Chapter 1: Introduction to the 2006 Guidelines

CHAPTER 1

INTRODUCTION TO
THE 2006 GUIDELINES

2006 IPCC Guidelines for National Greenhouse Gas Inventories 1.1

Volume 1: General Guidance and Reporting

Authors
Kristin Rypdal (Norway), Newton Paciornik (Brazil)

Simon Eggleston (TSU), Justin Goodwin (UK), William Irving (USA), Jim Penman (UK),
and Mike Woodfield (UK)

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 Chapter 1: Introduction to the 2006 Guidelines

Contents

1 Introduction to the 2006 Guidelines

1.1 Concepts .............................................................................................................................................. 1.4
1.2 Estimation methods ............................................................................................................................. 1.6
1.3 Structure of the Guidelines .................................................................................................................. 1.7
1.4 Inventory quality ................................................................................................................................. 1.7
1.5 Compiling an inventory ....................................................................................................................... 1.8

References ......................................................................................................................................................... 1.12

Figures

Figure 1.1 Inventory development cycle ............................................................................................. 1.10

Boxes

Box 1.1 Using the flow diagram (Figure 1.1) and the 2006 Guidelines – Livestock example ........ 1.11

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Volume 1: General Guidance and Reporting

1 INTRODUCTION TO THE 2006 GUIDELINES

The 2006 IPCC Guidelines for National Greenhouse Gas Inventories (2006 Guidelines) were produced at the
invitation of the United Nations Framework Convention on Climate Change (UNFCCC) to update the Revised
1996 Guidelines and associated good practice guidance1 which provide internationally agreed2 methodologies
intended for use by countries to estimate greenhouse gas inventories to report to the UNFCCC. This chapter
provides an introduction to the 2006 Guidelines for a broad range of users, including countries and inventory
compilers setting out to prepare inventory estimates for the first time. Sections 1.1 to 1.3 describe the
overarching framework of these Guidelines, focusing on scope, approach, and structure. Sections 1.4 through 1.5
present step-by-step guidance on how to use the 2006 Guidelines for compiling a greenhouse gas inventory.

1.1 CONCEPTS
Inventories rely on a few key concepts for which there is a common understanding. This helps ensure that
inventories are comparable between countries, do not contain double counting or omissions, and that the time
series reflect actual changes in emissions.

Anthropogenic emissions and removals

Anthropogenic emissions and removals means that greenhouse gas emissions and removals included in national
inventories are a result of human activities. The distinction between natural and anthropogenic emissions and
removals follows straightforwardly from the data used to quantify human activity. In the Agriculture, Forestry
and Other Land Use (AFOLU) Sector, emissions and removals on managed land are taken as a proxy for
anthropogenic emissions and removals, and interannual variations in natural background emissions and removals,
though these can be significant, are assumed to average out over time.

National territory
National inventories include greenhouse gas emissions and removals taking place within national territory and
offshore areas over which the country has jurisdiction. There are some special issues that are described in
Section 8.2.1 of Volume 1. For example, emissions from fuel use in road transport is included in the emissions of
the country where the fuel is sold and not where the vehicle is driven, as fuel sale statistics are widely available
and usually much more accurate.

Inventory year and time series

National inventories contain estimates for the calendar year during which the emissions to (or removals from)
the atmosphere occur. Where suitable data to follow this principle are missing, emissions/removals may be
estimated using data from other years applying appropriate methods such as averaging, interpolation and
extrapolation. A sequence of annual greenhouse gas inventory estimates (e.g., each year from 1990 to 2000) is
called a time series. Because of the importance of tracking emissions trends over time, countries should ensure
that a time series of estimates is as consistent as possible.

Inventory reporting
A greenhouse gas inventory report includes a set of standard reporting tables covering all relevant gases,
categories and years, and a written report that documents the methodologies and data used to prepare the
estimates. The 2006 Guidelines provide standardised reporting tables, but the actual nature and content of the
tables and written report may vary according to, for example, a country’s obligations as a Party to the UNFCCC.
The 2006 Guidelines provide worksheets to assist with the transparent application of the most basic (or Tier 1)
estimation methodology.

