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Chapter 1: Introduction

1.1 Background

Greenhouse gases present in the Earth’s atmosphere trap the warmth from the sun, keeping temperatures stable and preventing all the Earth’s warmth from radiating away into space. Without these gases, Earth would be too cold to support life as we know it. We call these gases, primarily water vapour, carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), greenhouse gases because they act like the glass in a greenhouse. Until recently the greenhouse has existed in a state of natural balance, with the heat gained from the sun being matched by the heat lost by radiation back out to space. Although there have been climatic changes in the past, there have been no significant climatic changes since the start of human civilisation 10,000 years ago. Earlier changes have been either gradual, occurring over tens or hundreds of thousands of years, or when not gradual (when caused for example by major meteorite impacts) have extinguished much of the life on Earth.

In the past 50 to 100 years, human activity has changed markedly and rapidly. These changes have impacted significantly on the atmosphere. Worldwide there have been developments in transportation, agriculture and industry. These activities produce greenhouse gases, and as a consequence the concentration of these gases in Earth’s atmosphere has increased. The greenhouse balance has been upset and more heat has been trapped. The Earth has begun to warm and the climate to change.

There is evidence of climate change effects, including raised temperatures and sea levels and the increased frequency of extreme weather events. The occurrence of these changes is projected to be more pronounced, and the rate of change more rapid.

1.1.1 The United Nations Framework Convention on Climate Change and the Kyoto Protocol

At a global level, the science of climate change is assessed by the Intergovernmental Panel on Climate Change (IPCC). In 1990 the IPCC concluded that human-induced climate change was a threat to our future. In response, the United Nations General Assembly convened a series of meetings that culminated in the adoption of the United Nations Framework Convention on Climate Change (UNFCCC) at the Earth Summit in Rio de Janeiro in May 1992.

The UNFCCC took effect on 21 March 1994 and has been signed and ratified by 188 nations including New Zealand.

The main objective of the UNFCCC is to achieve “stabilisation of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic (caused by humans) interference with the climate system. Such a level should be achieved within a time-frame sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner” (United Nations, 1992).

All countries that ratify the UNFCCC are required to address climate change through national or regional programmes. This includes preparing for adaptation to the impacts of climate change, protecting and enhancing carbon sinks (eg, forests), monitoring emissions trends via greenhouse gas inventories and, for developed countries, providing financial assistance to developing countries.

Developed countries party to the UNFCCC agreed to non-binding targets to reduce greenhouse gas emissions to 1990 levels by 2000.

Only a few countries made appreciable progress towards achieving their targets. The international community recognised that the UNFCCC alone was not enough to ensure greenhouse gas levels would be reduced to safe levels, and that more urgent action was needed. In response, Parties launched a new round of talks for stronger and more detailed commitments for developed countries. After two and a half years of negotiations, the Kyoto Protocol was adopted in Kyoto, Japan, on 11 December 1997. New Zealand ratified the Kyoto Protocol on 19 December 2002. The Protocol came into force on 16 February 2005.

The Kyoto Protocol shares the UNFCCC’s objective, principles and institutions, but significantly strengthens the UNFCCC by committing Annex I Parties (OECD members and countries whose economies are in transition) to individual, legally-binding targets to limit or reduce their greenhouse gas emissions. Only Parties to the Convention that have also become Parties to the Protocol, by ratifying, accepting, approving, or acceding to it, are bound by the Protocol’s commitments. Article 3 of the Kyoto Protocol states that the Annex I Parties ratifying the Protocol shall individually or jointly ensure that their aggregate anthropogenic greenhouse gas emissions do not exceed their “assigned amounts”. The goal is to reduce aggregate emissions by at least 5 per cent below 1990 levels in the commitment period 2008 to 2012.

The “assigned amount” is the maximum amount of emissions (measured as the equivalent in carbon dioxide) that a Party may emit over the commitment period to comply with its emissions target. New Zealand’s target is 100 per cent of the level in 1990. New Zealand’s assigned amount over the commitment period is the gross emissions in 1990 multiplied by 5, ie, for the five years of the commitment period. Gross emissions do not include emissions and removals from the land use, land-use change and forestry sector (LULUCF) unless this sector was a source of emissions in 1990.

To achieve their targets, Annex I Parties must put in place domestic policies and measures to address emissions. This can be achieved in either of two ways: the quantity of greenhouse gases emitted can be reduced or carbon dioxide presently in the atmosphere can be removed using carbon sinks (eg, trees).

