;
40.2 ;
20.1 !
9.0 j
7.3 !
6.2 \
6,756.2 i
5.870.3 i
+ Does not exceed 0.05 Tg C02 Eq. Notes: Totals may not sum due to independent rounding. Emissions
^^^^^M
5,665.5 i 5,840.0
5,448.6 ! 5,623.3
64.4 ! 65.7
40.0 j 41.1
27.0 ! 26.3
21.8 I 22.5
18.9 \ 18.0
13.5 ! 13.3
9.1 ! 9.2
6.7 ! 6.1
5.9 ! 5.4
4.2 ! 4.2
1.9 I 2.0
2.0 I 1.7
1.6 ! 1.4
(896.4) ! (902.5)
105.3 ! 100.2
620.5 i 614.5
203.1 ! 203.5
124.5 i 123.9
118.6 I 116.4
63.7 ! 61.0
37.6 ! 37.5
28.3 j 28.7
22.3 I 21.9
7.3 ! 7.5
8.3 j 7.5
4.4 ! 4.4
1.7 I 1.7
0.8 j 0.8
+ i +
0.1 I 0.1
423.5 i 425.3
296.3 ! 297.6
58.7 ! 58.3
20.1 | 19.8
17.1 ! 17.5
14.6 ! 14.9
8.4 j 8.5
7.7 ! 8.1
0.4 ! 0.5
0.2 | 0.2
0.9 ! 0.9
120.0 ! 121.3
51.3 j 57.8
30.4 ! 29.8
15.5 ! 14.4
8.9 j 7.9
7.7 j 7.4
6.1 I 4.0
6,829.5 I 7,001.2
5,933.1 i 6,098.7

Change from 1990 to 2000
841.5 16.8%
843.4 17.6%
(19.7) -23.1%
7.8 23.4%
(4.6) -14.9%
8.4 59.5%
(0.5) -2.7%
2.1 18.5%
4.0 77.5%
0.5 j 9.9%
(0.9) -14.3%
0.0 i 0.9%
0.7 50.1%
(0.3) i -13.1%
0.6 ! 70.2%
195.3 -17.8%
(13.6) -12.0%
(36.8) -5.6%
(9.9) -4.7%
(4.0) -3.1%
(4.9) -4.0%
(26.2) j -30.0%
8.3 28.3%
4.5 18.4%
(4.6) -17.3%
(0.4) -5.0%
0.4 5.3%
(0.5) -10.9%
0.5 42.1%
0.1 14.8%
(0.0) -57.1%
(0.0) -26.4%
38.0 9.8%
30.5 j 11.4%
7.4 14.4%
1.9 j 10.9%
1.5 9.3%
2.1 16.5%
1.4 20.1%
(6.8) -45.6%
0.1 24.1%
(0.1) -20.7%
(0.1) -8.1%
27.7 29.6%
56.8 i 6025.4%
(5.2) -14.8%
(16.8) -53.7%
(10.2) -56.1%
4.5 157.5%
(1.5) -27.3%
870.5 i 14.2%
1 065 8 21 2%

a Sinks are only included in net emissions total. weighted using GWP values from IPCC Second Assessment Report (1996)
b Emissions from International Bunker Fuels are not included in totals. in keeping with UNFCCC reporting guidelines.
1990-2000 Trends



Annual Percent Change
• Total GHG emissions rose 1 4.2 percent since 1 990 (2.5 percent since 1 999)

• Dominant gas emitted was C02, mostly from fossil fuel combustion
• Methane emissions decreased by 5.6 percent
• Nitrous oxide emissions increased by 9.8 percent
• HFC, RFC, and SF6 emissions have grown by over 29.6 percent
U <3 J ~
U.S. GHG Emissions by Gas


• Carbon Dioxide • Methane
Nitrous Oxide • MFCs, PFCs, & SF6
8,000-
7,000 " K AR9 D,D/U ' ' •
£. 6 302 D,T"OD u,*rut. ^^^^^^ ^^^^^m ^^^^mm ^^^^^m
minimi
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000












1%
o
-1%






21%
2.0%
11.7% I
1 „„
-0.9%

T- oj co <3- un
O) O) O) O) Ol
O) O) O) O) O)



in U.S. GHG Emissions
2.9%

125%
1.2% 1.1% 1
0.1%


CD r — co O) o
O) O) O) O) O
O) O) O) O) O
T- T- T- T- OJ

U.S. Greenhouse Gas Emissions Per Capita
and Per Dollar of Gross Domestic Product


140 n
130 -
o
^ 120 -
II
1 110-
^ 100 '
c
90 -
80 -

" 	
O T- OJ CO <3-
O) O) O) O) O3


O) O) O) O)

RealGDj>
Population
Emissions per capita
*" «^^ Emissions
^^^^ per SGDP
LO CD [^ CO O) O
O) O) O) O) O) O
O) O) O) O) O) O

c/EPA
United States
Environmental Protection
Agency
Office of Air and Radiation (6204N) • EPA 430-F-02-008 • April 2002
Recycled/Recyclable
Printed with Vegetable Oil Based Inks on Recycled Paper
(Minimum 50% Postconsumer) Process Chlorine Free

