Figure ES-1 |
![]() |
Figure ES-2 Annual Percent Change in U.S. GHG Emissions ![]() |
Figure ES-3 Absolute Change in U.S. GHG Emissions Since 1990 ![]() |
Gas — Source |
1990 |
1991 |
1992 |
1993 |
1994 |
1995 |
1996 |
1997 |
CO2 |
1,344.3 |
1,329.8 |
1,349.6 |
1,379.2 |
1,403.5 |
1,419.2 |
1,469.3 |
1,487.9 |
![]() |
1,327.2 |
1,312.6 |
1,332.4 |
1,360.6 |
1,383.9 |
1,397.8 |
1,447.7 |
1,466.0 |
![]() |
2.3 |
2.6 |
2.6 |
3.5 |
3.6 |
4.5 |
4.3 |
4.2 |
![]() |
8.9 |
8.7 |
8.8 |
9.3 |
9.6 |
9.9 |
9.9 |
10.2 |
![]() |
3.3 |
3.2 |
3.3 |
3.4 |
3.5 |
3.7 |
3.8 |
3.9 |
![]() |
1.4 |
1.3 |
1.2 |
1.1 |
1.5 |
1.9 |
2.0 |
2.1 |
![]() |
1.1 |
1.1 |
1.1 |
1.1 |
1.1 |
1.2 |
1.2 |
1.2 |
![]() |
0.2 |
0.2 |
0.2 |
0.2 |
0.2 |
0.3 |
0.3 |
0.3 |
![]() |
(311.5) |
(311.5) |
(311.5) |
(208.6) |
(208.6) |
(208.6) |
(208.6) |
(208.6) |
![]() |
27.1 |
27.8 |
29.0 |
29.9 |
27.4 |
25.4 |
25.4 |
26.6 |
CH4 |
169.9 |
171.0 |
172.5 |
172.0 |
175.5 |
178.6 |
178.3 |
179.6 |
![]() |
2.3 |
2.4 |
2.4 |
2.4 |
2.4 |
2.5 |
2.5 |
2.2 |
![]() |
1.4 |
1.4 |
1.4 |
1.4 |
1.4 |
1.4 |
1.4 |
1.4 |
![]() |
24.0 |
22.8 |
22.0 |
19.2 |
19.4 |
20.3 |
18.9 |
18.8 |
![]() |
32.9 |
33.3 |
33.9 |
34.1 |
33.5 |
33.2 |
33.7 |
33.5 |
![]() |
1.6 |
1.6 |
1.6 |
1.6 |
1.6 |
1.6 |
1.5 |
1.6 |
![]() |
0.3 |
0.3 |
0.3 |
0.4 |
0.4 |
0.4 |
0.4 |
0.4 |
![]() |
+ |
+ |
+ |
+ |
+ |
+ |
+ |
+ |
![]() |
32.7 |
32.8 |
33.2 |
33.6 |
34.5 |
34.9 |
34.5 |
34.1 |
![]() |
14.9 |
15.4 |
16.0 |
16.1 |
16.7 |
16.9 |
16.6 |
17.0 |
![]() |
2.5 |
2.5 |
2.8 |
2.5 |
3.0 |
2.8 |
2.5 |
2.7 |
![]() |
0.2 |
0.2 |
0.2 |
0.2 |
0.2 |
0.2 |
0.2 |
0.2 |
![]() |
56.2 |
57.6 |
57.8 |
59.7 |
61.6 |
63.6 |
65.1 |
66.7 |
![]() |
0.9 |
0.9 |
0.9 |
0.9 |
0.9 |
0.9 |
0.9 |
0.9 |
![]() |
+ |
+ |
+ |
+ |
+ |
+ |
+ |
+ |
N2O |
95.7 |
97.6 |
100.1 |
100.4 |
108.3 |
105.4 |
108.2 |
109.0 |
![]() |
3.8 |
3.8 |
3.9 |
3.9 |
4.0 |
4.0 |
4.1 |
4.1 |
![]() |
13.6 |
14.2 |
15.2 |
15.9 |
16.7 |
17.0 |
17.4 |
17.5 |
![]() |
4.7 |
4.9 |
4.6 |
4.9 |
5.2 |
5.2 |
5.4 |
3.9 |
![]() |
3.3 |
3.3 |
3.4 |
3.5 |
3.7 |
3.7 |
3.9 |
3.8 |
![]() |
2.6 |
2.8 |
2.8 |
2.9 |
2.9 |
2.9 |
3.0 |
3.0 |
![]() |
65.3 |
66.2 |
68.0 |
67.0 |
73.4 |
70.2 |
72.0 |
74.1 |
![]() |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
![]() |
2.1 |
2.1 |
2.2 |
2.2 |
2.2 |
2.3 |
2.3 |
2.3 |
![]() |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
![]() |
0.2 |
0.2 |
0.2 |
0.3 |
0.2 |
0.2 |
0.2 |
0.2 |
HFCs, PFCs, and SF6 |
22.2 |
21.6 |
23.0 |
23.4 |
25.9 |
30.8 |
34.7 |
37.1 |
![]() |
0.3 |
0.2 |
0.4 |
1.4 |
4.0 |
9.5 |
11.9 |
14.7 |
![]() |
4.9 |
4.7 |
4.1 |
3.5 |
2.8 |
2.7 |
2.9 |
2.9 |
![]() |
9.5 |
8.4 |
9.5 |
8.7 |
8.6 |
7.4 |
8.5 |
8.2 |
![]() |
0.2 |
0.4 |
0.6 |
0.8 |
1.0 |
1.2 |
1.4 |
1.3 |
![]() |
5.6 |
5.9 |
6.2 |
6.4 |
6.7 |
7.0 |
7.0 |
7.0 |
![]() |
1.7 |
2.0 |
2.2 |
2.5 |
2.7 |
3.0 |
3.0 |
3.0 |
