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
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 this report as an opportunity
to fulfill these commitments.
This chapter summarizes the latest information on U.S. anthropogenic greenhouse gas emission trends from 1990
through 2010. 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 Intergovernmental Panel on Climate Change (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. emission inventory has continued to incorporate new
methodologies and data from the 2006 IPCC Guidelines for National Greenhouse Gas Inventories (IPCC 2006).
The structure of this report is consistent with the UNFCCC guidelines for inventory reporting.4 For most source
categories, the IPCC methodologies were expanded, resulting in a more comprehensive and detailed estimate of
emissions.
[BEGIN BOX]
Box ES-1: Methodological approach for estimating and reporting U.S. emissions and sinks
In following the UNFCCC requirement under Article 4.1 to develop and submit national greenhouse gas emissions
inventories, the emissions and sinks presented in this report are organized by source and sink categories and
calculated using internationally-accepted methods provided by the IPCC.5 Additionally, the calculated emissions
and sinks in a given year for the United States are presented in a common manner in line with the UNFCCC
reporting guidelines for the reporting of inventories under this international agreement.6 The use of consistent
methods to calculate emissions and sinks by all nations providing their inventories to the UNFCCC ensures that
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 Xa) 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
.
4 See < http://unfccc.int/resource/docs/2006/sbsta/eng/09.pdf>.
5 See < http://www.ipcc-nggip.iges.or.jp/public/index.html>.
6 See < http://unfccc.int/national_reports/annex_i_ghg_inventories/national_inventories_submissions/items/5270.php>.
Executive Summary ES-1
-------
these reports are comparable. In this regard, U.S. emissions and sinks reported in this inventory report are
comparable to emissions and sinks reported by other countries. Emissions and sinks provided in this inventory do
not preclude alternative examinations, but rather this inventory report presents emissions and sinks in a common
format consistent with how countries are to report inventories under the UNFCCC. The report itself follows this
standardized format, and provides an explanation of the IPCC methods used to calculate emissions and sinks, and
the manner in which those calculations are conducted.
On October 30, 2009, the U.S. Environmental Protection Agency (EPA) published a rule for the mandatory
reporting of greenhouse gases (GHG) from large GHG emissions sources in the United States. Implementation of 40
CFR Part 98 is referred to as the Greenhouse Gas Reporting Program (GHGRP). 40 CFR part 98 applies to direct
greenhouse gas emitters, fossil fuel suppliers, industrial gas suppliers, and facilities that inject C02 underground for
sequestration or other reasons. Reporting is at the facility level, except for certain suppliers of fossil fuels and
industrial greenhouse gases. For calendar year 2010, the first year in which data were reported, facilities in 29
categories provided in 40 CFR part 98 were required to report their 2010 emissions by the September 30, 2011
reporting deadline.7 The GHGRP dataset and the data presented in this inventory report are complementary and, as
indicated in the respective planned improvements sections in this report's chapters, EPA is analyzing how to use
facility-level GHGRP data to improve the national estimates presented in this inventory.
[END BOX]
ES.1. Background Information
Naturally occurring greenhouse gases include water vapor, carbon dioxide (C02), methane (CH4), nitrous oxide
(N20), and ozone (03). 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.8 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.
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 (S02) or elemental carbon emissions, can also affect the absorptive characteristics
of the atmosphere.
Although the direct greenhouse gases C02, CH4, and N20 occur naturally in the atmosphere, human activities have
changed their atmospheric concentrations. From the pre-industrial era (i.e., ending about 1750) to 2010,
concentrations of these greenhouse gases have increased globally by 39, 158, and 19 percent, respectively (IPCC
2007 and NOAA/ESLR 2009).
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
7 See and .
8 Emissions estimates of CFCs, HCFCs, halons and other ozone-depleting substances are included in the annexes of the
Inventory report for informational purposes.
ES-2 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2010
-------
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 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).9 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 C02, and therefore GWP-
weighted emissions are measured in teragrams (or million metric tons) of C02 equivalent (Tg C02 Eq.).10'11 All
gases in this Executive Summary are presented in units of Tg C02 Eq.
The UNFCCC reporting guidelines for national inventories were updated in 2006,12 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 2010 are consistent with estimates developed prior to
the publication of the IPCC Third Assessment Report (TAR) (IPCC 2001) and the IPCC Fourth Assessment Report
(AR4) (IPCC 2007). 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 report in both C02 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 this report. The
GWP values used in this report are listed below in Table ES-1.
Table ES-1: Global Warming Potentials (100-Year Time Horizon) Used in this Report
Gas GWP
co2 1
CH4* 21
N20 310
HFC-23 11,700
HFC-32 650
HFC-125 2,800
HFC-134a 1,300
HFC-143a 3,800
HFC-152a 140
HFC-227ea 2,900
HFC-236fa 6,300
HFC-4310mee 1,300
CF4 6,500
C2F6 9,200
C4F10 7,000
C6Fi4 7,400
SF6 23,900
Source: IPCC (1996)
* The CH4 GWP includes the direct
effects and those indirect effects due
9 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.
10 Carbon comprises 12/44ths of carbon dioxide by weight.
11 One teragram is equal to 1012 grams or one million metric tons.
12 See .
Executive Summary ES-3
-------
to the production of tropospheric
ozone and stratospheric water vapor.
The indirect effect due to the
production of C02 is not included.
Global warming potentials are not provided for CO, NOx, NMVOCs, S02, 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).
ES.2. Recent Trends in U.S. Greenhouse Gas Emissions and Sinks
In 2010, total U.S. greenhouse gas emissions were 6,821.8 Tg or million metric tons C02 Eq. Total U.S. emissions
have increased by 10.5 percent from 1990 to 2010, and emissions increased from 2009 to 2010 by 3.2 percent (213.5
Tg C02 Eq.). The increase from 2009 to 2010 was primarily due to an increase in economic output resulting in an
increase in energy consumption across all sectors, and much warmer summer conditions resulting in an increase in
electricity demand for air conditioning that was generated primarily by combusting coal and natural gas. Since
1990, U.S. emissions have increased at an average annual rate of 0.5 percent.
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 2010.
Figure ES-1: U.S. Greenhouse Gas Emissions by Gas
Figure ES-2: Annual Percent Change in U.S. Greenhouse Gas Emissions
Figure ES-3: Cumulative Change in Annual U.S. Greenhouse Gas Emissions Relative to 1990
Table ES-2: Recent Trends in U.S. Greenhouse Gas Emissions and Sinks (Tg or million metric tons C02 Eq.)
