United States
Environmental Protection
Agency
April 2010
Inventory of U.S. Greenhouse Gas Emissions and Sinks.
1990-2008
Executive
Summary
An emissions inventory that identifies and quantifies a country's primary anthropogenic1 sources and sinks of
greenhouse gases is essential for addressing climate change. This inventory adheres to both (1) a comprehensive
and detailed set of methodologies for estimating sources and sinks of anthropogenic greenhouse gases, and (2)
a common and consistent mechanism that enables Parties to the United Nations Framework Convention on Climate Change
(UNFCCC) to compare the relative contribution of different emission sources and greenhouse gases to climate change.
In 1992, the United States signed and ratified the UNFCCC. As stated in Article 2 of the UNFCCC, "The ultimate objective
of this Convention and any related legal instruments that the Conference of the Parties may adopt is to achieve, in accordance
with the relevant provisions of the Convention, stabilization of greenhouse gas concentrations in the atmosphere at a level
that would prevent dangerous anthropogenic interference with the
climate system. Such a level should be achieved within a time-
frame sufficient to allow ecosystems to adapt naturally to climate
change, to ensure that food production is not threatened and to
enable economic development to proceed in a sustainable manner."2
Parties to the Convention, by ratifying, "shall develop.
periodically update, publish and make available...national
All material taken from Vne Inventory of U.S.
Greenhouse Gas Emissions and Sinks:
1990-2008, U.S. Environmental Protection
Agency, Office of Atmospheric Programs,
EPA 430-R-10-006, April 2010. You may -—-—--»-. — -- ----- -— -
inventories of anthropogenic emissions by sources and removals
by sinks of all greenhouse gases not controlled by the Montreal
Protocol, using comparable methodologies..."3 The United
States views the Inventory report as an opportunity to fulfill
these commitments.
electronically download the full Inventory
report from U.S. EPA's Climate Change
web page at: www.epa.gov/climatechange/
emissions/usinventoryreport.html.
This chapter summarizes the latest information on U.S.
anthropogenic greenhouse gas emission trends from 1990 through
2008. To ensure that the U.S. emissions inventory is comparable to those of other UNFCCC Parties, the estimates presented
here were calculated using methodologies consistent with those recommended in the Revised 1996 IPCC Guidelines
for National Greenhouse Gas Inventories (IPCC/UNEP/OECD/IEA 1997), the IPCC Good Practice Guidance and
Uncertainty Management in National Greenhouse Gas Inventories (IPCC 2000), and the IPCC Good Practice Guidance
for Land Use, Land-Use Change, and Forestry (IPCC 2003). Additionally, the U.S. emissions inventory has begun to
incorporate new methodologies and data from the 2006 IPCC Guidelines for National Greenhouse Gas Inventories (IPCC
1 The term "anthropogenic", in this context, refers to greenhouse gas emissions and removals that are a direct result of human activities or are the result
of natural processes that have been affected by human activities (IPCC/UNEP/OECD/IEA 1997).
2 Article 2 of the Framework Convention on Climate Change published by the UNEP/WMO Information Unit on Climate Change. See .
3 Article 4(1 )(a) of the United Nations Framework Convention on Climate Change (also identified in Article 12). Subsequent decisions by the Conference
of the Parties elaborated the role of Annex I Parties in preparing national inventories. See .
Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008 1
-------
Box ES-1: Recalculations of Inventory Estimates
Each year, emission and sink estimates are recalculated and revised for all years in the Inventory of U.S. Greenhouse Gas Emissions and
Sinks as attempts are made to improve both the analyses themselves, through the use of better methods or data, and the overall usefulness
of the report. In this effort, the United States follows the IPCC Good Practice Guidance (IPCC 2000), which states, regarding recalculations
of the time series, "It is good practice to recalculate historic emissions when methods are changed or refined, when new source categories
are included in the national inventory, or when errors in the estimates are identified and corrected." In general, recalculations are made to
the U.S. greenhouse gas emission estimates either to incorporate new methodologies or, most commonly, to update recent historical data.
In each Inventory report, the results of all methodology changes and historical data updates are presented in the "Recalculations and
Improvements" chapter; detailed descriptions of each recalculation are contained within each source's description contained in the report, if
applicable. In general, when methodological changes have been implemented, the entire time series (in the case of the most recent inventory
report, 1990 through 2007) has been recalculated to reflect the change, per IPCC Good Practice Guidance. Changes in historical data are
generally the result of changes in statistical data supplied by other agencies. References for the data are provided for additional information.
2006). The structure of this report is consistent with the
UNFCCC guidelines for inventory reporting.4 For most
source categories, the Intergovernmental Panel on Climate
Change (IPCC) methodologies were expanded, resulting in
a more comprehensive and detailed estimate of emissions.
ES.1. Background Information
Naturally occurring greenhouse gases include water
vapor, carbon dioxide (CO2), methane (CH4), nitrous oxide
(N2O), and ozone (O3). Several classes of halogenated
substances that contain fluorine, chlorine, or bromine are also
greenhouse gases, but they are, for the most part, solely a
product of industrial activities. Chlorofluorocarbons (CFCs)
and hydrochlorofluorocarbons (HCFCs) are halocarbons that
contain chlorine, while halocarbons that contain bromine
are referred to as bromofluorocarbons (i.e., halons). As
stratospheric ozone depleting substances, CFCs, HCFCs.
and halons are covered under the Montreal Protocol on
Substances that Deplete the Ozone Layer. The UNFCCC
defers to this earlier international treaty. Consequently.
Parties to the UNFCCC are not required to include these
gases in their national greenhouse gas emission inventories.5
Some other fluorine-containing halogenated substances—
hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and
sulfur hexafluoride (SF6)—do not deplete stratospheric ozone
but are potent greenhouse gases. These latter substances are
addressed by the UNFCCC and accounted for in national
greenhouse gas emission inventories.
4 See .
5 Emissions estimates of CFCs, HCFCs, halons and other ozone-depleting
substances are included in the annexes of the Inventory report for
informational purposes.
There are also several gases that do not have a direct
global warming effect but indirectly affect terrestrial and/or
solar radiation absorption by influencing the formation or
destruction of greenhouse gases, including tropospheric and
stratospheric ozone. These gases include carbon monoxide
(CO), oxides of nitrogen (NOX), and non-CH4 volatile organic
compounds (NMVOCs). Aerosols, which are extremely small
particles or liquid droplets, such as those produced by sulfur
dioxide (SO2) or elemental carbon emissions, can also affect
the absorptive characteristics of the atmosphere.
Although the direct greenhouse gases CO2, CH4, and
N2O occur naturally in the atmosphere, human activities
have changed their atmospheric concentrations. From
the pre-industrial era (i.e., ending about 1750) to 2005.
concentrations of these greenhouse gases have increased
globally by 36, 148, and 18 percent, respectively (IPCC
2007).
Beginning in the 1950s, the use of CFCs and other
stratospheric ozone depleting substances (ODS) increased
by nearly 10 percent per year until the mid-1980s, when
international concern about ozone depletion led to the
entry into force of the Montreal Protocol. Since then, the
production of ODS is being phased out. In recent years, use
of ODS substitutes such as HFCs and PFCs has grown as
they begin to be phased in as replacements for CFCs and
HCFCs. Accordingly, atmospheric concentrations of these
substitutes have been growing (IPCC 2007).
Global Warming Potentials
Gases in the atmosphere can contribute to the greenhouse
effect both directly and indirectly. Direct effects occur when
the gas itself absorbs radiation. Indirect radiative forcing
occurs when chemical transformations of the substance
2 Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008
-------
produce other greenhouse gases, when a gas influences
the atmospheric lifetimes of other gases, and/or when a
gas affects atmospheric processes that alter the radiative
balance of the earth (e.g., affect cloud formation or albedo).6
The IPCC developed the Global Warming Potential (GWP)
concept to compare the ability of each greenhouse gas to trap
heat in the atmosphere relative to another gas.
The GWP of a greenhouse gas is defined as the ratio of
the time-integrated radiative forcing from the instantaneous
release of 1 kilogram (kg) of a trace substance relative to
that of 1 kg of a reference gas (IPCC 2001). Direct radiative
effects occur when the gas itself is a greenhouse gas. The
reference gas used is CO2, and therefore GWP-weighted
emissions are measured in teragrams (or million metric tons)
of CO2 equivalent (Tg CO2 Eq.).7'8 All gases in this Executive
Summary are presented in units of Tg CO2 Eq.
The UNFCCC reporting guidelines for national
inventories were updated in 2006,9 but continue to require
the use of GWPs from the IPCC Second Assessment Report
(SAR) (IPCC 1996). This requirement ensures that current
estimates of aggregate greenhouse gas emissions for 1990
to 2008 are consistent with estimates developed prior to the
publication of the IPCC Third Assessment Report (TAR)
and the IPCC Fourth Assessment Report (AR4). Therefore,
to comply with international reporting standards under
the UNFCCC, official emission estimates are reported by
the United States using SAR GWP values. All estimates
are provided throughout the inventory report in both CO2
equivalents and unweighted units. A comparison of emission
values using the SAR GWPs versus the TAR and AR4 GWPs
can be found in Chapter 1 and, in more detail, in Annex 6.1 of
the inventory report. The GWP values used in the inventory
report are listed in Table ES-1.
Global warming potentials are not provided for CO,
NOX, NMVOCs, SO2, and aerosols because there is no
agreed-upon method to estimate the contribution of gases
that are short-lived in the atmosphere, spatially variable, or
have only indirect effects on radiative forcing (IPCC 1996).
Table ES-1: Global Warming Potentials (100-Year Time
Horizon) Used in the Inventory Report
6 Albedo is a measure of the Earth's reflectivity, and is defined as the fraction
of the total solar radiation incident on a body that is reflected by it.