The Kyoto Protocol also defined three “flexibility mechanisms” to lower the overall costs of achieving its emissions targets:

  • Clean Development Mechanism (CDM)
  • Joint Implementation (JI)
  • emissions trading.

These mechanisms enable Parties to access cost-effective opportunities to reduce emissions or to remove carbon from the atmosphere through action in other countries. While the cost of limiting emissions varies considerably from region to region, the benefit for the atmosphere is the same, wherever the action is taken. More information on these mechanisms can be obtained from the website of the UNFCCC (

New Zealand greenhouse gas emissions profile

New Zealand’s emissions have increased since 1990 as the economy has strengthened and grown. One half of New Zealand’s emissions come from agriculture. This creates a unique greenhouse gas emission profile for New Zealand. The typical Annex 1 Party has the majority of emissions from industrial processes, electricity production and transportation activity.

Another consequence of this economic growth has been the increasing greenhouse gas emissions from the energy sector. In 2005, New Zealand’s emissions from this sector accounted for 43.4 per cent of the total emissions, making it the second largest source after agriculture. Emissions from the energy sector have increased consistently since 1998 in response to increasing demands for energy from transport, electricity generation, manufacturing industries and construction. Renewable energy sources dominate New Zealand's electricity generation with hydroelectric power producing approximately 60 per cent of annual generation (depending on rainfall). Geothermal makes up approximately 7 per cent on an annual basis with smaller contributions from other renewable sources such as biogas, waste heat, wood, and wind.

1.1.2 A national greenhouse gas inventory

The development and publication of an annual inventory of all human-induced emissions and removals of greenhouse gases not controlled by the Montreal Protocol is part of New Zealand’s obligations under the UNFCCC (Articles 4 and 12) and the Kyoto Protocol (Article 7). The inventory is the tool for measuring New Zealand’s progress against these obligations.

The content and format of the inventory is prescribed by the Intergovernmental Panel on Climate Change (IPCC, 1996; 2000; 2003) and relevant decisions of the Conference of the Parties (COP) to the UNFCCC, the most recent being FCCC/SBSTA/2004/8. A complete inventory submission requires two components: the national inventory report (National Inventory Report) and emissions and removal data in the Common Reporting Format (CRF). Inventories are subject to an annual three-stage international review process administered by the UNFCCC secretariat.

The inventory reports emissions and removals of the gases carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulphur hexafluoride (SF6) from six sectors: energy, industrial processes, solvents, agriculture, land use, land-use change and forestry (LULUCF) and waste. The indirect greenhouse gases carbon monoxide (CO), oxides of nitrogen (NOX) and non-methane volatile organic compounds (NMVOCs) are also included in the inventory as is sulphur dioxide (SO2). Only emissions and removals of the direct greenhouse gases, CO2, CH4, N2O, HFCs, PFCs and SF6 are reported in New Zealand’s total emissions under the UNFCCC and are accounted for under the Kyoto Protocol.

Greenhouse gases vary in their radiative activity and in their atmospheric residence time. Emissions are converted into carbon dioxide equivalents (CO2-e) to allow the integrated effect of emissions of the various gases to be compared. The national greenhouse gas inventory report presents emissions for each direct greenhouse gas as CO2-e. This conversion is achieved through global warming potentials (GWPs). Global warming potentials represent the relative warming effect or cumulative radiative forcing, of a unit mass of the gas when compared with the same mass of CO2 over a specific period. The UNFCCC reporting requirements (FCCC/SBSTA/2004/8) specify that the 100-year global warming potentials contained in the IPCC Second Assessment Report (IPCC, 1995) are used in national inventories (see section 1.9). The indirect effects of a number of gases (CO, NOx, SO2 and NMVOCs) cannot currently be quantified and consequently these gases do not have global warming potentials. In accordance with the UNFCCC reporting guidelines, gases that do not have global warming potentials are reported in the inventory but are not included in the inventory emissions total.

1.2 Institutional arrangements

The Climate Change Response Act 2002 (CCRA) came into force to enable New Zealand to meet its international obligations under the UNFCCC and the Kyoto Protocol. The CCRA names the person “who is for the time being the chief executive of the Ministry for the Environment” as New Zealand’s inventory agency. The section “Part 2 Institutional Arrangements Sub part 3 – Inventory Agency of the CCRA” (2002) specifies the primary functions of the inventory agency, including:

  • “to estimate annually New Zealand’s human-induced emissions by sources and removals by sinks of greenhouse gases” (32.1(a))
  • “to prepare New Zealand’s annual inventory report under Article 7.1 of the Protocol and New Zealand’s national communication (or periodic report) under Article 7.2 of the Protocol and Article 12 of the Convention” (32.1(b)(i) and (ii)).