1
The Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories (1996 Guidelines, IPCC, 1997), The Good
Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories (GPG2000, IPCC, 2000), and
The Good Practice Guidance for Land Use, Land-use Change and Forestry (GPG-LULUCF, IPCC, 2003).
2
See the Report of the Fourth Session of the Subsidiary Body for Scientific and Technological Advice
(FCCC/SBSTA/1996/20), paragraph 30; decisions 2/CP.3 and 3/CP.5 (UNFCCC reporting guidelines for preparation of
national communications by Parties included in Annex I to the Convention, part I: UNFCCC reporting guidelines on
annual inventories), decision 18/CP.8, revising the guidelines adopted under decisions 3/CP.5, and 17/CP.8 adopting
improved guidelines for the preparation of national communications from Parties not included in Annex I to the
Convention, and subsequent decisions 13/CP.9 and decision 15/CP.10.

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 Chapter 1: Introduction to the 2006 Guidelines

Greenhouse gases
The following greenhouse gases are covered in the 2006 Guidelines3:
• carbon dioxide (CO2)
• methane (CH4)
• nitrous oxide (N2O)
• hydrofluorocarbons (HFCs)
• perfluorocarbons (PFCs)
• sulphur hexafluoride (SF6)
• nitrogen trifluoride (NF3)
• trifluoromethyl sulphur pentafluoride (SF5CF3)
• halogenated ethers (e.g., C4F9OC2H5, CHF2OCF2OC2F4OCHF2, CHF2OCF2OCHF2 )
• and other halocarbons not covered by the Montreal Protocol including CF3I, CH2Br2 CHCl3, CH3Cl, CH2Cl2 4
The gases listed above have global warming potentials (GWPs) identified by the IPCC prior to finalisation of the
2006 Guidelines. A GWP compares the radiative forcing of a tonne of a greenhouse gas over a given time period
(e.g., 100 years) to a tonne of CO2. The 2006 Guidelines also provide methods for gases for which GWP values
were not available prior to finalisation, i.e., C3F7C(O)C2F5, C7F16, C4F6, C5F8 and c-C4F8O.
These gases are sometimes used as substitutes for gases that are included in the inventory and countries are
encouraged to provide estimates for them.

Other gases
The 2006 Guidelines also provide information for the reporting of the following precursors: nitrogen oxides
(NOx), ammonia (NH3), non-methane volatile organic compounds (NMVOC), carbon monoxide (CO) and
sulphur dioxide (SO2) although methods for estimating emissions of these gases are not given here.

Sectors and Categories

Greenhouse gas emission and removal estimates are divided into main sectors, which are groupings of related
processes, sources and sinks:
• Energy
• Industrial Processes and Product Use (IPPU)
• Agriculture, Forestry and Other Land Use (AFOLU)
• Waste
• Other (e.g., indirect emissions from nitrogen deposition from non-agriculture sources5)
Each sector comprises individual categories (e.g., transport) and sub-categories (e.g., cars). Ultimately, countries
will construct an inventory from the sub-category level because this is how IPCC methodologies are set out, and
total emissions calculated by summation. A national total is calculated by summing up emissions and removals
for each gas. An exception is emissions from fuel use in ships and aircraft engaged in international transport
which is not included in national totals, but is reported separately.
In order to calculate a national total it is necessary to choose an approach to include harvested wood products
(HWP). Countries can select any of the approaches reflected in Chapter 12 of Volume 4 for the AFOLU Sector
to do this.

3
The halogenated gases are typically emitted in smaller amounts than CO2, CH4 and N2O, but may have long atmospheric
lifetimes and strong radiative forcing effects.
4
For these gases, emissions could be estimated following the methods described in Section 3.10.2 of Volume 3 if necessary
data are available, and then could be reported under sub-category 2B10 ‘Other’.
5
Estimates include N2O emissions from deposition of anthropogenic nitrogen (N) from NOx/NH3 wherever deposited and
from whatever source (but not allocated to specific sectors). The reason for this is that emission factors for nitrogen
deposited are of the same magnitude for agricultural sources as for other nitrogen sources, even when the N is deposited in
the ocean.