Gas/Source
1990
2005
2006
2007
2008
2009
2010
co2
5,100.5
6,107.6
6,019.0
6,118.6
5,924.3
5,500.5
5,706.4
Fossil Fuel Combustion
4,738.3
5,746.5
5,653.0
5,757.8
5,571.5
5,206.2
5,387.8
Electricity Generation
1,820.8
2,402.1
2,346.4
2,412.8
2,360.9
2,146.4
2,258.4
Transportation
1,485.9
1,896.6
1,878.1
1,893.9
1,789.8
1,727.9
1,745.5
Industrial
846.4
816.4
848.1
844.4
806.5
726.6
777.8
Residential
338.3
357.9
321.5
341.6
349.3
339.0
340.2
Commercial
219.0
223.5
208.6
218.9
225.1
224.6
224.2
U.S. Territories
27.9
50.0
50.3
46.1
39.8
41.7
41.6
Non-Energy Use of Fuels
119.6
144.1
143.8
134.9
138.6
123.7
125.1
Iron and Steel Production &
Metallurgical Coke Production
99.6
66.0
68.9
71.1
66.1
42.1
54.3
Natural Gas Systems
37.6
29.9
30.8
31.0
32.8
32.2
32.3
Cement Production
33.3
45.2
45.8
44.5
40.5
29.0
30.5
Lime Production
11.5
14.4
15.1
14.6
14.3
11.2
13.2
Incineration of Waste
8.0
12.5
12.5
12.7
11.9
11.7
12.1
Limestone and Dolomite Use
5.1
6.8
8.0
7.7
6.3
7.6
10.0
Ammonia Production
13.0
9.2
8.8
9.1
7.9
7.9
8.7
Cropland Remaining Cropland
7.1
7.9
7.9
8.2
8.6
7.2
8.0
Urea Consumption for Non-
Agricultural Purposes
3.8
3.7
3.5
4.9
4.1
3.4
4.4
Soda Ash Production and Consumption
4.1
4.2
4.2
4.1
4.1
3.6
3.7
Petrochemical Production
3.3
4.2
3.8
3.9
3.4
2.7
3.3
ES-4 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2010
-------
Aluminum Production
6.8
4.1
3.8
4.3
4.5
3.0
3.0
Carbon Dioxide Consumption
1.4
1.3
1.7
1.9
1.8
1.8
2.2
Titanium Dioxide Production
1.2
1.8
1.8
1.9
1.8
1.6
1.9
Ferroalloy Production
2.2
1.4
1.5
1.6
1.6
1.5
1.7
Zinc Production
0.6
1.0
1.0
1.0
1.2
0.9
1.2
Phosphoric Acid Production
1.5
1.4
1.2
1.2
1.2
1.0
1.0
Wetlands Remaining Wetlands
1.0
1.1
0.9
1.0
1.0
1.1
1.0
Lead Production
0.5
0.6
0.6
0.6
0.5
0.5
0.5
Petroleum Systems
0.4
0.3
0.3
0.3
0.3
0.3
0.3
Silicon Carbide Production and
Consumption
0.4
0.2
0.2
0.2
0.2
0.1
0.2
Land Use, Land-Use Change, and
Forestry (Sink)"
(881.8)
(1,085.9)
(1,110.4)
(1,108.2)
(1,087.5)
(1,062.6)
(1,074.7)
Wood Biomass and Ethanol
Consumptionb
218.6
228.6
233.7
241.1
252.1
244.1
266.1
International Bunker Fuelsc
111.8
109.8
128.4
127.6
133.7
122.3
127.8
CH,
668.3
625.8
664.6
656.2
667.9
672.2
666.5
Natural Gas Systems
189.6
190.5
217.7
205.3
212.7
220.9
215.4
Enteric Fermentation
133.8
139.0
141.4
143.8
143.4
142.6
141.3
Landfills
147.7
112.7
111.7
111.7
113.1
111.2
107.8
Coal Mining
84.1
56.8
58.1
57.8
66.9
70.1
72.6
Manure Management
31.7
47.9
48.4
52.7
51.8
50.7
52.0
Petroleum Systems
35.2
29.2
29.2
29.8
30.0
30.7
31.0
Wastewater Treatment
15.9
16.5
16.7
16.6
16.6
16.5
16.3
Rice Cultivation
7.1
6.8
5.9
6.2
7.2
7.3
8.6
Stationary Combustion
7.5
6.6
6.2
6.5
6.6
6.3
6.3
Abandoned Underground Coal Mines
6.0
5.5
5.5
5.3
5.3
5.1
5.0
Forest Land Remaining Forest Land
2.5
8.1
17.9
14.6
OO
OO
5.8
4.8
Mobile Combustion
4.7
2.5
2.4
2.2
2.1
2.0
1.9
Composting
0.3
1.6
1.6
1.7
1.7
1.6
1.6
Petrochemical Production
0.9
1.1
1.0
1.0
0.9
0.8
0.9
Iron and Steel Production &
Metallurgical Coke Production
1.0
0.7
0.7
0.7
0.6
0.4
0.5
Field Burning of Agricultural Residues
0.2
0.2
0.2
0.2
0.2
0.2
0.2
Ferroalloy Production
+
+
+
+
+
+
+
Silicon Carbide Production and
Consumption
+
+
+
+
+
+
+
Incineration of Waste
+
+
+
+
+
+
+
International Bunker FuesF
0.2
0.1
0.2
0.2
0.2
0.1
0.2
n2o
316.2
331.9
336.8
334.9
317.1
304.0
306.2
Agricultural Soil Management
200.0
213.1
211.1
211.1
212.9
207.3
207.8
Stationary Combustion
12.3
20.6
20.8
21.2
21.1
20.7
22.6
Mobile Combustion
43.9
37.0
33.7
29.0
25.2
22.5
20.6
Manure Management
14.8
17.6
18.4
18.5
18.3
18.2
18.3
Nitric Acid Production
17.6
16.4
16.1
19.2
16.4
14.5
16.7
Wastewater Treatment
3.5
4.7
4.8
4.8
4.9
5.0
5.0
N20 from Product Uses
4.4
4.4
4.4
4.4
4.4
4.4
4.4
Forest Land Remaining Forest Land
2.1
7.0
15.0
12.2
7.5
5.1
4.3
Adipic Acid Production
15.8
7.4
8.9
10.7
2.6
2.8
2.8
Composting
0.4
1.7
1.8
1.8
1.9
1.8
1.7
Settlements Remaining Settlements
1.0
1.5
1.5
1.6
1.5
1.4
1.4
Incineration of Waste
0.5
0.4
0.4
0.4
0.4
0.4
0.4
Field Burning of Agricultural Residues
0.1
0.1
0.1
0.1
0.1
0.1
0.1
Wetlands Remaining Wetlands
+
+
+
+
+
+
+
International Bunker Fuels'
1.1
1.0
1.2
1.2
1.2
1.1
1.2
HFCs
36.9
115.0
116.0
120.0
117.5
112.1
123.0
Substitution of Ozone Depleting
0.3
99.0
101.9
102.7
103.6
106.3
114.6
Executive Summary ES-5
-------
Substances
HCFC-22 Production
36.4
15.8
13.8
17.0
13.6
5.4
8.1
Semiconductor Manufacture
0.2
0.2
0.3
0.3
0.3
0.3
0.3
PFCs
20.6
6.2
6.0
7.5
6.6
5.6
5.6
Semiconductor Manufacture
2.2
3.2
3.5
3.7
4.0
4.0
4.1
Aluminum Production
18.4
3.0
2.5
3.8
2.7
1.6
1.6
sf6
32.6
17.8
16.8
15.6
15.0
13.9
14.0
Electrical Transmission and
Distribution
26.7
13.9
13.0
12.2
12.2
11.8
11.8
Magnesium Production and Processing
5.4
2.9
2.9
2.6
1.9
1.1
1.3
Semiconductor Manufacture
0.5
1.0
1.0
0.8
0.9
1.0
0.9
Total
Net Emission (Sources and Sinks)
6,175.2
5,293.4
7.204.2
6.118.3
7,159.3
6,048.9
7,252.8
6,144.5
7,048.3
5,960.9
6,608.3
5,545.7
6,821.8
5,747.1
+ Does not exceed 0.05 Tg C02 Eq.
a Parentheses indicate negative values or sequestration. The net C02 flux total includes both emissions and sequestration, and
constitutes a net sink in the United States. Sinks are only included in net emissions total.
b Emissions from Wood Biomass and Ethanol Consumption are not included specifically in summing energy sector totals. Net
carbon fluxes from changes in biogenic carbon reservoirs are accounted for in the estimates for Land Use, Land-Use Change,
and Forestry.
c Emissions from International Bunker Fuels are not included in totals.
d Small amounts of PFC emissions also result from this source.