The CCRA also specifies the responsibilities of the inventory agency in carrying out its functions, including record keeping and publication of the inventory. Part 3 of the CCRA provides for the authorisation of inspectors to collect information needed to estimate emissions or removals of greenhouse gases.

The Ministry for the Environment (MfE) is responsible for overall development, compilation and submission of the annual inventory to the UNFCCC. The Ministry also produces estimates of emissions for the agriculture and waste sectors and emissions and removals from the LULUCF sector (except for planted forests which is provided by the Ministry of Agriculture and Forestry).

The Ministry of Economic Development (MED) collects and processes all emissions from the energy sector and CO2 emissions from the industrial processes sector. Emissions of the non-CO2 gases from the industrial processes sector are obtained through industry survey by consultants, contracted to the Ministry for the Environment.

The Ministry for Agriculture and Forestry (MAF) provides many of the statistics for the agriculture sector and removals data from planted forests in the LULUCF sector. The inventory estimates are underpinned by the research and modelling of researchers at New Zealand’s crown research institutes and universities.

New Zealand’s national statistical agency, Statistics New Zealand, provides many of the official statistics for the agriculture sector through a regular agricultural census and provides statistics on oil consumption from the transport sector through the “Deliveries of Petroleum Fuels by Industry” survey.

1.3 Inventory preparation processes

The inventory contains data from the base year (1990) to two years before the current calendar year. Generation of the data in the Common Reporting Format and production of the National Inventory Report occurs over the period February to April as activity data statistics and emission data become available from the various participating institutions mentioned in section 1.2 “Institutional arrangements”. The national inventory compilation occurs at the Ministry for the Environment using the UNFCCC “CRF Reporter” software. Ministry officials also undertake quality control checks on the data, calculate the inventory uncertainty, and undertake the key category assessment. The inventory and all required data for the submission to the UNFCCC are stored on the Ministry’s central computer network in a controlled file system. Once the inventory has gone through the initial quality checks at the UNFCCC Secretariat it is ready for public release (both as hard copy and on the MfE and UNFCCC websites).

New Zealand is required to have a national system in place for its greenhouse gas inventory under Article 5.1 of the Kyoto Protocol. New Zealand provided a full description of the national system in the initial report for the Kyoto Protocol. Many of the arrangements detailed in the guidelines for national systems are also described in this report. For example, designation of the national inventory agency, and the assignment of responsibilities for the inventory preparation process.

1.4 Methodologies and data sources used

The guiding documents in inventory preparation are the Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories (IPCC, 1996), the Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories (IPCC, 2000), Good Practice Guidance for Land Use, Land-Use Change and Forestry (IPCC, 2003) and the UNFCCC guidelines on reporting and review (FCCC/SBSTA/2004/8). The concepts contained in Good Practice Guidance are being implemented in stages, according to sector priorities and national circumstances.

Energy: Greenhouse gas emissions from the energy sector are calculated using an IPCC Tier 1 approach. Activity data (fuel consumed) are multiplied by the emission factors of specific fuels. Activity data comes from industry-supplied information via the Ministry of Economic Development and Statistics New Zealand (refer Chapter 3 and Annex 2). Carbon dioxide emission factors are usually New Zealand specific but applicable IPCC default factors are used for non-CO2 emissions where New Zealand data are not available or are not well supported.

Industrial processes: Carbon dioxide emissions and activity data for the industrial processes sector are supplied directly to the Ministry of Economic Development by industry sources. IPCC Tier 2 approaches are used and emission factors are country-specific. Activity data for the non-CO2 gases are collated through an industry survey through the Ministry for the Environment. Emissions of HFCs and PFCs are estimated using the IPCC Tier 2 approach and SF6 emissions from large users are assessed via the Tier 3a approach (IPCC, 2000).

Solvents: Very small amounts of nitrous oxide are emitted during use in medical applications. Estimates of NMVOC emissions are calculated using a consumption-based approach. Activity data are obtained through an industry survey.

Agriculture: Livestock population data are obtained from Statistics New Zealand, supplemented by estimates from the Ministry of Agriculture and Forestry. A Tier 2 (model) approach is used to estimate methane emissions from dairy cattle, non-dairy cattle, sheep and deer. The methodology uses animal productivity data to estimate dry matter intake. Methane production is determined from this intake. The same dry matter intake data are used to calculate nitrous oxide emissions from animal excreta. A Tier 1 approach is used for livestock species present in insignificant numbers.