7 Carbon comprises 12/44ths of carbon dioxide by weight.
8 One teragram is equal to 1012 grams or one million metric tons.
9 See .
Gas
C02
CH4*
N20
HFC-23
HFC-32
HFC-125
HFC-134a
HFC-143a
HFC-152a
HFC-227ea
HFC-236fa
HFC-4310mee
CF4
C2F6
C^F-io
C6Fi4
SF6
GWP
1
21
310
11,700
650
2,800
1,300
3,800
140
2,900
6,300
1,300
6,500
9,200
7,000
7,400
23,900
Source: IPCC (1996)
* The CH4 GWP includes the direct effects and those indirect effects due
to the production of tropospheric ozone and stratospheric water vapor.
The indirect effect due to the production of C02 is not included.
ES.2. Recent Trends in U.S.
Greenhouse Gas Emissions
and Sinks
In 2008, total U.S. greenhouse gas emissions were
6,956.8 Tg CO2 Eq. Overall, total U.S. emissions have risen
by approximately 14 percent from 1990 to 2008. Emissions
declined from 2007 to 2008, decreasing by 2.9 percent
(211.3 Tg CO2 Eq.). This decrease is primarily a result of a
decrease in demand for transportation fuels associated with
the record high costs of these fuels that occurred in 2008.
Additionally, electricity demand declined in 2008 in part due
to a significant increase in the cost of fuels used to generate
electricity. In 2008, temperatures were cooler in the United
States than in 2007, both in the summer and the winter.
This lead to an increase in heating related energy demand
in the winter; however, much of this increase was off set by a
decrease in cooling-related electricity demand in the summer.
Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008 3
-------
Figure ES-1 through Figure ES-3 illustrate the overall
trends in total U.S. emissions by gas, annual changes, and
absolute change since 1990. Table ES-2 provides a detailed
summary of U.S. greenhouse gas emissions and sinks for
1990 through 2008.
Figure ES-4 illustrates the relative contribution of the
direct greenhouse gases to total U.S. emissions in 2008.
The primary greenhouse gas emitted by human activities
in the United States was CO2, representing approximately
85.1 percent of total greenhouse gas emissions. The largest
source of CO2, and of overall greenhouse gas emissions.
was fossil fuel combustion. CH4 emissions, which have
declined by 5.5 percent since 1990, resulted primarily from
enteric fermentation associated with domestic livestock.
decomposition of wastes in landfills, and natural gas systems.
Agricultural soil management and mobile source fuel
combustion were the major sources of N2O emissions. Ozone
depleting substance substitute emissions and emissions of
HFC-23 during the production of HCFC-22 were the primary
contributors to aggregate HFC emissions. PFC emissions
resulted as a by-product of primary aluminum production
and from semiconductor manufacturing, while electrical
transmission and distribution systems accounted for most
SF6 emissions.
Overall, from 1990 to 2008 total emissions of CO2
increased by 820.4 Tg CO2 Eq. (16.1 percent), while CH4 and
N2O emissions decreased by 45.8 Tg CO2 Eq. (7.5 percent)
and 4.1 Tg CO2 Eq. (1.3 percent), respectively. During the
same period, aggregate weighted emissions of HFCs, PFCs,
and SF6 rose by 59.4 Tg CO2 Eq. (65.9 percent). From 1990
to 2008, HFCs increased by 90.0 Tg CO2 Eq. (243.7 percent),
PFCs decreased by 14.1 Tg CO2 Eq. (67.8 percent), and
SF6 decreased by 16.5 Tg CO2 Eq. (50.5 percent). Despite
being emitted in smaller quantities relative to the other
principal greenhouse gases, emissions of HFCs, PFCs,
and SF6 are significant because many of these gases have
extremely high global warming potentials and, in the cases
of PFCs and SF6, long atmospheric lifetimes. Conversely,
U.S. greenhouse gas emissions were partly offset by carbon
sequestration in forests, trees in urban areas, agricultural
soils, and landfilled yard trimmings and food scraps, which,
in aggregate, offset 13.5 percent of total emissions in 2008.
The following sections describe each gas' contribution to
total U.S. greenhouse gas emissions in more detail.
Figure ES-1
U.S. Greenhouse Gas Emissions by Gas
8,000 -
7,000 -
6,000 -
£ 5,000 -
o
|> 4,000 -
3,000 -
2,000 -
1,000-
HFCs, PFCs, & SF,
Nitrous Oxide
Methane
I Carbon Dioxide
Figure ES-2
Annual Percent Change in U.S. Greenhouse Gas Emissions
3%-
2%-
1%-
0%
-1% -
-2% -
-3% -
1?%1,%160/
Illiliiil •-•• I
i
ii
-2.9%
CM co ^ in to r- oo
Figure ES-3
Cumulative Change in Annual U.S. Greenhouse Gas
Emissions Relative to 1990
1,100
1,000
900
800
7°°
"1 600
500
400
300
200
100
-100
918
969
1,006
1,041
840
. -38
4 Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008
-------
Table ES-2: Recent Trends in U.S. Greenhouse Gas Emissions and Sinks (Tg C02 Eq. or million metric tons C02 Eq.)
Gas/Source
1990
1995
2000
2005
2006
2007
2008
C02
Fossil Fuel Combustion
Electricity Generation
Transportation
Industrial
Residential
Commercial
U.S. Territories
Non-Energy Use of Fuels
Iron and Steel Production &
Metallurgical Coke Production
Cement Production
Natural Gas Systems
Lime Production
Incineration of Waste
Ammonia Production and Urea
Consumption
Cropland Remaining Cropland
Limestone and Dolomite Use
Aluminum Production
Soda Ash Production and
Consumption
Petrochemical Production
Titanium Dioxide Production
Carbon Dioxide Consumption
Ferroalloy Production
Phosphoric Acid Production
Wetlands Remaining Wetlands
Petroleum Systems
Zinc Production
Lead Production
Silicon Carbide Production and
Consumption
Land Use, Land-Use Change,
and Forestry (Sink)*
Biomass - Woodb
International Bunker Fuelsb
Biomass - Ethanolb
CH4
Enteric Fermentation
Landfills
Natural Gas Systems
Coal Mining
Manure Management
Petroleum Systems
Wastewater Treatment
Forest Land Remaining Forest
Land
Rice Cultivation
Stationary Combustion
Abandoned Underground Coal
Mines
Mobile Combustion
5,100.8 5,427.3 5,977.2 6,108.4
4,735.71 5,029.5 5,593.41 5,753.3
1, 820.8 1 1,947.9 2,296.9 2,402.1
1,485.8 1,608.0 ! 1,809.5
845.4 862.6 852.2
339.1 353.3 371.2
216.7 ! 223.2 227.7
27.9 34.5 35.9
119.6 142.9 146.1
102.6
33.3
37.3
11.5
8.0
16.8
7.1
5.1
6.8
4.1
3.3
1.2
1.4
2.2
1.5
1.0
0.6
0.9
0.3
95.7
36.8
42.2
13.3
11.5
17.8
7.0
6.7
5.7
4.3
4.1
1.5
1.4
2.0
1.5
1.0
0.5
1.0
0.3
0.4 0.3
88.1
41.2
29.4
14.1
11.3
16.4
7.5
5.1
6.1
4.2
4.5
1.8
1.4
1.9
1.4
1.2
0.5
1.1
0.3
0.2
(909.4) (842.9) 1 (664.2)
215.2 229.1 218.1
111.8
4.2
613.4
132.4
149.3
129.5
84.1
29.3
33.9
23.5
3.2
7.1
7.4
6.0
99.8 98.5
7.7 9.2
613.2 586.0
143.7 136.8
144.1 120.7
132.6 130.7
67.1 60.4
33.9 38.6
32.0 30.2
24.8 1 25.2
4.3 14.3
7.6 7.5
7.1 6.6
8.2 1 7.4
4.7 4.3 3.4
1,895.3
825.6
358.4
221.3
50.6
136.5
67.7
45.9
29.5
14.4
12.6
12.8
7.9
6.8
4.1
4.2
4.2
1.8
1.3
1.4
1.4
1.1
0.5
0.5
0.3
0.2
(950.4)
206.9
110.5
22.6
553.2
136.7
125.6
103.6
56.9
42.2
28.2
24.3
9.8
6.8
6.6
5.6
2.5
6,017.2
5,652.8
2,346.4
1,876.7
850.7
322.1
206.0
50.9
141.4
70.5
46.6
29.5
15.1
12.7
12.3
7.9
8.0
3.8
4.2
3.8
1.8
1.7
1.5
1.2
0.9
0.5
0.5
0.3
0.2
(959.2)
207.9
129.1
30.5
568.2
139.0
127.1
103.1
58.3
42.3
28.2
24.5
21.6
5.9
6.2
5.5
2.3
6,120.2
5,757.0
2,412.8
1,893.7
842.2
341.7
217.4
49.1
135.3
72.8
45.2
30.8
14.6
13.3
14.0
8.3
7.7
4.3
4.1
3.9
1.9
1.9
1.6
1.2
1.0
0.5
0.4
0.3
0.2
(955.4)
207.4
127.1
38.3
569.2
141.2
126.5
99.5
58.1
45.9
28.8
24.4
20.0
6.2
6.5
5.7
2.2
5,921.2
5,572.8
2,363.5
1,785.3
819.3
342.7
219.5
42.5
134.2
69.0
41.1
30.0
14.3
13.1
11.8
7.6
6.6
4.5
4.1
3.4
1.8
1.8
1.6
1.2
0.9
0.5
0.4
0.3
0.2
(940.3)
198.4
135.2
53.3
567.6
140.8
126.3
96.4
67.6
45.0
29.1
24.3
11.9
7.2
6.7
5.9
2.0
Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008 5
-------
Table ES-2: Recent Trends in U.S. Greenhouse Gas Emissions and Sinks (Tg C02 Eq. or million metric tons C02 Eq.)