Total Emissions |
1,632.1 |
1,620.0 |
1,645.2 |
1,675.0 |
1,713.2 |
1,733.9 |
1,790.5 |
1,813.6 |
Net Emission |
1,320.6 |
1,308.5 |
1,333.7 |
1,466.5 |
1,504.7 |
1,525.4 |
1,582.0 |
1,605.0 |
Figure ES-4: 1997 Greenhouse Gas Emissions by
Gas
Figure
ES-4 illustrates the relative contribution of the direct greenhouse gases to
total U.S. emissions in 1997. The primary greenhouse gas emitted by human
activities was CO2. The largest source of CO2
and of overall greenhouse gas emissions in the United States was fossil fuel
combustion. Methane emissions resulted primarily from decomposition of wastes in
landfills, manure and enteric fermentation associated with domestic livestock,
natural gas systems, and coal mining. Emissions of N2O
were dominated by agricultural soil management and mobile source fossil fuel
combustion. The substitution of ozone depleting substances and emissions of
HFC-23 during the production of HCFC-22 were the primary contributors to
aggregate HFC emissions. PFC emissions came mainly from primary aluminum
production, while electrical transmission and distribution systems emitted the
majority of SF6.
As
the largest source of U.S. GHG emissions, CO2 from fossil
fuel combustion accounted for 81 percent of emissions in 1997 when each gas is
weighted by its
Global Warming Potential. Emissions from this source grew by 11 percent
(138.8 MMTCE) from 1990 to 1997 and were responsible for over three-quarters of
the increase in national emissions during this period. The annual increase in CO2
emissions from this source was 1.3 percent in 1997, down from the previous year
when emissions increased by 3.6 percent.
The
dramatic increase in fossil fuel combustion-related CO2
emissions in 1996 was primarily a function of two factors: 1) fuel switching by
electric utilities from natural gas to more carbon intensive coal as gas prices
rose sharply due to weather conditions, which drove up residential consumption
of natural gas for heating; and 2) higher petroleum consumption for
transportation. In 1997, by comparison, electric utility natural gas consumption
rose to regain much of the previous year’s decline as the supply available rose
due to lower residential consumption. Despite this increase in natural gas
consumption by utilities and relatively stagnant U.S. electricity consumption,
coal consumption rose in 1997 to offset the temporary shut-down of several
nuclear power plants. Petroleum consumption for transportation activities in
1997 also grew by less than one percent, compared to over three percent the
previous year (see Table ES-2). The annual increase in CO2
emissions from petroleum in 1997 is based on motor gasoline sales data from the
U.S. Energy Information Administration; it is expected to be revised upward with
the publication of future energy statistics.
