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Chapter 2: Trends in greenhouse gas emissions

2.1 Emission trends for aggregated greenhouse gas emissions

In 1990, New Zealand's total greenhouse gas emissions were equivalent to 61,510.70 Gg of CO2. In 2004, total greenhouse gas emissions have increased by 13,094.52 Gg (21.3 percent) to 74,605.22 Gg CO2 equivalent (Figure 2.1.1). Over the period 1990 to 2004, the average annual growth in overall emissions has been 1.5 percent per year.

Fluctuations in the trend are largely driven by emissions from public electricity generation. This category can show large year-to-year fluctuations because of the use of thermal stations to supplement the hydro-electric generation, during dry years. Generation in a year with normal rainfall requires lower gas and coal use and a year with less rainfall requires higher gas and coal use. This is a different trend from the steady increase in emissions from coal and gas used in electricity generation found in many other countries.

Figure 2.1.1 New Zealand's total greenhouse gas emissions 1990-2004

 

Year

Gg CO2 equivalent (thousands)

1990

61.51

1991

62.03

1992

63.86

1993

63.77

1994

64.17

1995

64.47

1996

65.94

1997

68.22

1998

67.18

1999

68.86

2000

70.04

2001

73.01

2002

73.47

2003

75.50

2004

74.61

2.2 Emission trends by gas

Carbon dioxide and methane dominate New Zealand's increase in greenhouse gas emissions (Figures 2.2.1, 2.2.2 and Table 2.2.1). In 2004, these gases comprised 81.8 percent of total CO2 equivalent emissions. Whereas CH4 and CO2 made equally large contributions to New Zealand's emissions in 1990, CO2 is now the major greenhouse gas in New Zealand's emissions profile. The other major gas in New Zealand's emissions profile is N2O.

Figure 2.2.1 New Zealand's emissions by gas in 2004 (all figures Gg CO2 equivalent)

 

Gas

Gg CO2 equivalent

Percent of total

Perfluorocarbons (PFCs)

87.70

0.1

Hydrofluorocarbons (HFCs)

597.14

0.8

Carbon dioxide (CO2) (without LULUCF)

34,038.90

45.6

Methane (CH4)

27,064.03

36.2

Nitrous oxide (N2O)

12,878.75

17.2

Sulphur hexafluoride (SF6)

21.49

0.0

The growth in CO2 represents the increased emissions from the energy sector. The growth in N2O is from increased emissions from animal excreta and the increased use of nitrogenous fertilisers in agriculture, eg, the amount of nitrogenous fertilisers used has increased six-fold since 1990.

Although the contribution of the other gases in the inventory is less than 1 percent of the total emissions, these gases have also undergone relative changes between 1990 and 2004. Emissions of PFCs have decreased 427.90 Gg due to improvements in the aluminium smelting process, and HFC emissions have increased from 0 to 597.36 Gg because of the use of HFCs as a substitute for the chlorofluorocarbons (CFCs) phased out under the Montreal Protocol.

Table 2.2.1 Emissions of greenhouse gases 1990 and 2004

Greenhouse gas emissions Gg CO2 equivalent Change from 1990 (Gg CO2 equivalent) Change from 1990 (%)
1990 2004

CO2 emissions (without LULUCF)

25,373.39

34,038.90

8,665.51

34.1

CH4

25,405.48

27,064.03

1,658.55

6.5

N2O

10,306.92

12,878.75

2,571.83

25.0

HFCs

0.00

597.14

597.14

-

PFCs

515.60

87.70

-427.90

-83.0

SF6

12.33

21.49

9.16

74.3

Figure 2.2.2 Change in New Zealand's emissions of CO2, CH4, and N2O from 1990-2004

Year

Absolute change in emissions from 1990 (Gg CO2 equivalent) (thousands)

 

CO2 (without LULUCF)

CH4

N2O

1990

0.00

0.00

0.00

1991

0.51

-0.16

0.02

1992

2.4

-0.25

0.10

1993

1.80

0.10

0.37

1994

1.91

0.42

0.66

1995

1.83

0.52

0.88

1996

2.85

0.68

0.99

1997

5.04

0.87

1.09

1998

3.73

0.88

1.15

1999

5.19

1.01

1.36

2000

5.66

1.37

1.72

2001

7.67

1.68

2.17

2002

7.66

1.62

2.49

2003

9.31

1.59

2.77

2004

8.67

1.66

2.57

2.3 Emission trends by source

New Zealand is unusual amongst developed nations in the share of its total greenhouse gas emissions that come from agriculture (Figure 2.3.1 and Table 2.3.1). In 2004, 49.4 percent of New Zealand's total emissions are produced by the agriculture sector, predominantly CH4 from ruminant farm animals, eg, dairy cows and sheep, and N2O from animal excreta and nitrogenous fertiliser use. The current level of emissions from the agriculture sector is 14.8 percent above the 1990 level (Figure 2.3.2). More detailed information on the agriculture sector is contained in Chapter 6.

Figure 2.3.1 New Zealand's sectoral greenhouse gas emissions in 2004 (all figures Gg CO2 equivalent, percentage of national total emissions in 2004)

 

Sector

Gg CO2 equivalent

Percent of total

Waste

1,839.98

2.5

Energy

31,647.91

42.4

Industrial Processes

4,202.53

5.6

Solvents & Other Product Use

48.36

0.1

Agriculture

36,866.67

49.4

The energy sector is the other large component of New Zealand's emissions profile comprising 42.4 percent of total emissions (refer Chapter 3). Emissions from the energy sector in 2004 are 7,992.76 Gg (33.8 percent) over the 1990 level and represent the highest sectoral growth in emissions. The growth in emissions from 1990 is primarily from road transport (increased by 4,855.03 Gg or 62.7 percent) and electricity generation (increased by 2,572.46 Gg or 73.6 percent).

