ANNEX 6 Additional Information
6.1.

Global Warming Potential Values

Global Warming Potential (GWP) is intended as a quantified measure of the globally averaged relative radiative
forcing impacts of a particular greenhouse gas. It is defined as the cumulative radiative forcing–both direct and indirect
effects⎯integrated over a specific period of time from the emission of a unit mass of gas relative to some reference gas(IPCC 2007). Carbon dioxide (CO2) was chosen as this reference gas. Direct effects occur when the gas itself is agreenhouse gas. Indirect radiative forcing occurs when chemical transformations involving the original gas produce a gas
or gases that are greenhouse gases, or when a gas influences other radiatively important processes such as theatmospheric lifetimes of other gases. The relationship between kilotons (kt) of a gas and million metric tons of CO 2
equivalents (MMT CO2 Eq.) can be expressed as follows: MMT MMT CO 2 Eq. = (kt of gas )  (GWP )   1,000 kt 
where,MMT CO2 Eq. =
kt
GWP
MMT

Million metric tons of CO2 equivalent=kilotons (equivalent to a thousand metric tons)=
Global warming potential=
Million metric tons

GWP values allow policy makers to compare the impacts of emissions and reductions of different gases.
According to the IPCC, GWP values typically have an uncertainty of 35 percent, though some GWP values have larger
uncertainty than others, especially those in which lifetimes have not yet been ascertained. In the following decision, thecountries who are Parties to the United Nations Framework Convention on Climate Change (UNFCCC) have agreed to use
consistent GWP values from the IPCC Fourth Assessment Report (AR4), based upon a 100 year time horizon, althoughother time horizon values are available (see Table A-252). While this Inventory uses agreed-upon GWP values according
to the specific reporting requirements of the UNFCCC, described below, unweighted gas emissions and sinks in kilotons(kt) are provided in the Trends chapter of this report (Table 2-2) and users of the Inventory can apply different metrics
and different time horizons to compare the impacts of different greenhouse gases.
…the global warming potential values used by Parties included in Annex I to the Convention (Annex I
Parties) to calculate the carbon dioxide equivalence of anthropogenic emissions by sources and removals bysinks of greenhouse gases shall be those listed in the column entitled “Global warming potential for given time
horizon” in table 2.14 of the errata to the contribution of Working Group I to the Fourth Assessment Report of
the Intergovernmental Panel on Climate Change, based on the effects of greenhouse gases over a 100-year time
140
horizon...
140F

Greenhouse gases with relatively long atmospheric lifetimes (e.g., CO2, CH4, N2O, HFCs, PFCs, SF6, and NF3) tend
to be evenly distributed throughout the atmosphere, and consequently global average concentrations can be
determined. However, short-lived gases such as water vapor, carbon monoxide, tropospheric ozone, other indirect
greenhouse gases (e.g., NOx and NMVOCs), and tropospheric aerosols (e.g., SO2 products and black carbon) vary

140 United Nations Framework Convention on Climate Change; <http://unfccc.int/resource/docs/2013/cop19/eng/10a03.pdf>;

31 January 2014; Report of the Conference of the Parties at its nineteenth session; held in Warsaw from 11 to 23 November
2013; Addendum; Part two: Action taken by the Conference of the Parties at its nineteenth session; Decision 24/CP.19; Revisionof the UNFCCC reporting guidelines on annual inventories for Parties included in Annex I to the Convention; p. 2. (UNFCCC
2014)

A-503

spatially, and consequently it is difficult to quantify their global radiative forcing impacts. GWP values are generally not
attributed to these gases that are short-lived and spatially inhomogeneous in the atmosphere.

Table A-252: IPCC AR4 Global Warming Potentials (GWP) and Atmospheric Lifetimes(Years) of Gases Used in this Report
Gas
Carbon dioxide (CO2)Methane (CH4)cNitrous oxide (N2O)
HFC-23
HFC-32
HFC-41
HFC-125
HFC-134a
HFC-143a
HFC-152a
HFC-227ea
HFC-236fa
HFC-43-10mee
CF4
C2F6
C3F8
C4F6e
c-C5F8eC4F10c-C4F8C5F12C6F14C2H2F4SF6
NF3Atmospheric Lifetime
See footnoteb
12d
114d
270
4.9
3.7
29
14
52
1.4
34.2
240
15.9
50,000d
10,000
2,600
1.1
31
2,600
3,200
4,100
3,200
10.6
3,200
740

100-year GWPa
125
298
14,800
675
150
3,500
1,430
4,470
124
3,220
9,810
1,640
7,390
12,200
8,830
0.003
1.97
8,860
10,300
9,160
9,300
1,000
22,80017,20020-year GWP
1
72289
12,000
2,330
490
6,350
3,830
5,890
437
5,310
8,100
4,140
5,210
8,630
6,310
NA
NA
6,330
7,310
6,510
6,600
2,900
16,30012,300500-year GWP
1
7.6
153
12,200
205
45
1,100
435
1,590
38
1,040
7,660
500
11,20018,20012,500NANA12,50014,70013,30013,300310
32,60020,700NA (Not Available)a GWP values used in this report are calculated over 100-year time horizon.
2 emitted, some fraction of the atmospheric increase in concentration is quickly absorbed by the oceans
and terrestrial vegetation, some fraction of the atmospheric increase will only slowly decrease over a number of years, and a small
portion of the increase will remain for many centuries or more.
c The methane GWP includes the direct effects and those indirect effects due to the production of tropospheric ozone andstratospheric water vapor. The indirect effect due to the production of CO2 is not included.
d Methane and N O have chemical feedback systems that can alter the length of the atmospheric response, in these cases, global
2mean atmospheric lifetime (LT) is given first, followed by perturbation time (PT), but only the perturbation time is listed here and not
the atmospheric residence time.
e See Table A-1 of 40 (CFR 98).
Source: IPCC (1996, 2007, 2013)b For a given amount of CO

Table A-253 presents direct GWP values for ozone depleting substances (ODSs). Ozone depleting substances
directly absorb infrared radiation and contribute to positive radiative forcing; however, their effect as ozone-depleters
also leads to a negative radiative forcing because ozone itself is a potent greenhouse gas. There is considerable
uncertainty regarding this indirect effect; direct GWP values are shown, but AR4 does provide a range of net GWP values
for ozone depleting substances. The IPCC Guidelines and the UNFCCC do not include reporting instructions for estimating
emissions of ODSs because their use is being phased out under the Montreal Protocol (see note below Table A-253). The
effects of these compounds on radiative forcing are not addressed in this report.

Table A-253: 100-year Direct Global Warming Potentials for Select Ozone Depleting
Substances
Gas
CFC-11
CFC-12
CFC-113

Direct GWP
4,750
10,9006,130A-504 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018

HCFC-22
HCFC-123
HCFC-124
HCFC-141b
HCFC-142b
CH3CCl3
CCl4
CH3Br
Halon-1211
Halon-1301

1,810
77
609
725
2,310
146
1,400
5
1,890
7,140

Note: Because these compounds have been shown to deplete stratospheric ozone, they are typically referred to as ODSs. However,they are also potent greenhouse gases. Recognizing the harmful effects of these compounds on the ozone layer, in 1987 many
governments signed the Montreal Protocol on Substances that Deplete the Ozone Layer to limit the production and importation of anumber of CFCs and other halogenated compounds. The United States furthered its commitment to phase-out ODSs by signing andratifying the Copenhagen Amendments to the Montreal Protocol in 1992. Under these amendments, the United States committed toending the production and importation of halons by 1994, and CFCs by 1996, and HCFCs by 2030.
Source: IPCC (2007).

The IPCC published its Fifth Assessment Report (AR5) in 2013, providing the most current and comprehensive
scientific assessment of climate change (IPCC 2013). Within this report, the GWP values were revised relative to the
IPCC’s Fourth Assessment Report (AR4) (IPCC 2007). Although the AR4 GWP values are used throughout this Inventory
report in line with UNFCCC inventory reporting guidelines, it is informative to review the changes to the 100-year GWP
values and the impact they have on the total GWP-weighted emissions of the United States. All GWP values use CO2 as areference gas; a change in the radiative efficiency of CO2 thus impacts the GWP of all other greenhouse gases. Since theSecond Assessment Report (SAR) and Third Assessment Report (TAR), the IPCC has applied an improved calculation of CO2
radiative forcing and an improved CO2 response function. The GWP values are drawn from IPCC (2007), with updates for
those cases where new laboratory or radiative transfer results have been published. Additionally, the atmospheric
lifetimes of some gases have been recalculated, and updated background concentrations were used. Table A-254 shows
how the GWP values of the other gases relative to CO2 tend to be larger in AR4 and AR5 because the revised radiative
forcing of CO2 is lower than in earlier assessments, taking into account revisions in lifetimes. Comparisons of GWP values
are based on the 100-year time horizon required for UNFCCC inventory reporting. However, there were some instancesin which other variables, such as the radiative efficiency or the chemical lifetime, were altered that resulted in further
increases or decreases in particular GWP values in AR5, including addressing inconsistencies with incorporating climate
carbon feedbacks. In addition, the values for radiative forcing and lifetimes have been calculated for a variety of
halocarbons. Updates in some well-mixed HFC compounds (including HFC-23, HFC-32, HFC-134a, and HFC-227ea) for AR4
result from investigation into radiative efficiencies in these compounds, with some GWP values changing by up to 40
percent; with this change, the uncertainties associated with these well-mixed HFCs are thought to be approximately 12
percent.
It should be noted that the use of IPCC AR4 GWP values for the current Inventory applies across the entire timeseries of the Inventory (i.e., from 1990 to 2018). As such, GWP comparisons throughout this chapter are presented
relative to AR4 GWPs.