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Reporting is generally organised according to the sector actually generating emissions or removals. There are
some exceptions to this practice, such as CO2 emissions from biomass combustion for energy, which are
reported in AFOLU Sector as part of net changes in carbon stocks. Where CO2 emissions are captured from
industrial processes or large combustion sources, emissions should be allocated to the sector generating the CO2
unless it can be shown that the CO2 is stored in properly monitored geological storage sites as set out in Chapter
5 of Volume 2.

1.2 ESTIMATION METHODS

As with the 1996 Guidelines and IPCC Good Practice Guidance the most common simple methodological
approach is to combine information on the extent to which a human activity takes place (called activity data or
AD) with coefficients which quantify the emissions or removals per unit activity. These are called emission
factors (EF). The basic equation is therefore:
Emissions = AD • EF

For example, in the energy sector fuel consumption would constitute activity data, and mass of carbon dioxide
emitted per unit of fuel consumed would be an emission factor. The basic equation can in some circumstances be
modified to include other estimation parameters than emission factors. Where time lags are involved, due for
example to the time it takes for material to decompose in a landfill or leakage of refrigerants from cooling
devices, other methods are provided, for example first order decay methods. The 2006 Guidelines also allow for
more complex modelling approaches, particularly at higher tiers.
Though this simple equation is widely used, the 2006 Guidelines also contain mass balance methods, for
example the stock change methods used in the AFOLU sector which estimates CO2 emissions from changes over
time in carbon content of living biomass and dead organic matter pools.
Carbon dioxide from the combustion or decay of short-lived biogenic material removed from where it was
grown is reported as zero in the Energy, IPPU and Waste Sectors (for example CO2 emissions from biofuels6,7,
and CO2 emissions from biogenic material in Solid Waste Disposal Sites (SWDS)). In the AFOLU Sector, when
using Tier 1 methods for short lived products, it is assumed that the emission is balanced by carbon uptake prior
to harvest, within the uncertainties of the estimates, so the net emission is zero. Where higher Tier estimation
shows that this emission is not balanced by a carbon removal from the atmosphere, this net emission or removal
should be included in the emission and removal estimates for AFOLU Sector through carbon stock change
estimates. Material with long lifetime is dealt with in the HWP section.
IPCC methods use the following concepts:
Good Practice: In order to promote the development of high quality national greenhouse gas inventories a
collection of methodological principals, actions and procedures were defined in the previous guidelines and
collectively referred to as good practice. The 2006 Guidelines retain the concept of good practice including the
definition introduced with GPG2000. This has achieved general acceptance amongst countries as the basis for
inventory development and says that inventories consistent with good practice are those which contain neither
over- nor under-estimates so far as can be judged, and in which uncertainties are reduced as far as practicable.
Tiers: A tier represents a level of methodological complexity. Usually three tiers are provided. Tier 1 is the
basic method, Tier 2 intermediate and Tier 3 most demanding in terms of complexity and data requirements.
Tiers 2 and 3 are sometimes referred to as higher tier methods and are generally considered to be more accurate.
Default data: Tier 1 methods for all categories are designed to use readily available national or international
statistics in combination with the provided default emission factors and additional parameters that are provided,
and therefore should be feasible for all countries.
Key Categories: The concept of key category8 is used to identify the categories that have a significant influence
on a country’s total inventory of greenhouse gases in terms of the absolute level of emissions and removals, the
trend in emissions and removals, or uncertainty in emissions and removals. Key Categories should be the priority
for countries during inventory resource allocation for data collection, compilation, quality assurance/quality
control and reporting.

6
CO2 emissions from the use of biofuels should be reported as an information item for QA/QC purposes.
7
In these guidelines peat is assumed not to be a biofuel.
8
Chapter 4 of Volume 1 provides more details of key categories and approaches to identifying key categories for national
inventories.

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Decision Trees: Decision trees for each category help the inventory compiler navigate through the guidance and
select the appropriate tiered methodology for their circumstances based on their assessment of key categories. In
general, it is good practice to use higher tier methods for key categories, unless the resource requirements to do
so are prohibitive.

