3. Greenhouse gas inventory
Introduction
The information provided in this chapter is fully consistent with the National Inventory Report including the Common Reporting Format tables that New Zealand submitted to the United Nations Framework Convention on Climate Change (UNFCC) on 15 April 2005.
The inventory totals emissions and removals of the gases carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulphur hexafluoride (SF6) from six sectors: energy; industrial processes; solvents; agriculture; land use, land-use change and forestry (LULUCF); and waste. As required in the UNFCCC reporting guidelines, the indirect greenhouse gases carbon monoxide (CO), oxides of nitrogen (NOX) and non-methane volatile organic compounds (NMVOC) are also included in the inventory as is sulphur dioxide (SO2).
The Climate Change Response Act 2002 which was enacted to enable New Zealand to meet its international obligations under the UNFCCC and the Kyoto Protocol, effectively establishes the Ministry for the Environment as New Zealand's inventory agency.
The Ministry for the Environment is responsible for overall development, compilation and submission of the annual greenhouse gas inventory submitted to the UNFCCC. In addition to this overall coordination and quality control role, the Ministry for the Environment produces the estimates of emissions and removals from the LULUCF sector (except planted forests), the waste sector, and the non-carbon dioxide gases from the industrial processes sector (obtained via industry consultants). The Ministry of Economic Development is responsible for compiling the energy sector emissions and carbon dioxide emissions from the industrial processes sector, and the Ministry of Agriculture and Forestry compiles emissions from the agriculture sector and removals from planted forests in the LULUCF sector. The inventory estimates are underpinned by the research and modelling by researchers at New Zealand's Crown research institutes and universities.
National trends in New Zealand's emissions and removals
The summary by gas and trend tables from the 2003 Common Reporting Format are provided in Annex 1 of this communication.
In 1990, New Zealand's total greenhouse gas emissions were equivalent to 61,525.43 Gg CO2. In 2003, total greenhouse gas emissions were 75,345.29 Gg CO2 equivalent [All emissions of non-carbon dioxide greenhouse gases are reported in this chapter as emissions of carbon dioxide equivalent using Global Warming Potentials (GWPs). GWPs represent the relative warming effect, or cumulative radiative forcing, of a unit mass of the gas when compared with the same mass of carbon dioxide over a specific period. The UNFCCC reporting requirements specify that the 100-year GWPs contained in the IPCC Second Assessment Report (IPCC, 1995) are to be used in national inventories.] equating to a 22.5 percent rise since 1990 (4NC Figure 13). Net removals of carbon dioxide through forest sinks increased from 21,366.19 Gg CO2 in 1990 to 22,861.60 Gg CO2 in 2003.
Fluctuations in the trend are largely driven by emissions from electricity generation. This category can show large year-to-year fluctuations because of the use of thermal stations to supplement the hydroelectric 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.
There have also been changes in the relative amounts of the different greenhouse gases emitted. Whereas methane and carbon dioxide contributed equally to New Zealand's emissions in 1990, carbon dioxide is now the major greenhouse gas in New Zealand's emissions profile (4NC Table 1). This is attributed to increased growth in the energy sector compared to the agriculture sector. However, the agriculture sector continues to dominate New Zealand's emissions profile in that 49.4 percent of total emissions in 2003 were produced by the agriculture sector (4NC Figure 14).
4NC Table 1: Emissions of greenhouse gases in 1990 and 2003
| Greenhouse Gas Emissions | Gg CO2 equivalent | Change from 1990 (percent) | |
|---|---|---|---|
| 1990 | 2003 | ||
Net CO2 emissions / removals |
3,944.36 |
11,833.84 |
200.02 |
CO2 emissions (without LULUCF) |
25,314.81 |
34,699.55 |
37.07 |
CH4 |
25,283.98 |
26,644.97 |
5.38 |
N2O |
10,398.71 |
13,499.53 |
29.82 |
HFCs |
0.00 |
403.96 |
NA |
PFCs |
515.60 |
84.90 |
-83.53 |
SF6 |
12.33 |
12.38 |
0.39 |
Total emissions without CO2 from LULUCF |
61,525.43 |
75,345.29 |
22.5 |
Source: Ministry for the Environment, 2005b
Source and sink category emission estimates and trends
Energy sector
The energy sector produced 32,320.92 Gg CO2 equivalent in 2003 and represented 42.9 percent of New Zealand's total greenhouse gas emissions. Emissions from the energy sector are now 37.0 percent above the 1990 baseline value of 23,594.11 Gg CO2 equivalent (4NC Figure 15). The sources contributing most to this increase since 1990 are emissions from road transportation (an increase of 58.4 percent) and public electricity and heat production (an increase of 83.3 percent). Emissions from transport contribute 43.3 percent of the energy sector's greenhouse gas emissions (4NC Figure 16). Greenhouse gas emissions from public electricity and heat generation are 19.8 percent of total energy greenhouse gas emissions. The large increase in emissions from electricity generation is because 2003 was a drier year than usual, resulting in less hydroelectric generation and a greater utilisation of coal-fired generation for 2003. Emissions from the manufacture of solid fuels and other energy industries sub-category have decreased by 80.6 percent from 1990, mainly due to the discontinuation of synthetic petrol production in 1997.