A-505

Table A-254: Comparison of GWP values and Lifetimes Used in the SAR, AR4, and AR5Lifetime (years)

GWP (100 year)
AR5 with
feedbacks

Gas
Carbon dioxide (CO2)Methane (CH4)e
Nitrous oxide (N2O)
Hydrofluorocarbons
HFC-23
HFC-32
HFC-125
HFC-134a
HFC-143a
HFC-152a
HFC-227ea
HFC-236fa
HFC-245fa
HFC-365mfc
HFC-43-10mee
Fully FluorinatedSpecies
SF6
CF4
C2F6
C3F8
C4F10
c-C4F8
C5F12
C6F14
NF3

AR5 with
feedbacksb
(%)
NC
36%
0%

12.4
121

SAR
1
21
310

AR4
1
25
298

AR5a
1
28
265

1
34
298

SAR
NC
(4)
12

270
4.9
29
14
52
1.4
34.2
240
7.6
8.6
15.9

222
5.2
28.2
13.4
47.1
1.5
38.9
242
7.7
8.7
16.1

11,700
650
2,800
1,300
3,800
140
2,900
6,300
950
860
1,300

14,800
675
3,500
1,430
4,470
124
3,220
9,810
1,030
794
1,640

12,400
677
3,170
1,300
4,800
138
3,350
8,060
858
804
1,650

13,856
817
3,691
1,549
5,508
167
3,860
8,998
1,032
966
1,952

(3,100)
(25)
(700)
(130)
(670)
16
(320)
(3,510)
(80)
66
(340)

-21%
-4%
-20%
-9%
-15%
13%
-10%
-36%
-8%
8%
-21%

(2,400)
2
(330)
(130)
330
14
130
(1,750)
(172)
10
10

-16%
+%
-9%
-9%
7%
11%
4%
-18%
-17%
1%
1%

(944)
142
191
119
1,038
43
640
(812)
2
172
312

-6%
21%
5%
8%
23%
35%
20%
-8%
+%
22%
19%

3,200
50,00010,000
2,600
2,600
3,200
4,100
3,200
740

3,200
50,00010,000
2,600
2,600
3,200
4,100
3,100
500

23,900
6,500
9,200
7,000
7,000
8,700
7,500
7,400
NA

22,8007,390
12,2008,830
8,860
10,3009,160
9,300
17,20023,500
6,630
11,100
8,900
9,200
9,540
8,550
7,910
16,10026,087
7,349
12,3409,878
10,213
10,5929,484
8,780
17,885

1,100(890)(3,000)(1,830)(1,860)(1,600)(1,660)(1,900)
NA

5%
-12%
-25%
-21%
-21%
-16%
-18%
-20%
NA

700
(760)
(1,100)
70
340
(760)
(610)
(1,390)(1,100)

3%
-10%
-9%
1%
4%
-7%
-7%
-15%
-6%

3,287
(41)
140
1,048
1,353
292
324
(520)
685

14%
-1%
1%
12%
15%
3%
4%
-6%
4%

SAR

AR4

AR5

c

d

d

12±3
120

8.7/12f
120/114f

264
5.6
32.6
14.6
48.3
1.5
36.5
209
NA
NA
17.1

3,200
50,00010,000
2,600
2,600
3,200
4,100
3,200
NA

b

Difference in GWP (Relative to AR4)AR5 with
feedbacksb
SAR (%)AR5a
AR5 (%)
NC
NC
NC
NC
-16%
3
12%
9
4%
(33)
-11%
0

Note: Parentheses indicate negative values.
+ Does not exceed 0.5 percent.
NC (No Change)
NA (Not Applicable)
a The GWP values presented here are the ones most consistent with the methodology used in the AR4 report. See footnote e for more information on GWPs for methane of fossil origin.
b The GWP values presented here from the AR5 report include climate-carbon feedbacks for the non-CO gases in order to be consistent with the approach used in calculating the CO lifetime.
22c For a given amount of CO emitted, some fraction of the atmospheric increase in concentration is quickly absorbed by the oceans and terrestrial vegetation, some fraction of the atmospheric2
increase will only slowly decrease over a number of years, and a small portion of the increase will remain for many centuries or more. See footnote e for more information on GWPs formethane of fossil origin.

A-506 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018

d No single lifetime can be determined for CO

2 (see IPCC 2007).
e The methane GWP includes the direct effects and those indirect effects due to the production of tropospheric ozone and stratospheric water vapor. Additionally, the AR5 reported separate

values for fossil versus biospheric methane in order to account for the CO2 oxidation product. The GWP associated with methane of fossil origin is not shown in this table. Per AR5, the GWP for
methane of fossil origin is 30 versus 28 using methodology most consistent with AR4. If using methodology to include climate carbon feedbacks, per the AR5 report, the value is higher by 2 for
GWP for methane of fossil origin, so would be 36 versus 34.
f Methane and N O have chemical feedback systems that can alter the length of the atmospheric response, in these cases, global mean residence time is given first, followed by perturbation
2
time.
Source: IPCC (2013), IPCC (2007), IPCC (1996).

A-507

The choice of GWP values between the SAR, AR4, and AR5 with or without climate-carbon feedbacks has an
impact on both the overall emissions estimated by the Inventory, as well as the trend in emissions over time. Tosummarize, Table A-255 shows the overall trend in U.S. greenhouse gas emissions, by gas, from 1990 through 2018 using
the four GWP sets. The table also presents the impact of SAR and AR5 GWP values with or without feedbacks on the
total emissions for 1990 and for 2018.

Table A-255: Effects on U.S. Greenhouse Gas Emissions Using SAR, AR4, and AR5 GWPvalues (MMT CO2 Eq.)
Gas

CO2
CH4
N2O
HFCs, PFCs, SF6,
and NF3
Total
Percent Change

Difference in Emissions Between 1990
and 2018 (Relative to 1990)
SAR
296.6
(117.6)
(0.1)

AR4
296.6
(140.0)
(0.1)

AR5a
296.6
(156.7)
(0.1)

AR5b
296.6
(190.3)(0.1)

Revisions to Annual Emission Estimates (Relative to AR4)
SAR
AR5a
AR5b
SAR
AR5a
AR5b
1990
2018
NC
NC
NC
NC
NC
NC
(123.9)92.9
278.8(101.5)
76.1
228.4
17.5
(48.1)
NC
17.5(48.1)
NC

71.3
250.2
4.0%

83.1
239.6
3.7%

81.7
221.4
3.4%

100.7
206.9
3.1%

(11.9)(118.3)
-1.8%

(9.0)
35.8
0.6%

1.2
280.0
4.4%

(23.8)(107.8)-1.6%(10.5)
17.5
0.3%

18.8
247.2
3.7%

Note: Totals may not sum due to independent rounding. Excludes sinks. Parentheses indicate negative values.
NC (No Change)a The GWP values presented here are the ones most consistent with the methodology used in the AR4 report.
b The GWP values presented here from the AR5 report include climate-carbon feedbacks for the non-CO gases in order to be
2
consistent with the approach used in calculating the CO2 lifetime. Additionally, for methane the AR5 reported separate values for fossil
versus biogenic methane in order to account for the CO2 oxidation product and that is not shown on this table. See footnotes to Table
A-250.

When the GWP values from the SAR are applied to the emission estimates presented in this report, total
emissions for the year 2018 are 6,568.9 MMT CO2 Eq., as compared to the official emission estimate of 6,676.6 MMT CO2
Eq. using AR4 GWP values (i.e., the use of SAR GWPs results in a 1.6 percent decrease relative to emissions estimatedusing AR4 GWPs).
Further, Table A-256 and Table A-257 show the comparison of emission estimates using AR5 GWP values
relative to AR4 GWP values without climate-carbon feedbacks for the non-CO2 gases, on an emissions and percent
change basis. Table A-258 and Table A-259 show the comparison of emission estimates using AR5 GWP values with141
climate-carbon feedbacks. The use of AR5 GWP values without climate-carbon feedbacks results in an increase inemissions of CH4 and SF6 relative to AR4 GWP values, but a decrease in emissions of other gases. The use of AR5 GWPvalues with climate-carbon feedbacks does not impact CO2 and N2O emissions; however, it results in an increase inemissions of CH4, SF6, and NF3 relative to AR4 GWP values, and has mixed impacts on emissions of other gases. Overall,these comparisons of AR4 and AR5 GWP values do not have a significant effect on calculated U.S. emissions, resulting in
an increase in emissions of less than 1 percent using AR5 GWP values, or approximately 4 percent when using AR5 GWPvalues with climate-carbon feedbacks. As with the comparison of SAR and AR4 GWP values presented above, the percent
change in emissions is equal to the percent change in the GWP for each gas; however, in cases where multiple gases are
emitted in varying amounts the percent change is variable over the years, such as with Substitution of Ozone Depleting
Substances.
14F

141 The IPCC AR5 report provides additional information on emission metrics. See <https://www.ipcc.ch/pdf/assessment-

report/ar5/wg1/WG1AR5_Chapter08_FINAL.pdf>.