Land use, land-use change and forestry: The LULUCF inventory is completed using a mix of IPCC Tier 2 and Tier 1 approaches. A Tier 2 approach is used for the “planted forest” subcategory of forest land. Changes in planted forest stocks are assessed from national forest survey data and computer modelling of the planted forest estate. A Tier 1 approach is used for the categories cropland, grassland, wetland, settlements and other land. Changes in land area for these categories are based on modified national land cover databases reclassified to the UNFCCC categories. The Land Cover Databases 1 and 2 were mapped in 1997 and 2002 (refer to Annex 3.3). Data for all other years are extrapolated from the changes observed between 1997 and 2002. At present, this is the best data available for reporting the LULUCF sector. The reporting will be improved significantly as a result of the Land Use and Carbon Analysis System (described in Annex 3.2).

Waste: Emissions from the waste sector are estimated using waste-survey data combined with population data. Calculation of emissions from solid-waste disposal uses an IPCC Tier 2 method with country-specific emission factors. Methane and nitrous oxide emissions from domestic and industrial wastewater handling are calculated using a refinement of the IPCC methodology (IPCC, 1996). There is no incineration of municipal waste in New Zealand. The only incineration is for small specific waste streams including medical, quarantine and hazardous wastes. For this inventory waste incineration emissions are reported to be negligible.

1.5 Key categories

The IPCC Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories (GPG) (IPCC, 2000) identifies a key category as “one that is prioritised within the national inventory system because its estimate has a significant influence on a country’s total inventory of direct greenhouse gases in terms of the absolute level of emissions, the trend in emissions, or both”. Key categories are identified within the inventory so that the resources available for inventory preparation and improvement are prioritised.

The key categories in the New Zealand inventory have been assessed using the Good Practice Guide Tier 1 level and trend methodologies (IPCC, 2000/2003). The Good Practice Guide methodologies identify sources of emissions and removals that sum to 95 per cent of the total level of emissions or 95 per cent of the trend of the inventory in absolute terms.

Following Good Practice Guidance for Land Use, Land-Use Change and Forestry (GPG-LULUCF) (IPCC, 2003) the key category analysis is performed once for the inventory excluding LULUCF categories and then repeated for the full inventory including the LULUCF categories. Non-LULUCF categories that are identified as key in the first analysis but that do not appear as key when the LULUCF categories are included are still to be considered as key categories.

The key categories identified in the 2005 inventory are summarised in table 1.5.1. The major contributions to the level analysis including LULUCF (table 1.5.2 a and b) are CO2 from “forest land remaining forest land” (24.9 per cent) and CH4 from enteric fermentation in domestic livestock (22.2 per cent).

The largest contribution to the trend analysis (refer to table 1.5.3) is from CH4 emissions from enteric fermentation in domestic livestock (17.6 per cent), CO2 emissions from road transportation (16.5 per cent), and CO2 emissions from stationary combustion of solid fuels (14.6 per cent). It is clear that these three categories have a major effect on the New Zealand inventory.

Although CO2 emissions from the industrial processes of ammonia and urea manufacture (CRF category 2B5) did not appear in the top 95 per cent of categories for the quantitative level and trend analyses, the source is considered a qualitative key category because of the large increase in nitrogenous fertiliser use observed in the agriculture sector.

There were two modifications to the IPCC suggested source categories to reflect New Zealand’s national circumstances. The category for fugitive emissions from geothermal operations was separated from the “fugitive emissions from fuels-oil and natural gas” category and CO2 emissions from “ammonia production” were included in the analysis. More information on the calculation of the level and trend analysis is included in Annex 1.

Table 1.5.1 Summary of key categories in the 2005 inventory (including and excluding LULUCF activities)

View summary of key categories in the 2005 inventory (including and excluding LULUCF activities) (large table)

Table 1.5.2 (a&b) Key category analysis for the 2005 inventory – Tier 1 level assessment including LULUCF (a) and excluding LULUCF (b)

View key category analysis for the 2005 inventory – Tier 1 level assessment including LULUCF and excluding LULUCF (large table)

Table 1.5.3 Key category analysis for the 2005 inventory – Tier 1 trend assessment including LULUCF (a) and excluding LULUCF (b)

View key category analysis for the 2005 inventory – Tier 1 trend assessment including LULUCF and excluding LULUCF (large table)

1.6 Quality assurance and quality control

Quality assurance (QA) and quality control (QC) are an integral part of preparing New Zealand’s inventory. The Ministry for the Environment developed a QA/QC plan in 2004 as required by the UNFCCC guidelines (FCCC/CP/2004/8) to formalise, document and archive the procedures. The plan is regularly reviewed and updated in conjunction with New Zealand’s inventory improvement plan.