Emissions from the industrial processes and waste sectors are a much smaller component comprising 5.6 percent and 2.5 percent respectively of all greenhouse gas emissions in 2004. Emissions from the industrial processes sector have been increasing steadily and are now 987.82 Gg (30.7 percent) over the 1990 baseline. This growth is primarily from increased CO2 emissions from cement production (an increase of 118.11 Gg or 32.2 percent) over 1990), urea (nitrogenous fertiliser) manufacture (an increase of 105.35 Gg or 38.6 percent) over 1990) and HFC consumption (from 0 in 1990 to 597.36 Gg in 2004). The increase has been offset by PFC emissions from aluminium manufacture decreasing by 427.90 Gg (83.0 percent) since 1990 as a result of improvements to the smelting process (refer to section 4.4.2).

Emissions from the waste sector are now 642.83 Gg CO2 equivalent (-25.9 percent) below the 1990 baseline. The majority of the reduction has occurred in the solid waste disposal on land category. This is a result of a number of initiatives to improve solid waste management practices in New Zealand, including preparing guidelines for the development and operation of landfills, closure and management of landfill sites, and consent conditions for landfills under New Zealand's Resource Management Act.

New Zealand's relatively small manufacturing base means that the solvent sector is much lower than in many other countries. In 2004, the solvent sector emitted 48.36 Gg of NMVOC.

The Land use, Land-use Change and Forestry (LULUCF) sector represents a major sink for New Zealand removing 32.8 percent of all greenhouse gas emissions in 2004. Net removals in 2004 were 29.0 percent above net removals in 1990. Variations in planting rates and the impact of harvest regimes affect the size of this sink from year to year.

Table 2.3.1 Sectoral emissions of greenhouse gases in 1990 and 2004

Sector Gg CO2 equivalent Change from 1990 (Gg CO2 equivalent) Change from 1990 (%)
1990 2004

Energy

23,655.15

31,647.91

7,992.76

33.8

Industrial processes

3,214.61

4,202.53

987.92

30.7

Solvent and other product

41.54

48.36

6.82

16.4

Agriculture

32,116.58

36,866.67

4,750.08

14.8

Land-use change and forestry

-18,977.92

-24,482.63

-5504.71

29.0

Waste

2,482.81

1,839.98

-642.83

-25.9

Figure 2.3.2 Change in sectoral greenhouse gas emissions from 1990-2004

 

Year

Absolute change in emissions from 1990 (Gg CO2 equivalent) (thousands)

 

Total emissions

Energy

Industrial Processes

Solvents

Agriculture

Waste

1990

0.00

0.00

0.00

0.00

0.00

0.00

1991

0.51

0.28

0.28

0.00

-0.07

0.03

1992

2.35

2.0

0.37

0.00

-0.05

-0.01

1993

2.29

1.31

0.40

0.00

0.53

0.01

1994

2.71

1.56

0.32

0.00

1.08

-0.01

1995

3.00

1.46

0.18

0.00

1.52

-0.21

1996

4.49

2.51

0.36

0.00

1.75

-0.20

1997

6.79

4.85

0.08

0.00

1.99

-0.22

1998

5.71

3.44

0.39

0.01

2.12

-0.28

1999

7.39

4.79

0.44

0.01

2.53

-0.41

2000

8.54

5.29

0.37

0.01

3.26

-0.40

2001

11.50

7.24

0.65

0.01

4.06

-0.46

2002

11.96

7.23

0.85

0.01

4.39

-0.52

2003

13.98

8.65

1.14

0.01

4.75

-0.55

2004

13.07

7.99

0.99

0.01

4.75

-0.64

2.4 Emission trends for indirect greenhouse gases and SO2

The indirect greenhouse gases CO, NOx and NMVOC are also included in the inventory as is SO2. Emissions of these gases in 1990 and 2004 are shown in Table 2.4.1. There have been marked increases in the emissions of all gases. Indirect greenhouse gases are not included in New Zealand's total greenhouse gas emissions.

Table 2.4.1 Emissions of indirect greenhouse gases and SO2 in 1990 and 2004

Gas Gg of gas(es) Change from 1990 (Gg) Change from 1990 (%)
1990 2004

NOx

135.34

157.45

22.11

16.3

CO

474.61

611.57

136.96

28.9

NMVOC

133.86

169.72

35.86

26.8

SO2

54.28

75.51

21.23

39.1

Emissions of CO and NOx come largely from the energy sector. The energy sector produced 93.6 percent of total CO emissions in 2004. The largest single source was road transportation. Similarly, the energy sector was the largest source of NOx emissions (98.3 percent), with road transportation again dominating. Other large sources of NOx emissions are from manufacturing industries and construction and energy industries.

The energy sector was also the largest producer of NMVOC's and SO2. The energy sector produced 70.1 percent of NMVOC emissions in 2004 with emissions from road transportation comprising 62.7 percent of total NMVOC emissions. Other major sources of NMVOC's are in the solvent and other product use sector (18.8 percent) and the industrial processes sector (10.4 percent).

Emissions of SO2 from the energy sector comprised 85.2 percent of total SO2 emissions. The manufacturing industries and construction and energy industries made up 54.0 percent of total SO2 emissions. The other source of SO2 was from the industrial processes sector.