(continued)
Gas/Source
1990
1995
2000
2005
2006
2007
2008
Composting
Field Burning of Agricultural
Residues
Petrochemical Production
Iron and Steel Production &
Metallurgical Coke Production
Ferroalloy Production
Silicon Carbide Production and
Consumption
Incineration of Waste
International Bunker Fuelsb
N20
Agricultural Soil Management
Mobile Combustion
Nitric Acid Production
Manure Management
Stationary Combustion
Forest Land Remaining Forest
Land
Wastewater Treatment
N20 from Product Uses
Adipic Acid Production
Composting
Settlements Remaining
Settlements
Field Burning of Agricultural
Residues
Incineration of Waste
Wetlands Remaining Wetlands
International Bunker Fuels'3
MFCs
Substitution of Ozone Depleting
Substances0
HCFC-22 Production
Semiconductor Manufacture
PFCs
Aluminum Production
Semiconductor Manufacture
SF6
Electrical Transmission and
Distribution
Magnesium Production and
Processing
Semiconductor Manufacture
0.3
0.8
0.9
1.0
+
+
+
0.2
322.3
203.5
43.9
18.9
14.4
12.8
2.7
3.7
4.4
15.8
0.4
1.0
0.4
0.7
0.7
1.1
1.0
+
+
+
0.1
342.5
205.9
54.0
21.0
15.5
13.3
3.7
4.0
4.6
17.6
0.8
1.2
0.4
0.5 0.5
+ 1 +
Lit 0.9
36.9 62.2
0.3 29.0
36.4 33.0
0.2 0.3
20.8 15.6
18.5 11.8
2.2 3.8
32.6 27.9
26.6 21.4
5.4 5.6
1.3
0.9
1.2
0.9
+
+
+
0.1
345.5
210.1
53.2
20.7
16.7
14.5
12.1
4.5
4.9
5.5
1.4
1.1
0.5
0.4
+
0.9
103.2
74.3
28.6
0.3
13.5
8.6
4.9
19.1
15.0
3.0
1.6
0.9
1.1
0.7
+
+
+
0.1
328.3
215.8
36.9
17.6
16.6
14.7
8.4
4.7
4.4
5.0
1.7
1.5
0.5
0.4
+
1.0
119.3
103.2
15.8
0.2
6.2
3.0
3.2
17.8
14.0
2.9
0.5 0.9 1.1 1.0
1.6
0.9
1.0
0.7
+
+
+
0.2
329.5
211.2
33.6
17.2
17.3
14.5
18.0
4.8
4.4
4.3
1.8
1.5
0.5
0.4
+
1.2
121.8
107.7
13.8
0.3
6.0
2.5
3.5
17.0
13.2
2.9
1.0
1.7
1.0
1.0
0.7
+
+
+
0.2
327.7
211.0
30.3
20.5
17.3
14.6
16.7
4.9
4.4
3.7
1.8
1.6
0.5
0.4
+
1.2
127.4
110.1
17.0
0.3
7.5
3.8
3.6
16.1
12.7
2.6
0.8
1.7
1.0
0.9
0.6
+
+
+
0.2
318.2
215.9
26.1
19.0
17.1
14.2
10.1
4.9
4.4
2.0
1.8
1.6
0.5
0.4
+
1.2
126.9
113.0
13.6
0.3
6.7
2.7
4.0
16.1
13.1
2.0
1.1
Total
6,126.8 6,488.8
7,044.5
7,133.2 7,059.9 7,168.1
6,956.8
Net Emissions (Sources and Sinks) 5,217.3 5,646.0
6,380.2
6,182.8 6,100.7 6,212.7
6,016.4
+ Does not exceed 0.05 Tg C02 Eq.
a Parentheses indicate negative values or sequestration. The net C02 flux total includes
United States. Sinks are only included in net emissions total.
b Emissions from International Bunker Fuels and Biomass Combustion are not included
c Small amounts of RFC emissions also result from this source.
Note: Totals may not sum due to independent rounding.
both emissions and sequestration, and constitutes a sink in the
in totals.
6 Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008
-------
Figure ES-4
Figure ES-5
2008 Greenhouse Gas Emissions by Gas
(percents based on Tg C02 Eq.)
N20
4.6%
MFCs, PFCs,
&SF6
2.2%
Carbon Dioxide Emissions
The global carbon cycle is made up of large carbon
flows and reservoirs. Billions of tons of carbon in the form
of CO2 are absorbed by oceans and living biomass (i.e..
sinks) and are emitted to the atmosphere annually through
natural processes (i.e., sources). When in equilibrium, carbon
fluxes among these various reservoirs are roughly balanced.
Since the Industrial Revolution (i.e., about 1750), global
atmospheric concentrations of CO2 have risen about 36
percent (IPCC 2007), principally due to the combustion of
fossil fuels. Within the United States, fossil fuel combustion
accounted for 94.1 percent of CO2 emissions in 2008.
Globally, approximately 30,377 Tg of CO2 were added to the
atmosphere through the combustion of fossil fuels in 2008.
of which the United States accounted for about 19 percent.: °
Changes in land use and forestry practices can also emit
CO2 (e.g., through conversion of forest land to agricultural
or urban use) or can act as a sink for CO2 (e.g., through
net additions to forest biomass). In addition to fossil-fuel
combustion, several other sources emit significant quantities
of CO2. These sources include, but are not limited to non-
energy use of fuels, iron and steel production and cement
production (Figure ES-5).
As the largest source of U.S. greenhouse gas emissions.
CO2 from fossil fuel combustion has accounted for
approximately 79 percent of GWP-weighted emissions
since 1990, growing slowly from 77 percent of total GWP-
weighted emissions in 1990 to 80 percent in 2008. Emissions
10 Global CO2 emissions from fossil fuel combustion were taken from
Energy Information Administration International Energy Statistics 2009
< http://tonto.eia.doe.gov/cfapps/ipdbproject/IEDIndex3.cfm> EIA (2009).
2008 Sources of C02 Emissions
Fossil Fuel Combustion
Non-Energy Use of Fuels
Iron and Steel Production
& Metallurgical Coke Production
Cement Production
Natural Gas Systems
Lime Production
Incineration of Waste
Ammonia Production and
Urea Consumption
Cropland Remaining Cropland
Limestone and Dolomite Use
Aluminum Production
Soda Ash Production and Consumption
Petrochemical Production
Titanium Dioxide Production
Carbon Dioxide Consumption
Ferroalloy Production
Phosphoric Acid Production
Wetlands Remaining Wetlands I
Petroleum Systems I <0.5
Zinc Production
5,573
Lead Production
Silicon Carbide Production and
Consumption
<0.5
<0.5
<0.5
75 100
TgCO,Eq.
125 150
of CO2 from fossil fuel combustion increased at an average
annual rate of 1 percent from 1990 to 2008. The fundamental
factors influencing this trend include: (1) a generally growing
domestic economy over the last 19 years, and (2) significant
overall growth in emissions from electricity generation
and transportation activities. Between 1990 and 2008, CO2
emissions from fossil fuel combustion increased from 4,735.7
Tg CO2 Eq. to 5,572.8 Tg CO2 Eq.—an 18 percent total
increase over the nineteen-year period. From 2007 to 2008.
these emissions decreasedby 184.2 Tg CO2 Eq. (3.2 percent).
Historically, changes in emissions from fossil fuel
combustion have been the dominant factor affecting U.S.
emission trends. Changes in CO2 emissions from fossil fuel
combustion are influenced by many long-term and short-term
factors, including population and economic growth, energy
price fluctuations, technological changes, and seasonal
temperatures. On an annual basis, the overall consumption
of fossil fuels in the United States generally fluctuates in
response to changes in general economic conditions, energy
prices, weather, and the availability of non-fossil alternatives.
For example, in a year with increased consumption of
goods and services, low fuel prices, severe summer and
Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008 7
-------
winter weather conditions, nuclear plant closures, and lower
precipitation feeding hydroelectric dams, there would likely
be proportionally greater fossil fuel consumption than a
year with poor economic performance, high fuel prices.
mild temperatures, and increased output from nuclear and
hydroelectric plants.
The five major fuel consuming sectors contributing to
CO2 emissions from fossil fuel combustion are electricity
generation, transportation, industrial, residential, and
commercial. CO2 emissions are produced by the electricity
generation sector as they consume fossil fuel to provide
electricity to one of the other four sectors, or "end-use"
sectors. For the discussion below, electricity generation
emissions have been distributed to each end-use sector
on the basis of each sector's share of aggregate electricity
consumption. This method of distributing emissions assumes
that each end-use sector consumes electricity that is generated
from the national average mix of fuels according to their
carbon intensity. Emissions from electricity generation are
also addressed separately after the end-use sectors have
been discussed.
Note that emissions from U.S. territories are calculated
separately due to a lack of specific consumption data for the
individual end-use sectors.
Figure ES- 6, Figure ES- 7, and Table ES-3 summarize
CO2 emissions from fossil fuel combustion by end-use sector.
Transportation End-Use Sector. Transportation activities
(excluding international bunker fuels) accounted for 32
percent of CO2 emissions from fossil fuel combustion in
2008.n Virtually all of the energy consumed in this end-use
sector came from petroleum products. Nearly 53 percent
of the emissions resulted from gasoline consumption for
personal vehicle use. The remaining emissions came from
other transportation activities, including the combustion of
diesel fuel in heavy-duty vehicles and jet fuel in aircraft.