1.6.1 Quality control

During the preparation of the 2005 inventory, the Ministry for the Environment continued to develop the Tier 1 QC checksheet first used in the preparation of the 2002 inventory. The quality checking was also expanded to include formal checks between the CRF tables and the National Inventory Report. The Tier 1 quality checks are based on the procedures suggested in Good Practice Guidance (IPCC, 2000). Further details (including examples of some of the checks carried out) are available in Annex 6. For the 2005 inventory, the Tier 1 QC checksheets were used on all key categories and a selection of non-key categories.

In addition to the formal quality control checks, data in the underpinning worksheets and entered into the UNFCCC secretariat’s CRF Reporter database are checked visually for anomalies, errors and omissions. In the preparation of the 2005 inventory, the Ministry for the Environment used the quality control checking procedures included in the CRF Reporter database to ensure the data submitted to the UNFCCC secretariat were complete.

1.6.2 Quality assurance

Quality assurance reviews of individual sectors and categories are commissioned by the Ministry for the Environment. As part of the quality assurance procedures for the 2005 inventory, the energy sector underwent a review during 2006. A list of previous quality assurance reviews, their key conclusions and follow up is included in Annex 6. In addition, the methodologies used in the agricultural and LULUCF sectors have undergone scientific peer-review before inclusion in New Zealand’s inventory.

A large part of the data in the energy and agriculture sectors are compiled using data collected in national surveys. These surveys are conducted and administered by Statistics New Zealand, which conducts its own rigorous quality assurance and quality control procedures on the data.

1.6.3 UNFCCC annual inventory review

New Zealand’s greenhouse gas inventory was reviewed in 2001 and 2002 as part of a pilot study of the technical review process (UNFCCC, 2001a; 2001b; 2001c; 2003), where the inventory was subject to detailed in-country, centralised and desk review procedures. The inventories submitted for the years 2001/2003 were reviewed during a centralised review process. The 2004 inventory was reviewed as part of the Kyoto Protocol initial review. This was an in-country review held from 19 to 24 February 2007. In all instances, the reviews were conducted by a review team comprising of experts nominated by Parties to the UNFCCC. Review reports are available from the UNFCCC website (

1.7 Inventory uncertainty

Uncertainty estimates are an essential element of a complete greenhouse gas emissions and removals inventory. The purpose of uncertainty information is not to dispute the validity of the inventory estimates, but to help prioritise efforts to improve the accuracy of inventories in the future and guide decisions on methodological choice (IPCC, 2000). Inventories prepared following the Good Practice Guidance methodologies (IPCC 2000; 2003) will typically contain a wide range of emission estimates, varying from carefully measured and demonstrably complete data on emissions to order-of-magnitude estimates of highly variable estimates such as N2O fluxes from soils and waterways.

New Zealand has included a Tier 1 uncertainty analysis as required by the inventory guidelines (FCCC/SBSTA/2004/8) and Good Practice Guidance (IPCC 2000; 2003). Uncertainties in the categories are combined to provide uncertainty estimates for the entire inventory in any year and the uncertainty in the overall inventory trend over time. LULUCF categories have been included using the absolute value of any removals of CO2 (table A7.1). Table A7.2 calculates the uncertainty only in emissions, ie, excluding LULUCF removals.

The calculated uncertainty for New Zealand’s total inventory (emissions and removals) in 2005 is ± 16.9 per cent. The uncertainty in the overall trend from 1990 to 2005 is lower at ± 4.7 per cent. The uncertainty in total emissions (excluding removals) is ± 20.7 per cent with ± 5.5 per cent uncertainty in the trend of emissions. The trend is critical to the UNFCCC and Kyoto Protocol reporting where New Zealand’s emissions are compared to the 1990 baseline.