Sector | Fuel Type | 1995–1996 | 1996–1997 |
Electric Utility | Coal | 5.7% | 2.9% |
Electric Utility | Natural Gas | -14.6% | 8.7% |
Residential | Natural Gas | 8.1% | -4.4% |
Transportation* | Petroleum | 3.4% | 0.3% |
* Excludes emissions from International Bunker Fuels. |
º | Aggregate HFC and PFC emissions
resulting from the substitution of ozone depleting substances (e.g., CFCs)
increased dramatically (by 14.4 MMTCE). This increase was partly offset,
however, by reductions in PFC emissions from aluminum production (41
percent) and HFC emissions from HCFC-22 production (14 percent), both as a
result of voluntary industry emission reduction efforts and, in the former
case, from falling domestic aluminum production. |
º | Combined N2O and CH4 emissions
from mobile source fossil fuel combustion rose by 3.9 MMTCE (26 percent),
primarily due to increased rates of N2O generation in highway vehicles. |
º | Methane emissions from the
decomposition of waste in municipal and industrial landfills rose by 10.5
MMTCE (19 percent) as the amount of organic matter in landfills steadily
accumulated. |
º | Emissions from coal mining
dropped by 5.2 MMTCE (21 percent) as the use of methane from degasification
systems increased significantly. |
º | Nitrous oxide emissions from
agricultural soil management increased by 8.8 MMTCE (13 percent) as
fertilizer consumption and cultivation of nitrogen fixing crops rose. |
º | An additional domestic adipic
acid plant installed emission control systems in 1997; this was estimated to
have resulted in a 1.4 MMTCE (27 percent) decline in emissions from 1996 to
1997 despite an increase in production. |
Box ES-1: Recent Trends in Various U.S. Greenhouse Gas Emissions-Related Data
![]() |
Table ES-3: Recent Trends in Various U.S. Data (Index 1990 = 100)
Variable |
1990 |
1991 |
1992 |
1993 |
1994 |
1995 |
1996 |
1997 |
Growth Rate (g) |
GHG Emissions (a) |
100 |
99 |
101 |
103 |
105 |
106 |
110 |
111 |
1.5% |
Energy Consumption (b) |
100 |
100 |
101 |
104 |
106 |
108 |
112 |
112 |
1.6% |
Fossil Fuel Consumption (c) |
100 |
99 |
101 |
104 |
106 |
107 |
110 |
112 |
1.6% |
Electricity Consumption (c) |
100 |
102 |
102 |
105 |
108 |
111 |
114 |
115 |
2.0% |
GDP (d) |
100 |
99 |
102 |
104 |
108 |
110 |
114 |
118 |
2.5% |
Population (e) |
100 |
101 |
102 |
103 |
104 |
105 |
106 |
107 |
1.0% |
Atmospheric CO2 Concentration (f) |
100 |
100 |
101 |
101 |
101 |
102 |
102 |
103 |
0.4% |
(a) GWP weighted values (b) Energy content weighted values. Source: DOE/EIA (c) Source: DOE/EIA (d) Gross Domestic Product in chained 1992 dollars (BEA 1998) (e) (U.S. Census Bureau 1998) (f) Mauna Loa Observatory, Hawaii (Keeling and Whorf 1998) (g) Average annual growth rate |
Figure ES-5 U.S. Greenhouse Gas Emissions Per Capita and Per Dollar of Gross Domestic Product |