Note: Totals may not sum due to independent rounding.
Figure ES-4 illustrates the relative contribution of the direct greenhouse gases to total U.S. emissions in 2010. The
primary greenhouse gas emitted by human activities in the United States was C02, representing approximately 83.6
percent of total greenhouse gas emissions. The largest source of C02, and of overall greenhouse gas emissions, was
fossil fuel combustion. CH4 emissions, which have decreased by 0.3 percent since 1990, resulted primarily from
natural gas systems, enteric fermentation associated with domestic livestock, and decomposition of wastes in
landfills. Agricultural soil management, mobile source fuel combustion and stationary fuel combustion were the
major sources of N20 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
from semiconductor manufacturing and as a by-product of primary aluminum production, while electrical
transmission and distribution systems accounted for most SF6 emissions.
Figure ES-4: 2010 Greenhouse Gas Emissions by Gas (percentages based on Tg C02 Eq.)
Overall, from 1990 to 2010, total emissions of C02 increased by 605.9 Tg C02 Eq. (11.9 percent), while total
emissions of CH4 and N20 decreased by 1.7 Tg C02Eq. (0.3 percent), and 10.0 Tg C02 Eq. (3.2 percent),
respectively. During the same period, aggregate weighted emissions of HFCs, PFCs, and SF6 rose by 52.5 Tg C02
Eq. (58.2 percent). From 1990 to 2010, HFCs increased by 86.1 Tg C02 Eq. (233.1 percent), PFCs decreased by
15.0 Tg C02 Eq. (72.7 percent), and SF6 decreased by 18.6 Tg C02 Eq. (57.0 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 15.8 percent of total emissions in 2010. The following sections describe each gas's contribution to total U.S.
greenhouse gas emissions in more detail.
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
C02 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 C02 have risen
about 39 percent (IPCC 2007 and NOAA/ESLR 2009), principally due to the combustion of fossil fuels. Within the
ES-6 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2010
-------
United States, fossil fuel combustion accounted for 94.4 percent of C02 emissions in 2010. Globally, approximately
30,313 Tg of C02 were added to the atmosphere through the combustion of fossil fuels in 2009, of which the United
States accounted for about 18 percent.13 Changes in land use and forestry practices can also emit C02 (e.g., through
conversion of forest land to agricultural or urban use) or can act as a sink for C02 (e.g., through net additions to
forest biomass). In addition to fossil-fuel combustion, several other sources emit significant quantities of C02. These
sources include, but are not limited to non-energy use of fuels, iron and steel production and cement production
(Figure ES-5).
Figure ES-5: 2010 Sources of C02 Emissions
As the largest source of U.S. greenhouse gas emissions, C02 from fossil fuel combustion has accounted for
approximately 78 percent of GWP-weighted emissions since 1990, growing slowly from 77 percent of total GWP-
weighted emissions in 1990 to 79 percent in 2010. Emissions of C02 from fossil fuel combustion increased at an
average annual rate of 0.7 percent from 1990 to 2010. The fundamental factors influencing this trend include (1) a
generally growing domestic economy over the last 21 years, and (2) an overall growth in emissions from electricity
generation and transportation activities. Between 1990 and 2010, C02 emissions from fossil fuel combustion
increased from 4,738.3 Tg C02 Eq. to 5,387.8 Tg C02 Eq.—a 13.7 percent total increase over the twenty-one-year
period. From 2009 to 2010, these emissions increased by 181.6 Tg C02 Eq. (3.5 percent).
Historically, changes in emissions from fossil fuel combustion have been the dominant factor affecting U.S.
emission trends. Changes in C02 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. In the short term, the overall consumption of fossil fuels in the United States fluctuates
primarily 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 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. In the long term,
energy consumption patterns respond to changes that affect the scale of consumption (e.g., population, number of
cars, and size of houses), the efficiency with which energy is used in equipment (e.g., cars, power plants, steel mills,
and light bulbs) and behavioral choices (e.g., walking, bicycling, or telecommuting to work instead of driving).
Figure ES-6: 2010 C02 Emissions from Fossil Fuel Combustion by Sector and Fuel Type
Figure ES-7: 2010 End-Use Sector Emissions of C02, CH4, and N20 from Fossil Fuel Combustion
The five major fuel consuming sectors contributing to C02 emissions from fossil fuel combustion are electricity
generation, transportation, industrial, residential, and commercial. C02 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.
13 Global C02 emissions from fossil fuel combustion were taken from Energy Information Administration International Energy
Statistics 2010 < http://tonto.eia.doe.gov/cfapps/ipdbproject/IEDIndex3.cfm> EIA (2010a).
Executive Summary ES-7
-------
Figure ES-6, Figure ES-7, and Table ES-3 summarize C02 emissions from fossil fuel combustion by end-use sector.
Table ES-3: C02 Emissions from Fossil Fuel Combustion by Fuel Consuming End-Use Sector (Tg or million metric
tons C02 Eq.)
End-Use Sector
I'm
2005
2006
2007
2008
2009
2010
Transportation
1,901.3
1,882.6
1,899.0
1,794.5
1,732.4
1,750.0
Combustion
1,485.9
1,896.6
1,878.1
1,893.9
1,789.8
1,727.9
1,745.5
Electricity
3.0
4.7
4.5
5.1
4.7
4.5
4.5
Industrial
1,533.1
1,553.3
1,560.2
1,559.8
1,503.8
1,328.6
1,415.4
Combustion
846.4
816.4
848.1
844.4
806.5
726.6
777.8
Electricity
686.8
737.0
712.0
715.4
697.3
602.0
637.6
Residential
931.4
1,214.7
1,152.4
1,205.2
1,192.2
1,125.5
1,183.7
Combustion
338.3
357.9
321.5
341.6
349.3
339.0
340.2
Electricity
593.0
856.7
830.8
863.5
842.9
786.5
843.5
Commercial
757.0
1,027.2
1,007.6
1,047.7
1,041.1
978.0
997.1
Combustion
219.0
223.5
208.6
218.9
225.1
224.6
224.2
Electricity
538.0
803.7
799.0
828.8
816.0
753.5
772.9
U.S. Territories3
21.')