The high uncertainty in a given year is dominated by emissions of CH4 from enteric fermentation (Chapter 6, section 6.2) and N2O emissions from agricultural soils (section 6.5). These categories comprise 12.1 per cent and 8.9 per cent respectively of the uncertainty as a percentage of New Zealand’s total emissions and removals. The apparent high uncertainty in these categories reflects the inherent variability when estimating emissions from natural systems, eg, the uncertainty in cattle dry-matter intake and CH4 emissions per unit of dry matter. With the agricultural sector comprising approximately half of New Zealand’s emissions, high uncertainty in a given year is inevitable. Removals of CO2 from forest land are also a major contribution to the uncertainty for 2005 at 6.2 per cent of New Zealand’s total emissions and removals. In comparison, the uncertainty in CO2 emissions from burning of fossil fuels is significantly lower at only 1.5 per cent of the total.

Uncertainty in the trend is dominated by CO2 emissions from the energy sector, at 2.8 per cent of the trend. This is because of the size of the sector and because the uncertainty in energy activity data are greater than the uncertainty in energy emission factors. The other major contributors to trend uncertainty are removals of CO2 by forest land (Chapter 7, section 7.2) and CH4 from enteric fermentation in domestic livestock.

In most instances, the uncertainty values are determined by either expert judgement from sectoral or industry experts, by analysis of emission factors or activity data, or by referring to uncertainty ranges quoted in the IPCC documentation. A Monte Carlo simulation was used to determine uncertainty for CH4 from enteric fermentation and N2O from agricultural soils in the 2001/2002 inventory. The 95 per cent confidence intervals developed from the Monte Carlo simulation were extended to the 2005 inventory.

1.8 Inventory completeness

The New Zealand inventory for the 2005 year can be described as complete, with all IPCC source and sink categories reported that occur in New Zealand or that have emissions assessed to be above a negligible level. There are some small sources which remain “not estimated” (NE), eg, CH4 emissions from waste incineration. Explanations on why these are reported as not estimated are found under the appropriate sector chapters. In accordance with Good Practice Guidance, New Zealand has focused its resources for inventory development on the key categories. Some categories considered to have negligible emissions are reported as “not estimated”. Where this has occurred explanations have been provided in the National Inventory Report and in the CRF tables.

The LULUCF data are the best estimate possible using the data that are presently available. The Land Use and Carbon Analysis System (LUCAS) is being developed to improve the accuracy of these data. Estimates using this system will be included when available. Development of the LUCAS will also reduce uncertainty by using country-specific emission and removal factors and use spatial data mapped specifically for UNFCCC reporting. Details of the LUCAS development are included in Annex 3.2.

1.9 General notes


Standard metric prefixes used in this inventory are:

kilo (k) = 103 (thousand)

mega (M) = 106 (million)

giga (G) = 109

tera (T) = 1012

peta (P) = 1015

Emissions are generally expressed in gigagrams (Gg) in the inventory tables:

1 gigagram (Gg) = 1,000 tonnes = 1 kilotonne (kt)

1 megatonne (Mt) = 1,000,000 tonnes = 1,000 Gg


CO2 carbon dioxide

CH4 methane

N2O nitrous oxide

PFCs perfluorocarbons

HFCs hydrofluorocarbons

SF6 sulphur hexafluoride

CO carbon monoxide

NMVOC non-methane volatile organic compounds

NOx oxides of nitrogen

SO2 sulphur dioxide

Common Global Warming Potentials

CO2 = 1

CH4 = 21

N2O = 310

CF4 = 6,500

C2F6 = 9,200

SF6 = 23,900

HFC–32 = 650

HFC–125 = 2,800

HFC–134a = 1,300

HFC–143a = 3,800

HFC–227ea = 2,900

Conversion factors

From element basis to molecular mass

C >> CO2: C x 44/12 (3.67)

C >> CH4: C x 16/12 (1.33)

N >> N2O: N x 44/28 (1.57)

From molecular mass to element basis

CO2 >> C: CO2 x 12/44 (0.27)

CH4 >> C: CO2 x 12/16 (0.75)

N2O >> N: N2O x 28/44 (0.64)


In the common reporting format tables, the following standard indicators are used:

NO (not occurring) when the activity or process does not occur in New Zealand.

NA (not applicable) when the activity occurs in New Zealand but the nature of the process does not result in emissions or removals.

NE (not estimated) where it is known that the activity occurs in New Zealand but there are no data or methodology available to derive an estimate of emissions. Even if emissions are considered to be negligible, an emission estimated should be reported, if calculated, or the notation key “NE” used.

IE (included elsewhere) where emissions or removals are estimated but included elsewhere in the inventory (summary table 9 of the Common Reporting Format tables details the source category where these emissions or removals are reported).

C (confidential) where reporting at a disaggregated level could lead to the disclosure of confidential information.