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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 61,525.43Gg of CO2. In 2003, total greenhouse gas emissions increased by 22.5% to 75,345.29Gg CO2 equivalent (Figure 2.1.1). Over the period 1990 to 2003, the average annual growth in overall emissions has been 1.48% 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 hydro-electric generation, which cannot meet the demand for electricity 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 1990-2003

Year Gg CO2 equivalent
1990 61,525.43
1991 62,033.02
1992 63,552.73
1993 63,457.24
1994 63,768.75
1995 64,277.82
1996 65,665.38
1997 67,876.39
1998 66,732.62
1999 68,535.28
2000 69,695.65
2001 72,623.27
2002 73,233.20
2003 75,345.29

2.2 Emission trends by gas

CO2 and CH4 dominate New Zealand's increase in greenhouse gas emissions (Figures 2.2.1, 2.2.2 and Table 2.2.1). In 2003, these gases comprised 81.4% 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 third major gas in New Zealand's emissions profile is N2O.

Figure 2.2.1 New Zealand's emissions by gas in 2003 (all figures Gg CO2 equivalent)

Gas Gg CO2 equivalent Percent of total
CO2 (without LULUCF) 34,699.55 46.0
CH4 26,644.97 35.4
N2O 13,499.53 17.9
HFCs 403.96 0.5
PFCs 84.90 0.1
SF6 12.38 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 e.g. the amount of nitrogenous fertilisers used has increased five-fold since 1990.

Although the contribution of the other gases in the inventory is less than 1% of the total emissions, these gases have also undergone relative changes between 1990 and 2003: emissions of PFCs have decreased 83.5% due to improvements in the aluminium smelting process and HFC emissions have increased from 0 to 403.96 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 in 1990 and 2003

Greenhouse gas emissions Gg CO2 equivalent Change from 1990 (%)
1990 2003

CO2 emissions (without LULUCF)

25,314.81

34,699.55

37.1

CH4

25,283.98

26,644.97

5.4

N2O

10,398.71

13,499.53

29.8

HFCs

0.00

403.96

NA

PFCs

515.60

84.90

-83.5

SF6

12.33

12.38

0.39

Figure 2.2.2 Change in New Zealand's emissions of CO2, CH4, and N2O from 1990-2003

Year Percent change in emissions from 1990
  CO2 CH4 N2O
1990 0 0 0
1991 2.03 -0.66 0.25
1992 9.39 -2.35 1.16
1993 7.11 -1.18 3.97
1994 7.47 -0.32 7.07
1995 7.29 0.84 9.37
1996 11.30 1.18 10.46
1997 20.22 1.10 11.39
1998 14.79 1.48 12.13
1999 20.50 2.38 14.28
2000 22.48 3.49 18.09
2001 30.29 4.91 23.00
2002 30.40 5.07 26.68
2003 37.07 5.38 29.82

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 2003, 49.4% of New Zealand's total emissions were produced by the agriculture sector, predominantly CH4 from ruminant farm animals e.g. dairy cows and sheep, and N2O from animal excreta and nitrogenous fertiliser use. The current level of emissions from the agriculture sector is 15.6% 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 2003 (all figures Gg CO2 equivalent, percentage of national total emissions in 2003)

Sector Gg CO2 equivalent Percent of total
Energy 32,320.92 42.9
Industrial processes 4,014.19 5.3
Solvents and other products 48.36 0.1
Agriculture 37,203.24 49.4
Waste 1,754.48 2.3

The energy sector is the other large component of New Zealand's emissions profile comprising 42.9% of total emissions (refer Chapter 3). Emissions from the energy sector in 2003 are 37.0% over the 1990 level and represent the highest sectoral growth in emissions. The growth in emissions is primarily from road transport (increased 58.4%) and electricity generation (increased 83.3%). The 2003 year was a dryer year than usual, resulting in greater reliance on coal for electricity generation. Emissions of CO2 from New Zealand's only power station able to run on coal (and gas) approximately doubled between 2002 and 2003.

