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You are here: The issues Contains: Climate change Contains: New Zealand’s greenhouse gas emissions Contains:

New Zealand’s greenhouse gas inventory 1990-2005

New Zealand’s Greenhouse Gas Inventory 1990-2005 was submitted on 4 May 2007 to the United Nations Framework on Climate Change Convention (UNFCCC). The inventory is compiled annually by the Ministry with input from relevant agencies as a requirement of the UNFCCC and the Kyoto Protocol.

The inventory collects information on man-made (anthropogenic) greenhouse gas emissions to provide a snapshot of New Zealand’s emissions.  The inventory reports greenhouse gas emissions from six sectors: energy, industrial processes, solvents, agriculture, land-use change and forestry, and waste for the years 1990-2005.

As well as the current emissions and removals (eg, forest sinks), the inventory records how emissions are changing by showing the trends from 1990. Carbon dioxide (CO2), methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulphur hexafluoride are included in New Zealand's total greenhouse gas figures.

There is a time lag in getting all the data together and analysing it. This means the data published in any given year is 15 months behind (ie, the 2005 inventory published in 2007 is for data from 1990 to end of 2005).

2005 data

The following is a summary of New Zealand’s emissions from the 1990-2005 inventory:

  1. Total greenhouse gas emissions in 2005 were 77.2 million tonnes of carbon dioxide equivalents (Mt CO2-e). Total emissions have increased 24.7 per cent (15.3 Mt CO2-e) over the 1990 levels (refer Figure 1).
  2. There have been changes in the relative amounts of the different greenhouse gases emitted. In 1990 CH4 and CO2 contributed equally to New Zealand’s emissions. In 2005, CO2 was the major greenhouse gas in New Zealand’s emissions profile. This is caused by increased growth in the energy sector compared to the agriculture sector.
  3. In 2005 the agriculture sector contributed 48.5 per cent to the total emissions. The energy sector contributed 43.4 per cent. The balance of emissions was made up by industrial processes (5.6 per cent), waste (2.4 per cent) and solvents (0.1 per cent).
  4. The largest single source of emissions in 2005 was from methane from enteric fermentation of ruminant animals (31.0 per cent of the total emissions). Carbon dioxide from road transport was the next biggest source contributing 16.4 per cent of total emissions (total transport is 18.4 per cent of total emissions).
  5. Emissions from the waste sector have decreased 25.9 per cent (a 0.6 Mt CO2-e reduction).
  6. Net removals of CO2 through forest sinks increased from 18,980.6 Gg CO2 in 1990 to 24,500.8 Gg CO2 in 2005.
  7. The increase in emissions from 2004 to 2005 is the result of the change in proportion of fossil fuels used in electricity generation each year. In a low-rainfall year the level of the hydro lakes is below average which in turn reduces hydro electricity supply. This requires more fossil fuel-based thermal generation to ensure security of supply. As a result greenhouse gas emissions from electricity generation rise. This was the case in 2005.
  8. The peak and trough pattern of emissions resulting from electricity production due to the availability of hydro electricity generation will remain a feature of New Zealand’s greenhouse gas profile
  9. The variation in emissions from year to year is clearly shown in Figure 1. The annual average growth in emissions is 1.4 per cent. 

Figure 1: Trend in New Zealand’s total greenhouse gas emissions for different sectors from 1990 to 2005

See figure at its full size (including the text description).

Some key greenhouse gas increases are in the following areas:

  • Emissions from enteric fermentation in dairy cattle have increased 70.5 per cent (3.5 Mt CO2-e) since 1990 due to the rapid expansion of dairy farming in New Zealand. These emissions result from fermentation that takes place in the digestive systems of ruminant animals such as cattle.
  • Emissions from nitrogen fertiliser use have increased 500 per cent (1.3 Mt CO2-e) since 1990. The increase in dairy farming and increased dairy stocking rates has lead to an increase in nitrogen-based fertiliser application.
  • Within the road transport category emissions from diesel combustion have significantly increased by 236 per cent (3.7 Mt CO2-e) since 1990.
  • By comparison, emissions from petrol have increased 27.4 per cent (1.6 Mt CO2-e) since 1990.