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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 61,852.8 Gg carbon dioxide equivalent (CO2-e). In 2007, total greenhouse gas emissions had increased by 13,697.4 Gg CO2-e (22.1 per cent) to 75,550.2 Gg CO2-e (Figure 2.1.1). Between 1990 and 2007, the average annual growth in overall emissions was 1.3 per cent per year.

New Zealand’s total emissions trend is different to many other countries. Instead of a predictable increase or decline in emissions, the trend for New Zealand consists of year-to-year fluctuations (Figure 2.1.1). These fluctuations are largely due to the change in proportion of non-renewable energy used in electricity and heat production affecting CO2 emissions (Figure 3.2.2). This is further explained in section 3.2.1.

Figure 2.1.1 New Zealand’s total greenhouse gas emissions from 1990 to 2007

Figure 2.1.1 New Zealand's total greenhouse gas emissions from 1990 to 2007

Year Gg CO2-equivalent
1990 61,852.8
1991 62,036.4
1992 63,219.6
1993 62,953.0
1994 64,117.1
1995 64,466.5
1996 66,030.3
1997 68,885.5
1998 66,970.2
1999 68,616.3
2000 70,597.7
2001 73,115.8
2002 73,452.4
2003 76,005.1
2004 75,054.0
2005 77,174.7
2006 77,599.1
2007 75,550.2

2.2 Emission trends by gas

Inventory reporting under the Climate Change Convention covers six direct greenhouse gases: CO2, methane (CH4), nitrous oxide (N2O), sulphur hexafluoride (SF6), perfluorocarbons (PFCs) and hydrofluorocarbons (HFCs). Figure 2.2.1 shows New Zealand’s 2007 profile by gas. Figure 2.2.3 shows the change in each direct greenhouse gas between 1990 and 2007. Trends in CO2, CH4 and N2O emissions over the period 1990–2007 are shown in Figure 2.2.3. In accordance with the Climate Change Convention reporting guidelines (UNFCCC, 2006), indirect greenhouse gases are included in inventory reporting but not in the national emissions total. These indirect gases include carbon monoxide (CO), sulphur dioxide (SO2), oxides of nitrogen (NOx), and non-methane volatile organic compounds (NMVOCs).

Removals of CO2 from the atmosphere are reported in the LULUCF sector.

Carbon dioxide contributed the largest share of all 2007 emissions at 35,231.5 Gg CO2-e (46.6 per cent). Carbon dioxide emissions increased 9,893.9 Gg CO2-e (39.1 per cent) from the 1990 level of 25,337.6 Gg CO2-e. Between 2006 and 2007, CO2 emissions decreased 1,012.9 Gg CO2-e (3.0 per cent). This was due to the commissioning of Genesis’s Energy combined gas turbine at Huntly leading to a corresponding reduction in coal-fired electricity generation.

Methane (excluding LULUCF) contributed 26,560.1 Gg CO2-e (35.2 per cent) of total emissions in 2007. Methane emissions grew by 1,131.6 Gg CO2-e (4.5 per cent) from the 1990 level of 25,428.5 Gg CO2-e. Between 2006 and 2007, CH4 emissions decreased 1,012.9 Gg CO2-e (2.8 per cent). This was due to a drought throughout the summer and autumn of 2007/2008. The drought affected many regions, leading to reduced livestock numbers and productivity. The reduction in livestock population, especially in sheep and deer, led to a 679.8 Gg CO2-e (2.7 per cent) decrease in CH4 emissions.

Nitrous oxide (excluding LULUCF) contributed 12,845.6 Gg CO2-e (17.0 per cent) of emissions in 2007. Emissions increased by 2,416.3 Gg CO2-e (23.2 per cent) from the 1990 level of 10,429.3 Gg CO2-e. Between, 2006 and 2007 emissions decreased 383.2 Gg CO2-e (2.9 per cent). This was due to the drought affecting livestock productivity. Nitrous oxide emission from the agriculture sector decreased 381.4 Gg CO2-e (3.0 per cent).

Perfluorocarbons, SF6 and HFCs contributed the remaining 913.0 Gg CO2-e (1.2 per cent) of emissions in 2007.

Emissions of PFCs have decreased 600.5 Gg CO2-e (93.5 per cent) from the 642.2 Gg CO2-e in 1990, to 41.7 Gg CO2-e in 2007.