1.3 STRUCTURE OF THE GUIDELINES

Volumes: The 2006 IPCC Guidelines contain 5 volumes, one for each sector (Volumes 2-5) and one for general
guidance applicable to all sectors (Volume 1).
• Volume 1: General Guidance and Reporting
• Volume 2: Energy
• Volume 3: Industrial Processes and Product Use (IPPU)
• Volume 4: Agriculture, Forestry and Other Land Use (AFOLU)
• Volume 5: Waste
This five-volume structure means the cross referencing will be required between two volumes at most: Volume 1
(General Guidance and Reporting), and the relevant sectoral volume.
Chapters: Volume 1 contains chapters that provide detailed cross-cutting guidance by topic as described in
more detail in Section 1.5. Volumes 2-5 contain chapters that provide methodological guidance for specific
emission and removal categories, along with specific recommendations for uncertainty, QA/QC, time series
consistency, and reporting. The volume and chapter structure is presented in Table 1 in the Overview of the 2006
Guidelines.
Annexes: Annexes are intended to include additional often detailed information beyond what is necessary for a
Tier 1 estimate, for example extended data tables.
Appendices: The 2006 IPCC Guidelines present some technical material in appendices, where emissions or
removals are poorly understood and where there is insufficient information available to develop reliable, globally
applicable, default methods for a particular source or sink. Countries may use appendices as a basis for further
methodological development, but a national inventory can be considered complete without the inclusion of
estimates for these sources.
Worksheets: Worksheets are tools designed to provide easy calculation of Tier 1 methodologies. Worksheets
are not provided for higher tiers, although they can also be used where the higher tier method is similar to Tier 1
(e.g., where national data is used instead of default data). Some more complex approaches are provided in
spreadsheets in the attached CD.
Reporting Tables: The reporting tables are intended to give sufficient detail required for transparent reporting
of national greenhouse gas inventories and follow a disaggregated category list. They include summary tables,
sectoral tables, background tables and trend tables. The background tables include summary activity data for
increased transparency and to facilitate comparison of data across countries. Reporting tables also include results
of a key category analysis and uncertainty assessment. Reporting also includes memo items (emissions to be
reported but not included in national totals) and information items for increased transparency.

1.4 INVENTORY QUALITY

These guidelines provide guidance on ensuring quality on all steps of the inventory compilation – from data
collection to reporting. They also provide tools to focus resources on the areas where they will most benefit the
overall inventory and encourage continuous improvement. Experience has demonstrated that using a good
practice approach is a pragmatic means of building inventories that are consistent, comparable, complete,
accurate and transparent – and maintaining them in a manner that improves inventory quality over time.
Indicators of inventory quality are:
Transparency: There is sufficient and clear documentation such that individuals or groups other than the
inventory compilers can understand how the inventory was compiled and can assure themselves it meets the
good practice requirements for national greenhouse gas emissions inventories. Documentation and reporting
guidance is provided in Chapter 8, Reporting Guidance and Tables, of Volume 1 and in the respective chapters
of Volume 2-6 (see also Volume 1, Chapter 6, QA/QC and Verification).