Industrial End-Use Sector. Industrial CO2 emissions.
resulting both directly from the combustion of fossil fuels
and indirectly from the generation of electricity that is
consumed by industry, accounted for 27 percent of CO2
from fossil fuel combustion in 2008. Approximately 54
percent of these emissions resulted from direct fossil fuel
11 If emissions from international bunker fuels are included, the
transportation end-use sector accounted for 35 percent of U.S. emissions
from fossil fuel combustion in 2008.
combustion to produce steam and/or heat for industrial
processes. The remaining emissions resulted from consuming
electricity for motors, electric furnaces, ovens, lighting, and
other applications.
Residential and Commercial End-Use Sectors. The
residential and commercial end-use sectors accounted for
21 and 19 percent, respectively, of CO2 emissions from
fossil fuel combustion in 2008. Both sectors relied heavily
on electricity for meeting energy demands, with 71 and
79 percent, respectively, of their emissions attributable to
electricity consumption for lighting, heating, cooling, and
Figure ES-6
2008 C02 Emissions from Fossil Fuel Combustion by
Sector and Fuel Type
2,500 -|
2,000 -
1,500 -
1,000 -
500 -
0 -1
Petroleum
2,363
• Coal MM
• Natural Gas
Relative Contribution -j ygg
by Fuel Type
• II
-••_•
Note: Electricity generation also includes emissions of less than 0.5 Tg C02 Eq. from
geothermal-based electricity generation.
Figure ES-7
2008 End-Use Sector Emissions of C02, CH4, and
N20 from Fossil Fuel Combustion
2,000 -,
^1,500 -
cT
u
i?
1,000 -
500 -
0 -
I From Direct Fossil
Fuel Combustion
I From Electricity
Consumption
1,050
1,818
1,518
1,193
43
U.S. Commercial Residential Industrial Transportation
Territories
8 Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008
-------
Table ES-3: C02 Emissions from Fossil Fuel Combustion by Fuel Consuming End-Use Sector (Tg C02 Eq.)
End-Use Sector
1990
1995
2000
2005
2006
2007
2008
Transportation
Combustion
Electricity
Industrial
Combustion
Electricity
Residential
Combustion
Electricity
Commercial
Combustion
Electricity
1,488.8
1,485.8
3.0
1,532.2
845.4
686.8
932.2
339.1
593.0
754.6
216.7
538.0
1,900.1
1,895.3
4.7
1,562.5
825.6
737.0
1,215.1
358.4
856.7
1,025.0
221.3
803.7
1,881.2
1,876.7
4.5
1,562.8
850.7
712.0
1,152.9
322.1
830.8
1,005.0
206.0
799.0
1,898.8
1,893.7
5.0
1,572.2
842.2
730.0
1,197.9
341.7
856.1
1,039.1
217.4
821.7
1,789.9
1,785.3
4.7
1,510.9
819.3
691.6
1,184.5
342.7
841.8
1,044.9
219.5
825.4
U.S. Territories3
27.9
34.5
35.9
50.6
50.9
49.1
42.5
Total
4,735.7
5,029.5
5,593.4
5,753.3 5,652.8 5,757.0 5,572.8
Electricity Generation 1,820.8
1,947.9
2,296.9
2,402.1 2,346.4 2,412.8
2,363.5
Note: Totals may not sum due to independent rounding. Combustion-related emissions from electricity generation are allocated based on aggregate
national electricity consumption by each end-use sector.
a Fuel consumption by U.S. territories (i.e., American Samoa, Guam, Puerto Rico, U.S. Virgin Islands, Wake Island, and other U.S. Pacific Islands) is
included in this report.
operating appliances. The remaining emissions were due to
the consumption of natural gas and petroleum for heating
and cooking.
Electricity Generation. The United States relies on
electricity to meet a significant portion of its energy demands.
especially for lighting, electric motors, heating, and air
conditioning. Electricity generators consumed 37 percent of
U.S. energy from fossil fuels and emitted 42 percent of the
CO2 from fossil fuel combustion in 2008. The type of fuel
combusted by electricity generators has a significant effect
on their emissions. For example, some electricity is generated
with low CO2 emitting energy technologies, particularly non-
fossil options such as nuclear, hydroelectric, or geothermal
energy. However, electricity generators rely on coal for over
half of their total energy requirements and accounted for 95
percent of all coal consumed for energy in the United States
in 2008. Consequently, changes in electricity demand have
a significant impact on coal consumption and associated
CO2 emissions.
Other significant CO2 trends included the following:
• CO2 emissions from non-energy use of fossil fuels
have increased 14.6 Tg CO2 Eq. (12.2 percent) from
1990 through 2008. Emissions from non-energy uses
of fossil fuels were 134.2 Tg CO2 Eq. in 2008, which
constituted 2.3 percent of total national CO2 emissions.
approximately the same proportion as in 1990.
CO2 emissions from iron and steel production and
metallurgical coke production decreased from 2007
to 2008 (3.8 Tg CO2 Eq.), continuing a trend of
decreasing emissions from 1990 through 2008 of 33
percent. This decline is due to the restructuring of the
industry, technological improvements, and increased
scrap utilization.
In 2008, CO2 emissions from cement production
decreased by 4.1 Tg CO2 Eq. (9.0 percent) from 2007.
After decreasing in 1991 by two percent from 1990
levels, cement production emissions grew every year
through 2006; emissions decreased in the last two years.
Overall, from 1990 to 2008, emissions from cement
production increased by 24 percent, an increase of 7.9
Tg CO2 Eq.
Net CO2 flux from Land Use, Land-Use Change, and
Forestry increased by 30.9 Tg CO2 Eq. (3 percent) from
1990 through 2008. This increase was primarily due
to an increase in the rate of net carbon accumulation
in forest carbon stocks, particularly in aboveground
and belowground tree biomass, and harvested wood
pools. Annual carbon accumulation in landfilled yard
trimmings and food scraps slowed over this period, while
the rate of carbon accumulation in urban trees increased.
Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008 9
-------
Methane Emissions
According to the IPCC, CH4 is more than 20 times as
effective as CO2 at trapping heat in the atmosphere. Over the
last two hundred and fifty years, the concentration of CH4
in the atmosphere increased by 148 percent (IPCC 2007).
Anthropogenic sources of CH4 include landfills, natural gas
and petroleum systems, agricultural activities, coal mining.
wastewater treatment, stationary and mobile combustion, and
certain industrial processes (see Figure ES- 8).
Some significant trends inU.S. emissions of CH4 include
the following:
• Enteric Fermentation is the largest anthropogenic source
of CH4 emissions in the United States. In 2008, enteric
fermentation CH4 emissions were 140.8 Tg CO2 Eq.
(25 percent of total CH4 emissions), which represents
an increase of 8.5 Tg CO2Eq. (6.4 percent) since 1990.
• Landfills are the second largest anthropogenic source
of CH4 emissions in the United States, accounting for
22 percent of total CH4 emissions (126.3 Tg CO2 Eq.)
in 2008. From 1990 to 2008, net CH4 emissions from
landfills decreased by 23.0 Tg CO2 Eq. (15 percent).
with small increases occurring in some interim years.
This downward trend in overall emissions is the result
of increases in the amount of landfill gas collected and
combusted,12 which has more than offset the additional
CH4 emissions resulting from an increase in the amount
of municipal solid waste landfilled.
• CH4 emissions from natural gas systems were 96.4 Tg
CO2 Eq. in 2008; emissions have declined by 33.1 Tg
CO2 Eq. (26 percent) since 1990. This decline is due to
improvements in technology and management practices.
as well as some replacement of old equipment.
• In 2008, CH4 emissions from coal mining were 67.6
Tg CO2 Eq., a 9.6 Tg CO2 Eq. (16 percent) increase
over 2007 emission levels. The overall decline of
16.4 Tg CO2 Eq. (20 percent) from 1990 results
from the mining of less gassy coal from underground
mines and the increased use of CH4 collected from
degasification systems.
• CH4 emissions from manure management increased
by 54 percent since 1990, from 29.3 Tg CO2 Eq. in
Figure ES-8
2008 Sources of CH4 Emissions
Enteric Fermentation
Landfills
Natural Gas Systems
Coal Mining
Manure Management
Petroleum Systems ^^|
Wastewater Treatment ^H
Forest Land Remaining Forest Land ^
Rice Cultivation |
Stationary Combustion |
Abandoned Underground Coal Mines |
Mobile Combustion
Composting
Field Burning of Agricultural Residues
Petrochemical Production
Iron and Steel Production
& Metallurgical Coke Production I
Ferroalloy Production | <0.5
Silicon Carbide Production and Consumption | <0.5
Incineration of Waste I <0.5
20 4G
60 80 100 120 140
Tg CO, Eq.
12 The CO2 produced from combusted landfill CH4 at landfills is not counted
in national inventories as it is considered part of the natural C cycle of
decomposition.
1990 to 45.0 Tg CO2 Eq. in 2008. The majority of this
increase was from swine and dairy cow manure, since
the general trend in manure management is one of
increasing use of liquid systems, which tends to produce
greater CH4 emissions. The increase in liquid systems is
the combined result of a shift to larger facilities, and to
facilities in the West and Southwest, all of which tend
to use liquid systems. Also, new regulations limiting
the application of manure nutrients have shifted manure
management practices at smaller dairies from daily
spread to manure managed and stored on site.
Nitrous Oxide Emissions
N2O is produced by biological processes that occur in
soil and water and by a variety of anthropogenic activities
in the agricultural, energy-related, industrial, and waste
management fields. While total N2O emissions are much
lower than CO2 emissions, N2O is approximately 300 times
more powerful than CO2 at trapping heat in the atmosphere.