50.0
50.3
46.1
39.8
41.7
41.6
Total
4,73N.3
5,746.5
5,653.0
5,757.8
5,571.5
5,206.2
5,387.8
Electricity Generation
1.820.K
2,402.1
2,346.4
2,412.8
2,360.9
2,146.4
2,258.4
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.
Transportation End-Use Sector. Transportation activities (excluding international bunker fuels) accounted for 32
percent of C02 emissions from fossil fuel combustion in 2010.14 Virtually all of the energy consumed in this end-
use sector came from petroleum products. Nearly 65 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. From 1990 to 2010, transportation
emissions rose by 18 percent due, in large part, to increased demand for travel and the stagnation of fuel efficiency
across the U.S. vehicle fleet. The number of vehicle miles traveled by light-duty motor vehicles (passenger cars and
light-duty trucks) increased 34 percent from 1990 to 2010, as a result of a confluence of factors including population
growth, economic growth, urban sprawl, and low fuel prices over much of this period.
Industrial End-Use Sector. Industrial C02 emissions, resulting both directly from the combustion of fossil fuels and
indirectly from the generation of electricity that is consumed by industry, accounted for 26 percent of C02 from
fossil fuel combustion in 2010. Approximately 55 percent of these emissions resulted from direct fossil fuel
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. In contrast to the other
end-use sectors, emissions from industry have steadily declined since 1990. This decline is due to structural changes
in the U.S. economy (i.e., shifts from a manufacturing-based to a service-based economy), fuel switching, and
efficiency improvements.
Residential and Commercial End-Use Sectors. The residential and commercial end-use sectors accounted for 22
and 19 percent, respectively, of C02 emissions from fossil fuel combustion in 2010. Both sectors relied heavily on
electricity for meeting energy demands, with 71 and 78 percent, respectively, of their emissions attributable to
electricity consumption for lighting, heating, cooling, and operating appliances. The remaining emissions were due
to the consumption of natural gas and petroleum for heating and cooking. Emissions from these end-use sectors
have increased 29 percent since 1990, due to increasing electricity consumption for lighting, heating, air
conditioning, and operating appliances.
14 If emissions from international bunker fuels are included, the transportation end-use sector accounted for 34.0 percent of U.S.
emissions from fossil fuel combustion in 2010.
ES-8 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2010
-------
Electricity Generation. The United States relies on electricity to meet a significant portion of its energy demands.
Electricity generators consumed 36 percent of U.S. energy from fossil fuels and emitted 42 percent of the C02 from
fossil fuel combustion in 2010. The type of fuel combusted by electricity generators has a significant effect on their
emissions. For example, some electricity is generated with low C02 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 94 percent of all coal consumed for energy in the
United States in 2010. Consequently, changes in electricity demand have a significant impact on coal consumption
and associated C02 emissions.
Other significant C02 trends included the following:
• C02 emissions from non-energy use of fossil fuels have increased 5.5 Tg C02 Eq. (4.6 percent) from 1990
through 2010. Emissions from non-energy uses of fossil fuels were 125.1 Tg C02 Eq. in 2010, which
constituted 2.2 percent of total national C02 emissions, approximately the same proportion as in 1990.
• C02 emissions from iron and steel production and metallurgical coke production increased by 12.2 Tg C02
Eq. (28.9 percent) from 2009 to 2010, upsetting a trend of decreasing emissions. Despite this, from 1990
through 2010 emissions declined by 45.5 percent (45.3 Tg C02 Eq.). This decline is due to the
restructuring of the industry, technological improvements, and increased scrap utilization.
• In 2010, C02 emissions from cement production increased by 1.5 Tg C02 Eq. (5.1 percent) from 2009.
After decreasing in 1991 by two percent from 1990 levels, cement production emissions grew every year
through 2006; emissions decreased in the three years prior to 2010. Overall, from 1990 to 2010, emissions
from cement production have decreased by 8.3 percent, a decrease of 2.8 Tg C02 Eq.
• Net C02 uptake from Land Use, Land-Use Change, and Forestry increased by 192.8 Tg C02 Eq. (21.9
percent) from 1990 through 2010. 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.
Methane Emissions
Methane (CH4) is more than 20 times as effective as C02 at trapping heat in the atmosphere (IPCC 1996). Over the
last two hundred and fifty years, the concentration of CH4 in the atmosphere increased by 158 percent (IPCC 2007).
Anthropogenic sources of CH4 include natural gas and petroleum systems, agricultural activities, landfills, coal
mining, wastewater treatment, stationary and mobile combustion, and certain industrial processes (see Figure ES-8).
Figure ES-8: 2010 Sources of CH4 Emissions
Some significant trends in U.S. emissions of CH4 include the following:
• Natural gas systems were the largest anthropogenic source category of CH4 emissions in the United States
in 2010 with 215.4 Tg C02 Eq. of CH4 emitted into the atmosphere. Those emissions have increased by
25.8 Tg C02 Eq. (13.6 percent) since 1990.
• Enteric fermentation is the second largest anthropogenic source of CH4 emissions in the United States. In
2010, enteric fermentation CH4 emissions were 141.3 Tg C02 Eq. (21.2 percent of total CH4 emissions),
which represents an increase of 7.5 Tg C02 Eq. (5.6 percent) since 1990.
• Landfills are the third largest anthropogenic source of CH4 emissions in the United States, accounting for
16.2 percent of total CH4 emissions (107.8 Tg C02 Eq.) in 2010. From 1990 to 2010, CH4 emissions from
landfills decreased by 39.8 Tg C02 Eq. (27.0 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
Executive Summary ES-9
-------
collected and combusted,15 which has more than offset the additional CH4 emissions resulting from an
increase in the amount of municipal solid waste landfilled.
• In 2010, CH4 emissions from coal mining were 72.6 Tg C02 Eq., a 2.5 Tg C02 Eq. (3.5 percent) increase
over 2009 emission levels. The overall decline of 11.5 Tg C02 Eq. (13.6 percent) from 1990 results from
the mining of less gassy coal from underground mines and the increased use of CH4 collected from
degasification systems.
• Methane emissions from manure management increased by 64.0 percent since 1990, from 31.7 Tg C02 Eq.
in 1990 to 52.0 Tg C02 Eq. in 2010. 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
N20 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 N20 emissions are much
lower than C02 emissions, N20 is approximately 300 times more powerful than C02 at trapping heat in the
atmosphere (IPCC 1996). Since 1750, the global atmospheric concentration of N20 has risen by approximately 19
percent (IPCC 2007). The main anthropogenic activities producing N20 in the United States are agricultural soil
management, fuel combustion in motor vehicles, stationary fuel combustion, manure management and nitric acid
production (see Figure ES-9).
Figure ES-9: 2010 Sources of N20 Emissions
Some significant trends in U.S. emissions of N20 include the following:
• In 2010, N20 emissions from mobile combustion were 20.6 Tg C02 Eq. (approximately 6.7 percent of U.S.
N20 emissions). From 1990 to 2010, N20 emissions from mobile combustion decreased by 53.1 percent.
However, from 1990 to 1998 emissions increased by 25.6 percent, due to control technologies that reduced
NOx emissions while increasing N20 emissions. Since 1998, newer control technologies have led to an
overall decline in N20 from this source.