A-508 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018

Table A-256: Change in U.S. Greenhouse Gas Emissions Using AR5 a without Climate-Carbon
Feedbacks Relative to AR4 GWP Values (MMT CO2 Eq.)
Gas
CO2
CH4
N2O
HFCs
PFCs
SF6
NF3
Unspecified Mix of HFCs,
PFCs, SF6, and NF3
Total

1990
NC
92.9
(48.1)
(7.5)
(2.4)
0.9
(+)

2005
NC
81.5
(47.9)(11.0)
(0.6)
0.4
(+)

2014
NC
76.7
(49.8)(10.0)
(0.5)
0.2
(+)

2015
NC
76.6
(49.1)(10.2)
(0.5)
0.2
(+)

2016
NC
74.9
(47.2)(10.0)
(0.4)
0.2
(+)

2017
NC
75.6
(46.6)(10.3)
(0.4)
0.2
(+)

2018
NC
76.1
(48.1)(10.1)
(0.4)
0.2
(+)

NA
35.8

NA
22.3

NA
16.6

NA
17.0

NA
17.5

NA
18.4

NA
17.6

Notes: Total emissions presented without LULUCF. Totals may not sum due to independent rounding. Parentheses indicate negativevalues.
+ Absolute value does not exceed 0.05 MMT CO2 Eq.
NC (No Change)
NA (Not Applicable)
a The GWP values presented here are the ones most consistent with the methodology used in the AR4 report. The AR5 report has also
calculated GWP values (shown in Table A-258) where climate-carbon feedbacks have been included for the non-CO2 gases in order tobe consistent with the approach used in calculating the CO2 lifetime. Additionally, for methane the AR5 reported separate values forfossil versus biogenic methane in order to account for the CO2 oxidation product and that is not shown on this table. See footnotes toTable A-250.

Table A-257: Change in U.S. Greenhouse Gas Emissions Using AR5 a without Climate-Carbon
Feedbacks Relative to AR4 GWP Values (Percent)
Gas/Source
CO2
CH4
N2O
SF6
NF3
HFCs
Substitution of Ozone
Depleting Substances
HCFC-22 Productionb
Electronics Industryc
Magnesium Production andProcessingd
PFCs
Electronics Industryc
Aluminum Productione
Substitution of Ozone
Depleting Substancesd,fUnspecified Mix of HFCs,
PFCs, SF6, and NF3
Electronics Industry
Total

1990
NC
12.0%
(11%)
3.1%
(6.4%)(16.1%)

2005
NC
12.0%
(11%)
3.1%
(6.4%)(8.6%)

2014
NC
12.0%
(11%)
3.1%
(6.4%)(6.0%)

2015
NC
12.0%
(11%)
3.1%
(6.4%)(6.0%)

2016
NC
12.0%
(11%)
3.1%
(6.4%)(5.8%)

2017
NC
12.0%
(11%)
3.1%
(6.4%)(6.0%)

2018
NC
12.0%
(11%)
3.1%
(6.4%)(5.9%)

11.3%(16.2%)(16.2%)(7.2%)(16.2%)(16.4%)(5.7%)(16.2%)(16.8%)(5.7%)(16.2%)(16.4%)(5.6%)(16.2%)(16.7%)(5.7%)(16.2%)(16.6%)(5.7%)(16.2%)(16.2%)

0.0%(10.0%)(9.4%)(10.1%)

0.0%(9.6%)(9.1%)(10.1%)(9.1%)(9.5%)(9.2%)(10.0%)(9.1%)(9.5%)(9.2%)(10.0%)(9.1%)(9.5%)(9.3%)(9.9%)(9.1%)(9.5%)(9.4%)(9.8%)(9.1%)(9.6%)(9.4%)(9.9%)

0.0%(10.3%)(10.3%)(10.3%)(10.3%)(10.3%)(10.3%)

NA

NA

NA

NA

NA

NA

NA

NA
0.6%

NA
0.3%

NA
0.2%

NA
0.3%

NA
0.3%

NA
0.3%

NA
0.3%

Note: Total emissions presented without LULUCF. Parentheses indicate negative values.
NC (No Change)
NA (Not Applicable)
a The GWP values presented here are the ones most consistent with the methodology used in the AR4 report. The AR5 report has also
calculated GWP values (shown in Table A-259) where climate-carbon feedbacks have been included for the non-CO2 gases in order tobe consistent with the approach used in calculating the CO2 lifetime. Additionally, the AR5 reported separate values for fossil versus
biogenic methane in order to account for the CO2 oxidation product.

A-509

b HFC-23 emitted.
c Emissions from HFC-23, CF , C F , C F , C F , SF , as well as other HFCs and PFCs used as heat transfer fluids.
4
2 6
3 8
4 8
6
d Zero change in beginning of time series since emissions were zero.
e PFC emissions from CF

4 and C2F6.
f PFC emissions from CF .
4

Table A-258: Change in U.S. Greenhouse Gas Emissions Using AR5 with Climate-Carbon
Feedbacksa Relative to AR4 GWP Values (MMT CO2 Eq.)
Gas
CO2
CH4
N2O
HFCs
PFCs
SF6
NF3
Unspecified Mix of HFCs,
PFCs, SF6, and NF3
Total

1990
NC
278.8
NC
(2.9)
(+)
4.2
+

2005
NC
244.6
NC
9.5
+
1.7
+

2014
NC
230.0
NC
17.3
+
0.9
+

2015
NC
229.9
NC
17.9
+
0.8
+

2016
NC
224.7
NC
18.1
+
0.9
+

2017
NC
226.9
NC
17.8
+
0.9
+

2018
NC
228.4
NC
18.0
+
0.9
+

NA
280.0

NA
255.9

NA
248.4

NA
248.6

NA
243.8

NA
245.6

NA
247.3

Notes: Total emissions presented without LULUCF. Totals may not sum due to independent rounding. Parentheses indicate negativevalues.
+ Absolute value does not exceed 0.05 MMT CO2 Eq.
NC (No Change)
NA (Not Applicable)
a The GWP values presented here from the AR5 report include climate-carbon feedbacks for the non-CO gases in order to be
2
consistent with the approach used in calculating the CO2 lifetime. Additionally, for methane the AR5 reported separate values for fossil
versus biogenic methane in order to account for the CO2 oxidation product and that is not shown on this table. See footnotes to Table
A-250.

Table A-259: Change in U.S. Greenhouse Gas Emissions Using AR5 with Climate-Carbon
Feedbacksa Relative to AR4 GWP Values (Percent)
Gas/Source
CO2
CH4
N2O
SF6
NF3
HFCs
Substitution of Ozone
Depleting Substances
HCFC-22 Productionb
Electronics Industryc
Magnesium Production
and Processingd
PFCs
Electronics Industryc
Aluminum Productione
Substitution of Ozone
Depleting Substancesd,fUnspecified Mix of HFCs,
PFCs, SF6, and NF3
Electronics Industry
Total

1990
NC
36.0%
NC
14.4%
4.0%
(6.2%)

2005
NC
36.0%
NC
14.4%
4.0%
7.4%

2014
NC
36.0%
NC
14.4%
4.0%
10.4%

2015
NC
36.0%
NC
14.4%
4.0%
10.5%

2016
NC
36.0%
NC
14.4%
4.0%
10.6%

2017
NC
36.0%
NC
14.4%
4.0%
10.3%

2018
NC
36.0%
NC
14.4%
4.0%
10.5%

34.6%
(6.4%)(6.4%)

9.9%(6.4%)(6.5%)

11.0%(6.4%)(7.1%)

11.0%(6.4%)(6.6%)

10.9%(6.4%)(6.9%)

10.9%(6.4%)(6.8%)

10.8%(6.4%)(6.3%)

0.0%(0.2%)
0.6%(0.3%)

0.0%
0.3%
0.9%
(0.3%)

8.3%
0.4%
0.8%
(0.1%)

8.3%
0.4%
0.8%
(0.1%)

8.3%
0.5%
0.7%
0.0%

8.3%
0.4%
0.6%
0.0%

8.3%
0.3%
0.5%
(0.1%)

0.0%(0.6%)(0.6%)(0.6%)(0.6%)(0.6%)(0.6%)

NA
NA
4.4%

NA
NA
3.5%

NA
NA
3.6%

NA
NA
3.7%

NA
NA
3.7%

NA
NA
3.8%

NA
NA
3.7%

Notes: Total emissions presented without LULUCF. Parentheses indicate negative values. Excludes Sinks.
NC (No Change)
NA (Not Applicable)

A-510 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018

+ Does not exceed 0.05 percent.
a The GWP values presented here from the AR5 report include climate-carbon feedbacks for the non-CO gases in order to be
2
consistent with the approach used in calculating the CO2 lifetime. Additionally, for methane the AR5 reported separate values for fossil
versus biogenic methane in order to account for the CO2 oxidation product and that is not shown on this table. See footnotes to Table
A-250.
b HFC-23 emitted.
c Emissions from HFC-23, CF , C F , C F , C F , SF , as well as other HFCs and PFCs used as heat transfer fluids.
4
2 6
3 8
4 8
6
d Zero change in beginning of time series since emissions were zero.
e PFC emissions from CF and C F .
42 6
f PFC emissions from CF .
4

6.2.

