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Annex 1: Key categories

A1.1 Methodology used for identifying key categories

The key categories in the New Zealand inventory have been assessed according to the methodologies provided in good practice guidance (IPCC, 2000). The methodology applied was determined using the decision tree shown in Figure A1.1.

Figure A1.1 Decision tree to identify key source categories (Figure 7.1 (IPCC, 2000))

Figure A1.1 Decision tree to identify key source categories (Figure 7.1 (IPCC, 2000))

Question. Are inventory data available for more than one year?
No - Parties should determine key source categories using the Tier 1 Level assessment and qualitative assessment.
Yes - Question: Are country-specific uncertainty estimates available for each source category estimate?
No - Parties should determine key source categories using the Tier 1 Level assessment, trend assessment and qualitative assessment.
Yes - Determine key source categories using the Tier 2 level and trend assessment, incorporating national uncertainty estimates and evaluating qualitative criteria.

For this inventory submission, the Tier 1 level and trend assessment were applied, including the LULUCF sector and excluding the LULUCF sector (IPCC 2000, 2003). The “including LULUCF” level and trend assessments are calculated as per equations 5.4.1 and 5.4.2 of GPG-LULUCF. The “excluding LULUCF” level and trend assessments are calculated as per equations 7.1 and 7.2 of good practice guidance (IPCC, 2000). Key categories are defined as those categories whose cumulative percentages, when summed in decreasing order of magnitude, contributed 95 per cent of the total level or trend.

A1.2 Disaggregation

The classification of categories follows the classification outlined in Table 7.1 of good practice guidance (IPCC, 2000) by:

  • identifying categories at the level of IPCC categories using CO2 equivalent emissions and considering each greenhouse gas from each category separately

  • aggregating categories that use the same emission factors

  • including LULUCF categories at the level shown in GPG-ULUCF Table 5.4.1.

There was one modification to the suggested categories to reflect New Zealand’s national circumstances. The fugitive emissions from the oil and natural gas category – was divided into two categories: fugitive emissions from oil and gas operations and fugitive emissions from geothermal operations. This is to reflect that New Zealand generates a significant amount of energy from geothermal sources that cannot be included as oil or gas operations.

A1.3 Tables 7.A1–7.A3 of the IPCC Good Practice Guidance

Table A1.1 Results of the key category level analysis for 99 per cent of the total emissions and removals for New Zealand in 2007. Key categories are those that comprise 95 per cent of the total.

(a) Tier 1 Category Level Assessment - including LULUCF
IPCC Categories Gas 2007 estimate 
(Gg CO2-e)
Level assessment Cumulative total
Emissions from enteric fermentation in domestic livestock CH4 23326.38 23.0 23.0
Conversion to forest land CO2 15253.73 15.0 38.0
Mobile combustion – road vehicles CO2 13281.35 13.1 51.1
Forest land remaining forest land CO2 9311.50 9.2 60.3
Emissions from stationary combustion – gas CO2 8723.65 8.6 68.9
Emissions from agricultural soils – animal production N2O 7346.67 7.2 76.1
Emissions from stationary combustion – solid CO2 4473.87 4.4 80.5
Indirect emissions from nitrogen used in agriculture  N2O 3270.66 3.2 83.8
Emissions from stationary combustion – liquid CO2 2644.94 2.6 86.4
Direct emissions from agricultural soils N2O 1680.74 1.7 88.0
Emissions from the iron and steel industry CO2 1646.24 1.6 89.7
Emissions from solid waste disposal sites CH4 1437.95 1.4 91.1
Mobile combustion – aviation CO2 915.10 0.9 92.0
Consumption of halocarbons and SF6 – refrigeration and air conditioning HFCs & PFCs 779.64 0.8 92.7
Fugitive emissions from oil and gas operations CO2 754.57 0.7 93.5
Emissions from manure management CH4 729.10 0.7 94.2
Emissions from cement production CO2 687.90 0.7 94.9
 
Cropland remaining cropland CO2 649.67 0.6 95.5
Emissions from aluminium production CO2 579.05 0.6 96.1
Conversion to grassland CO2 436.83 0.4 96.5
Fugitive emissions from oil and gas operations CH4 378.72 0.4 96.9
Fugitive emissions from geothermal operations CO2 301.47 0.3 97.2
Mobile combustion – marine CO2 300.11 0.3 97.5
Fugitive emissions from coal mining and handling CH4 261.83 0.3 97.7
Emissions from hydrogen production CO2 224.90 0.2 98.0
Emissions from wastewater handling CH4 202.49 0.2 98.2
Emissions from wastewater handling N2O 179.19 0.2 98.3
Emissions from ammonia/urea production CO2 360.06 0.4 98.7
Mobile combustion – rail CO2 164.88 0.2 98.9
Mobile combustion – road vehicles N2O 147.48 0.1 99.0

 

Table A1.2 Results of the key category level analysis for 99 per cent of the total emissions and removals for New Zealand in 1990. Key categories are those that comprise 95 per cent of the total.