• N20 emissions from adipic acid production were 2.8 Tg C02 Eq. in 2010, and have decreased significantly
in recent years due to the widespread installation of pollution control measures. Emissions from adipic acid
production have decreased by 82.2 percent since 1990 and by 84.0 percent since a peak in 1995.
• N20 emissions from stationary combustion increased 10.3 Tg C02 Eq. (84.4 percent) from 1990 through
2010. N20 emissions from this source increased primarily as a result of an increase in the number of coal
fluidized bed boilers in the electric power sector.
• Agricultural soils accounted for approximately 67.9 percent of N20 emissions in the United States in 2010.
Estimated emissions from this source in 2010 were 207.8 Tg C02 Eq. Annual N20 emissions from
agricultural soils fluctuated between 1990 and 2010, although overall emissions were 3.9 percent higher in
2010 than in 1990.
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
15 The C02 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.
ES-10 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2010
-------
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
IPCC has evaluated (IPCC 1996).
Other emissive sources of these gases include electrical transmission and distribution systems, HCFC-22 production,
semiconductor manufacturing, aluminum production, and magnesium production and processing (see Figure ES-10).
Figure ES-10: 2010 Sources of HFCs, PFCs, and SF6 Emissions
Some significant trends in U.S. HFC, PFC, and SF6 emissions include the following:
• Emissions resulting from the substitution of ozone depleting substances (ODS) (e.g., CFCs) have been
consistently increasing, from small amounts in 1990 to 114.6 Tg C02 Eq. in 2010. 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-out of ODS required under the Montreal Protocol came 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 77.8 percent (28.3 Tg C02 Eq.) from 1990
through 2010, 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 of thermal oxidation at some plants to reduce HFC-23
emissions.
• SF6 emissions from electric power transmission and distribution systems decreased by 55.7 percent (14.9
Tg C02 Eq.) from 1990 to 2010, primarily because of higher purchase prices for SF6 and efforts by industry
to reduce emissions.
• PFC emissions from aluminum production decreased by 91.5 percent (16.9 Tg C02 Eq.) from 1990 to
2010, due to both industry emission reduction efforts and declines in domestic aluminum production.
ES.3. Overview of Sector Emissions and Trends
In accordance with the Revised 1996 IPCC 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 twenty-one-year period of 1990 to 2010, total
emissions in the Energy and Agriculture sectors grew by 645.8 Tg C02 Eq. (12.2 percent), and 40.6 Tg C02 Eq.
(10.5 percent), respectively. Emissions slightly decreased in the Industrial Processes sector by 10.5 Tg C02 Eq. (3.4
percent), while emissions from the Waste and Solvent and Other Product Use sectors decreased by 35.2 Tg C02 Eq.
(21.0 percent) and less than 0.1 Tg C02 Eq. (0.4 percent), respectively. Over the same period, estimates of net C
sequestration in the Land Use, Land-Use Change, and Forestry (LULUCF) sector (magnitude of emissions plus C02
flux from all LULUCF source categories) increased by 187.0 Tg C02 Eq. (21.5 percent).
Figure ES-11: U.S. Greenhouse Gas Emissions and Sinks by Chapter/IPCC Sector
Table ES-4: Recent Trends in U.S. Greenhouse Gas Emissions and Sinks by Chapter/IPCC Sector (Tg or million
metric tons C02 Eq.)
Chapter/IPCC Sector 1990 2005 2006 2007 2008 2009 2010
Energy 5,287.7 6,282.4 6,214.4 6,294.3 6,125.4 5,752.7 5,933.5
Industrial Processes 313.9 330.1 335.5 347.3 319.1 268.2 303.4
Executive Summary ES-11
-------
Solvent and Other Product Use
4.4
4.4
4.4
4.4
4.4
4.4
4.4
Agriculture
387.8
424.6
425.4
432.6
433.8
426.4
428.4
Land-Use Change and Forestry
13.8
25.6
43.2
37.6
27.4
20.6
19.6
Waste
167.7
137.2
136.5
136.7
138.2
136.0
132.5
Total Emissions
6,175.2
7,204.2
7,159.3
7,252.8
7,048.3
6,608.3
6,821.8
Land-Use Change and Forestry (Sinks)
(881.8)
(1,085.9)
(1,110.4)
(1,108.2)
(1,087.5)
(1,062.6)
(1,074.7)
Net Emissions (Emissions and Sinks)
5,293.4
6,118.3
6,048.9
6,144.5
5,960.9
5,545.7
5,747.1
* 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.
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. C02 emissions for the period of 1990 through 2010. In 2010,
approximately 85 percent of the energy consumed in the United States (on a Btu basis) was produced through the
combustion of fossil fuels. The remaining 15 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 N20
emissions (50 percent and 14 percent of total U.S. emissions of each gas, respectively). Overall, emission sources in
the Energy chapter account for a combined 87.0 percent of total U.S. greenhouse gas emissions in 2010.
Figure ES-12: 2010 U.S. Energy Consumption by Energy Source
Industrial Processes
The Industrial Processes chapter contains by-product 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 C02, CH4, and N20. 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, C02 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 4.4 percent of U.S. greenhouse gas emissions in 2010.
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 N20 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 2010.
Agriculture
The Agricultural chapter contains anthropogenic emissions from agricultural activities (except fuel combustion,
which is addressed in the Energy chapter, and agricultural C02 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 N20 were the primary greenhouse gases emitted by agricultural activities. CH4 emissions from
enteric fermentation and manure management represented 21.2 percent and 7.8 percent of total CH4 emissions from
ES-12 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2010
-------
anthropogenic activities, respectively, in 2010. Agricultural soil management activities such as fertilizer application
and other cropping practices were the largest source of U.S. N20 emissions in 2010, accounting for 67.9 percent. In
2010, emission sources accounted for in the Agricultural chapters were responsible for 6.3 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 N20, and emissions and
removals of C02 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 resulted in a net uptake (sequestration) of C in the United States. Forests (including vegetation,
soils, and harvested wood) accounted for 86 percent of total 2010 net C02 flux, urban trees accounted for 9 percent,
mineral and organic soil carbon stock changes accounted for 4 percent, and landfilled yard trimmings and food
scraps accounted for 1 percent of the total net flux in 2010. 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 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 2010 resulted in a net C sequestration of 1,074.7 Tg C02 Eq.
(Table ES-5). This represents an offset of 18.8 percent of total U.S. C02 emissions, or 15.8 percent of total
greenhouse gas emissions in 2010. Between 1990 and 2010, total land use, land-use change, and forestry net C flux
resulted in a 21.9 percent increase in C02 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 or million metric tons C02 Eq.)
