OKLAHOMA GREENHOUSE GAS EMISSIONS AND SINKS
INVENTORY: SUMMARY

=igure 1. OK Greenhouse Gas Emissions, 1990 and 1999

OK Greenhouse Gas Emissions
1990 and 1999

30.0 -i
25.0
20.0
15.0
10.0
5.0
0.0
-5.0
-10.0

ID

O

-15.0



1

~ 1990
¦ 1999

Energy Industrial Agriculture Land Use Waste
Processes

Sector

The Oklahoma Department of Environmental Quality's (DEQ) report, Inventory of Oklahoma
Greenhouse Gas Emissions and Sinks: 1990 and 1999, provides a detailed inventory of sources
and sinks of greenhouse gases in Oklahoma.1 In 1990 Oklahoma emitted greenhouse gases in
the amount of 23.2 million metric tons of carbon equivalent (MMTCE). In 1999, emissions were
28.3 MMTCE, an overall increase of approximately 22 percent. Emissions from energy use
increased slightly (9 percent), and emissions from industrial processes and agriculture both
increased moderately (-36 percent). Emissions from waste increased 151 percent. This
increase was due to an increase in total waste disposed (over 10 million tons) and different
assumptions about the percent of waste in large versus small landfills in the two years.2 Land
use (including carbon sequestration in forests and landfills) accounted for a large sink in 1990
and 1999, which was estimated to be about 10.5 MMTCE in both years.3

1	Emissions were estimated using methods from EPA's 1999 El IP Document Series, Volume VIII:
Estimating Greenhouse Gas Emissions.

2	Oklahoma DEQ assumed zero large landfills in 1990 while in 1999 they assumed 81 percent of all waste
was in large landfills. The EIIP methodology for calculating emissions from landfills assumes that the
amount of methane gas generated per unit of waste is higher in large landfills than in small landfills. This
difference in methodology resulted in an emissions increase of almost 0.4 MMTCE.

3	For forest carbon sequestration, Oklahoma DEQ estimated average annual carbon sequestration during
the period 1986 through 1993 and used this estimate for both 1990 and 1999. Forest inventories of
Oklahoma were performed by the Forest Service for 1986 and 1993.


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Table 1. OK Greenhouse Gas Emissions by Gas and by Sector, 1990 and 1999

1990

C02
(MMTCE)

CH4
(MMTCE)

N20
(MMTCE)

HFCs,
PFCs, and

SF6
(MMTCE)

Total
(MMTCE)

Energy

23.8

2.9

0.2

*

27.0

Industrial Processes

0.3

*

0.3

0.1

0.8

Agriculture

*

3.2

2.4

*

5.6

Land Use4

-10.5

*

*

*

-10.5

Waste

*

0.3

*

*

0.3

Net Emissions

13.7

6.4

3.0

0.1

23.2

1999

C02
(MMTCE)

ch4

(MMTCE)

N20
(MMTCE)

HFCs,
PFCs, and

SF6
(MMTCE)

Total
(MMTCE)

Energy

26.6

2.5

0.3

*

29.3

Industrial Processes

0.4

*

0.4

0.2

1.1

Agriculture

*

5.0

2.6

*

7.6

Land Use4

-10.5

*

*

*

-10.5

Waste

*

0.8

*

*

0.8

Net Emissions

16.5

8.2

3.4

0.2

28.3

Note: Totals may differ from the sum of the sources due to independent rounding.

An asterisk (*) indicates emissions of the gas from this sector were zero, insignificant, or not reported.

All emissions are reported in million metric tons of carbon equivalent (MMTCE).

Carbon dioxide (C02) accounted for the majority of Oklahoma's emissions; these emissions
were primarily due to burning of fossil fuels for the production of electricity and, to a lesser
extent, combustion for the transportation and industrial energy sectors. Other sources made
minor contributions to C02 emissions. Methane (CH4) was the next largest contributor, resulting
from natural gas and oil systems, enteric fermentation, and manure management. Nitrous oxide
(N20), the third largest contributor, came chiefly from agricultural soil management.
Hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) from
industrial processes each made up a small share of the total emissions as well. The increase in
HFC/PFC/SF6 emissions in 1999 was largely a result of the replacement of ozone-depleting
substances (CFCs) with HFCs, which have high global warming potentials.

Per capita emissions were 7.4 MTCE in 1990 and 8.4 MTCE in 1999. In both years, Oklahoma's
per capita emissions were above the national average, which was 6.5 MTCE per capita in 1990
and 1999.

4 Landfill carbon sequestration is included in this summary in the land use category; however, Oklahoma
DEQ included it in the waste category.


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