![]() |
Box ES-2: Greenhouse Gas Emissions from Transportation Activities
![]() ![]() ![]() ![]() |
Gas — Vehicle Type |
1990 |
1991 |
1992 |
1993 |
1994 |
1995 |
1996 |
1997 |
CO2 |
405.0 |
396.7 |
402.4 |
406.8 |
422.1 |
430.7 |
445.3 |
446.5 |
![]() |
169.3 |
167.8 |
172.0 |
173.5 |
172.5 |
175.6 |
160.8 |
162.6 |
![]() |
77.5 |
77.2 |
77.2 |
80.5 |
87.2 |
89.2 |
109.9 |
111.1 |
![]() |
57.3 |
55.1 |
56.7 |
59.9 |
62.7 |
64.2 |
68.3 |
69.5 |
![]() |
2.7 |
2.9 |
2.9 |
3.1 |
3.3 |
3.5 |
3.0 |
3.0 |
![]() |
50.5 |
48.4 |
47.4 |
47.6 |
49.6 |
48.3 |
50.5 |
50.1 |
![]() |
16.4 |
15.9 |
16.4 |
11.7 |
13.9 |
16.8 |
18.5 |
15.4 |
![]() |
7.5 |
6.9 |
7.4 |
6.8 |
8.0 |
8.1 |
8.8 |
9.0 |
![]() |
23.8 |
22.5 |
22.4 |
23.8 |
24.9 |
24.9 |
25.5 |
25.8 |
![]() |
27.1 |
27.8 |
29.0 |
29.9 |
27.4 |
25.4 |
25.4 |
26.6 |
CH4 |
1.4 |
1.4 |
1.4 |
1.4 |
1.4 |
1.4 |
1.4 |
1.4 |
![]() |
0.8 |
0.7 |
0.7 |
0.7 |
0.7 |
0.7 |
0.6 |
0.6 |
![]() |
0.4 |
0.4 |
0.4 |
0.4 |
0.4 |
0.4 |
0.5 |
0.5 |
![]() |
0.1 |
0.1 |
0.1 |
0.2 |
0.2 |
0.2 |
0.2 |
0.2 |
![]() |
+ |
+ |
+ |
+ |
+ |
+ |
+ |
+ |
![]() |
+ |
+ |
+ |
+ |
+ |
+ |
+ |
+ |
![]() |
+ |
+ |
+ |
+ |
+ |
+ |
+ |
+ |
![]() |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
![]() |
+ |
+ |
+ |
+ |
+ |
+ |
+ |
+ |
N2O |
13.6 |
14.2 |
15.2 |
15.9 |
16.7 |
17.0 |
17.4 |
17.5 |
![]() |
8.7 |
9.1 |
9.7 |
10.1 |
10.0 |
10.1 |
8.9 |
9.1 |
![]() |
3.4 |
3.7 |
3.9 |
4.2 |
5.1 |
5.2 |
6.8 |
6.8 |
![]() |
0.7 |
0.7 |
0.7 |
0.7 |
0.8 |
0.8 |
0.9 |
0.9 |
![]() |
0.5 |
0.5 |
0.5 |
0.5 |
0.5 |
0.5 |
0.5 |
0.5 |
![]() |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
![]() |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
![]() |
0.2 |
0.2 |
0.2 |
0.2 |
0.2 |
0.2 |
0.2 |
0.2 |
HFCs |
+ |
+ |
0.2 |
0.7 |
1.3 |
2.5 |
3.6 |
4.5 |
![]() |
+ |
+ |
0.2 |
0.7 |
1.3 |
2.5 |
3.6 |
4.5 |
Total |
420.0 |
412.3 |
419.1 |
424.8 |
441.5 |
451.6 |
467.7 |
469.9 |
![]() |
Gas — Fuel Type or Source |
1990 |
1991 |
1992 |
1993 |
1994 |
1995 |
1996 |
1997 |
CO2 |
476.8 |
473.4 |
472.5 |
490.7 |
494.8 |
494.1 |
513.2 |
532.3 |
![]() |
409.0 |
407.2 |
411.8 |
428.7 |
430.2 |
433.0 |
457.5 |
470.9 |
![]() |
41.2 |
41.1 |
40.7 |
39.5 |
44.0 |
47.2 |
40.3 |
43.8 |
![]() |
26.6 |
25.1 |
19.9 |
22.5 |
20.6 |
14.0 |
15.4 |
17.6 |
![]() |
0.1 |
0.1 |
0.1 |
0.1 |
+ |
+ |
+ |
+ |
CH4 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
![]() |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
0.1 |
N2O |
2.0 |
2.0 |
2.0 |
2.1 |
2.1 |
2.1 |
2.2 |
2.3 |
![]() |
2.0 |
2.0 |
2.0 |
2.1 |
2.1 |
2.1 |
2.2 |
2.3 |
SF6 |
5.6 |
5.9 |
6.2 |
6.4 |
6.7 |
7.0 |
7.0 |
7.0 |
![]() |
5.6 |
5.9 |
6.2 |
6.4 |
6.7 |
7.0 |
7.0 |
7.0 |
Total |
484.6 |
481.4 |
480.8 |
499.3 |
503.7 |
503.3 |
522.5 |
541.7 |