Ozone Depleting Substance Emissions

Ozone is present in both the stratosphere, 142 where it shields the earth from harmful levels of ultraviolet
radiation, and at lower concentrations in the troposphere, 143 where it is the main component of anthropogenic
photochemical “smog.” Chlorofluorocarbons (CFCs), halons, carbon tetrachloride, methyl chloroform, andhydrochlorofluorocarbons (HCFCs), along with certain other chlorine and bromine containing compounds, have beenfound to deplete the ozone levels in the stratosphere. These compounds are commonly referred to as ozone depleting
substances (ODSs). If left unchecked, stratospheric ozone depletion could result in a dangerous increase of ultraviolet
radiation reaching the earth’s surface. In 1987, nations around the world signed the Montreal Protocol on Substancesthat Deplete the Ozone Layer. This landmark agreement created an international framework for limiting, and ultimately
eliminating, the production of most ozone depleting substances. ODSs have historically been used in a variety ofindustrial applications, including refrigeration and air conditioning, foam blowing, fire extinguishing, sterilization, solvent
cleaning, and as an aerosol propellant.
142F

143F

In the United States, the Clean Air Act Amendments of 1990 provide the legal instrument for implementation of
the Montreal Protocol controls. The Clean Air Act classifies ozone depleting substances as either Class I or Class II,
depending upon the ozone depletion potential (ODP) of the compound. 144 The production of CFCs, halons, carbon
tetrachloride, and methyl chloroform—all Class I substances—has already ended in the United States. However, large
amounts of these chemicals remain in existing equipment, 145 and stockpiles of the ODSs, as well as material recoveredfrom equipment being decommissioned, are used for maintaining the existing equipment. As a result, emissions of Class I
compounds will continue, albeit generally in decreasing amounts, for many more years. Class II designated substances,
all of which are HCFCs, have been, or are being, phased out at later dates than Class I compounds because they havelower ODPs. These compounds served, and in some cases continue to serve, as interim replacements for Class I
compounds in many industrial applications. The use and emissions of HCFCs in the United States is anticipated tocontinue for several decades as equipment that use Class II substances are retired from use. Under current Montreal
Protocol controls, however, the production for domestic use of all HCFCs in the United States must end by the year 2030.
14F

145F

In addition to contributing to ozone depletion, CFCs, halons, carbon tetrachloride, methyl chloroform, and
HCFCs are also potent greenhouse gases. However, the depletion of the ozone layer has a cooling effect on the climatethat counteracts the direct warming from tropospheric emissions of ODSs. Stratospheric ozone influences the earth’s
radiative balance by absorption and emission of longwave radiation from the troposphere as well as absorption ofshortwave radiation from the sun; overall, stratospheric ozone has a warming effect.

142 The stratosphere is the layer from the top of the troposphere up to about 50 kilometers. Approximately 90 percent of

atmospheric ozone is within the stratosphere. The greatest concentration of ozone occurs in the middle of the stratosphere, ina region commonly called the ozone layer.
143 The troposphere is the layer from the ground up to about 11 kilometers near the poles and 16 kilometers in equatorial
regions (i.e., the lowest layer of the atmosphere, where humans live). It contains roughly 80 percent of the mass of all gases in
the atmosphere and is the site for weather processes including most of the water vapor and clouds.
144 Substances with an ozone depletion potential of 0.2 or greater are designated as Class I. All other designated substancesthat deplete stratospheric ozone but which have an ODP of less than 0.2 are Class II.
145 Older refrigeration and air-conditioning equipment, fire extinguishing systems, and foam products blown with CFCs/HCFCs
may still contain Class I ODS.

A-511

The IPCC has prepared both direct GWP values and net (combined direct warming and indirect cooling) GWP
ranges for some of the most common ozone depleting substances (IPCC 2007). See Annex 6.1 Global Warming Potential
Values, for a listing of the direct GWP values for ODS.
Although the IPCC emission inventory guidelines do not require the reporting of emissions of ozone depleting
substances, the United States believes that the inventory presents a more complete picture of climate impacts when we
include these compounds. Emission estimates for several ozone depleting substances are provided in Table A-260.

Table A-260: Emissions of Ozone Depleting Substances (kt)CompoundClass I
CFC-11
CFC-12
CFC-113
CFC-114
CFC-115
CarbonTetrachloride
Methyl Chloroform
Halon-1211
Halon-1301
Class II
HCFC-22
HCFC-123
HCFC-124
HCFC-141b
HCFC-142b
HCFC-225ca/cb

1990

2005

2014

2015

2016

2017 2018

29
135
59
4
8
4

12
23
17
1
2
0

24
5
0
0
+
0

25
4
0
0
+
0

25
3
0
0
+
0

25
2
0
0
+
0

20
1
0
0
+
0

223
2
2

0
2
+

0
1
+

0
1
+

0
1
+

0
1
+

0
1
+

31
0
0
1
1
+

74
1
2
4
4
3

61
1
1
10
2
11

57
1
+
10
2
12

54
1
+
9
3
13

50
1
+
8
4
14

47
1
+
12
4
15

+ Does not exceed 0.5 kt.

Methodology and Data Sources
Emissions of ozone depleting substances were estimated using the EPA’s Vintaging Model. The model, named
for its method of tracking the emissions of annual “vintages” of new equipment that enter into service, is a “bottom-up”
model. It models the consumption of chemicals based on estimates of the quantity of equipment or products sold,
serviced, and retired each year, and the amount of the chemical required to manufacture and/or maintain theequipment. The Vintaging Model makes use of this market information to build an inventory of the in-use stocks of theequipment in each of the end-uses. Emissions are estimated by applying annual leak rates, service emission rates, anddisposal emission rates to each population of equipment. By aggregating the emission and consumption output from thedifferent end-uses, the model produces estimates of total annual use and emissions of each chemical. Please see Annex
3.9, Methodology for Estimating HFC and PFC Emissions from Substitution of Ozone Depleting Substances, of thisInventory for a more detailed discussion of the Vintaging Model.

Uncertainties
Uncertainties exist with regard to the levels of chemical production, equipment sales, equipment
characteristics, and end-use emissions profiles that are used by these models. Please see the Substitution of Ozone
Depleting Substances section of this report for a more detailed description of the uncertainties that exist in the Vintaging
Model.

A-512 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018

6.3.

Sulfur Dioxide Emissions

Sulfur dioxide (SO2), emitted into the atmosphere through natural and anthropogenic processes, affects the
Earth's radiative budget through photochemical transformation into sulfate aerosols that can (1) scatter sunlight back tospace, thereby reducing the radiation reaching the Earth's surface; (2) affect cloud formation; and (3) affect atmosphericchemical composition (e.g., stratospheric ozone, by providing surfaces for heterogeneous chemical reactions). The
overall effect of SO2-derived aerosols on radiative forcing is believed to be negative (IPCC 2007). However, because SO 2 isshort-lived and unevenly distributed through the atmosphere, its radiative forcing impacts are highly uncertain. Sulfur
dioxide emissions have been provided below in Table A-261.
The major source of SO2 emissions in the United States is the burning of sulfur containing fuels, mainly coal.
Metal smelting and other industrial processes also release significant quantities of SO2. The largest contributor to U.S.
emissions of SO2 is electricity generation, accounting for 47.8 percent of total SO2 emissions in 2018 (see Table A-262);
coal combustion accounted for approximately 92.0 percent of that total. The second largest source was industrial fuelcombustion, which produced 20.0 percent of 2018 SO2 emissions (see Table A-261). Overall, SO2 emissions in the UnitedStates decreased by 88.1 percent from 1990 to 2018. The majority of this decline came from reductions from electricity
generation, primarily due to increased consumption of low sulfur coal from surface mines in western states.
Sulfur dioxide is important for reasons other than its effect on radiative forcing. It is a major contributor to theformation of urban smog and acid rain. As a contributor to urban smog, high concentrations of SO2 can cause significant
increases in acute and chronic respiratory diseases. In addition, once SO2 is emitted, it is chemically transformed in theatmosphere and returns to earth as the primary contributor to acid deposition, or acid rain. Acid rain has been found toaccelerate the decay of building materials and paints, cause the acidification of lakes and streams, and damage trees. As
a result of these harmful effects, the United States has regulated the emissions of SO2 under the Clean Air Act. The EPA
has also developed a strategy to control these emissions via four programs: (1) the National Ambient Air Quality
146
147
Standards program, (2) New Source Performance Standards, (3) the New Source Review/Prevention of Significant
148
149
Deterioration Program, and (4) the Sulfur Dioxide Allowance Program.
146F