(a) Tier 1 Category Level Assessment - including LULUCF
IPCC Categories Gas Base year estimate 
(Gg CO2-e)
Level assessment Cumulative total
Emissions from enteric fermentation in domestic livestock CH4 21818.97 26.6 26.6
Conversion to forest land CO2 13059.41 15.9 42.5
Emissions from stationary combustion – gas CO2 7691.22 9.4 51.9
Mobile combustion – road vehicles CO2 7516.28 9.2 61.0
Emissions from agricultural soils – animal production N2O 6853.06 8.3 69.4
Forest land remaining forest land CO2 5614.43 6.8 76.2
Emissions from stationary combustion – solid CO2 3139.65 3.8 80.0
Indirect emissions from nitrogen used in agriculture  N2O 2703.13 3.3 83.3
Emissions from stationary combustion – liquid CO2 2505.28 3.1 86.4
Emissions from solid waste disposal sites CH4 2063.21 2.5 88.9
Emissions from the iron and steel industry CO2 1310.88 1.6 90.5
Mobile combustion – aviation CO2 771.68 0.9 91.4
PFCs from aluminium production PFCs 642.22 0.8 92.2
Emissions from manure management CH4 578.70 0.7 92.9
Cropland remaining cropland CO2 515.64 0.6 93.5
Direct emissions from agricultural soils N2O 487.19 0.6 94.1
Conversion to grassland CO2 482.70 0.6 94.7
Emissions from aluminium production CO2 443.27 0.5 95.3
 
Emissions from cement production CO2 441.67 0.5 95.8
Fugitive emissions from geothermal operations CO2 376.16 0.5 96.3
Grassland remaining grassland CO2 350.80 0.4 96.7
Fugitive emissions from coal mining and handling CH4 272.13 0.3 97.0
Fugitive emissions from oil and gas operations CO2 263.75 0.3 97.3
Fugitive emissions from oil and gas operations CH4 262.63 0.3 97.7
Mobile combustion – marine CO2 244.24 0.3 98.0
Emissions from wastewater handling CH4 206.95 0.3 98.2
Emissions from wastewater handling N2O 153.47 0.2 98.4
Emissions from hydrogen production CO2 152.29 0.2 98.6
Emissions from ammonia/urea production CO2 277.67 0.3 98.9
Conversion to settlement CO2 97.16 0.1 99.0

 

Table A1.3 Results of the key category trend analysis for 99 per cent of the total emissions and removals for New Zealand in 2007. Key categories are those that comprise 95 per cent of the total.

(a) Tier 1 Category Trend Assessment - including LULUCF
IPCC Categories Gas Base year estimate 
(Gg CO2-e)
2007 estimate 
(Gg CO2-e)
Trend assessment Contribution to trend Cumulative total
Mobile combustion – road vehicles CO2 7516.28 13281.35 0.032 20.5 20.5
Emissions from enteric fermentation in domestic livestock CH4 21818.97 23326.38 0.029 18.7 39.1
Forest land remaining forest land CO2 5614.43 9311.50 0.019 12.2 51.3
Emissions from agricultural soils – animal production N2O 6853.06 7346.67 0.009 5.8 57.0
Emissions from solid waste disposal sites CH4 2063.21 1437.95 0.009 5.7 62.7
Direct emissions from agricultural soils N2O 487.19 1680.74 0.009 5.5 68.3
Conversion to forest land CO2 13059.41 15253.73 0.007 4.5 72.8
Emissions from stationary combustion - gas CO2 7691.22 8723.65 0.006 4.0 76.8
Consumption of halocarbons and SF6 – refrigeration and air conditioning HFCs & PFCs 0.00 779.64 0.006 4.0 80.8
PFCs from aluminium production PFCs 642.22 40.27 0.006 3.9 84.7
Emissions from stationary combustion – solid CO2 3139.65 4473.87 0.005 3.0 87.7
Emissions from stationary combustion – liquid CO2 2505.28 2644.94 0.004 2.3 90.0
Fugitive emissions from oil and gas operations CO2 263.75 754.57 0.003 2.2 92.2
Fugitive emissions from geothermal operations CO2 376.16 301.47 0.001 0.8 93.1
Conversion to grassland CO2 482.70 436.83 0.001 0.8 93.9
Emissions from cement production CO2 441.67 687.90 0.001 0.7 94.6
Conversion to cropland CO2 37.35 128.68 0.001 0.4 95.0
 
Consumption of halocarbons and SF6 – aerosols and metered dose inhalers HFCs & PFCs 0.00 75.57 0.001 0.4 95.4
Fugitive emissions from coal mining and handling CH4 272.13 261.83 0.001 0.4 95.8
Indirect emissions from nitrogen used in agriculture  N2O 2703.13 3270.66 0.001 0.4 96.2
Mobile combustion – road vehicles N2O 64.49 147.48 0.001 0.3 96.5
Mobile combustion – rail CO2 84.76 164.88 0.000 0.3 96.8
Fugitive emissions from oil and gas operations CH4 262.63 378.72 0.000 0.3 97.1
Emissions from wastewater handling CH4 206.95 202.49 0.000 0.3 97.4
Mobile combustion – aviation CO2 771.68 915.10 0.000 0.2 97.6
Emissions from hydrogen production CO2 152.29 224.90 0.000 0.2 97.8
Mobile combustion – road vehicles CH4 69.10 53.91 0.000 0.2 97.9
Emissions from aluminium production CO2 443.27 579.05 0.000 0.2 98.1
Emissions from the iron and steel industry CO2 1310.88 1646.24 0.000 0.1 98.2
Emissions from lime production CO2 81.62 124.26 0.000 0.1 98.3
Conversion to settlement CO2 97.16 97.16 0.000 0.1 98.4
Emissions from limestone & dolomite use CO2 18.53 43.73 0.000 0.1 98.6
Emissions from ammonia/urea production CO2 277.67 360.06 0.000 0.1 98.6
Non–CO2 emissions from stationary combustion N2O 68.83 100.74 0.000 0.1 98.7
Emissions from waste incineration CO2 12.91 0.93 0.000 0.1 98.8
Emissions from manure management CH4 578.70 729.10 0.000 0.1 98.9
Emissions from agricultural residue burning CH4 21.38 13.16 0.000 0.1 98.9
Forest land remaining forest land CH4 16.02 32.57 0.000 0.1 99.0