Since 1750, the global atmospheric concentration of N2O has
risen by approximately 18 percent (IPCC 2007). The main
anthropogenic activities producing N2O in the United States
are agricultural soil management, fuel combustion in motor
vehicles, nitric acid production, stationary fuel combustion.
10 Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008
-------
manure management, and adipic acid production (see Figure
ES-9).
Some significant trends in U.S. emissions of N2O include
the following:
• Agricultural soils accounted for approximately 68
percent of N2O emissions in the United States in 2008.
Estimated emissions from this source in 2008 were 215.9
Tg CO2 Eq. Annual N2O emissions from agricultural
soils fluctuated between 1990 and 2008, although
overall emissions were 6.1 percent higher in 2008
than in 1990. N2O emissions from this source have not
shown any significant long-term trend, as they are highly
sensitive to the amount of N applied to soils (which has
not changed significantly over the time-period), and to
weather patterns and crop type.
• In 2008, N2O emissions from mobile combustion were
26.1 Tg CO2 Eq. (approximately 8 percent of U.S. N2O
emissions). From 1990 to 2008, N2O emissions from
mobile combustion decreased by 40 percent. However.
from 1990 to 1998 emissions increased by 26 percent.
due to control technologies that reduced NOX emissions
while increasing N2O emissions. Since 1998, newer
control technologies have led to a steady decline inN2O
from this source.
Figure ES-9
2008 Sources of N?0 Emissions
216
Agricultural Soil Management
Mobile Combustion
Nitric Acid Production
Manure Management
Stationary Combustion
Forest Land Remaining Forest Land
Wastewater Treatment ^^|
N20 from Product Uses ^H
Adipic Acid Production |
Composting |
Settlements Remaining Settlements I
Field Burning of Agricultural Residues
Incineration of Waste | <0.5
Wetlands Remaining Wetlands | <0.5
N20 as a Portion
of all Emissions
10
20 30
Tg C02 Eq.
40
• N2O emissions from adipic acid production were 2.0
Tg CO2 Eq. in 2008, and have decreased significantly
since 1996 from the widespread installation of pollution
control measures. Emissions from adipic acid production
have decreased by 87 percent since 1990, and emissions
from adipic acid production have remained consistently
lower than pre-1996 levels since 1998.
HFC, PFC, and SF6 Emissions
HFCs and PFCs are families of synthetic chemicals that
are used as alternatives to ODS, which are being phased out
under the Montreal Protocol and Clean Air Act Amendments
of 1990. HFCs and PFCs do not deplete the stratospheric
ozone layer, and are therefore acceptable alternatives under
the Montreal Protocol.
These compounds, however, along with SF6, are
potent greenhouse gases. In addition to having high
global warming potentials, SF6 and PFCs have extremely
long atmospheric lifetimes, resulting in their essentially
irreversible accumulation in the atmosphere once emitted.
Sulfur hexafluoride is the most potent greenhouse gas the
fPCC has evaluated.
Other emissive sources of these gases include HCFC-22
production, electrical transmission and distribution systems.
semiconductor manufacturing, aluminum production, and
magnesium production and processing (see Figure ES-10).
Some significant trends in U.S. HFC, PFC, and SF6
emissions include the following:
• Emissions resulting from the substitution of ODS (e.g..
CFCs) have been consistently increasing, from small
amounts in 1990 to 113.0 Tg CO2 Eq. in2008. Emissions
from ODS substitutes are both the largest and the fastest
growing source of HFC, PFC, and SF6 emissions. These
emissions have been increasing as phase-outs required
under the Montreal Protocol come into effect, especially
after 1994, when full market penetration was made
for the first generation of new technologies featuring
ODS substitutes.
• HFC emissions from the production of HCFC-22
decreased by 63 percent (22.8 Tg CO2 Eq.) from 1990
through 2008, due to a steady decline in the emission
rate of HFC-23 (i.e., the amount of HFC-23 emitted
per kilogram of HCFC-22 manufactured) and the use
Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008 11
-------
Figure ES-10
Figure ES-11
2008 Sources of MFCs, PFCs, and SF6 Emissions
Substitution of Ozone
Depleting Substances
HCFC-22 Production
Electrical Transmission
and Distribution
Aluminum Production
Magnesium Production |
and Processing
10
20 30
Tg C02 Eq.
40
50
of thermal oxidation at some plants to reduce HFC-23
emissions.
SF6 emissions from electric power transmission and
distribution systems decreased by 51 percent (13.6
Tg CO2 Eq.) from 1990 to 2008, primarily because of
higher purchase prices for SF6 and efforts by industry
to reduce emissions.
PFC emissions from aluminum production decreased by
85 percent (15.8 Tg CO2 Eq.) from 1990 to 2008, due
to both industry emission reduction efforts and lower
domestic aluminum production.
U.S. Greenhouse Gas Emissions and Sinks
by Chapter/IPCC Sector
7,500 -
7,000 -
6,500 -
6,000
5,500
5,000
. 4,500-
S 4,000 -
o1 3,500-
£ 3,000-
"- 2,500 -
2,000 -
1,500-
1,000-
500-
0
(500) -
(1,000) -I
Waste
Industrial Processes / LULUCF (sources)
Agric
Land Use, Land-Use Change and Forestry (sinks)
CD r^ CQ
Note: Relatively smaller amounts of GWP-weighted emissions are also emitted from the
Solvent and Other Product Use Sector.
ES.3. Overview of Sector Emissions
and Trends
In accordance with the Revised 1996IPCC Guidelines
for National Greenhouse Gas Inventories (IPCC/UNEP/
OECD/IEA 1997), and the 2003 UNFCCC Guidelines on
Reporting and Review (UNFCCC 2003), Figure ES-11 and
Table ES-4 aggregate emissions and sinks by these chapters.
Emissions of all gases can be summed from each source
category from IPCC guidance. Over the nineteen-year period
of 1990 to 2008, total emissions in the Energy, Industrial
Processes, and Agriculture sectors climbed by 775.0 Tg CO2
Table ES-4: Recent Trends in U.S. Greenhouse Gas Emissions and Sinks by Chapter/IPCC Sector (Tg C02 Eq.)
Chapter/IPCC Sector
Energy
Industrial Processes
Solvent and Other Product Use
Agriculture
Land Use, Land-Use Change, and
Forestry (Emissions)
Waste
Total Emissions
Net C02 Flux from Land Use, Land-Use
Change, and Forestry (Sinks)3
Net Emissions (Sources and Sinks)
1990
5,224.1
318.3
4.4l
387.8 1
15.0
177.2
6,126.8
(909.4)
5,217.3
1995
5,545.8
339.1
4.6
407.7
17.2
174.5
6,488.8
(842.9)
5,646.0
2000
6,087.5
351.9
4.9 1
410.91
36.3
153.0
7,044.5
(664.2)
6,380.2
2005
6,187.9
334.7
4.4
419.7
28.6
158.0
7,133.2
(950.4)
6,182.8
2006
6,089.1
339.7
4.4
417.2
49.8
159.7
7,059.9
(959.2)
6,100.7
2007
6,182.9
350.9
4.4
423.0
47.6
159.3
7,168.1
(955.4)
6,212.7
2008
5,999.0
334.5
4.4
427.5
32.2
159.1
6,956.8
(940.3)
6,016.4
"The net C02 flux total includes both emissions and sequestration, and constitutes a sink in the United States. Sinks are only included in net emissions total.
Note: Totals may not sum due to independent rounding. Parentheses indicate negative values or sequestration.
12 Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008
-------
Eq. (15 percent), 16.2 Tg CO2 Eq. (5 percent), and 39.7 Tg
CO2 Eq. (10 percent), respectively. Emissions decreased in
the Waste and Solvent and Other Product Use sectors by
18.1 Tg CO2 Eq. (10 percent) and less than 0.1 Tg CO2 Eq.
(0.4 percent), respectively. Over the same period, estimates
of net C sequestration in the Land Use, Land-Use Change.
and Forestry sector (magnitude of emissions plus CO2 flux
from all LULUCF source categories) increased by 13.7 Tg
CO2Eq. (1.5 percent).
Energy
The Energy chapter contains emissions of all greenhouse
gases resulting from stationary and mobile energy activities
including fuel combustion and fugitive fuel emissions.
Energy-related activities, primarily fossil fuel combustion.
accounted for the vast majority of U.S. CO2 emissions for
the period of 1990 through 2008. In 2008, approximately
84 percent of the energy consumed in the United States (on
a Btu basis) was produced through the combustion of fossil
fuels. The remaining 16 percent came from other energy
sources such as hydropower, biomass, nuclear, wind, and
solar energy (see Figure ES-12). Energy-related activities are
also responsible for CH4 and N2O emissions (37 percent and
13 percent of total U.S. emissions of each gas, respectively).
Overall, emission sources in the Energy chapter account for a
combined 86 percent of total U.S. greenhouse gas emissions
in 2008.
Figure ES-12
2008 U.S. Energy Consumption by Energy Source
Renewable
Energy
7.4%
Nuclear Electric
Power
Industrial Processes
The Industrial Processes chapter contains byproduct
or fugitive emissions of greenhouse gases from industrial
processes not directly related to energy activities such as
fossil fuel combustion. For example, industrial processes
can chemically transform raw materials, which often release
waste gases such as CO2, CH4, and N2O. These processes
include iron and steel production and metallurgical coke
production, cement production, ammonia production and
urea consumption, lime production, limestone and dolomite
use (e.g., flux stone, flue gas desulfurization, and glass
manufacturing), soda ash production and consumption.
titanium dioxide production, phosphoric acid production.
ferroalloy production, CO2 consumption, silicon carbide
production and consumption, aluminum production.
petrochemical production, nitric acid production, adipic
acid production, lead production, and zinc production.