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The U.S. Inventory of Greenhouse Gas Emissions and Sinks:

Global Warming Potentials
(100 Year Time Horizon)
the cumulative radiative forcing effects of a gas
Carbon dioxide (C02) 1 1 over a specified time horizon resulting from the
Methane (CH4)* 21 23 emission of a unit mass of gas relative to a
Nitrous oxide (N20) 310 296 reference gas. The GWP-weighted emissions of
HFC-23 11,700 12,000 direct greenhouse gases in the U.S. Inventory
HFC-125 2,800 3,400 are presented in terms of equivalent emissions
HFC-134a 1,300 1,300 of carbon dioxide (C02), using units of teragrams
HFC-143a 3,800 4,300 of carbon dioxide equivalents (Tg C02 Eq.).
HFC-152a 14° 12° Conversion-
HFC ??7pa 2 900 3 500 ^0™™
HFC-236fa 6,300 9,400 Tg = O^g = 10^ metric tons
HFC-4310mee 1,300 1,500 = 1 million metric tons
CF4 6,500 5,700 The molecular weight of carbon is 12, and
C2F6 9,200 1 1 ,900 the molecular weight of oxygen is 1 6; there-
C4F10 7,000 8,600 fore, the molecular weight of C02 is 44 (i.e.,
C6F14 7,400 9,000 12 + [16x2]), as compared to 12 for carbon
SF6 23,900 22,200 alone. Thus carbon comprises 12/44ths of
' IPCC Second Assessment Report (1996) carbon dioxide by weight.
b IPCC Third Assessment Report (2001)
Conversion from gigagrams of gas to teragrams
The methane GWP includes the direct effects ,. .,a
• !• i LL i !• i of rarhon nioxinp pnmva pnt^1
and those indirect effects due to the production of ul Udluun UIUAIUK equivalent.
tropospheric ozone and stratospheric water vapor.
The indirect effect due to the production of C02 is / r_ \ / Tn \
nntinrlnHoH Tn PO Fn — 1 "9 lYfGWPlYI U 1
lguU2tq- UgasJX(bWK)Xl10oOGa/
Note: GWP values from the IPCC Second
Assessment Report are used in accordance with
UNFCCC guidelines

Guide to Metric Unit Prefixes
Atto(a) 1018 .000000000000000001
FemtO (f) 1 0 15 .000000000000001
Pico(p) 1012 .000000000001
Nano (n) 1 0~9 .000000001
Micro(^) 10-6 .000001
Milli(m) 10-3 .001
Centi (c) 10-2 .01
Deci (d) 10-1 -1
Deca (da) 10 10
Hecto (h) 102 100
Kilo(k) 103 ,000
Mega(M) 106 ,000,000
Giga(G) 109 ,000,000,000
Tera(T) 1012 ,000,000,000,000
Peta(P) 1015 ,000,000,000,000,000
Exa(E) 1018 ,000,000,000,000,000,000

Unit Conversions
^H 1 pound = 0.454 kilograms =16 ounces
^^^^H 1 kilogram = 2.205 pounds =35. 27 ounces
^^^H 1 short ton = 0.9072 metric tons =2,000 pounds
^^^^H 1 metric ton = 1.1 023 short tons = 1,000 kilograms
... „ noooo , . 00 0, ro ...
^^^^H 1 cubic meter = 35.315 cubic feet =1,000 liters
1 1 U.S. gallon = 3.78541 liters = 0.03175 barrels = 0.02381 barrels petroleum
I 1 liter = 0.2642 U.S. gallons = 0.0084 barrels = 0.0063 barrels petroleum
^^^H 1 barrel = 31.5 U.S. gallons =119 liters = 0.75 barrels petroleum
^^^^H 1 barrel petroleum = 42 U.S. gallons =159 liters
• 1 foot = 0.3048 meters = 1 2 inches
^gjjj^g 1 mj|e = 1.609 kilometers =5,280feet
^H 1 kilometer =0.6214 miles = 3,280.84 feet
• 1 square mile = 2. 590 square kilometers =640 acres
1 square kilometer = 0.386 square miles =100 hectares
• .1acre = 43, 560 square feet = 0.4047 hectares = 4,047 square meters


Energy Conversions 2388xio calories
The common energy unit used in 23 88 metric tons of cmde oN equiva|ent
international reports of greenhouse g 478x-| Q8 gtu
gas emissions is the joule. A joule 277j800 ki|owatt_hours
is the energy required to move an
object one meter with the force of Energy Units
one Newton. A terajoule (TJ) is one Btu British therma| unit ^ Btu
trillion (1012) joules. A British thermal MBtu Thousand Btu 1x103Btu
unit (Btu, the customary U.S. energy MMBtu Million Btu 1x106Btu
unit) is the quantity of heat required BBtu BillionBtu 1x109Btu
to raise the temperature of one pound fBtu Trillion Btu 1x1 012 Btu
of water one degree Fahrenheit at or QBtu Quadrillion Btu 1x1 015 Btu
near 39.2 Fahrenheit.
Qnnrrp fnr all Hata- // Q Inventnrv nf Rreenhnuze Kx Fmiffinnf anH Q/'nte 1QQH 7nnn (TPA 9009



fm°m cIS'SHoi Fuel Combusted x Carbon Content Coefficient
TomSlS x Fraction Oxidized x (44/1 2)
May include adjustments for carbon stored in fossil fuel-based products,
emissions from international bunker fuels, or emissions from territories
Carbon Intensity of Different Fuel Types
The amount of carbon in fossil fuels per unit of energy content varies significantly by fuel type.
For example, coal contains the highest amount of carbon per unit of energy, while petroleum
has about 25 percent less carbon than coal, and natural gas about 45 percent less.