Sink Category
199(1
2005
2006
2007
2008
2009
2010
Forest Land Remaining Forest Land
(701.4)
(940.9)
(963.5)
(959.2)
(938.3)
(910.6)
(921.8)
Cropland Remaining Cropland
(29.4)
(18.3)
(19.1)
(19.7)
(18.1)
(17.4)
(15.6)
Land Converted to Cropland
2.2
5.9
5.9
5.9
5.9
5.9
5.9
Grassland Remaining Grassland
(52.2)
(8.9)
(8.8)
(8.6)
(8.5)
(8.3)
(8.3)
Land Converted to Grassland
(19.8)
(24.4)
(24.2)
(24.0)
(23.8)
(23.6)
(23.6)
Settlements Remaining Settlements
(57.1)
(87.8)
(89.8)
(91.9)
(93.9)
(95.9)
(98.0)
Other (Landfilled Yard Trimmings and Food
Scraps)
(24.2)
(11.6)
(11.0)
(10.9)
(10.9)
(12.7)
(13.3)
Total
(881.8)
(1,085.9) (1,110.4) (1,108.2)
(1,087.5) (1,062.6)
(1,074.7)
Note: Totals may not sum due to independent rounding. Parentheses indicate net sequestration.
Emissions from Land Use, Land-Use Change, and Forestry are shown in Table ES-6. Liming of agricultural soils
and urea fertilization in 2010 resulted in C02 emissions of 3.9 Tg C02 Eq. (3,906 Gg) and 4.1 Tg C02 Eq. (4,143
Gg), respectively. Lands undergoing peat extraction (i.e., Peatlands Remaining Peatlands) resulted in C02
emissions of 1.0 Tg C02 Eq. (983 Gg), and N20 emissions of less than 0.05 Tg C02 Eq. The application of
synthetic fertilizers to forest soils in 2010 resulted in direct N20 emissions of 0.4 Tg C02 Eq. (1 Gg). Direct N20
emissions from fertilizer application to forest soils have increased by 455 percent since 1990, but still account for a
relatively small portion of overall emissions. Additionally, direct N20 emissions from fertilizer application to
settlement soils in 2010 accounted for 1.4 Tg C02 Eq. (5 Gg). This represents an increase of 43 percent since 1990.
Forest fires in 2010 resulted in CH4 emissions of 4.8 Tg C02 Eq. (231 Gg), and in N20 emissions of 4.0 Tg C02 Eq.
(14 Gg).
Table ES-6: Emissions from Land Use, Land-Use Change, and Forestry (Tg or million metric tons C02 Eq.)
Executive Summary ES-13
-------
Source Category
1990
2005
2006
2007
2008
2009
2010
co2
8.1
8.9
8.8
9.2
9.6
8.3
9.0
Cropland Remaining Cropland: Liming
of Agricultural Soils
4.7
4.3
4.2
4.5
5.0
3.7
3.9
Cropland Remaining Cropland: Urea
Fertilization
2.4
3.5
3.7
3.8
3.6
3.6
4.1
Wetlands Remaining Wetlands: Peatlands
Remaining Peatlands
1.0
1.1
0.9
1.0
1.0
1.1
1.0
CH,
2.5
8.1
17.9
14.6
8.8
5.8
4.8
Forest Land Remaining Forest Land:
Forest Fires
2.5
8.1
17.9
14.6
8.8
5.8
4.8
n2o
3.1
8.5
16.5
13.8
9.0
6.5
5.7
Forest Land Remaining Forest Land:
Forest Fires
2.1
6.6
14.6
11.9
7.2
4.7
4.0
Forest Land Remaining Forest Land:
Forest Soils
0.1
0.4
0.4
0.4
0.4
0.4
0.4
Settlements Remaining Settlements:
Settlement Soils
1.0
1.5
1.5
1.6
1.5
1.4
1.4
Wetlands Remaining Wetlands: Peatlands
Remaining Peatlands
+
+
+
+
+
+
+
Total
13.8
25.6
43.2
37.6
27.4
20.6
19.6
+ Less than 0.05 Tg C02 Eq.
Note: Totals may not sum due to independent rounding.
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 81.4 percent of this chapter's emissions, and 16.2 percent of total U.S. CH4
emissions.16 Additionally, wastewater treatment accounts for 16.1 percent of Waste emissions, 2.5 percent of U.S.
CH4 emissions, and 1.6 percent of U.S. N20 emissions. Emissions of CH4 and N20 from composting are also
accounted for in this chapter; generating emissions of 1.6 Tg C02 Eq. and 1.7 Tg C02 Eq., respectively. Overall,
emission sources accounted for in the Waste chapter generated 1.9 percent of total U.S. greenhouse gas emissions in
2010.
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 2010.
Figure ES-13: Emissions Allocated to Economic Sectors
16 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.
ES-14 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2010
-------
Table ES-7: U.S. Greenhouse Gas Emissions Allocated to Economic Sectors (Tg or million metric tons C02 Eq.)
Implied Sectors
1990
2005
2006
2007
2008
2009
2010
Electric Power Industry
1,866.2
2,448.8
2,393.0
2,459.1
2,405.8
2,191.4
2,306.5
Transportation
1,545.2
2,017.5
1,994.5
2,002.4
1,889.8
1,819.3
1,834.0
Industry
1,564.8
1,438.1
1,499.8
1,489.6
1,448.5
1,317.2
1,394.2
Agriculture
431.9
496.0
516.7
517.6
505.8
492.8
494.8
Commercial
388.0
374.3
359.9
372.2
381.8
382.0
381.7
Residential
345.4
371.3
336.1
358.4
368.4
360.0
365.2
U.S. Territories
33
58.2
59.3
53.5
48.4
45.5
45.5
Total Emissions
6,175.2
7,204.2
7,159.3
7,252.8
7,048.3
6,608.3
6,821.8
Land Use, Land-Use Change, and Forestry
(Sinks)
(881.8)
(1,085.9)
(1,110.4)
(1,108.2)
(1,087.5)
(1,062.6)
(1,074.7)
Net Emissions (Sources and Sinks)
5,293.4
6,118.3
6,048.9
6,144.5
5,960.9
5,545.7
5,747.1
Note: Totals may not sum due to independent rounding. Emissions include C02, CH4, N20, HFCs, PFCs, and SF6.
See Table 2-12 for more detailed data.
Using this categorization, emissions from electricity generation accounted for the largest portion (34 percent) of
U.S. greenhouse gas emissions in 2010. Transportation activities, in aggregate, accounted for the second largest
portion (27 percent), while emissions from industry accounted for the third largest portion (20 percent) of U.S.
greenhouse gas emissions in 2010. 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 N20 emissions from agricultural soil management and CH4
emissions from enteric fermentation. The commercial and residential sectors accounted for 6 and 5 percent,
respectively, of emissions and U.S. territories accounted for 1 percent of emissions; emissions from these sectors
primarily consisted of C02 emissions from fossil fuel combustion.
C02 was also emitted and sequestered by a variety of activities related to forest management practices, tree 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, industry, transportation, and
agriculture economic sectors according to retail sales of electricity.17 These source categories include C02 from
fossil fuel combustion and the use of limestone and dolomite for flue gas desulfurization, C02 and N20 from
incineration of waste, CH4 and N20 from stationary sources, and SF6 from electrical transmission and distribution
systems.
When emissions from electricity are distributed among these sectors, industrial activities account for the largest
share of U.S. greenhouse gas emissions (30 percent) in 2010. Transportation is the second largest contributor to
total U.S. emissions (27 percent). The residential and commercial sectors contributed the next largest shares of total
U.S. greenhouse gas emissions in 2010. Emissions from these sectors increase substantially when emissions from
electricity are included, due to their relatively large share of electricity consumption (e.g., lighting, appliances, etc.).