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Completeness: Estimates are reported for all relevant categories of sources and sinks, and gases. Geographic
areas within the scope of the national greenhouse gas inventory are recommended in these Guidelines. Where
elements are missing their absence should be clearly documented together with a justification for exclusion (see
Volumes 2-5).
Consistency: Estimates for different inventory years, gases and categories are made in such a way that
differences in the results between years and categories reflect real differences in emissions. Inventory annual
trends, as far as possible, should be calculated using the same method and data sources in all years and should
aim to reflect the real annual fluctuations in emissions or removals and not be subject to changes resulting from
methodological differences. (See Chapter 2: Approaches to Data Collection, Chapter 4: Methodological Choice
and Identification of Key Categories, and Chapter5: Time Series Consistency in Volume 1.)
Comparability: The national greenhouse gas inventory is reported in a way that allows it to be compared with
national greenhouse gas inventories for other countries. This comparability should be reflected in appropriate
choice of key categories (see Volume 1, Chapter 4), and in the use of the reporting guidance and tables and use
of the classification and definition of categories of emissions and removals presented in Table 8.2 of Chapter 8,
and Volumes 2-5.
Accuracy: The national greenhouse gas inventory contains neither over- nor under-estimates so far as can be
judged. This means making all endeavours to remove bias from the inventory estimates (see especially Chapter 2,
Approaches to Data Collection, and Chapter 3, Uncertainties, in Volume 1 and Volumes 2-5).
Uncertainty assessment (details provided in Chapter 3 of Volume 1) is an important component of good practice
in national greenhouse gas inventory development. The uncertainty analysis characterises the range and
likelihood of possible values for the national inventory as a whole as well as for its components. Awareness of
the uncertainty of parameters and results provides inventory compilers with insight when evaluating suitable data
for the inventory during the data collection and compilation phases. Uncertainty assessment also helps identify
the categories that contribute most to the overall uncertainty, which helps the inventory compiler prioritise future
inventory improvements.
The 2006 Guidelines encourage continuous improvement and rigor through QA/QC and verification activities. A
number of concepts and tools in Chapter 6 in Volume 1 are provided to support efficient inventory management,
checking and continuous improvement. These activities will ensure that the best use of limited resources can be
made and a quality consistent with good practice is achieved for each inventory.
Regular communication and consultation with providers of data is recommended throughout the inventory
activities (from data collection to final reporting). This communication will build working relationships between
data supplier and inventory compilers that will benefit the inventory both in terms of efficiency and quality. This
activity will also help to keep the inventory compilers informed of the development of new datasets and even
provide opportunities to influence the planning and specifications of data provider’s data collection activities.

1.5 COMPILING AN INVENTORY

Compiling a greenhouse gas inventory is a step-by-step process. This section provides guidance on these steps
for the inventory compiler, i.e., the person, persons or institutions who put together or compose the inventory
from materials gathered from several sources. Compilation includes the collection of data, estimation of
emissions and removals, checking and verification, uncertainty assessment and reporting.
Before undertaking estimates of emissions and removals from specific categories an inventory compiler should
become familiar with the material in Volume 1 General Guidance and Reporting. This Volume provides good
practice guidance on issues that are common to all the estimation methods covered by the sector-specific
guidance provided in Volumes 2 to 5 and reporting instructions.
Summary of Volume 1:
• Data collection: Collection of data is a fundamental part of inventory preparation. Chapter 2 of Volume 1
provides guidance on initiating and maintaining a data collection program. It covers evaluating existing
sources of data, and planning new emission measurements and surveys, extensive reference is made to
guidance provided by other organisations. The chapter links the data collection process to the other general
issues.
• Uncertainty assessment: Estimates of uncertainty are needed for all relevant source and sink categories,
greenhouse gases, inventory totals as a whole, and their trends. Chapter 3, Uncertainties, provides practical
guidance for estimating and combining uncertainties, along with a discussion of the conceptual
underpinnings of inventory uncertainty. Uncertainty issues related to specific category of emissions and
removals are addressed in Volumes 2-5.