Additionally, emissions from industrial processes release
HFCs, PFCs, and SF6. Overall, emission sources in the
Industrial Process chapter account for 5 percent of U.S.
greenhouse gas emissions in 2008.
Solvent and Other Product Use
The Solvent and Other Product Use chapter contains
greenhouse gas emissions that are produced as a by-product
of various solvent and other product uses. In the United States.
emissions from N2O from product uses, the only source of
greenhouse gas emissions from this sector, accounted for
about 0.1 percent of total U.S. anthropogenic greenhouse gas
emissions on a carbon equivalent basis in 2008.
Agriculture
The Agriculture chapter contains anthropogenic
emissions from agricultural activities (except fuel combustion.
which is addressed in the Energy chapter, and agricultural
CO2 fluxes, which are addressed in the Land Use, Land-
Use Change, and Forestry Chapter). Agricultural activities
contribute directly to emissions of greenhouse gases through
a variety of processes, including the following source
categories: enteric fermentation in domestic livestock.
livestock manure management, rice cultivation, agricultural
soil management, and field burning of agricultural residues.
CH4 and N2O were the primary greenhouse gases emitted
by agricultural activities. CH4 emissions from enteric
Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008 13
-------
fermentation and manure management represented 25 percent
and 8 percent of total CH4 emissions from anthropogenic
activities, respectively, in 2008. Agricultural soil management
activities such as fertilizer application and other cropping
practices were the largest source of U.S. N2O emissions in
2008, accounting for 68 percent. In 2008, emission sources
accounted for in the Agriculture chapter were responsible for
6.1 percent of total U.S. greenhouse gas emissions.
Land Use, Land-Use Change, and Forestry
The Land Use, Land-Use Change, and Forestry chapter
contains emissions of CH4 and N2O, and emissions and
removals of CO2 from forest management, other land-use
activities, and land-use change. Forest management practices.
tree planting in urban areas, the management of agricultural
soils, and the landfilling of yard trimmings and food scraps
have resulted in a net uptake (sequestration) of C in the United
States. Forests (including vegetation, soils, and harvested
wood) accounted for 84 percent of total 2008 net CO2 flux.
urban trees accounted for 10 percent, mineral and organic soil
carbon stock changes accounted for 5 percent, and landfilled
yard trimmings and food scraps accounted for 1 percent of the
total net flux in 2008. The net forest sequestration is a result
of net forest growth and increasing forest area, as well as a net
accumulation of carbon stocks in harvested wood pools. The
net sequestration in urban forests is a result of net tree growth
in these areas. In agricultural soils, mineral and organic soils
sequester approximately 5.9 times as much C as is emitted
from these soils through liming and urea fertilization. The
mineral soil C sequestration is largely due to the conversion
of cropland to permanent pastures and hay production, a
reduction in summer fallow areas in semi-arid areas, an
increase in the adoption of conservation tillage practices.
and an increase in the amounts of organic fertilizers (i.e..
manure and sewage sludge) applied to agriculture lands. The
landfilled yard trimmings and food scraps net sequestration is
due to the long-term accumulation of yard trimming carbon
and food scraps in landfills.
Land use, land-use change, and forestry activities in
2008 resulted in a net C sequestration of 940.3 Tg CO2 Eq.
(Table ES- 5). This represents an offset of 16 percent of
total U.S. CO2 emissions, or 14 percent of total greenhouse
gas emissions in 2008. Between 1990 and 2008, total land
use, land-use change, and forestry net C flux resulted in a
3.4 percent increase in CO2 sequestration, primarily due
to an increase in the rate of net C accumulation in forest C
stocks, particularly in aboveground and belowground tree
biomass, and harvested wood pools. Annual C accumulation
in landfilled yard trimmings and food scraps slowed over this
period, while the rate of annual C accumulation increased
in urban trees.
Table ES- 5: Net C02 Flux from Land Use, Land-Use Change, and Forestry (Tg C02 Eq.)
Sink Category 1990 1995 2005 2005 2006 2007 2008
Forest Land Remaining Forest Land
Cropland Remaining Cropland
Land Converted to Cropland
Grassland Remaining Grassland
Land Converted to Grassland
Settlements Remaining Settlements
Other (Landfilled Yard Trimmings and
Food Scraps)
(806.6)
(18.3)
5.9
(9.0)
(24.6)
(87.8)
(10.1)
(812.5)
(19.1)
5.9
(8.9)
(24.5)
(89.8)
(806.9)
(19.7)
5.9
(8.8)
(24.3)
(91.9)
(791.9)
(18.1)
5.9
(8.7)
(24.2)
(93.9)
(10.3) (9.8) (9.5)
Total
(909.4)
(842.9)
(664.2)
(950.4) (959.2) (955.4) (940.3)
Note: Totals may not sum due to independent rounding. Parentheses indicate net sequestration.
14 Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008
-------
Table ES-6. Emissions from Land Use, Land-Use Change, and Forestry (Tg C02 Eq.)
Source Category
1990
1995
2000
2005 2006 2007 2008
C02
Cropland Remaining Cropland: Liming of Agricultural
Soils
Urea Fertilization
Wetlands Remaining Wetlands: Peatlands Remaining
Peatlands
CH4
Forest Land Remaining Forest Land: Forest Fires
N20
Forest Land Remaining Forest Land: Forest Fires
Forest Land Remaining Forest Land: Forest Soils
Settlements Remaining Settlements: Settlement Soils
Wetlands Remaining Wetlands: Peatlands Remaining
Peatlands
8.1
4.7
2.4
1.0
3.2
3.2
3.7
2.6
0.1
1.0
8.1
4.4
2.7
1.0
4.3
4.3
4.9
3.5
0.2
1.2
8.8
4.3
3.2
1.2
14.3
14.3
13.2
11.7
0.4
1.1
8.9
4.3
3.5
1.1
9.8
9.8
9.8
8.0
0.4
1.5
8.8
4.2
3.7
0.9
21.6
21.6
19.5
17.6
0.4
1.5
9.3
4.5
3.8
1.0
20.0
20.0
18.3
16.3
0.4
1.6
8.6
3.8
3.8
0.9
11.9
11.9
11.7
9.7
0.4
1.6
Total
15.0
17.2
36.3
28.6 49.8 47.6 32.2
+ Less than 0.05 Tg C02 Eq.
Note: Totals may not sum due to independent rounding.
Emissions from Land Use, Land-Use Change, and
Forestry are shown in Table ES-6. The application of
crushed limestone and dolomite to managed land (i.e..
liming of agricultural soils) and urea fertilization resulted
in CO2 emissions of 7.6 Tg CO2 Eq. in 2008, an increase
of 8 percent relative to 1990. The application of synthetic
fertilizers to forest and settlement soils in 2008 resulted in
direct N2O emissions of 1.9 Tg CO2 Eq. Direct N2O emissions
from fertilizer application to forest soils have increased by
422 percent since 1990, but still account for a relatively
small portion of overall emissions. Additionally, direct N2O
emissions from fertilizer application to settlement soils
increased of 62 percent since 1990. Non-CO2 emissions from
forest fires in 2008 resulted in CH4 emissions of 11.9 Tg CO2
Eq., and in N2O emissions of 9.7 Tg CO2 Eq. CO2 and N2O
emissions from peatlands totaled 0.9 Tg CO2 Eq. and less
than 0.01 Tg CO2 Eq. in 2008, respectively.
Waste
The Waste chapter contains emissions from waste
management activities (except incineration of waste, which
is addressed in the Energy chapter). Landfills were the
largest source of anthropogenic greenhouse gas emissions
in the Waste chapter, accounting for just over 79 percent of
this chapter's emissions, and 22 percent of total U.S. CH4
emissions.13 Additionally, wastewater treatment accounts
13 Landfills also store carbon, due to incomplete degradation of organic
materials such as wood products and yard trimmings, as described in the
Land-Use, Land-Use Change, and Forestry chapter of the Inventory report.
for 18 percent of Waste emissions, 4 percent of U.S. CH4
emissions, and 2 percent of U.S. N2O emissions. Emissions of
CH4 and N2O from composting are also accounted for in this
chapter; generating emissions of 1.7 Tg CO2 Eq. and 1.8 Tg
CO2 Eq., respectively. Overall, emission sources accounted
for in the Waste chapter generated 2.3 percent of total U.S.
greenhouse gas emissions in 2008.
ES.4. Other Information
Emissions by Economic Sector
Throughout the Inventory of U.S. Greenhouse Gas
Emissions and Sinks report, emission estimates are grouped
into six sectors (i.e., chapters) defined by the IPCC: Energy;
Industrial Processes; Solvent Use; Agriculture; Land Use.
Land-Use Change, and Forestry; and Waste. While it is
important to use this characterization for consistency with
UNFCCC reporting guidelines, it is also useful to allocate
emissions into more commonly used sectoral categories.
This section reports emissions by the following economic
sectors: Residential, Commercial, Industry, Transportation.
Electricity Generation, Agriculture, and U.S. Territories.
Table ES-7 summarizes emissions from each of these
sectors, and Figure ES-13 shows the trend in emissions by
sector from 1990 to 2008.
Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008 15
-------
Table ES-7: U.S. Greenhouse Gas Emissions Allocated to Economic Sectors (Tg C02 Eq.)
Implied Sectors
1990
1995
2000
2005
2006
2007
2008
Electric Power Industry
Transportation
Industry
Agriculture
Commercial
Residential
U.S. Territories
2,443.5
2,016.1
1,350.9
494.1
399.0
370.7
58.9
2,387.5
1,993.0
1,380.2
515.1
389.2
334.9
60.0
2,454.0
2,003.5
1,374.2
518.0
404.4
356.2
57.8
2,404.2
1,886.1
1,342.4
504.1
410.9
359.3
49.9
Total Emissions
6,126.8
6,488.8
7,044.5
7,133.2 7,059.9 7,168.1 6,956.8
Land Use, Land-Use Change, and
Forestry (Sinks) (909.4) I (842.9) (664.2)
(950.4) (959.2) (955.4) (940.3)
Net Emissions (Sources and Sinks) 5,217.3
5,646.0
6,380.2
6,182.8 6,100.7 6,212.7 6,016.4
Note: Totals may not sum due to independent rounding. Emissions include C02, CH4, N20, MFCs, PFCs, and SF6.
