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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 61,900.2 Gg CO2 equivalent (CO2-e). In 2005, total greenhouse gas emissions had increased by 15,258.9 Gg (24.7 per cent) to 77,159.1 Gg CO2-e. (Figure 2.1.1). between 1990 and 2005, the average annual growth in overall emissions was 1.3 per cent.

Fluctuations in the trend are largely driven by emissions from the “public electricity and heat production” category. This category shows large year-to-year fluctuations because of the use of fossil fuels in thermal stations to supplement hydro-electric generation during dry years. Electricity generation in a year with hydro storage below average requires higher gas and coal use compared to a year with average rainfall and hydro storage. 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 1990–2005

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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 2005, these gases comprised 81.7 per cent of total CO2 equivalent emissions. In 1990 CH4 and CO2 made equally large contributions to New Zealand’s total emissions. In 2005, CO2 was the major greenhouse gas in New Zealand’s emissions profile, followed by CH4 and N2O.

Figure 2.2.1 New Zealand’s emissions by gas in 2005 (all figures Gg CO2-e)

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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 (HFCs, PFCs and SF6) in the inventory is around 1 per cent of the total emissions, these gases have also undergone relative changes between 1990 and 2005. Emissions of PFCs have decreased by 434.9 Gg due to improvements in the aluminium smelting process. HFC emissions have increased from 0 to 741.6 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 2005

Greenhouse gas emissions Gg CO2-equivalent Change from 1990 (Gg CO2 /equivalent) Change from 1990 (%)
  1990 2005    

CO2 emissions (without LULUCF)

25,462.3

35,879.8

10,417.5

40.9

CH4

25,492.7

27,175.3

1,682.6

6.6

N2O

10,417.2

13,259.9

2,842.7

27.3

HFCs

0.0

741.6

741.6

-

PFCs

515.6

80.7

–434.9

–84.3

SF6

12.3

21.8

9.5

77.2

Figure 2.2.2 Change in New Zealand’s emissions of CO2, CH4, and N2O from 1990 to 2005

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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 2005, 48.5 per cent of New Zealand’s total emissions were 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 15.2 per cent 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 2005 (all figures Gg CO2-e, percentage of national total emissions in 2005)

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The energy sector is the other large component of New Zealand’s emissions profile comprising 43.4 per cent of total emissions (refer Chapter 3). Emissions from the energy sector in 2005 were 9,904.2 Gg CO2-e (42.0 per cent) above the 1990 level and represent the highest sectoral growth in emissions. The growth in emissions from 1990 is primarily from road transport (increased by 4961.9 Gg CO2-e or 64.7 per cent) and electricity generation (increased by 4,697.2 Gg CO2-e or 134.5 per cent).

Emissions from the industrial processes and waste sectors are a much smaller component comprising 5.6 per cent and 2.4 per cent respectively of all greenhouse gas emissions in 2005. Emissions from the industrial processes sector have been increasing steadily and are now 1,045.5 Gg CO2-e (31.8 per cent) above the 1990 baseline. This growth is primarily from increased CO2 emissions from cement production (an increase of 127.0 Gg CO2-e or 28.8 per cent over 1990), urea (nitrogenous fertiliser) manufacture (an increase of 71.66 Gg CO2-e or 26.1 per cent over 1990) and HFC consumption (from 0 in 1990 to 741.6 Gg CO2-e in 2005). The increase has been partially offset by PFC emissions from aluminium manufacture decreasing by 434.9 Gg CO2-e (84.3 per cent) since 1990 as a result of improvements to the smelting process (refer to section 4.4.2).

Emissions from the waste sector are now 645.7 Gg CO2-e (–25.9 per cent) below the 1990 baseline. The majority of the reduction has occurred in the solid waste disposal on land category, as a result of initiatives to improve solid waste management practices in New Zealand. This includes preparation of 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 emissions from the solvent sector are very small. In 2005, the solvent sector emitted 48.4 Gg of NMVOC.

The Land use, Land-use Change and Forestry (LULUCF) sector represents a major sink for New Zealand removing 31.8 per cent of all greenhouse gas emissions in 2005. Net removals in 2005 were 29.1 per cent 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 2005

Sector Gg CO2-equivalent Change from 1990 (Gg CO2-equivalent) Change from 1990 (%)
  1990 2005    

Energy

23,577.5

33,481.7

9,904.2

42.0

Industrial processes

3,291.2

4,336.7

1,045.5

31.8

Solvent and other product

41.5

48.4

6.9

16.6

Agriculture

32,497.1

37,445.3

4,948.2

15.2

Land-use change and forestry

–18,980.6

–24,500.8

–5,520.2

29.1

Waste

2,492.8

1,847.1

–645.7

–25.9

Figure 2.3.2 Change in sectoral greenhouse gas emissions from 1990 to 2005

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2.4 Emission trends for indirect greenhouse gases and SO2

The indirect greenhouse gases SO2, CO, NOx and NMVOC are also reported in the inventory. Emissions of these gases in 1990 and 2005 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 2005

Gas Gg of gas(es) Change from 1990 (Gg) Change from 1990 (%)
  1990 2005    

NOx

104.1

163.4

59.3

57.0

CO

535.3

657.5

122.2

22.8

NMVOC

133.7

166.5

24.5

18.3

SO2

54.3

83.8

29.5

54.3

Emissions of CO and NOx come largely from the energy sector. The energy sector produced 85.8 per cent of total CO emissions in 2005. The largest single source was “road transportation”. Similarly, the energy sector was the largest source of NOx emissions (97.8 per cent), 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 71.3 per cent of NMVOC emissions in 2005 with emissions from “road transportation” comprising 63.1 per cent of total NMVOC emissions. Other major sources of NMVOC’s are in the solvent and other product use sector (20.3 per cent) and the industrial processes sector (8.4 per cent).

Emissions of SO2 from the energy sector comprised 86.3 per cent of total SO2 emissions. The “energy industries” category contributed 29.2 per cent, “manufacturing industries and construction” 24.5 per cent and “transport” 16.0 per cent of total SO2 emissions. The other source of SO2 was from the industrial processes sector.