147F

148F

149F

Table A-261: SO2 Emissions (kt)Sector/Source
EnergyStationary Sources
Oil and Gas Activities
Mobile Sources
Waste Combustion
Industrial Processes andProduct Use
Other Industrial Processes
Miscellaneousa
Chemical and Allied Product
Manufacturing
Metals Processing
Storage and Transport
Solvent Use
Degreasing
Graphic Arts
Dry Cleaning
Surface Coating
Other Industrial

1990
19,62818,407
390
793
38

2005
12,364
11,541
180
619
25

2014
3,742
3,532
94
88
27

2015
2,844
2,635
94
87
27

2016
2,187
1,978
94
87
27

2017
2,050
1,841
94
87
27

2018
1,983
1,774
94
87
27

1,307
362
11

831
327
114

497
151
136

497
151
136

497
151
136

497
151
136

497
151
136

269
659
6
0
0
0
NA
0
0

228
158
2
+
0
0
0
0
+

112
95
3
+
0
0
0
0
+

112
95
3
+
0
0
0
0
+

112
95
3
+
0
0
0
0
+

112
95
3
+
0
0
0
0
+

112
95
3
+
0
0
0
0
+

146 [42 U.S.C § 7409, CAA § 109]
147 [42 U.S.C § 7411, CAA § 111]
148 [42 U.S.C § 7473, CAA § 163]
149 [42 U.S.C § 7651, CAA § 401]

A-513

Nonindustrial
Agriculture
Agricultural Burning
Waste
Landfills
Wastewater Treatment
Miscellaneousa
Total

NA
NA
NA
+
+
+
+
20,935

NA
NA
NA
1
1
0
0
13,196

NA
NA
NA
1
1
0
0
4,240

NA
NA
NA
1
1
0
0
3,342

NA
NA
NA
1
1
0
0
2,685

NA
NA
NA
1
1
0
0
2,548

NA
NA
NA
1
1
0
0
2,481

Note: Totals may not sum due to independent rounding.
+ Does not exceed 0.5 kt
NA (Not Applicable)a Miscellaneous includes other combustion and fugitive dust categories.
Source: Data taken from EPA (2018) and disaggregated based on EPA (2003).

Table A-262: SO2 Emissions from Electricity Generation (kt)
Fuel Type
Coal
Oil
Gas
Internal Combustion
Other
Total

1990
13,808580
145
NA14,433

2005
8,680
458
174
57
71
9,439

2014
2,706
143
54
18
22
2,943

2015
1,881
99
38
12
15
2,046

2016
1,277
67
26
8
10
1,388

Note: Totals may not sum due to independent rounding.
NA (Not Applicable)
Source: Data taken from EPA (2018) and disaggregated based on EPA (2003).

A-514 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018

2017
1,151
61
23
8
9
1,252

2018
1,090
57
22
7
9
1,185

6.4.

Complete List of Source Categories

Chapter/Source
EnergyFossil Fuel Combustion
Non-Energy Use of Fossil Fuels
Stationary Combustion (excluding CO2)
Mobile Combustion (excluding CO2)
Coal Mining
Abandoned Underground Coal Mines
Petroleum Systems
Natural Gas Systems
Abandoned Oil and Gas Wells
Incineration of Waste
Industrial Processes and Product Use
Cement Production
Lime Production
Glass Production
Other Process Uses of Carbonates
Ammonia Production
Urea Consumption for Non-Agricultural Purposes
Nitric Acid Production
Adipic Acid Production
Caprolactam, Glyoxal, and Glyoxylic Production
Carbide Production and Consumption
Titanium Dioxide Production
Soda Ash Production
Petrochemical Production
HCFC-22 Production
Carbon Dioxide Consumption
Phosphoric Acid Production
Iron and Steel Production & Metallurgical Coke Production
Ferroalloy Production
Aluminum Production
Magnesium Production and Processing
Lead Production
Zinc Production
Electronics Industry
Substitution of Ozone Depleting Substances
Electrical Transmission and Distributing
N2O from Product Uses
AgricultureEnteric Fermentation
Manure Management
Rice Cultivation
LimingUrea Fertilization
Field Burning of Agricultural Residues
Agricultural Soil Management
Land Use, Land-Use Change, and Forestryc
Forest Land Remaining Forest Land
Land Converted to Forest Land
Cropland Remaining CroplandGas(es)CO2
CO2
CH4, N2O, CO, NOx, NMVOC
CH4, N2O, CO, NOx, NMVOC
CH4CH4CO2, CH4, N2O
CO2, CH4, N2O
CO2, CH4
CO2, CH4, N2O, NOx, CO, NMVOC
CO2
CO2
CO2
CO2
CO2
CO2
N2O
N2O
N2O
CO2, CH4CO2
CO2CO2, CH4
HFC-23CO2CO2CO2, CH4
CO2, CH4
CO2, CF4, C2F6
CO2, HFCs, SF6
CO2CO2
N2O, HFCs, PFCs,a SF6, NF3
HFCs, PFCsb
SF6
N2O
CH4
CH4, N2O
CH4
CO2
CO2
CH4, N2O, NOx, CO
N2O
CO2, CH4, N2O, NOx, CO
CO2
CO2

A-515

Land Converted to Cropland
Grassland Remaining Grassland
Land Converted to Grassland
Wetlands Remaining Wetlands
Land Converted to Wetlands
Settlements Remaining Settlements
Land Converted to Settlements
Waste
Landfills
Wastewater Treatment
Composting

CO2
CO2, CH4, N2O, NOx, CO
CO2
CO2, CH4, N2O
CO2, CH4
CO2, N2O
CO2
CH4, NOx, CO, NMVOC
CH4, N2O, NOx, CO, NMVOC
CH4, N2O

a Includes HFC-23, CF , C F , as well as a mix other HFCs and PFCs used as heat transfer fluids.
4
2 6
b Includes HFC-23, HFC-32, HFC-125, HFC-134a, HFC-143a, HFC-236fa, CF , HFC-152a, HFC-227ea, HFC-245fa, HFC-4310mee,
4

and PFC/PFPEs.
c The LULUCF Sector includes CH and N O emissions to the atmosphere and net carbon stock changes. The term “flux” is4
2
used to describe the net emissions of greenhouse gases accounting for both the emissions of CO 2 to and the removals of
CO2 from the atmosphere. Removal of CO2 from the atmosphere is also referred to as “carbon sequestration.”

6.5.

Constants, Units, and Conversions

Metric Prefixes
Although most activity data for the United States is gathered in customary U.S. units, these units are converted
into metric units per international reporting guidelines. Table A-263 provides a guide for determining the magnitude of
metric units.

Table A-263: Guide to Metric Unit Prefixes
Prefix/Symbol
atto (a)femto (f)pico (p)nano (n)micro (µ)
milli (m)centi (c)deci (d)deca (da)hecto (h)kilo (k)mega (M)giga (G)tera (T)peta (P)exa (E)

Factor
10-18
10-15
10-12
10-9
10-6
10-3
10-2
10-1
10
102
103
106
109
1012
1015
1018

Unit Conversions
1 kilogram
1 pound
1 short ton
1 metric ton

=
=
=
=

1 cubic meter =1 cubic foot=
1 U.S. gallon =2.205 pounds
0.454 kilograms
2,000 pounds
1,000 kilograms==

0.9072 metric tons
1.1023 short tons

35.315 cubic feet
0.02832 cubic meters3.785412 liters

A-516 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018

1 barrel (bbl)
1 barrel (bbl)
1 liter===

0.159 cubic meters
42 U.S. gallons
0.001 cubic meters

1 foot1 meter
1 mile1 kilometer

=
=
=
=

0.3048 meters3.28 feet
1.609 kilometers0.621 miles

1 acre1 square mile==

43,560 square feet =0.4047 hectares
2.589988 square kilometers

Degrees Celsius =Degrees Kelvin ==4,047 square meters(Degrees Fahrenheit – 32)*5/9
Degrees Celsius + 273.15

Density Conversions 150
150F

MethaneCarbon dioxide

1 cubic meter = 0.67606 kilograms
1 cubic meter = 1.85387 kilograms

Natural gas liquids
Unfinished oils
AlcoholLiquefied petroleum gas
Aviation gasoline
Naphtha jet fuelKerosene jet fuelMotor gasoline
Kerosene
NaphthaDistillate
Residual oil
Lubricants
Bitumen
Waxes
Petroleum coke
Petrochemical feedstocks
Special naphtha
Miscellaneous products

1 metric ton
1 metric ton
1 metric ton
1 metric ton
1 metric ton
1 metric ton
1 metric ton
1 metric ton
1 metric ton
1 metric ton
1 metric ton
1 metric ton
1 metric ton
1 metric ton
1 metric ton
1 metric ton
1 metric ton
1 metric ton
1 metric ton

=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=

11.6 barrels
7.46 barrels
7.94 barrels
11.6 barrels
8.9 barrels
8.27 barrels
7.93 barrels
8.53 barrels
7.73 barrels
8.22 barrels
7.46 barrels
6.66 barrels
7.06 barrels
6.06 barrels
7.87 barrels
5.51 barrels
7.46 barrels
8.53 barrels
8.00 barrels

=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=

1,844.2 liters
1,186.04 liters
1,262.36 liters
1,844.2 liters
1,415.0 liters
1,314.82 liters
1,260.72 liters
1,356.16 liters
1,228.97 liters
1,306.87 liters
1,186.04 liters
1,058.85 liters
1,122.45 liters
963.46 liters
1,251.23 liters876.02 liters
1,186.04 liters
1,356.16 liters
1,271.90 liters

Energy Conversions
Converting Various Energy Units to Joules
The common energy unit used in international reports of greenhouse gas emissions is the joule. A joule is theenergy required to push with a force of one Newton for one meter. A terajoule (TJ) is one trillion (10 12) joules. A British
thermal unit (Btu, the customary U.S. energy unit) is the quantity of heat required to raise the temperature of one poundof water one degree Fahrenheit at or near 39.2 degrees Fahrenheit.