Converting Various Physical Units to Energy Units
The values in the following table provide conversion factors from physical units to energy
equivalent units and from energy units to carbon contents. These factors can be used as
default factors, if local data are not available.
Conversion Factors to Energy Units (Heat Equivalents)
Heat Contents and Carbon Content Coefficients of Various Fuel Types
• Carbon Content Coefficients Fraction
Fuel Type Heat Content (Tg Carbon/EJ) Oxidized
Solid Fuels (TJ/Gg)
Anthracite Coal 24.94 25.46 0.99
Bituminous Coal 26.39 24.51 0.99
Sub-bituminous Coal 18.94 24.89 0.99
Lignite 14.21 26.22 0.99
Coke 27.40 24.23 0.99
Unspecified 27.62 24.40 0.99
Gas Fuels (MJ/Cubic Meter)
Natural Gas (dry) 36.37 13.71 0.995
Liquid Fuels (MJ/Liter)
Crude Oil 34.64 19.14 0.99
Nat Gas Liquids and LRGs 22.56 16.10 0.99
Other Liquids 34.79 19.14 0.99
Motor Gasoline 31.37 18.35 0.99
Aviation Gasoline 30.15 17.89 0.99
Kerosene 33.86 18.69 0.99
Jet Fuel 33.86 18.32 0.99
Distillate Fuel 34.79 18.91 0.99
Residual Oil 37.55 20.37 0.99
Naptha for Petrofeed 31.34 17.19 0.99
Petroleum Coke 35.98 26.40 0.99
Other Oil for Petrofeed 34.79 18.91 0.99
Special Napthas 31.34 18.82 0.99
Lubricants 36.22 19.18 0.99
Waxes 33.07 18.78 0.99
AsphalVRoad Oil 39.63 19.54 0.99
Still Gas 35.83 16.60 0.99
Misc. Products 34.61 19.14 0.99
Notes: For fuels with annually variable heat contents and carbon content coefficients, 1 999 U.S. average values
are presented. U.S. fossil fuel energy statistics are generally presented using gross calorific values (GCV)
(i.e., higher heating values). However, this data has been adjusted to correspond to international standards,
which are to report energy statistics in terms of net calorific values (NCV) (i.e., lower heating values). To convert
between gross and net calorific values while accounting for heat associated with the water content of the fuels, the
heat content of solid and liquid fuels was multiplied by 0.95, and the heat content of gaseous fuels was multi-
plied by 0.90. Dividing by these values will convert from NCV back to GCV.
Density Conversions
Methane (Natural Gas) 1 cubic meter 35.32 cubic feet 0.676 kilograms
Carbon dioxide 1 cubic meter 35.32 cubic feet 1.854 kilograms
Natural gas liquids 1 metric ton 11. 60 barrels 1,844.20 liters
Unfinished oils 1 metric ton 7.46 barrels 1,186.04 liters
Alcohol 1 metric ton 7.94 barrels 1,262.36 liters
Liquefied petroleum gas 1 metric ton 11. 60 barrels 1,844.20 liters
Aviation gasoline Imetricton 8.90 barrels 1,415.00 liters
Naphtha jet fuel Imetricton 8.27 barrels 1,314.82 liters
Kerosene jet fuel Imetricton 7.93 barrels 1,260.72 liters
Motor gasoline Imetricton 8.53 barrels 1,356.16 liters
Kerosene Imetricton 7.73 barrels 1,228.97 liters
Naphtha Imetricton 8.22 barrels 1,306.87 liters
Residual oil Imetricton 6.66 barrels 1,058.85 liters
Lubricants Imetricton 7.06 barrels 1,122.45 liters
Bitumen Imetricton 6.06 barrels 963.46 liters
Waxes Imetricton 7.87 barrels 1,251.23 liters
Petroleum coke Imetricton 5.51 barrels 876.02 liters
Petrochemical feedstocks Imetricton 7.46 barrels 1,186.04 liters
Special naphtha Imetricton 8.53 barrels 1,356.16 liters
Miscellaneous products Imetricton = 8.00 barrels = 1,271.90 liters
Note: Gas densities are at room temperature and pressure.
For more information on calculating C02
emissions per kWh, download E-GRID at: http://www.epa.gov/a.rmarkets/egr,d/
For other related information, see: http://www.epa.gov/globalwarming
http://www.unfcc.de
                    Download the Inventory at: http://www.epa.gov/globalwarming/publications/emissions

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