Emissions of SF6 have decreased 0.5 Gg CO2-e (3.3 per cent), from the 1990 level of 15.2 Gg CO2-e to the 2007 level of 14.7 Gg CO2-e.

In 1990, no HFCs were used in New Zealand. In 2007, 856.6 Gg CO2-e of HFC emissions were produced.

The growth in CO2 emissions from 1990 and 2006 represented the increased emissions from the energy sector, particularly in road transport and energy generation. The growth in N2O is from the increase in emissions from animal excreta and the increase in the use of nitrogenous fertilisers in the agriculture sector. The amount of nitrogenous fertilisers used in New Zealand 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 large relative changes between 1990 and 2007. Emissions of PFCs have decreased due to improvements in the aluminium smelting process. Hydrofluorocarbon emissions have increased because of their use as a substitute for chlorofluorocarbons (CFCs) phased out under the Montreal Protocol. No emissions of HFCs occurred in 1990 therefore no percentage has been shown in Table 2.2.1 and Figure 2.2.1.

Table 2.2.1 New Zealand’s greenhouse gas emissions in 1990 and 2007

Greenhouse gas emissions Gg CO2-equivalent Change from 1990 (Gg CO2-equivalent) Change from 1990 (%)
1990 2007
CO2 (excluding LULUCF) 25,337.6 35,231.5 9,893.9 39.0
CH4 (excluding LULUCF) 25,428.5 26,560.1 1,131.6 4.6
N2O (excluding LULUCF) 10,429.3 12,845.6 2,416.3 23.2
HFCs 0.0 856.6 856.6 NA
PFCs 642.2 41.7 -600.5 -93.5
SF6 15.2 14.7 -0.5 -3.3
Total 61,852.8 75,550.2 13,697.4 22.1

Note: The per cent change for hydrofluorocarbons is not applicable (NA) as there was no production of hydrofluorocarbons in 1990.

Figure 2.2.1 New Zealand’s total greenhouse gas emissions by gas: 2007

Figure 2.2.1 New Zealand's total greenhouse gas emissions by gas: 2007

Gas Gg CO2-equivalent
CO2 35,231.5
CH4 26,560.1
N2O 12,845.6
HFCs, PFCs & SF6 913.0

Figure 2.2.2 Change in New Zealand’s emissions 1990 to 2007 by gas

Note: The per cent change for hydrofluorocarbons is not applicable (NA) as there was no production of hydrofluorocarbons in 1990.

Gas 1990
(Gg CO2-equivalent)
2007
(Gg CO2-equivalent)
CO2 25,337.6 35,231.5
CH4 25,478.5 26,560.1
N2O 10,429.3 12,845.6
HFC’s - 856.6
PFC’s 642.2 41.7
SF6 15.2 14.7

Figure 2.2.3 Change in New Zealand’s emissions of CO2, CH4, and N2O from 1990 to 2007

Year Absolute change in emissions from 1990 (Gg CO2-equivalent)
  CO2 (excluding LULUCF) CH4  (including LULUCF) N2O (including LULUCF)
1990 0.0 0.0 0.0
1991 542.8 -66.5 30.3
1992 2,379.2 -577.3 -81.5
1993 1,803.1 -401.8 148.4
1994 1,884.3 247.2 543.1
1995 1,872.0 290.7 802.0
1996 2,861.5 574.4 917.8
1997 5,153.2 1,120.7 1,118.4
1998 3,720.6 618.2 1,019.4
1999 4,987.2 838.2 1,223.0
2000 5,750.7 1,600.2 1,678.2
2001 7,663.4 1,731.8 2,103.2
2002 7,763.7 1,507.6 2,404.5
2003 9,568.2 1,758.0 2,726.2
2004 8,857.2 1,648.2 2,799.7
2005 10,514.8 1,802.8 2,916.9
2006 10,906.8 1,975.1 2,810.8
2007 9,893.9 1,143.8 2,427.6

2.3 Emission trends by source

The agriculture sector was the largest source of emissions, contributing 36,430.0 Gg CO2-e (48.2 per cent) of total emissions in 2007 (Table 2.3.1 and Figure 2.3.1). Consequently, New Zealand has a unique emissions profile. In other developed countries, agricultural emissions are typically around 11 per cent of national emissions. In 2007, New Zealand’s agricultural emissions had increased by 3,918.9 Gg CO2-e (12.1 per cent) from the 1990 level of 32,511.1 Gg CO2-e (Figure 2.3.2). The agriculture sector contributed 12,360.5 Gg CO2-e (96.2 per cent) of New Zealand’s total N2O emissions and 24,069.5 Gg CO2-e (90.6 per cent) of total CH4 emissions in 2007.