In all sectors except agriculture, C02 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 2010.
Table ES-8: U.S Greenhouse Gas Emissions by Economic Sector with Electricity-Related Emissions Distributed
17 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.
Executive Summary ES-15
-------
(Tg or million metric tons C02 Eq.)
Implied Sectors
1990
2005
2006
2007
2008
2009
2010
Industry
2,237."
2,159.9
2,198.5
2,185.9
2,131.5
1,905.8
2,019.0
Transportation
1,548.3
2,022.3
1,999.1
2,007.6
1,894.6
1,823.9
1,838.6
Residential
953.2
1,244.6
1,183.4
1,238.5
1,227.3
1,162.9
1,226.6
Commercial
939.4
1,193.6
1,174.8
1,216.9
1,213.3
1,151.3
1,171.0
Agriculture
462.9
525.5
544.2
550.5
533.3
518.9
521.1
U.S. Territories
33."
58.2
59.3
53.5
48.4
45.5
45.5
Total Emissions
6,175.2
7,204.2
7,159.3
7,252.8
7,048.3
6,608.3
6,821.8
Land Use, Land-Use Change, and
Forestry (Sinks)
(881.8)
(1,085.9)
(1,110.4)
(1,108.2)
(1,087.5)
(1,062.6)
(1,074.7)
Net Emissions (Sources and Sinks)
5,293.4
6,118.3
6,048.9
6,144.5
5,960.9
5,545.7
5,747.1
See Table 2-14 for more detailed data.
Figure ES-14: Emissions with Electricity Distributed to Economic Sectors
[BEGIN BOX]
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 2010; (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 0.5 percent
since 1990. This rate is slightly slower than that for total energy and for fossil fuel consumption, and much slower
than that for electricity consumption, overall gross domestic product and national population (see Figure ES-15).
Table ES-9: Recent Trends in Various U.S. Data (Index 1990 = 100)
Variable
19911
2005
2006
2007
2008
2009
2010
Growth
Rate3
GDP"
100
157
161
165
164
158
163
2.5%
Electricity Consumption0
100
134
135
137
136
131
137
1.6%
Fossil Fuel Consumption0
100
119
117
119
116
109
113
0.6%
Energy Consumption0
100
119
118
121
119
113
117
0.8%
Population"1
100
118
120
121
122
123
123
1.1%
Greenhouse Gas Emissions6
100
117
116
117
114
107
110
0.5%
a Average annual growth rate
b Gross Domestic Product in chained 2005 dollars (BEA 2010)
c Energy content-weighted values (EIA 2010b)
d U.S. Census Bureau (2010)
e GWP-weighted values
Figure ES-15: U.S. Greenhouse Gas Emissions Per Capita and Per Dollar of Gross Domestic Product
Source: BEA (2010), U.S. Census Bureau (2010), and emission estimates in this report.
ES-16 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2010
-------
[END BOX]
Indirect Greenhouse Gases (CO, NOx, NMVOCs, and SO2)
The reporting requirements of the UNFCCC* request that information be provided on indirect greenhouse gases,
which include CO, NOx, NMVOCs, and S02. 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 S02, 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 S02 (EPA
2010, EPA 2009),19 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.
Table ES-10: Emissions of NOx, CO, NMVOCs, and S02 (Gg)
Gas/Activity
1990
2005
2006
2007
2008
2009
2010
NOx
21,705
15,899
15,039
14,380
13,545
11,467
11,467
Mobile Fossil Fuel Combustion
10,862
9,012
8,488
7,965
7,441
6,206
6,206
Stationary Fossil Fuel Combustion
10,02.'
5,858
5,545
5,432
5,148
4,159
4,159
Industrial Processes
591
569
553
537
520
568
568
Oil and Gas Activities
139
321
319
318
318
393
393
Incineration of Waste
82
129
121
114
106
128
128
Agricultural Burning
8
6
7
8
8
8
8
Solvent Use
1
3
4
4
4
3
3
Waste
2
2
2
2
2
2
CO
129,976
70,791
67,227
63,613
59,993
51,431
51,431
Mobile Fossil Fuel Combustion
119,360
62,692
58,972
55,253
51,533
43,355
43,355
Stationary Fossil Fuel Combustion
5,000
4,649
4,695
4,744
4,792
4,543
4,543
Industrial Processes
4,125
1,555
1,597
1,640
1,682
1,549
1,549
Incineration of Waste
978
1,403
1,412
1,421
1,430
1,403
1,403
Agricultural Burning
268
184
233
237
270
247
247
Oil and Gas Activities
302
318
319
320
322
345
345
Waste
1
7
7
7
7
7
7
Solvent Use
5
2
2
2
2
2
2
NMVOCs
20,930
13,761
13,594
13,423
13,254
9,313
9,313
Mobile Fossil Fuel Combustion
10,932
6,330
6,037
5,742
5,447
4,151
4,151
Solvent Use
5,216
3,851
3,846
3,839
3,834
2,583
2,583
Industrial Processes
2,422
1,997
1,933
1,869
1,804
1,322
1,322
Stationary Fossil Fuel Combustion
912
716
918
1,120
1,321
424
424
Oil and Gas Activities
554
510
510
509
509
599
599
Incineration of Waste
222
241
238
234
230
159
159
Waste
673
114
113
111
109
76
76
Agricultural Burning
NA
NA
NA
NA
NA
NA
NA
so2
20,935
13,466
12,388
11,799
10,368
8,599
8,599
Stationary Fossil Fuel Combustion
18,40"
11,541
10,612
10,172
8,891
7,167
7,167
Industrial Processes
1,30"
831
818
807
795
798
798
Mobile Fossil Fuel Combustion
793
889
750
611
472
455
455
Oil and Gas Activities
390
181
182
184
187
154
154
18 See .
19 NOx and CO emission estimates from field burning of agricultural residues were estimated separately, and therefore not taken
from EPA (2008).
Executive Summary ES-17
-------
Incineration of Waste
38
24
24
24
23
24
24
Waste
+SS
1
1
1
1
1
1
Solvent Use
+
+
+
+
+
+
Agricultural Burning
NA
NA
NA
NA
NA
NA
NA
Source: (EPA 2010, EPA 2009) except for estimates from field burning of agricultural residues.
NA (Not Available)
Note: Totals may not sum due to independent rounding.
+ Does not exceed 0.5 Gg.
Key Categories
The 2006 IPCC Guidelines for National Greenhouse Gas Inventories (IPCC 2006) 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."20 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 any key categories that were not
identified in either of the quantitative analyses.
Figure ES-16 presents 2010 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.
Figure ES-16: 2010 Key Categories
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 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 C02 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. 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
20 See Chapter 7 "Methodological Choice and Recalculation" in IPCC (2000).
ES-18 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2010
-------
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.
[BEGIN BOX]
Box ES- 3: 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 2006 IPCC
Guidelines (IPCC 2006), which states, "Both methodological changes and refinements over time are an essential
part of improving inventory quality. It is good practice to change or refine methods" when: available data have
changed; the previously used method is not consistent with the IPCC guidelines for that category; a category has
become key; the previously used method is insufficient to reflect mitigation activities in a transparent manner; the
capacity for inventory preparation has increased; new inventory methods become available; and for correction of
errors." 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 2010) has been
recalculated to reflect the change, per the 2006 IPCC Guidelines (IPCC 2006). 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.