4NC Figure 16: Emissions from the energy sector: fuel combustion category in 2003 (all figures Gg CO2 equivalent)
Industrial processes sector
New Zealand's industrial processes sector totalled 4,014.19 Gg CO2 equivalent in 2003 and represented 5.3 percent of total greenhouse gas emissions. Emissions from industrial processes are now 25 percent above the 1990 baseline of 3,211.70 Gg CO2 equivalent (4NC Figure 17). The sector is dominated by emissions from the metal production category (carbon dioxide and perfluorocarbons) at 58.3 percent of sectoral emissions (4NC Figure 18).
Emissions from the metal production industry comprised 2,339.64 Gg CO2 equivalent in 2003 and have increased 1.5 percent from the 2,305.79 Gg CO2 equivalent recorded in 1990. Carbon dioxide emissions account for 96.6 percent of emissions in this category with another 3.4 percent from perfluorocarbons. In 2003, the level of carbon dioxide emissions has increased by 26.4 percent over the 1990 baseline. However, the level of perfluorocarbons has decreased from 515.60 Gg CO2 equivalent in 1990 to 84.90 Gg CO2 equivalent in 2003, a decrease of 83.5 percent. The decrease in perfluorocarbon emissions is because the sole aluminium smelter in New Zealand now has a low anode-effect duration by world standards.
There is no manufacturing of hydrofluorocarbons and perfluorocarbons in New Zealand. However, emissions of hydrofluorocarbons totalled 403.96 Gg CO2 equivalent in 2003 which is an increase of 382 percent from the 1995 level of 83.78 Gg CO2 equivalent. Emissions of sulphur hexafluoride (SF6), primarily used in electrical switchgear and transformers, have increased and from 12.33 Gg CO2 equivalent in 1990 to 12.38 Gg CO2 equivalent in 2003.
Solvent and other product use
Emissions from the solvents and other product use sector in 2003 comprised 31.61 Gg of non-methane volatile organic compounds. This is an increase of 30.4 percent from 24.24 Gg in 1990. The categories dominating the sector are non-methane volatile organic compounds emissions from paint application and other uses (4NC Figure 19).
4NC Figure: 19: Emissions of NMVOC from the solvent and other product use sector in 2003 (all figures Gg NMVOC)
In 2003, nitrous oxide (N2O) emissions from anaesthesia use totalled 0.16 Gg of nitrous oxide or 48.36 Gg CO2 equivalent. This is a 16.4 percent increase over the 1990 baseline.
Agriculture sector
The agriculture sector emissions totalled 37,203.24 Gg CO2 equivalent and represented 49.4 percent of all greenhouse gas emissions in 2003. Emissions in this sector are now 15.6 percent higher than the 1990 level of 32,193.76 Gg CO2 equivalent (4NC Figure 20). The increase is attributable to a 9.6 percent increase in methane (CH4) emissions from enteric fermentation and a 29.4 percent increase in nitrous oxide emissions (N2O) from the agricultural soils category.
Emissions of methane from enteric fermentation dominate the sector, producing 63.4 percent of carbon dioxide equivalent emissions in the sector (4NC Figure 21) and 31.3 percent of New Zealand's total emissions. Nitrous oxide emissions from agricultural soils are the other major component of the sector, comprising 34.9 percent of agricultural emissions.
Since 1984, there have been changes in the balance of livestock species. There has been a trend of increased dairy production and deer numbers for meat and velvet production due to the prevailing good world prices. This has been counterbalanced by land coming out of sheep production and consequently decreased sheep numbers. Beef numbers have remained relatively static. There have also been productivity increases across all major animal species and classes. At the same time there has been an expansion of the land used for plantation forestry. The land area used for horticulture has not changed significantly since 1990, although the types of produce grown have changed with less grain but more vegetables, fruit and grapes for wine production.
Land use, land-use change and forestry sector
The land use, land-use change and forestry (LULUCF) sector accounted for the removal of approximately 30.3 percent of New Zealand's total greenhouse gas emissions in 2003. Net removals from the LULUCF sector in 2003 (including emissions of methane and nitrous oxide) totalled 22,861.60 Gg CO2 equivalent and are 7.0 percent above net removals in 1990 (4NC Figure 22).