Between 2006 and 2007, emissions from the agriculture sector decreased 1,061.2 Gg CO2-e (2.8 per cent) (Figure 2.3.3). This was due to a drought throughout the summer and autumn of 2007/2008. The drought affected many regions, leading to reduced livestock numbers and productivity. The reduction in livestock population, especially in sheep and deer, led to a 679.8 Gg CO2-e (2.7 per cent) decrease in CH4 emissions. Decreases in livestock productivity led to a 3.0 per cent (381.4 Gg CO2-e) decrease in N2O emissions.

The energy sector was the source of 32,653.1 Gg CO2-e (43.2 per cent) of total emissions in 2007. In 2007, energy emissions had increased by 9,200.3 Gg CO2-e (39.2 per cent) from the 1990 level of 23,452.8 Gg CO2-e. This growth in emissions was primarily from electricity generation, heat production and transport.

Between 2006 and 2007, emissions from the energy sector decreased 1,357.5 Gg CO2-e (4.0 per cent). This was due to the commissioning of Genesis Energy’s combined cycle gas turbine at Huntly and the corresponding reduction in coal-fired electricity generation.

The industrial processes sector accounted for 4,601.9 Gg CO2-e (6.1 per cent) of total emissions in 2007. Emissions from the industrial processes sector had increased 1,192.7 Gg CO2-e (35.0 per cent) from the 1990 level of 3,409.2 Gg CO2-e. This increase is mainly due to growth in emissions from metal production and due to the consumption of hydrofluorocarbons.

Between 2006 and 2007, emissions from the industrial processes sector increased by 368.1 Gg CO2-e (8.7 per cent). This was caused by two factors. Firstly, there was an increase in HFCs and PFCs used as replacement refrigerants for CFCs and HCFCs, in refrigeration and air-conditioning equipment. Secondly, one cement company was running at full production in 2007.

In 2007, the solvent and other product use sector was a minor contributor to New Zealand’s total greenhouse gas emissions. It was responsible for 43.4 Gg CO2-e (less than 1 per cent) of total emissions in 2007.

The waste sector accounted for 1,821.8 Gg CO2-e (2.4 per cent) of total emissions in 2007. Emissions from the waste sector had decreased by 616.4 Gg CO2-e (25.3 per cent) from the 1990 level of 2,438.2 Gg CO2-e. This decrease is due to initiatives to improve solid waste management practices in New Zealand.

Under the LULUCF sector, net removals were estimated to be 23,836.0 Gg CO2-e in 2007. LULUCF removals had increased by 5,697.5 Gg CO2-e (31.4 per cent) from the 1990 level of 18,138.5 Gg CO2-e. LULUCF removals fluctuate with the planting and harvesting of New Zealand’s planted forest.

Table 2.3.1 New Zealand’s sectoral emissions of greenhouse gases in 1990 and 2007

Sector Gg CO2-equivalent Change from 1990 (Gg CO2-equivalent) Change from 1990 (%)
1990 2007
Energy 23,452.8 32,653.1 9,200.3 39.2
Industrial processes 3,409.2 4,601.9 1,192.7 35.0
Solvent and other product use 41.5 43.4 1.9 4.5
Agriculture 32,511.1 36,430.0 3,918.9 12.1
Waste 2,438.2 1,821.8 –616.4 –25.3
Total (excluding LULUCF) 61,852.8 75,550.2 13,697.4 22.1
LULUCF (including CH4 & N2O) –18,138.5 –23,836.0 –5,697.5 31.4
Net Total (including LULUCF) 43,714.3 51,714.2 7,999.9 18.3

Figure 2.3.1 New Zealand’s total greenhouse gas emissions by sector: 2007

Figure 2.3.1 New Zealand's total greenhouse gas emissions by sector: 2007

Note: The Industrial processes emissions shown here, includes emissions from the solvents and other product use sector.