150 Reference: EIA (2007)

A-517

1 TJ =

2.3881011 calories
23.88 metric tons of crude oil equivalent947.8 million Btus
277,800 kilowatt-hours

Converting Various Physical Units to Energy Units
Data on the production and consumption of fuels are first gathered in physical units. These units must be
converted to their energy equivalents. The conversion factors in Table A-264 can be used as default factors, if local data
are not available. See Appendix A of EIA’s Monthly Energy Review, November 2019 (EIA 2019) for more detailed
information on the energy content of various fuels.

Table A-264: Conversion Factors to Energy Units (Heat Equivalents)
Fuel Type (Units)
Solid Fuels (Million Btu/Short ton)
Anthracite coal
Bituminous coalSub-bituminous coalLigniteCoke
Natural Gas (Btu/Cubic foot)Liquid Fuels (Million Btu/Barrel)
Motor gasoline
Aviation gasoline
KeroseneJet fuel, kerosene-type
Distillate fuelResidual oil
Naphtha for petrochemicals
Petroleum coke
Other oil for petrochemicals
Special naphthas
Lubricants
Waxes
Asphalt
Still gas
Misc. products

Factor
22.57
23.89
17.14
12.87
21.49
1,036
5.054
5.048
5.670
5.670
5.825
6.287
5.248
6.024
5.825
5.248
6.065
5.537
6.636
6.000
5.796

Note: For petroleum and natural gas, Monthly Energy
Review, November 2019 (EIA 2019). For coal ranks, State
Energy Data Report 1992 (EIA 1993). All values are given inhigher heating values (gross calorific values).

A-518 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018

6.6.
ABS
AC
ACC
AEDT
AEO
AER
AF&PA
AFEAS
AFOLU
AFV
AGA
AGR
AHEF
AHRI
AISI
ALU
ANGA
ANL
APC
API
APTA
AR4
AR5
ARI
ARMA
ARMS
ASAE
ASLRRA
ASR
ASTM
AZR
BCEF
BEA
BIER
BLM
BoC
BOD
BOD5
BOEM
BOEMRE
BOF
BRS
BSEE
BTS
Btu
C
C&D
C&EN
CAAA
CAFOS
CaO

Abbreviations
Acrylonitrile butadiene styrene
Air conditioner
American Chemistry Council
FAA Aviation Environmental Design Tool
Annual Energy Outlook
All-electric range
American Forest and Paper Association
Alternative Fluorocarbon Environmental Acceptability Study
Agriculture, Forestry, and Other Land Use
Alternative fuel vehicle
American Gas Association
Acid gas removal
Atmospheric and Health Effect Framework
Air-Conditioning, Heating, and Refrigeration InstituteAmerican Iron and Steel Institute
Agriculture and Land Use
American Natural Gas Alliance
Argonne National Laboratory
American Plastics Council
American Petroleum InstituteAmerican Public Transportation Association
IPCC Fourth Assessment Report
IPCC Fifth Assessment Report
Advanced Resources International
Autoregressive moving-average
Agricultural Resource Management Surveys
American Society of Agricultural Engineers
American Short-line and Regional Railroad Association
Annual Statistical Report
American Society for Testing and Materials
American Zinc Recycling
Biomass conversion and expansion factors
Bureau of Economic Analysis, U.S. Department of Commerce
Beverage Industry Environmental Roundtable
Bureau of Land Management
Bureau of Census
Biological oxygen demand
Biochemical oxygen demand over a 5-day period
Bureau of Ocean Energy Management
Bureau of Ocean Energy Management, Regulation and Enforcement
Basic oxygen furnace
Biennial Reporting System
Bureau of Safety and Environmental Enforcement
Bureau of Transportation Statistics, U.S. Department of Transportation
British thermal unit
CarbonConstruction and demolition waste
Chemical and Engineering News
Clean Air Act Amendments of 1990
Concentrated Animal Feeding Operations
Calcium oxide

A-519

CAPP
CARB
CBI
C-CAP
CDAT
CEAP
CEFM
CEMS
CFC
CFR
CGA
CH4
CHAPA
CHP
CI
CIGRE
CKD
CLE
CMA
CMM
CMOP
CMR
CNG
CO
CO2
COD
COGCC
CONUS
CRF
CRM
CRP
CSRA
CTIC
CVD
CWNS
d.b.h
DE
DESC
DFAMS
DGGS
DHS
DLA
DM
DOC
DOC
DoD
DOE
DOI
DOM
DOT
DRE
DRI
EAF
EDB
EDF

Canadian Association of Petroleum Producers
California Air Resources Board
Confidential business information
Coastal Change Analysis Program
Chemical Data Access Tool
USDA-NRCS Conservation Effects Assessment Program
Cattle Enteric Fermentation ModelContinuous emission monitoring system
Chlorofluorocarbon
Code of Federal Regulations
Compressed Gas Association
MethaneCalfornia Health and Productivity Audit
Combined heat and power
Confidence intervalInternational Council on Large Electric Systems
Cement kiln dust
Crown Light Exposure
Chemical Manufacturer’s Association
Coal mine methane
Coalbed Methane Outreach Program
Chemical Market Reporter
Compressed natural gas
Carbon monoxide
Carbon dioxide
Chemical oxygen demandColorado Oil and Gas Conservation Commission
Continental United States
Common Reporting Format
Component ratio method
Conservation Reserve Program
Carbon Sequestration Rural Appraisals
Conservation Technology Information Center
Chemical vapor deposition
Clean Watershed Needs Survey
Diameter breast height
Digestible energy
Defense Energy Support Center-DoD’s Defense Logistics Agency
Defense Fuels Automated Management System
Division of Geological & Geophysical Surveys
Department of Homeland Security
DoD’s Defense Logistics Agency
Dry matter
Degradable organic carbon
U.S. Department of Commerce
U.S. Department of Defense
U.S. Department of Energy
U.S. Department of the Interior
Dead organic matter
U.S. Department of Transportation
Destruction or removal efficiencies
Direct Reduced Iron
Electric arc furnace
Aircraft Engine Emissions Databank
Environmental Defense Fund

A-520 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018

EER
EF
EFMA
EJ
EGR
EGU
EIA
EIIP
EOR
EPA
EREF
ERS
ETMS
EV
EVI
FAA
FAO
FAOSTAT
FAS
FCCC
FEB
FERC
FGD
FHWA
FIA
FIADB
FIPR
FOD
FOEN
FQSV
FSA
FTP
g
G&B
GaAs
GCV
GDP
GEI
GHG
GHGRP
GIS
GJ
GOADS
GOM
GPG
GRI
GSAM
GTI
GWP
ha
HBFC
HC
HCFC
HCFO

Energy economy ratio
Emission factor
European Fertilizer Manufacturers Association
Exajoule
Exhaust gas recirculation
Electric generating unit
Energy Information Administration, U.S. Department of Energy
Emissions Inventory Improvement Program
Enhanced oil recovery
U.S. Environmental Protection Agency
Environment Research & Education Foundation
Economic Research Service
Enhanced Traffic Management System
Electric vehicle
Enhanced Vegetation Index
Federal Aviation Administration
Food and Agricultural Organization
Food and Agricultural Organization database
Fuels Automated System
Framework Convention on Climate Change
Fiber Economics Bureau
Federal Energy Regulatory Commission
Flue gas desulfurization
Federal Highway Administration
Forest Inventory and Analysis
Forest Inventory and Analysis Database
Florida Institute of Phosphate ResearchFirst order decay
Federal Office for the Environment
First-quarter of silicon volume
Farm Service Agency
Federal Test Procedure
Gram
Gathering and boosting
Gallium arsenide
Gross calorific value
Gross domestic productGulfwide Emissions Inventory
Greenhouse gas
EPA’s Greenhouse Gas Reporting Program
Geographic Information Systems
GigajouleGulf Offshore Activity Data System
Gulf of Mexico
Good Practice GuidanceGas Research InstituteGas Systems Analysis Model
Gas Technology Institute
Global warming potential
HectareHydrobromofluorocarbon
Hydrocarbon
Hydrochlorofluorocarbon
Hydrochlorofluoroolefin