Emissions from the industrial processes and waste sectors are a much smaller component comprising 5.3% and 2.3% respectively of all greenhouse gas emissions in 2003. Emissions from the industrial processes sector have been increasing steadily and are now 25.0% over the 1990 baseline. This growth is primarily from increased CO2 emissions from cement production (an increase of 44% over 1990) and urea (nitrogenous fertiliser) manufacture (an increase of 41% over 1990). The increase has been offset by PFC emissions from aluminium manufacture decreasing by 84% since 1990 as a result of improvements to the smelting process (refer section 4.4.2 - aluminium).

Emissions from the waste sector are now 29.3% below the 1990 baseline. The majority of this 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 2003, the solvent sector emitted 31.61 Gg of NMVOC.

The 'land-use, land-use change and forestry' (LULUCF) sector represents the major sink for New Zealand removing 30.3% of all greenhouse gas emissions in 2003. Net removals in 2003 were 7.0% 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 2003

Greenhouse gas emissions Gg CO2 equivalent Change from 1990 (%)
1990 2003

Energy

23,594.11

32,320.92

37.0

Industrial processes

3,211.70

4,014.19

25.0

Solvent and other product use

41.54

48.36

16.4

Agriculture

32,193.76

37,203.24

15.6

Land-use, land-use change and forestry

-21,366.19

-22,861.60

7.0

Waste

2,480.06

1,754.48

-29.3

Figure 2.3.2 Change in sectoral greenhouse gas emissions from 1990-2003

Year Percent change in emissions from 1990
Energy Industrial Processes Solvents Agriculture Waste
1990 0 0 0 0 0
1991 1.2 8.6 3.0 -0.2 1.0
1992 8.6 11.4 3.7 -0.2 -13.1
1993 5.5 12.6 5.2 1.7 -13.2
1994 6.5 -0.1 6.7 3.5 -17.1
1995 6.3 3.5 8.2 4.9 -17.0
1996 10.7 8.5 10.5 5.6 -18.8
1997 20.8 1.8 11.2 6.3 -26.6
1998 14.6 8.4 11.9 6.7 -26.9
1999 20.3 10.9 12.7 8.0 -28.0
2000 22.5 9.3 13.4 10.3 -30.8
2001 30.7 14.4 14.2 12.9 -30.7
2002 30.8 19.1 16.4 14.2 -30.3
2003 37.0 25.0 16.4 15.6 -29.3

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 2003 are shown in Table 2.4.1. However, these totals are not included in New Zealand's total emissions. There have been marked increases in the emissions of all gases.

Table 2.4.1 Emissions of indirect greenhouse gases and SO2 in 1990 and 2003

Gas Gg of gas(es) Change from 1990 (%)
1990 2003

NOx

138.48

168.60

21.8

CO

574.09

682.83

18.9

NMVOC

135.47

166.18

22.7

SO2

60.67

79.33

30.8

Emissions of CO and NOx come largely from the energy sector. The energy sector produced 85.7% of total CO emissions in 2003. The largest single source was road transportation emissions which accounted for 88.6% of the energy sector CO emissions or 75.9% of total CO emissions. Similarly, the energy sector was the largest source of NOx emissions (96.8%) with road transportation emissions comprising 40.9% of total NOx emissions. Other large sources of NOx emissions are from the 'manufacturing industries and construction' category (17.4%) and energy industries (17.6%).

The energy sector was also the largest producer of NMVOC and SO2. The energy sector produced 71.5% of NMVOC emissions in 2003 with emissions from road transportation comprising 62.2% of total NMVOC emissions. Other major sources of NMVOC are in the 'solvent and other product use' sector (19.0%) and the industrial processes sector (9.5%).

Emissions of SO2 from the energy sector comprised 84.0% of total SO2 emissions. The 'manufacturing industries and construction' category was the largest single source at 29.0% of total SO2 emissions. The other source of SO2 was from the industrial processes sector.