Sector Gg CO2-e
Energy 32,653.1
Industrial processes 4,601.9
Solvent and other product 43.4
Agriculture 36,430.0
Land-use change and forestry -23,836.0
Waste 1,821.8

Figure 2.3.2 Change in New Zealand’s sectoral greenhouse gas emissions from 1990 to 2007

Figure 2.3.2 Change in New Zealand's sectoral greenhouse gas emissions from 1990 to 2007

Sector 1990
(Gg CO2-equivalent)
2007
(Gg CO2-equivalent)
Energy 23,452.8 32,653.1
Industrial processes 3,409.2 4,601.9
Solvents and other product use 41.5 43.4
Waste 2,438.2 1,821.8
Agriculture 32,511.1 36,430.0

Figure 2.3.3 Change in New Zealand’s sectoral greenhouse gas emissions from 1990 to 2007

Figure 2.3.3 Change in New Zealand's sectoral greenhouse gas emissions from 1990 to 2007

Year Absolute change in emissions from 1990 (Gg CO2 equivalent)
  Total emissions Energy Industrial Processes Solvents Agriculture Waste
1990 0.0 0.0 0.0 0.0 0.0 0.0
1991 183.5 298.0 -173.5 1.2 23.0 34.7
1992 1,366.8 2,012.3 -80.8 1.6 -567.9 1.6
1993 1,100.2 1,356.5 -104.3 2.2 -179.6 25.4
1994 2,264.2 1,614.1 -163.0 2.8 799.3 11.1
1995 2,613.6 1,589.9 -19.0 3.4 1,217.8 -178.5
1996 4,177.5 2,622.4 147.7 4.3 1,558.9 -155.9
1997 7,032.6 5,024.6 -101.1 4.7 2,269.4 -164.8
1998 5,117.4 3,574.6 107.9 5.0 1,660.0 -230.1
1999 6,763.5 4,708.0 269.5 5.3 2,149.7 -369.0
2000 8,744.8 5,534.4 238.8 5.6 3,324.9 -358.8
2001 11,263.0 7,403.0 368.1 5.9 3,892.8 -406.8
2002 11,599.6 7,498.6 541.9 14.6 3,998.3 -453.7
2003 14,152.2 9,097.2 878.4 10.9 4,625.1 -459.3
2004 13,201.1 8,392.4 643.6 6.8 4,677.7 -519.3
2005 15,321.9 10,026.2 857.7 2.8 5,008.0 -572.8
2006 15,746.3 10,557.8 824.5 -1.2 4,980.1 -614.9
2007 13,697.3 9,200.3 1,192.7 1.9 3,918.9 -616.4

2.4 Emission trends for indirect greenhouse gases and SO2

The indirect greenhouse gas emissions SO2, CO, NOx and NMVOC are also reported in the inventory. Emissions of these gases in 1990 and 2007 are shown in Table 2.4.1. There were increases in the emissions of all of these gases. Indirect greenhouse gases do not account towards New Zealand’s greenhouse gas emissions total.

Table 2.4.1 New Zealand’s emissions of indirect greenhouse gases in 1990 and 2007

Gas Gg of gas(es) Change from 1990 (Gg) Change from 1990 (%)
1990 2007
NOx 108.2 158.8 50.6 46.8
CO 561.4 738.0 176.6 31.4
NMVOC 132.1 174.4 42.3 32.0
SO2 53.5 72.7 19.2 35.9
Total 855.2 1,143.9 288.7 33.8

Emissions of CO and NOx are largely from the energy sector. The energy sector produced 89.2 per cent of total CO emissions in 2007. The largest single source of CO emissions was from the road transportation subcategory. Similarly, the energy sector was the largest source of NOx emissions (97.9 per cent), with the road transportation subcategory dominating. Other large sources of NOx emissions were from the manufacturing industries, construction and energy industries subcategories.

The energy sector was also the largest producer of NMVOCs, producing 71.8 per cent of NMVOC emissions in 2007. Emissions from road transportation comprised 61.9 per cent of total NMVOC emissions. Other major sources of NMVOC were in the solvent and other product use sector (19.8 per cent) and the industrial processes sector (8.4 per cent).

In 2007, emissions of SO2 from the energy sector comprised 84.0 per cent of total SO2 emissions. The energy industries category contributed 18.7 per cent, manufacturing industries and construction, 29.8 per cent, and the transport category, 17.7 per cent, of total SO2 emissions. The industrial processes sector contributed 16.0 per cent of SO2. Aluminium production accounted for 9.7 per cent of SO2 emissions.