New Zealand’s greenhouse gas emissions

  • Image, NZ greenhouse gas emissions.

    Greenhouse gases (GHGs) absorb heat from Earth’s surface, warming the atmosphere and changing our climate. New Zealand’s share of GHG emissions is very small, but our gross emissions per person are high. Emissions mainly come from combustion of fossil fuels that emit carbon dioxide (CO2), and agriculture which emits methane (CH4) and nitrous oxide (N2O). Carbon dioxide remains in the atmosphere much longer than other major GHGs. Because of this, today’s global CO2 emissions will continue to influence atmospheric CO2 concentrations for a very long time. Methane and N2O trap heat better than CO2 but leave the atmosphere faster. Reducing emissions of CH4 and N2O will decrease concentrations in the atmosphere more quickly.

    We classified New Zealand’s greenhouse gas emissions as national indicator.

    Key findings

    Image, Increasing trend.    Increasing trend

    New Zealand’s gross GHG emissions increased 24 percent from 1990 to 2015 but 2015 emissions were lower than the highest emissions, which occurred in 2006. This trend was assessed at the 95 percent confidence level. Our net GHG emissions increased 64 percent from 1990 to 2015 due to reduced uptake of CO2 from forests. In 2015, gross GHG emissions were almost equally made up of long-lived CO2 – 45 percent of total GHG emissions and non-CO2 (CH4 and N2O – 53 percent of total GHG emissions) gases.

    • In 2015, the energy sector produced 87 percent of all CO2 emissions.
      • Road vehicle emissions were up 80 percent from 1990, and made up 37 percent of all CO2 emissions in 2015.

      • Manufacturing and construction emissions were up 43 percent from 1990, and made up 19 percent of all CO2 emissions in 2015.

      • Electricity generation and heating made up only 11 percent of all CO2 emissions in 2015. This contrasts with most countries where electricity generation is the main source of CO2.

    • CH4 from livestock digestion increased 5 percent from 1990 and made up 35 percent of all emissions in 2015. This was 82 percent of all CH4 emissions and 73 percent of all agricultural emissions.
    • Of all N2O emissions, 94 percent came from agricultural soils in 2015, mainly due to nitrogen fertiliser. Overall, N2O emissions increased 48 percent from 1990 and now make up 21 percent of all agricultural emissions to 2015.
    • Net uptake of CO2 from the atmosphere by land use, land use change, and forestry decreased 21 percent from 1990 to 2015 due to higher harvesting rates of planted forests.

    Figure 1

    Note: LULUCF – land use, land-use change, and forestry. Greenhouse gas emissions are in kilotonnes of CO2 equivalent (kt CO2-e).

    Figure 2

    Graph, New Zealand's greenhouse gas emissions by sector, 2015.

    Note: Greenhouse gas emissions are in kilotonnes of CO2 equivalent (kt CO2-e).

    Figure 3

    Graph, New Zealand's gross carbon dioxide emissions by sector, 2015.

    Note: Energy sector is broken down by subcategory. Greenhouse gas emissions are in kilotonnes of CO2 equivalent (kt CO2-e). Emissions by waste are 1.21 kt CO2-e.

    Figure 4

    Note: Greenhouse gas emissions are in kilotonnes of CO2 equivalent (kt CO2-e).

    Definition and methodology

    New Zealand’s greenhouse gas (GHG) emissions indicator measures gases that are added to the atmosphere through human activities. It does not include natural sources such as biological processes or volcanic emissions.

    We obtained emissions data from New Zealand’s greenhouse gas inventory, which is produced by the Ministry for the Environment as part of New Zealand’s reporting obligation under the United Nations Framework Convention on Climate Change and the Kyoto Protocol (Ministry for the Environment, 2017). However, the data are not the same as those used to show New Zealand’s contribution to global GHG emissions, which are produced using the World Resources Institute’s Climate Analysis lndicators Tool 2.0.

    The inventory reports on four GHGs (or, in the case of F-gases, groups of GHGs) because of their ability to absorb heat and their relatively long residence time in the atmosphere.

    • Carbon dioxide (CO2) is added to the atmosphere primarily through the combustion of fossil fuels (coal, oil, and gas), and from some chemical reactions, such as the production of cement. Once emitted, a fraction of it can remain in the atmosphere for thousands of years (Archer et al, 2009). It is removed from the atmosphere primarily through biomass production from photosynthesis and dissolution in the oceans.
    • Methane (CH4) is emitted by livestock and the decomposition of organic matter (such as in landfills) as well as during the production and transportation of coal and natural gas. Over a span of 100 years it is 25 times more effective than CO2 at trapping heat, despite its average lifetime in the atmosphere of about 12 years.
    • Nitrous oxide (N2O) is emitted primarily from agriculture, but also industrial processes and fossil fuel combustion. Over a span of 100 years it is 298 times more effective than CO2 at trapping heat, and has an average atmospheric lifetime of 114 years.
    • Fluorinated gases (F-gases) are very strong human-made GHGs used in products such as refrigerators and air conditioners. Emissions to the atmosphere come during production and through losses during product use. Their average lifetimes in the atmosphere vary from days to 50,000 years.

    Gross emissions include emissions from agriculture, energy, industrial processes and product use, and waste. Net emissions also include emissions and removals from land use, land-use change, and forestry. GHG global warming potentials and lifetimes are obtained from the IPCC Fourth Assessment Report (IPCC, 2007), consistent with Ministry for the Environment GHG emissions inventory reports. However, updated values are available in the 2014 IPCC report.

    Data quality

    We classified New Zealand’s greenhouse gas emissions as national indicator.

    Relevance

     Image, Direct relevance.  This national indicator is a direct measure of the ‘human activities generating greenhouse gases’ topic.

    Accuracy

       The accuracy of the data source is of high quality.

    See Data quality information for more detail.

    References

    Archer, D, Eby, M, Brovkin, V, Ridgwell, A, Cao, L, Mikolajewicz, U,… Tokos, K (2009). Atmospheric lifetime of fossil fuel carbon dioxide. Annual Review of Earth and Planetary Science, 37, 117–134.

    Intergovernmental Panel on Climate Change (IPCC) (2007). Climate change 2007: The physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S, Qin, D, Manning, M, Chen, Z, Marquis, M, Averyt, KB, Tignor, M, & Miller, HL (Eds)]. Cambridge and New York: Cambridge University Press.

    Ministry for the Environment (2017). New Zealand’s greenhouse gas inventory 1990–2015. Available from www.mfe.govt.nz

    Archived pages

    See New Zealand’s greenhouse gas emissions (archived October 2017).

    Updated 19 October 2017

Top
  • Share this page
  • Share this page to Facebook
  • Share this page to Twitter
  • Share this page to Google+