See Table 2-12 of the Inventory report for more detailed data.
Using this categorization, emissions from electricity
generation accounted for the largest portion (35 percent)
of U.S. greenhouse gas emissions in 2008. Transportation
activities, in aggregate, accounted for the second largest
portion (27 percent), while emissions from industry
accounted for the third largest portion (19 percent) of U.S.
greenhouse gas emissions in 2008. In contrast to electricity
generation and transportation, emissions from industry have
in general declined over the past decade. The long-term
decline in these emissions has been due to structural changes
in the U.S. economy (i.e., shifts from a manufacturing-
based to a service-based economy), fuel switching, and
energy efficiency improvements. The remaining 19 percent
of U.S. greenhouse gas emissions were contributed by.
in order of importance, the agriculture, commercial, and
residential sectors, plus emissions from U.S. territories.
Activities related to agriculture accounted for 7 percent of
U.S. emissions; unlike other economic sectors, agricultural
sector emissions were dominated by N2O emissions from
agricultural soil management and CH4 emissions from enteric
fermentation. The commercial sector accounted for 6 percent
of emissions while the residential sector accounted for 5
percent of emissions and U.S. territories accounted for 1
percent of emissions; emissions from these sectors primarily
consisted of CO2 emissions from fossil fuel combustion.
CO2 was also emitted and sequestered by a variety
of activities related to forest management practices, tree
Figure ES-13
Emissions Allocated to Economic Sectors
2,500 -
2,000 -
1,500-
1,000-
500-
0-
Electric Power Industry
Transportation
s
Industry
griculture
Commercial
Residential
Note: Does not include U.S. Territories.
planting in urban areas, the management of agricultural soils.
and landfilling of yard trimmings.
Electricity is ultimately consumed in the economic
sectors described above. Table ES-8 presents greenhouse
gas emissions from economic sectors with emissions related
to electricity generation distributed into end-use categories
(i.e., emissions from electricity generation are allocated to
the economic sectors in which the electricity is consumed).
To distribute electricity emissions among end-use sectors.
emissions from the source categories assigned to electricity
generation were allocated to the residential, commercial.
16 Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008
-------
Table ES-8: U.S Greenhouse Gas Emissions by Economic Sector with Electricity-Related Emissions Distributed (Tg
C02 Eq.)
Implied Sectors
Industry
Transportation
Commercial
Residential
Agriculture
U.S. Territories
Total Emissions
Land Use, Land-Use Change, and
Forestry (Sinks)
Net Emissions (Sources and Sinks)
1990
2,179.8
1,548.2
946.8
954.0
464.2
33.7
6,126.8
(909.4)
5,217.3
1995
2,228
1,698
1,000
1,024
497
40,
.0
,3
,2
,5
,1
,7
6,488.8
(842.9)
5,646.0
2,
1,
1,
1,
7,
2000
239.2
935.8
141.5
162.4
518.7
46.9
044.5
(664.2)
6,
380.2
2,
2,
1,
1,
7,
2005
071.1
020.9
216.5
242.2
523.5
58.9
133.2
(950.4)
6,
182.8
2006
2,077.3
1,997.6
1,202.2
1,180.3
542.5
60.0
7,059.9
(959.2)
6,100.7
2007
2,084.2
2,008.6
1,240.1
1,226.9
550.5
57.8
7,168.1
(955.4)
6,212.7
2008
2,018.4
1,890.8
1,250.6
1,215.6
531.6
49.9
6,956.8
(940.3)
6,016.4
See Table 2-14 of the Inventory report for more detailed data.
Figure ES-14
Emissions with Electricity Distributed
to Economic Sectors
2,500 -
2,000 -
1,500-
1,000-
500-
0-
Industry
Transportation
Residential
Commercial
Agriculture
Note: Does not include U.S. Territories.
industry, transportation, and agriculture economic sectors
according to retail sales of electricity.14 These source
categories include CO2 from fossil fuel combustion and the
use of limestone and dolomite for flue gas desulfurization.
CO2 and N2O from incineration of waste, CH4 and N2O from
stationary sources, and SF6 from electrical transmission and
distribution systems.
When emissions from electricity are distributed among
these sectors, industry accounts forthe largest share of U.S.
14 Emissions were not distributed to U.S. territories, since the electricity
generation sector only includes emissions related to the generation of
electricity in the 50 states and the District of Columbia.
greenhouse gas emissions (29 percent) in 2008. Emissions
from the residential and commercial sectors also increase
substantially when emissions from electricity are included.
due to their relatively large share of electricity consumption
(e.g., lighting, appliances, etc.). Transportation activities
remain the second largest contributor to total U.S. emissions
(27 percent) despite the considerable decline in emissions
from this sector during the past year. In all sectors except
agriculture, CO2 accounts for more than 80 percent of
greenhouse gas emissions, primarily from the combustion of
fossil fuels. Figure ES-14 shows the trend in these emissions
by sector from 1990 to 2008.
Indirect Greenhouse Gases (CO, NOX,
NMVOCs, and S02)
The reporting requirements of the UNFCCC15 request
that information be provided on indirect greenhouse gases.
which include CO, NOX, NMVOCs, and SO2. These gases do
not have a direct global warming effect, but indirectly affect
terrestrial radiation absorption by influencing the formation
and destruction of tropospheric and stratospheric ozone, or.
in the case of SO2, by affecting the absorptive characteristics
of the atmosphere. Additionally, some of these gases may
react with other chemical compounds in the atmosphere to
form compounds that are greenhouse gases.
Since 1970, the United States has published estimates
of annual emissions of CO, NOX, NMVOCs, and SO2 (EPA
' See .
Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008 17
-------
Box ES-2: Recent Trends in Various U.S. Greenhouse Gas Emissions-Related Data
Total emissions can be compared to other economic and social indices to highlight changes over time. These comparisons include: (1)
emissions per unit of aggregate energy consumption, because energy-related activities are the largest sources of emissions; (2) emissions
per unit of fossil fuel consumption, because almost all energy-related emissions involve the combustion of fossil fuels; (3) emissions per
unit of electricity consumption, because the electric power industry—utilities and nonutilities combined—was the largest source of U.S.
greenhouse gas emissions in 2008; (4) emissions per unit of total gross domestic product as a measure of national economic activity; and
(5) emissions per capita.
Table ES-9 provides data on various statistics related to U.S. greenhouse gas emissions normalized to 1990 as a baseline year.
Greenhouse gas emissions in the United States have grown at an average annual rate of 0.7 percent since 1990. This rate is slightly slower
than that for total energy, approximately the same as for fossil fuel consumption, and much slower than that for either electricity consumption
or overall gross domestic product. Total U.S. greenhouse gas emissions have also grown slightly slower than national population since 1990
(see Figure ES-15).
Table ES-9: Recent Trends in Various U.S. Data (Index 1990 = 100)
Variable
1990
1995
2000
2005
2006
2007
2008
Growth
Rate"
GDPb
Electricity Consumption0
Fossil Fuel Consumption0
Energy Consumption0
Population"1
Greenhouse Gas Emissions6
162
135
117
118
119
115
165
138
119
120
120
117
166
136
115
118
121
114
2.9%
1.8%
0.8%
0.9%
1.1%
0.7%
1 Average annual growth rate
1 Gross Domestic Product in chained 2000 dollars (BEA 2009)
: Energy content-weighted values (EIA 2009)
J U.S. Census Bureau (2009)
'- GWP-weighted values
Figure ES-15
U.S. Greenhouse Gas Emissions Per Capita and
Per Dollar of Gross Domestic Product
Real GDP
Population
Emissions
per capita
Emissions
per $GDP
Source: BEA (2009), U.S. Census Bureau (2009), and emission estimates in the Inventory report.
Note: Does not include U.S. Territories.
