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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 61,639.97Gg of CO2. In 2002, total greenhouse gas emissions have increased by 21.6 % to 74,976.34Gg CO2 equivalent (Figure 2.1.1). Over the period 1990 to 2002, the average annual growth in overall emissions has been 1.65% per year.
2.2 Emission trends by gas
CO2 and CH4 dominate New Zealand's greenhouse gas emissions (Figure 2.2.1 and Table 2.2.1). In 2002, these gases comprised 81.8% of total CO2 equivalent emissions. Whereas CH4 made the largest contribution 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.
The largest increases over the 1990 baseline include CO2 and N2O, with a smaller increase in CH4 (Figure 2.2.2). 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 2002: SF6 emissions have increased 4.7% due to increased use in electric switchgear, emissions of PFCs have decreased 83.8% due to improvements in the aluminium smelting process, and HFC emissions have increased from 0 to 387.59 Gg because of the use of HFCs as a substitute for the chlorofluorocarbons phased out under the Montreal Protocol.
Table 2.2.1 Emissions of greenhouse gases 1990 and 2002
| Greenhouse Gas Emissions | Gg CO2 equivalent | Change from 1990 (%) | |
|---|---|---|---|
| 1990 | 2002 | ||
CO2 emissions (without LUCF) |
25,254.24 |
33,769.80 |
33.7 |
CH4 |
25,570.53 |
27,562.86 |
7.8 |
N2O |
10,287.26 |
13,159.68 |
27.9 |
HFCs |
0.00 |
387.59 |
|
PFCs |
515.60 |
83.50 |
-83.8 |
SF6 |
12.33 |
12.91 |
4.7 |
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 2002, 49.2% of New Zealand's total emissions are produced by the agriculture sector, predominantly CH4 from ruminant farm animals e.g. dairy cows and sheep, and N2O from animal excrement and nitrogenous fertiliser use. The current level of emissions from the agriculture sector is 15.5% above the 1990 level (Figure 2.3.2).
The energy sector is the other large component of New Zealand's emissions profile comprising 42.8 % of total emissions. Emissions from the energy sector in 2002 are 35.0% over the 1990 level and represent the highest sectoral growth in emissions. The growth in emissions is primarily from road transport (increased 62.5%) and electricity generation (increased 58.1%).
Figure 2.3.1 New Zealand's sectoral greenhouse gas emissions in 2002 (all figures Gg CO2 equivalent, percentage of national total emissions in 2002)
Emissions from the industrial processes and waste sectors are a much smaller component comprising 4.7% and 3.2% respectively of all greenhouse gas emissions in 2002. Industrial processes emissions have been increasing steadily and are now 20.5% over the 1990 baseline. However, emissions from waste are now 17.7% below the 1990 baseline. The majority of the reduction has occurred in the solid waste disposal on land category. New Zealand's relatively small manufacturing base means that the solvent sector is much lower than in many other countries. In 2002, the solvent sector emitted 31.63Gg of NMVOC.
The LUCF sector represents the major sink for New Zealand removing 32.5% of all greenhouse gas emissions in 2002. Net removals in 2002 are 11.3% above net removals in 1990. Variations in planting rates and the impact of harvest regimes effect the size of this sink from year to year.
Table 2.3.1 Sectoral emissions of greenhouse gases in 1990 and 2002
| Sector | Gg CO2 equivalent | Change from 1990 (%) | |
|---|---|---|---|
| 1990 | 2002 | ||
Energy |
23,746.84 |
32,047.22 |
35.0 |
Industrial processes |
2,934.09 |
3,535.12 |
20.5 |
Solvent and other product use |
41.54 |
48.36 |
16.4 |
Agriculture |
31,911.15 |
36,856.64 |
15.5 |
Land-use change and forestry |
-21,665.87 |
-24,076.44 |
11.1 |
Waste |
2,908.46 |
2,394.18 |
-17.7 |
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 2002 are shown in Table 2.4.1, however, the 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 2002
| Gas | Gg of gas(es) | Change from 1990 (%) | |
|---|---|---|---|
| 1990 | 2002 | ||
NOx |
138.72 |
204.88 |
47.7 |
CO |
564.91 |
732.66 |
29.7 |
NMVOC |
133.56 |
173.13 |
29.6 |
SO2 |
61.40 |
67.65 |
10.2 |
Emissions of CO and NOx come largely from the energy sector. The energy sector produced 86.5% of total CO emissions in 2002. The largest single source was road transportation emissions which accounted for 71.8% of total CO emissions. Similarly, the energy sector was the largest source of NOx emissions, with road transportation emissions comprising 50.1% of total NOx emissions. Other large sources of NOx emissions are from the manufacturing industries and construction category and energy industries.
The energy sector was also the largest producer of NMVOC's and SO2. The energy sector produced 68.7% of NMVOC emissions in 2002 with emissions from road transportation comprising 60.4% of total NMVOC emissions. Other major sources of NMVOC's are in the solvent and other product use sector (18.3%) and the industrial processes sector (13.0%).
Emissions of SO2 from the energy sector comprised 81.6% of total SO2 emissions. The manufacturing industries and construction category was the largest single source at 32.0% of total SO2 emissions. The other source of SO2 was from the industrial processes sector.