[END BOX]
Executive Summary ES-19
-------
-------
8,000
7,000
6,000
£ 5,000
o
° 4,000
CD
I—
3,000
2,000
1,000
¦ HFCs, PFCs, & SFe Nitrous Oxide
¦ Methane
6 237 6,360 6,457
Carbon Dioxide
6,757 6,803 6,
7>104 6 988 7,022 7,053 7,163 7£04 7,159 ^253 Jfj
Figure ES-1: U.S. Greenhouse Gas Emissions by Gas
-6.2%
1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Figure ES-2: Annual Percent Change in U.S. Greenhouse Gas Emissions
988 1'029 984
1,078
Figure ES-3: Cumulative Change in Annual U.S. Greenhouse Gas Emissions Relative to 1990
-------
Figure ES-4: 2010 Greenhouse Gas Emissions by Gas (percents based on Tg C02 Eq.)
Fossil Fuel Combustion
Non-Energy Use of Fuels
Iron and Steel Prod. & Metallurgical Coke Prod.
Natural Gas Systems
Cement Production
Lime Production
Incineration of Waste
Limestone and Dolomite Use
Ammonia Production
Cropland Remaining Cropland
Urea Consumption for Non-Agricultural Purposes
Soda Ash Production and Consumption
Petrochemical Production
Aluminum Production
Carbon Dioxide Consumption
Titanium Dioxide Production
Ferroalloy Production
Zinc Production
Phosphoric Acid Production
Wetlands Remaining Wetlands
Lead Production
Petroleum Systems
Silicon Carbide Production and Consumption
Figure ES-5: 2010 Sources of C02 Emissions
5,388
C02 as a Portion
of all Emissions
< 0.5
< 0.5
25 50 75 100
Tg C02 Eq.
125
150
-------
2,500 n
2,000
1,500
1,000 -
500
0 J
Relative Contribution
by Fuel Type
2,258
1
42
224
Petroleum
i Coal
Natural Gas
340
778
Figure ES-6: 2010 C02 Emissions from Fossil Fuel Combustion by Sector and Fuel Type
Note: Electricity generation also includes emissions of less than 0.5 Tg C02 Eq. from geothermal-based electricity generation.
2,000 -i
1,500
8 1,000 -
500
0 J
From Direct Fossil Fuel Combustion
¦ From Electricity Consumption
1,005
42
1,195
1,425
1,773
Figure ES-7: 2010 End-Use Sector Emissions of C02, CH4, and N20 from Fossil Fuel Combustion
-------
Natural Gas Systems
Enteric Fermentation
Landfills
Coal Mining
Manure Management
Petroleum Systems
Wastewater Treatment
Rice Cultivation
Stationary Combustion
Abandoned Underground Coal Mines
Forest Land Remaining Forest Land
Mobile Combustion
Composting
Petrochemical Production
Iron and Steel Prod. & Metallurgical Coke Prod.
Field Burning of Agricultural Residues
Ferroalloy Production
Silicon Carbide Production and Consumption
Incineration of Waste
CH4 as a Portion
of all Emissions
9.8%
< 0.5
< 0.5
< 0.5
< 0.5
25
50
75
Figure ES-8: 2010 Sources of CH4 Emissions
Agricultural Soil Management
Stationary Combustion
Mobile Combustion
Manure Management
Nitric Acid Production
Wastewater Treatment
N20 from Product Uses
Forest Land Remaining Forest Land
Adipic Acid Production
Composting
Settlements Remaining Settlements
Incineration of Waste
Field Burning of Agricultural Residues
Wetlands Remaining Wetlands
Figure ES-9: 2010 Sources of N20 Emissions
100 125
Tg C02 Eq.
150 175 200 225
208
< 0.5
< 0.5
< 0.5
N20 as a Portion
of all Emissions
4.5%
o
10
20
30
Tg C02 Eq.
-------
Substitution of Ozone Depleting Substances
115
Electrical Transmission and Distribution
HCFC-22 Production
Semiconductor Manufacture
Aluminum Production
Magnesium Production and Processing
HFCs, PFCs, and SF6 as a Portion
of all Emissions
2.1%
0
10
Tg C02 Eq.
20
Figure ES-10: 2010 Sources of HFCs, PFCs, and SF6 Emissions
7,500
7,000
6,500
6,000
5,500
5,000
4,500
4,000
&
LU
3,500
o
3,000
o
CD
2,500
I—
2,000
1,500
1,000
500
0
(500)
(1,000)
(1,500)
Industrial Processes
Agriculture
Waste
LULUCF (sources)
Energy
Land Use, Land-Use Change and Forestry (sinks)
Note: Relatively smaller amounts of GWP-meighted emissions are also emitted from the Solvent and Other Product Use sectors
Figure ES-11: U.S. Greenhouse Gas Emissions and Sinks by Chapter/IPCC Sector
-------
Renewable
Energy
Nuclear Electric r no/
Figure ES-12: 2010 U.S. Energy Consumption by Energy Source
Figure ES-13: Emissions Allocated to Economic Sectors
Note: Does not include U.S. Territories.
-------
Figure ES-14: Emissions with Electricity Distributed to Economic Sectors
Note: Does not include U.S. Territories.
Figure ES-15: U.S. Greenhouse Gas Emissions Per Capita and Per Dollar of Gross Domestic Product
-------
C02 Emissions from Stationary Combustion (Coal) Electricity Gen.
C02 Emissions from Mobile Combustion: Road
C02 Emissions from Stationary Combustion (Gas) Electricity Gen.
C02 Emissions from Stationary Combustion - Gas - Industrial
C02 Emissions from Stationary Combustion - Oil - Industrial
C02 Emissions from Stationary Combustion - Gas - Residential
Fugitive Emissions from Natural Gas Systems
C02 Emissions from Stationary Combustion - Gas - Commercial
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
Emissions from Substitutes for Ozone Depleting Substances
CH4 Emissions from Landfills
C02 Emissions from Stationary Combustion - Coal - Industrial
C02 Emissions from Mobile Combustion: Other
C02 Emissions from Stationary Combustion - Oil - Residential
Fugitive Emissions from Coal Mining
C02 Em. from Iron and Steel Prod. & Metallurgical Coke Prod.
CH4 Emissions from Manure Management
C02 Emissions from Stationary Combustion - Oil - Commercial
Indirect N20 Emissions from Applied Nitrogen
C02 Emissions from Mobile Combustion: Marine
C02 Emissions from Stationary Combustion - Oil - U.S. Territories
C02 Emissions from Natural Gas Systems
Fugitive Emissions from Petroleum Systems
Non-C02 Emissions from Stationary Combustion - Electricity Gen.
CH4 Emissions from Rice Cultivation
Key Categories as a Portion of All
Emissions
200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000
Tg C02 Eq.
Figure ES-16: 2010 Key Categories
Notes: For a complete discussion of the key category analysis, see Annex 1.
Black bars indicate a Tier 1 level assessment key category.
Gray bars indicate a Tier 2 level assessment key category.
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