18 Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008
-------
Table ES-10: Emissions of NOx, CO, NMVOCs, and S02 (Gg)
Gas/Activity
NOX
Mobile Fossil Fuel Combustion
Stationary Fossil Fuel Combustion
Industrial Processes
Oil and Gas Activities
Incineration of Waste
Agricultural Burning
Solvent Use
Waste
CO
Mobile Fossil Fuel Combustion
Stationary Fossil Fuel Combustion
Industrial Processes
Incineration of Waste
Agricultural Burning
Oil and Gas Activities
Waste
Solvent Use
NMVOCs
Mobile Fossil Fuel Combustion
Solvent Use
Industrial Processes
Stationary Fossil Fuel Combustion
Oil and Gas Activities
Incineration of Waste
Waste
Agricultural Burning
S02
Stationary Fossil Fuel Combustion
Industrial Processes
Mobile Fossil Fuel Combustion
Oil and Gas Activities
Incineration of Waste
Waste
Solvent Use
Agricultural Burning
Source: EPA (2009), disaggregated based
NA (Not Available)
1990
21,
10,
10,
728
862
023
591
139
op
30
I
130,536
119,
5,
4,
20,
10,
5,
2,
20,
18,
1,
360
000
125
978
766
302
1
930
932
216
422
912
554
222
673
NA
935
407
307
793
390
38
I
NA
1995
21,
10,
9,
109,
97,
5,
3,
1,
227
536
862
607
100
88
30
3
1
114
630
383
959
073
745
316
2
5
19,520
8,
5,
2,
16,
14,
1,
745
609
642
973
582
237
731
NA
891
724
117
672
335
42
1
1
NA
on EPA (2003) except for estimates from field
2000
19,145
10,199
8,053
626
111
114
37
3
2
92,872
83,559
4,340
2,126
1,670
888
146
8
45
15,227
7,229
4,384
1,773
1,077
388
257
119
NA
14,830
12,849
1,031
632
287
29
1
1
NA
2005
15,933
9,012
5,858
569
321
129
40
3
2
71,555
62,692
4,649
1,555
1,403
930
318
7
2
13,761
6,330
3,851
1,997
716
510
241
114
NA
13,466
11,541
831
889
181
24
1
0
NA
2006
15,071
8,488
5,545
553
319
121
40
4
2
67,909
58,972
4,695
1,597
1,412
905
319
7
2
13,594
6,037
3,846
1,933
918
510
238
113
NA
12,388
10,612
818
750
182
24
1
0
NA
2007
14,410
7,965
5,432
537
318
114
38
4
2
64,348
55,253
4,744
1,640
1,421
960
320
7
2
13,423
5,742
3,839
1,869
1,120
509
234
111
NA
11,799
10,172
807
611
184
24
1
0
NA
2008
13,578
7,441
5,148
520
318
106
40
4
2
60,739
51,533
4,792
1,682
1,430
970
322
7
2
13,254
5,447
3,834
1,804
1,321
509
230
109
NA
10,368
8,891
795
472
187
23
1
0
NA
burning of agricultural residues.
Note: Totals may not sum due to independent rounding.
2008),16 which are regulated under the Clean Air Act. Table
ES-10 shows that fuel combustion accounts for the majority
of emissions of these indirect greenhouse gases. Industrial
processes—such as the manufacture of chemical and allied
products, metals processing, and industrial uses of solvents—
are also significant sources of CO, NOX, and NMVOCs.
16 NOX and CO emission estimates from field burning of agricultural residues
were estimated separately, and therefore not taken from EPA (2008).
Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008 19
-------
Figure ES-16
2008 Key Categories
C02 Emissions from Stationary Combustion - Coal
C02 Emissions from Mobile Combustion: Road & Other
C02 Emissions from Stationary Combustion - Gas
C02 Emissions from Stationary Combustion - Oil
Direct N20 Emissions from Agricultural Soil Management
C02 Emissions from Mobile Combustion: Aviation
CH4 Emissions from Enteric Fermentation
C02 Emissions from Non-Energy Use of Fuels
CH4 Emissions from Landfills
Emissions from Substitutes for Ozone Depleting Substances
Fugitive CH4 Emissions from Natural Gas Systems
C02 Emissions from Iron and Steel Production & Metallurgical Coke Production
Fugitive CH4 Emissions from Coal Mining
Indirect N20 Emissions from Applied Nitrogen
CH4 Emissions from Manure Management
C02 Emissions from Cement Production
Fugitive CH4 Emissions from Petroleum Systems
N20 Emissions from Manure Management
Non-CO, Emissions from Stationary Combustion
Key Categories as a
Portion of all Emissions
0 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000 2,200
Tg C02 Eq.
Note: For a complete discussion of the key category analysis, see Annex 1 of the Inventory report. Darker bars indicate a Tier 1 level assessment key category. Lighter bars indicate a Tier 2 level assessment key category.
Key Categories
The IPCC's Good Practice Guidance (IPCC 2000)
defines a key category as a "[source or sink category] that
is prioritized within the national inventory system because
its estimate has a significant influence on a country's total
inventory of direct greenhouse gases in terms of the absolute
level of emissions, the trend in emissions, or both."17 By
definition, key categories are sources or sinks that have the
greatest contribution to the absolute overall level of national
emissions in any of the years covered by the time series. In
addition, when an entire time series of emission estimates
is prepared, a thorough investigation of key categories
must also account for the influence of trends of individual
source and sink categories. Finally, a qualitative evaluation
of key categories should be performed, in order to capture
17 See Chapter 7 "Methodological Choice and Recalculation" in IPCC
(2000).
any key categories that were not identified in either of the
quantitative analyses.
Figure ES-16 presents 2008 emission estimates for
the key categories as defined by a level analysis (i.e., the
contribution of each source or sink category to the total
inventory level). The UNFCCC reporting guidelines request
that key category analyses be reported at an appropriate
level of disaggregation, which may lead to source and sink
category names which differ from those used elsewhere in
the inventory report. For more information regarding key
categories, see section 1.5 and Annex 1 of the inventory report.
Quality Assurance and Quality Control
(QA/QC)
The United States seeks to continually improve the
quality, transparency, and credibility of the Inventory of
U.S. Greenhouse Gas Emissions and Sinks. To assist in these
efforts, the United States implemented a systematic approach
to QA/QC. While QA/QC has always been an integral part
20 Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008
-------
of the U.S. national system for inventory development, the
procedures followed for the current inventory have been
formalized in accordance with the QA/QC plan and the
UNFCCC reporting guidelines.
Uncertainty Analysis of Emission Estimates
While the current U.S. emissions inventory provides a
solid foundation for the development of a more detailed and
comprehensive national inventory, there are uncertainties
associated with the emission estimates. Some of the current
estimates, such as those for CO2 emissions from energy-
related activities and cement processing, are considered
to have low uncertainties. For some other categories
of emissions, however, a lack of data or an incomplete
understanding of how emissions are generated increases
the uncertainty associated with the estimates presented.
Acquiring a better understanding of the uncertainty
associated with inventory estimates is an important step in
helping to prioritize future work and improve the overall
quality of the Inventory report. Recognizing the benefit of
conducting an uncertainty analysis, the UNFCCC reporting
guidelines follow the recommendations of the IPCC Good
Practice Guidance (IPCC 2000) and require that countries
provide single estimates of uncertainty for source and
sink categories.
Currently, a qualitative discussion of uncertainty is
presented for all source and sink categories. Within the
discussion of each emission source, specific factors affecting
the uncertainty surrounding the estimates are discussed. Most
sources also contain a quantitative uncertainty assessment, in
accordance with UNFCCC reporting guidelines.
Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008 21
-------
References
BEA (2009) "Current Dollar and Real Gross Domestic
Product." National Economic Accounts. Bureau
of Economic Analysis (BEA), U.S. Department of
Commerce, Washington, DC. Available online at
.
EIA (2009) International Energy Statistics 2009. Energy
Information Administration, U.S. Department of Energy.
Available online at .
EPA (2008) "1970-2007 Average annual emissions, all
criteria pollutants in MS Excel." National Emissions
Inventory (NEI) Air Pollutant Emissions Trends Data.
Office of Air Quality Planning and Standards. Available
online at
EPA (2003) E-mail correspondence. Air pollutant data.
Office of Air Pollution to the Office of Air Quality
Planning and Standards, U.S. Environmental Protection
Agency (EPA). December 22, 2003.
IPCC (2007) Climate Change 2007: The Physical Science
Basis. Contribution of Working Group I to the Fourth
Assessment Report of the Intergovernmental Panel on
Climate Change. S. Solomon, D. Qin, M. Manning, Z.
Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller
(eds.). Cambridge University Press. Cambridge, United
Kingdom 996 pp.
IPCC (2006) 2006 IPCC Guidelines for National
Greenhouse Gas Inventories. The National Greenhouse
Gas Inventories Programme, The Intergovernmental Panel
on Climate Change, H.S. Eggleston, L. Buendia, K. Miwa.
T Ngara, and K. Tanabe (eds.). Hayama, Kanagawa, Japan.
IPCC (2003) Good Practice Guidance for Land Use,
Land-Use Change, and Forestry. National Greenhouse Gas
Inventories Programme, The Intergovernmental Panel on
Climate Change, J. Penman, et al. (eds.). Available online
at . August 13, 2004.
IPCC (2001) Climate Change 2001: The Scientific
Basis. Intergovernmental Panel on Climate Change.
J.T. Houghton, Y. Ding, D.J. Griggs, M. Noguer, PJ.
van der Linden, X. Dai, C.A. Johnson, and K. Maskell
(eds.). Cambridge University Press. Cambridge, United
Kingdom.
IPCC (2000) Good Practice Guidance and Uncertainty
Management in National Greenhouse Gas Inventories.
National Greenhouse Gas Inventories Programme.
Intergovernmental Panel on Climate Change. Montreal.
May 2000. IPCC-XWDoc. 10 (1.IV.2000).
IPCC (1996) Climate Change 1995: The Science of
Climate Change. Intergovernmental Panel on Climate
Change, J.T. Houghton, L.G. MeiraFilho, B.A.
Callander, N. Harris, A. Kattenberg, and K. Maskell.
(eds.). Cambridge University Press. Cambridge, United
Kingdom.
IPCC/UNEP/OECD/IEA (1997) Revised 1996 IPCC
Guidelines for National Greenhouse Gas Inventories.
Intergovernmental Panel on Climate Change, United
Nations Environment Programme, Organization for
Economic Co-Operation and Development, International
Energy Agency. Paris, France.
UNFCCC (2003) National Communications: Greenhouse
Gas Inventories from Parties included in Annex I to the
Convention, UNFCCC Guidelines on Reporting and
Review. Conference of the Parties, Eighth Session, New
Delhi. (FCCC/CP/2002/8). March 28, 2003.
U.S. Census Bureau (2009) U.S. Census Bureau
International Database (IDB). Available online at
.
22 Executive Summary of the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008
-------
-------
United States
Environmental Protection
k Agency
United States
Environmental Protection Agency
EPA 430-S-10-001
April 2010
Office of Atmospheric Programs (6207J)
Washington, DC 20460
Official Business
Penalty for Private Use
------- |