A-521

HDDV
HDGV
HDPE
HF
HFC
HFO
HFE
HHV
HMA
HMIWI
HTF
HTS
HWP
IBF
IC
ICAO
ICBA
ICE
ICR
IEA
IFO
IGES
IISRP
ILENR
IMO
IPAA
IPCC
IPPU
ITC
ITRS
JWR
KCA
kg
kt
kWh
LDPE
LDT
LDV
LEV
LFG
LFGTE
LHV
LKD
LLDPE
LMOP
LNG
LPG
LTO
LULUCF
M&R
MARPOL
MC
MCF
MCL
MCFD

Heavy duty diesel vehicle
Heavy duty gas vehicle
High density polyethylene
Hydraulically fractured
Hydrofluorocarbon
Hydrofluoroolefin
Hydrofluoroethers
Higher Heating Value
Hot Mix Asphalt
Hospital/medical/infectious waste incinerator
Heat Transfer Fluid
Harmonized Tariff Schedule
Harvested wood productInternational bunker fuels
Integrated Circuit
International Civil Aviation Organization
International Carbon Black Association
Internal combustion engine
Information Collection Request
International Energy Agency
Intermediate Fuel Oil
Institute of Global Environmental Strategies
International Institute of Synthetic Rubber Products
Illinois Department of Energy and Natural Resources
International Maritime Organization
Independent Petroleum Association of America
Intergovernmental Panel on Climate Change
Industrial Processes and Product Use
U.S. International Trade Commission
International Technology Roadmap for Semiconductors
Jim Walters Resources
Key category analysis
Kilogram
Kiloton
Kilowatt hour
Low density polyethylene
Light-duty truck
Light-duty vehicle
Low emission vehicles
Landfill gas
Landfill gas-to-energy
Lower Heating Value
Lime kiln dust
Linear low density polyethylene
EPA’s Landfill Methane Outreach Program
Liquefied natural gas
Liquefied petroleum gas(es)Landing and take-off
Land Use, Land-Use Change, and Forestry
Metering and regulating
International Convention for the Prevention of Pollution from Ships
Motorcycle
Methane conversion factor
Maximum Contaminant Levels
Thousand cubic feet per day

A-522 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018

MDI
MDP
MECS
MEMS
MER
MGO
MgO
MJ
MLRA
mm
MMBtu
MMCF
MMCFD
MMS
MMT
MMTCE
MMT CO2 Eq.
MODIS
MoU
MOVES
MPG
MRLC
MRV
MSHA
MSW
MT
MTBE
MTBS
MVAC
MY
N2O
NA
NACWA
NAHMS
NAICS
NAPAP
NARR
NAS
NASA
NASF
NASS
NC
NCASI
NCV
ND
NE
NEH
NEI
NEMA
NEMS
NESHAP
NEU
NEV
NF3

Metered dose inhalers
Management and design practices
EIA Manufacturer’s Energy Consumption Survey
Micro-electromechanical systems
Monthly Energy Review
Marine gas oil
Magnesium oxide
Megajoule
Major Land Resource Area
Millimeter
Million British thermal units
Million cubic feet
Million cubic feet per day
Minerals Management Service
Million metric tons
Million metric tons carbon equivalentMillion metric tons carbon dioxide equivalent
Moderate Resolution Imaging Spectroradiometer
Memorandum of Understanding
U.S. EPA’s Motor Vehicle Emission Simulator model
Miles per gallon
Multi-Resolution Land Characteristics Consortium
Monitoring, reporting, and verification
Mine Safety and Health Administration
Municipal solid waste
Metric ton
Methyl Tertiary Butyl Ether
Monitoring Trends in Burn Severity
Motor vehicle air conditioning
Model year
Nitrous oxide
Not applicable; Not available
National Association of Clean Water Agencies
National Animal Health Monitoring System
North American Industry Classification System
National Acid Precipitation and Assessment Program
North American Regional Reanalysis Product
National Academies of Sciences, Engineering, and Medicine
National Aeronautics and Space Administration
National Association of State Foresters
USDA’s National Agriculture Statistics Service
No change
National Council of Air and Stream Improvement
Net calorific value
No data
Not estimatedNational Engineering Handbook
National Emissions Inventory
National Electrical Manufacturers Association
National Energy Modeling System
National Emission Standards for Hazardous Air Pollutants
Non-Energy Use
Neighborhood Electric Vehicle
Nitrogen trifluoride

A-523

NFI
NGL
NIR
NLA
NLCD
NMOC
NMVOC
NMOG
NO
NO
NO2
NOx
NOAA
NOF
NPDES
NPP
NPRA
NRBP
NRC
NRCS
NREL
NRI
NSCEP
NSCR
NSPS
NWS
OAG
OAP
OAQPS
ODP
ODS
OECD
OEM
OGJ
OGOR
OH
OMS
ORNL
OSHA
OTA
OTAQ
OVS
PADUS
PAH
PCA
PCC
PDF
PECVD
PET
PET
PEVM
PFC
PFPE
PHEV
PHMSA

National forest inventory
Natural gas liquids
National Inventory Report
National Lime Association
National Land Cover Dataset
Non-methane organic compounds
Non-methane volatile organic compoundNon-methane organic gas
Nitric oxide
Not occurring
Nitrogen dioxide
Nitrogen oxides
National Oceanic and Atmospheric Administration
Not on feed
National Pollutant Discharge Elimination System
Net primary productivity
National Petroleum and Refiners Association
Northeast Regional Biomass Program
National Research Council
Natural Resources Conservation Service
National Renewable Energy Laboratory
National Resources Inventory
National Service Center for Environmental Publications
Non-selective catalytic reduction
New source performance standards
National Weather Service
Official Airline Guide
EPA Office of Atmospheric Programs
EPA Office of Air Quality Planning and Standards
Ozone depleting potential
Ozone depleting substances
Organization of Economic Co-operation and Development
Original equipment manufacturers
Oil & Gas Journal
Oil and Gas Operations Reports
Hydroxyl radical
EPA Office of Mobile Sources
Oak Ridge National Laboratory
Occupational Safety and Health Administration
Office of Technology Assessment
EPA Office of Transportation and Air Quality
Offset verification statement
Protected Areas Database of the United States
Polycyclic aromatic hydrocarbons
Portland Cement Association
Precipitate calcium carbonate
Probability Density Function
Plasma enhanced chemical vapor deposition
Polyethylene terephthalate
Potential evapotranspiration
PFC Emissions Vintage Model
Perfluorocarbon
Perfluoropolyether
Plug-in hybrid vehicles
Pipeline and Hazardous Materials Safety Administration

A-524 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018

PI
PLS
POTW
ppbv
ppm
ppmv
pptv
PRCI
PRP
PS
PSU
PU
PVC
PV
QA/QC
QBtu
R&D
RECs
RCRA
RFA
RFS
RMA
RPA
RTO
SAE
SAGE
SAIC
SAN
SAR
SCR
SCSE
SDR
SEC
SEMI
SF6
SIA
SiC
SICAS
SNAP
SNG
SO2
SOC
SOG
SOHIO
SSURGO
STMC
SULEV
SWANA
SWDS
SWICS
TA
TAM
TAME
TAR

Productivity index
Pregnant liquor solution
Publicly Owned Treatment Works
Parts per billion (109) by volume
Parts per million
Parts per million (106) by volume
Parts per trillion (1012) by volume
Pipeline Research Council International
Pasture/Range/Paddock
Polystyrene
Primary Sample Unit
Polyurethane
Polyvinyl chloride
Photovoltaic
Quality Assurance and Quality Control
Quadrillion Btu
Research and Development
Reduced Emissions Completions
Resource Conservation and Recovery Act
Renewable Fuels Association
Renewable Fuel Standard
Rubber Manufacturers’ Association
Resources Planning Act
Regression-through-the-origin
Society of Automotive Engineers
System for assessing Aviation’s Global Emissions
Science Applications International Corporation
Styrene Acrylonitrile
IPCC Second Assessment Report
Selective catalytic reduction
South central and southeastern coastal
Steel dust recycling
Securities and Exchange Commission
Semiconductor Equipment and Materials Industry
Sulfur hexafluoride
Semiconductor Industry Association
Silicon carbide
Semiconductor International Capacity Statistics
Significant New Alternative Policy Program
Synthetic natural gas
Sulfur dioxide
Soil Organic Carbon
State of Garbage survey
Standard Oil Company of Ohio
Soil Survey Geographic Database
Scrap Tire Management Council
Super Ultra Low Emissions Vehicle
Solid Waste Association of North America
Solid waste disposal sites
Solid Waste Industry for Climate Solutions
Treated anaerobically (wastewater)
Typical animal mass
Tertiary amyl methyl ether
IPCC Third Assessment Report

A-525

TBtu
TDN
TEDB
TFI
TIGER
TJ
TLEV
TMLA
TPO
TRI
TSDF
TTB
TVA
UAN
UDI
UFORE
UG
U.S.
U.S. ITC
UEP
ULEV
UNEP
UNFCCC
USAA
USAF
USDA
USFS
USGS
USITC
VAIP
VAM
VKT
VMT
VOCs
VS
WBJ
WEF
WERF
WFF
WGC
WIP
WMO
WMS
WTE
WW
WWTP
ZEVs

6.7.

