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• Table 1.1: Sources of Natural and Anthropogenic Methane and Nitrous oxide
• References

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Chapter 1 - Introduction

Methane and nitrous oxide play an important role in the radiative balance of the atmosphere, and are particularly significant because their global warming potentials (GWP) are greater than that of carbon dioxide: methane GWP=21, nitrous oxide GWP=310 (FCCC, 1999). The Intergovernmental Panel on Climate Change (IPCC) has revised the GWP values slightly (methane GWP=23 and nitrous oxide=296), but these figures do not have to be used until the second commitment period.

While natural sources of methane and nitrous oxide are important contributors to the total emission load, the anthropogenic sources have increased sharply over the last two centuries and these are the concern of the United Nations Framework Convention on Climate Change (UNFCCC). IPCC estimates of sources are summarised in Table 1.1.

Table 1.1: Sources of Natural and Anthropogenic Methane and Nitrous oxide

Source	Methane (million tonnes per year)	Nitrous oxide (million tonnes N per year)
Natural (oceans, wetlands, soils etc)	110-210	9.0 (4.3-14.7)
Anthropogenic: Fossil fuel related Biosphere related	70-120 200-350	7.2 (2.1-19.7) 1.3 (0.7-1.8) 3.7-7.7?

Source: IPCC, 1996

New Zealand is not a major contributor of greenhouse gas emissions in the world, but its emissions are significant for the following reasons.

1. Methane and nitrous oxide are dominant in the national emissions profile, i.e. 59.5% of total emissions on a carbon dioxide equivalent basis (National Inventory)_.
2. The principal sources of methane and nitrous oxide are from pastoral agricultural lands and the animals that graze on them (55% of total emissions in 2000).
3. The gross levels of New Zealand's emissions (ignoring sinks) are steadily increasing and will exceed the 1990 levels by 50-75 000 000 tonnes carbon dioxide equivalent in the first commitment period on a `business-as-usual' basis (Ministry for the Environment).
4. The New Zealand government has decided to ratify the Kyoto Protocol. The government is determined to show leadership and control emissions consistent with its obligations under the Protocol.
5. Responsible management of its environment is part of the protection of New Zealand's `clean green' image on which the marketing of many of our exports depends.

The way to implementation of the decision to ratify the Protocol has been paved by the passage of the Climate Change Response Bill and decisions on policies related to meeting the nation's obligations under the Protocol. A statement of the government's policy and a National Interest Analysis can be found on the New Zealand Climate Change Project's website (www.climatechange.govt.nz).

In its development of policies, the government has adopted four guiding principles to meet the national goal of a significant reduction in greenhouse gas emissions by 2012 and a permanent downward track in the amounts produced.

1. They must result in permanent reductions in worldwide emissions over the long-term.
2. They need to be responsive to a changing international context.
3. They need to be consistent with a growing and sustainable economy.
4. They need to be designed so as not to disadvantage the vulnerable in our society.

Of particular significance are the decisions that relate to agriculture, and to the management of emissions from the agricultural sector, since these emissions represent about 55% of New Zealand's total greenhouse gas emissions.

Government's policy for agriculture is to exempt the sector from any charge for methane and nitrous oxide emissions arising from enteric fermentation or agricultural soils for at least the first commitment period (2008-2012). However, it expects that the agricultural industries will make a contribution to research during the period (and beyond) leading to developing technologies and systems that result in a permanent reduction in such emissions from the sector. This policy recognises that not only do commercial farms fall into the `competitiveness-at-risk' group of enterprises, but at present farmers have no effective means of reducing methane and nitrous oxide emissions in a meaningful way except by reducing numbers. Measurement of emissions from agricultural land and farm animals is also technically dificult and subject to uncertainty.

The Convenor of the Ministerial Group on Climate Change, the Minister of Agriculture, and the Primary Industries Council commissioned this review of recent and current research on abatement of agricultural non-carbon dioxide greenhouse gas emissions with a view to identifying the most pressing information needs and the most promising emission abatement options that warrant further research. It is anticipated that the review will be a platform for a research strategy to be pursued through a joint government/industry funded programme.

References

FCCC/CP/7 (1999): Review of the Implementation of Commitments and other Provisions of the Convention. UNFCCC Guidelines on Reporting and Review. UNFCCC, Secretariat IPCC.

IPCC (Intergovernmental Panel on Climate Change) (1996): Climate Change 1995. Impacts, Adaptations and Mitigation of Climate Change: Scientific-Technical Analyses. (Eds) Watson RT, Zinyowera MC, Moss RH. Cambridge University Press, Cambridge. 878p.

Ministry for the Environment (2001): National Communication 2001. Wellington, New Zealand.

New Zealand Climate Change Project (2002): National Inventory Report for New Zealand 1999-2000.Wellington, New Zealand. (http://www.climatechange.govt.nz )

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