New Zealand has a substantial estate of planted forests, mainly comprising Pinus radiata, created specifically for timber-supply purposes, and has well-established data on this estate's extent and characteristics. These forests have removed and stored substantially more carbon dioxide over the period 1990 to 2003 than has been emitted through forest harvesting of both the combined planted and natural forests. The average new planting rate (land reforested or afforested) over the past 30 years has been, on average, 44,900 hectares per year. In the period 1992 to 1998, new planting rates were high (averaging 69,000 hectares per year). During the early 1990s, there had been a period of significant harvesting. Since 1998 the rate of new planting has declined and in 2003, 19,900 hectares of new forest were established. Between 1990 and 2003, it is estimated that 660,000 hectares of new forest had been established as a result of afforestation and reforestation activities.
A current lack of land use and land-use change data consistent with the IPCC land categories, and covering the period 1990 through to 2003, limits complete reporting in this sector. However, in its 2003 inventory, New Zealand improved the completeness of the LULUCF sector reporting by including an initial (Tier 1) estimate for all LULUCF land-use categories from 1997 to 2003. Previously, New Zealand had only included information on net changes in the living biomass from forestry land use and emissions and removals from the planting of forest on grassland.
Research is being conducted on the carbon pools and fluxes in New Zealand's soils and natural forests through the Carbon Monitoring System plots, and specific data for 1990 are being developed as part of the New Zealand Carbon Accounting System. The Carbon Monitoring System and the New Zealand Carbon Accounting System are described in Box 2. These additional data will enable New Zealand to report a complete time-series for all LULUCF categories.
Box 2: The New Zealand Carbon Monitoring and Accounting System
Major ongoing work in the land use, land-use change and forestry (LULUCF) sector includes research and implementing a monitoring system for the carbon stocks and fluxes in soils, shrublands and natural forests. Initiated by the Ministry for the Environment in 1996, this five-year monitoring research project had the following objectives:
- the estimation of carbon storage in soils, shrublands and natural forests in 1990
- the development of a national system to determine soil carbon changes associated with land-use change
- the development of an effective information system to manage the above information.
In 1999, the soil and vegetation carbon monitoring systems developed during the first three years of the project were reviewed by an international panel of forestry and soil experts. This review was held in time for the key recommendations of the review to be undertaken before the development phase was concluded.
The statistical design of the vegetation carbon monitoring system provides for the establishment of 1,400 permanent field plots on an 8-by-8 kilometre grid across natural forest and shrublands for territorial New Zealand. Using 20-metre by 20-metre plots, measurements are taken of aboveground biomass, such as tree heights and diameters, understorey vegetation, litter, and coarse woody debris. The soil carbon monitoring system analyses soil samples to a depth of 0.3 metres for carbon content. One in every three of the vegetation plots is sampled for soils to reduce the uncertainty in some soil cells.
The soil and vegetation carbon monitoring systems are being implemented. Fieldwork over at least two more years will be required to install the complete network of field plots. Another five-year round of sampling will be required to validate the implementation and begin monitoring of any changes. The current intention is then to repeat these measurements every 10 years.
For the soil carbon monitoring system, 40 soil-paired plots sites are also being established to monitor key changes in soil carbon when land-use changes; that is, scrub to grassland, grassland to Kyoto forest and vice versa.
The New Zealand Carbon Accounting System is being developed. This system will account for human-induced carbon sources and sinks from New Zealand's land use, land-use change and forestry (LULUCF) activities, and (a) is appropriate for annual UNFCCC greenhouse gas emission LULUCF sector reporting; (b) enables accounting and reporting under the Kyoto Protocol; and (c) underpins scenario development and modelling capabilities that support New Zealand's climate change policy development.
The most developed module of the New Zealand Carbon Accounting System is for natural forests and shrublands based on the carbon monitoring system plots. New Zealand's natural forests cover 6.4 million hectares, and are largely protected, often as national parks. New Zealand has not, until now, needed to establish a national forest inventory to cover its protected forests. This is in sharp contrast to the advanced system used for monitoring and forecasting future wood supply from its 1.8 million hectares of plantation forests.
A monitoring and modelling module is under development for those areas where afforestation and reforestation activities have occurred since 1990 ("Kyoto forests"). This will involve inventory measurements from permanent plots coupled with the use of existing allometric equations or forest volume and carbon models, or both.
Waste sector
The waste sector emissions totalled 1,754.48 Gg CO2 equivalent in 2003 and represented 2.3 percent of all greenhouse gas emissions. Emissions in 2003 are now 29.3 percent below the 1990 baseline value of 2,480.06 Gg CO2 equivalent (4NC Figure 23). The reduction has occurred in the "solid waste disposal on land" category, which has decreased by 34.5 percent as a result of initiatives to improve solid waste management practices in New Zealand.
Emissions from the waste sector are calculated in three components (4NC Figure 24): solid waste disposal on land, wastewater handling and waste incineration (not shown in the figure as emissions are negligible and not estimated).