Trillion Btu
Total digestible nutrients
Transportation Energy Data Book
The Fertilizer Institute
Topologically Integrated Geographic Encoding and Referencing survey
Terajoule
Traditional low emissions vehicle
Total Manufactured Layer Area
Timber Product Output
Toxic Release Inventory
Hazardous waste treatment, storage, and disposal facility
Tax and Trade Bureau
Tennessee Valley Authority
Urea ammonium nitrate
Utility Data Institute
U.S. Forest Service’s Urban Forest Effects model
Underground (coal mining)
United States
United States International Trade Commission
United Egg Producers
Ultra low emission vehicle
United Nations Environmental Programme
United Nations Framework Convention on Climate Change
U.S. Aluminum Association
United States Air Force
United States Department of Agriculture
United States Forest Service
United States Geological Survey
U.S. International Trade Commission
EPA’s Voluntary Aluminum Industrial Partnership
Ventilation air methane
Vehicle kilometers traveled
Vehicle miles traveled
Volatile organic compounds
Volatile solids
Waste Business Journal
Water Environment Federation
Water Environment Research Federation
World Fab Forecast (previously WFW, World Fab Watch)
World Gas Conference
Waste in place
World Meteorological Organization
Waste management systems
Waste-to-energy
Wastewater
Wastewater treatment plant
Zero emissions vehicles

Chemical Formulas

Table A-265: Guide to Chemical Formulas
Symbol
Al
Al2O3
Br

Name
Aluminum
Aluminum oxide
BromineA-526 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018

C
CH4
C2H6
C3H8
CF4
C2F6
c-C3F6
C3F8
C4F6
c-C4F8
C4F10
c-C5F8
C5F12
C6F14
CF3I
CFCl3
CF2Cl2CF3Cl
C2F3Cl3
CCl3CF3
C2F4Cl2
C2F5Cl
CHCl2F
CHF2ClC2F3HCl2
C2F4HCl
C2FH3Cl2
C2H3F2Cl
CF3CF2CHCl2
CClF2CF2CHClF
CCl4
CHClCCl2
CCl2CCl2
CH3Cl
CH3CCl3
CH2Cl2
CHCl3
CHF3
CH2F2
CH3F
C2HF5
C2H2F4
CH2FCF3C2H3F3C2H3F3
CH2FCH2F
C2H4F2
CH3CH2F
C3HF7
CF3CF2CH2F
CF3CHFCHF2
C3H2F6C3H3F5
CHF2CH2CF3

CarbonMethaneEthanePropane
Perfluoromethane
Perfluoroethane, hexafluoroethane
Perfluorocyclopropane
Perfluoropropane
Hexafluoro-1,3-butadiene
Perfluorocyclobutane
Perfluorobutane
Perfluorocyclopentene
Perfluoropentane
Perfluorohexane
Trifluoroiodomethane
Trichlorofluoromethane (CFC-11)
Dichlorodifluoromethane (CFC-12)
Chlorotrifluoromethane (CFC-13)
Trichlorotrifluoroethane (CFC-113)*
CFC-113a*Dichlorotetrafluoroethane (CFC-114)
Chloropentafluoroethane (CFC-115)
HCFC-21Chlorodifluoromethane (HCFC-22)
HCFC-123
HCFC-124
HCFC-141b
HCFC-142b
HCFC-225ca
HCFC-225cb
Carbon tetrachloride
Trichloroethylene
Perchloroethylene, tetrachloroethene
Methylchloride
Methylchloroform
Methylenechloride
Chloroform, trichloromethane
HFC-23
HFC-32
HFC-41
HFC-125
HFC-134
HFC-134a
HFC-143*
HFC-143a*
HFC-152*
HFC-152a*
HFC-161
HFC-227ea
HFC-236cb
HFC-236ea
HFC-236fa
HFC-245ca
HFC-245fa

A-527

CF3CH2CF2CH3
C5H2F10
CF3OCHF2
CF2HOCF2H
CH3OCF3
CF3CHFOCF3
CF3CHClOCHF2
CF3CHFOCHF2
CF3CH2OCF3
CF3CF2OCH3CHF2CH2OCF3
CF3CH2OCHF2
CHF2CF2OCH3
CF3CH2OCH3
CF3CF2OCF2CHF2
CF3CF2OCH2CF3
CF3CF2CF2OCH3
CF3CF2OCH2CHF2
CF3CHFCF2OCH3CHF2CF2CF2OCH3CHF2CF2OCH2CHF2CHF2CF2CH2OCHF2
CF3CF2CH2OCH3CHF2CF2OCH2CH3
C4F9OCH3
C4F9OC2H5
CH2CFCF3

CHFCHCF3
CF3CHCHCF3C3H2ClF3
CHF2OCF2OC2F4OCHF2
CHF2OCF2OCHF2
CHF2OCF2CF2OCHF2
CH3OCH3
CH2Br2
CH2BrCl
CHBr3
CHBrF2
CH3Br
CF2BrCl
CF3Br(CBrF3)
CF3I
CO
CO2
CaCO3
CaMg(CO3)2
CaO
Cl
F
Fe
Fe2O3
FeSi
GaAs
H, H2
H2O

HFC-365mfc
HFC-43-10mee
HFE-125
HFE-134
HFE-143a
HFE-227ea
HCFE-235da2
HFE-236ea2
HFE-236fa
HFE-245cb2
HFE-245fa1
HFE-245fa2
HFE-254cb2
HFE-263fb2
HFE-329mcc2
HFE-338mcf2
HFE-347mcc3
HFE-347mcf2
HFE-356mec3
HFE-356pcc3
HFE-356pcf2
HFE-356pcf3
HFE-365mcf3
HFE-374pcf2
HFE-7100
HFE-7200
HFO-1234yf
HFO-1234ze(E)HFO-1336mzz(Z)HCFO-1233zd(E)H-Galden 1040x
HG-10
HG-01
Dimethyl ether
Dibromomethane
Dibromochloromethane
Tribromomethane
Bromodifluoromethane
Methylbromide
Bromodichloromethane (Halon 1211)
Bromotrifluoromethane (Halon 1301)
FIC-13I1
Carbon monoxide
Carbon dioxide
Calcium carbonate, Limestone
Dolomite
Calcium oxide, Limeatomic Chlorine
Fluorine
Iron
Ferric oxide
FerrosiliconGallium arsenide
atomic Hydrogen, molecular Hydrogen
Water

A-528 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018

H2O2
OH
N, N2
NH3
NH4+
HNO3
MgO
NF3
N2O
NO
NO2
NO3
NOx
Na
Na2CO3
Na3AlF6
O, O2
O3
S
H2SO4
SF6
SF5CF3
SO2
Si
SiC
SiO2

Hydrogen peroxide
Hydroxyl
atomic Nitrogen, molecular Nitrogen
Ammonia
Ammonium ion
Nitric acid
Magnesium oxide
Nitrogen trifluoride
Nitrous oxide
Nitric oxide
Nitrogen dioxide
Nitrate radical
Nitrogen oxides
Sodium
Sodium carbonate, soda ash
Synthetic cryolite
atomic Oxygen, molecular Oxygen
Ozone
atomic Sulfur
Sulfuric acidSulfur hexafluoride
Trifluoromethylsulphur pentafluoride
Sulfur dioxide
SiliconSilicon carbide
Quartz* Distinct isomers.

A-529

References
EIA (2019) Monthly Energy Review, November 2019. Energy Information Administration, U.S. Department of Energy,
Washington, DC. DOE/EIA-0035(2019/11). November 2019.
EIA (2007) Emissions of Greenhouse Gases in the United States 2006, Draft Report. Office of Integrated Analysis andForecasting, Energy Information Administration, U.S. Department of Energy, Washington, DC. DOE-EIA-0573 (2006).
EPA (2003) E-mail correspondence. Air pollutant data. Office of Air Pollution to the Office of Air Quality Planning andStandards, U.S. Environmental Protection Agency (EPA). December 22, 2003.
EIA (1993) State Energy Data Report 1992, DOE/EIA-0214(93), Energy Information Administration, U.S. Department ofEnergy. Washington, DC. December.
EPA (2019) “1970-2018 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. Last Modified March 2018.
Available online at: <https://www.epa.gov/air-emissions-inventories/air-pollutant-emissions-trends-data>.
EPA (2003) E-mail correspondence. Air pollutant data. Office of Air Pollution to the Office of Air Quality Planning andStandards, U.S. Environmental Protection Agency (EPA). December 22, 2003.
IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment
Report of the Intergovernmental Panel on Climate Change. [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen,
J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United
Kingdom and New York, NY, USA, 1535 pp.
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 (1996) Climate Change 1995: The Science of Climate Change. Intergovernmental Panel on Climate Change,
J.T.Houghton, L.G. Meira Filho, B.A. Callander, N. Harris, A. Kattenberg, and K. Maskell (eds.). Cambridge University
Press. Cambridge, United Kingdom.

A-530 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018