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• Key category analysis: Good practice guidance on how to identify key categories of emissions and
removals is provided in Chapter 4, Methodological Choice and Identification of Key Categories. The key
category concept is used, together with the decision trees in Volumes 2-5, to guide users in their
methodological choice for each category. These decision trees are the critical link between methodological
choice in the sector-specific volumes and the identification of key categories in Volume 1.
• Time series consistency: Ensuring the time series consistency of inventory estimates is essential for
establishing confidence in reported inventory trends. Chapter 5, Time Series Consistency, provides methods
for ensuring time-series consistency in cases where it is not possible to use the same method and/or data
over the entire period. This chapter also provides good practice guidance on when to recalculate estimates
for previous years and methods for accounting for changes in emissions and removals over time.
• Quality Assurance (QA) and Quality Control (QC): A QA/QC system is an important part of inventory
development. Chapter 6, QA/QC and Verification, describes the general QA/QC aspects to consider when
compiling an inventory of emissions and removals. Good practice guidance on sector specific quality
control checks are addressed in Volumes 2-5. Chapter 6 also describes techniques for verifying inventories
using external data.
• Precursors and indirect N2O emissions: Volume 1 also includes cross-sectoral guidance on dealing with
precursors and indirect emissions of N2O from deposition of nitrogen compounds (resulting from NOx and
NH3 emissions) in Chapter 7, Precursors and Indirect Emissions.
• Reporting: Chapter 8, Reporting Guidance and Tables, specifically addresses issues related to reporting,
including definitions of national territory, gases and reporting categories. Notation keys are introduced to
account for completeness and transparency in reporting. The definitions of categories of sources and sinks
take into account the structure of the sector guidance in Volume 2-5. The sectoral and summary reporting
tables to be applied for reporting emissions and removals of each category are included in Chapter 8.
Reporting tables on uncertainties, key category analysis, and emission trends have also been developed and
are included in Chapter 8.
Volumes 1 and Volumes 2 to 5 are complementary. After the compilers tasked with preparing estimates for
specific emission and removal categories have familiarised themselves with the general guidance in Volume 1
they should use the specific sectoral volume(s) appropriate to their categories so that they can apply the
requirements in a manner appropriate to their national circumstances. Figure 1.1 illustrates the steps of a typical
inventory cycle. Quality control measures should be implemented at each step and should be documented
according to the requirements of QA/QC and documentation given in Chapter 6 of Volume 1.
1. The first step for a revised or new greenhouse gas inventory is to identify the key categories for the
inventory so that resources can be prioritised. Where an inventory already exists, the key categories can be
identified quantitatively from the previous estimates (see Volume 1 Chapter 4). For a new inventory the
compiler will have to make a preliminary assessment based on local knowledge and expertise about large
emission sources and inventories in countries with similar national circumstances or, if possible, make
preliminary Tier 1 estimates to assist in identifying key categories.
Assessing the key categories helps the inventory compiler to focus effort and resources on the sectors that
contribute most to the overall inventory or inventory uncertainty and so helps to ensure that the best possible
inventory is compiled for the available resources.
2. Once the key categories have been identified, the inventory compiler should identify the appropriate method
for estimation for each category in the particular country circumstances. The sector-specific decision trees in
Volumes 2-5 and the generalised decision tree in Chapter 4 of Volume 1 provide guidance on selecting
appropriate methods. The selection of methods will be determined by the classification of a category as key
or not key, and by both the data and the resources available. Guidance on data collection is provided in
Chapter 2 of Volume 1.
3. Data collection should follow the selection of the appropriate methods. (See Chapter 2, 5 and 7 in Volume
1). Data collection activities should consider time series consistency and establish and maintain good
verification, documentation and checking procedures (QA/QC) to minimise errors and inconsistencies in the
inventory estimates. Data on uncertainties should if possible be collected at the same time. Guidance on the
collection of new data in a cost effective way and on uncertainties is provided in Chapter 2 and Chapter 3 of
Volume 1 respectively. QA/QC activities should continue throughout this process to minimise errors and
document data sources, methods and assumptions. The results of the data collection may lead to refinement
of the methods chosen.
4. Emissions and removals are estimated following the methodological choice and data collection. Care should
be taken to follow the general guidance in Chapter 5, Time Series Consistency in Volume 1 especially if the
data are incomplete for some years.

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5. Once the inventory estimates are complete, the next step is to perform an uncertainty analysis and key
category analysis (see Chapters 3 and 4 in Volume 1). These analyses may identify categories for which a
higher tier should be used and additional data collected.
6. Following the completion of the final quality assurance (QA) checks, the final step in the inventory process
is to report the inventory (See Chapter 8 in Volume 1). The aim here is to present the inventory in an as
concise and clear way as possible to enable users to understand the data, methods and assumptions used in
the inventory. Provision of concise relevant background information and explanations in the reports helps to
ensure the inventory (including the report) is transparent.
The inventory compiler should base future inventory revisions on previous inventories. Thus an iterative process
builds on and improves the inventory each time a new inventory is compiled as illustrated in Figure 1.1. When a
revised inventory is compiled, all years estimates should be reviewed for consistency and updated integrating
any feasible improvements where necessary. Chapter 5 in Volume 1 gives advice on compiling consistent time
series and provides good practice approaches for achieving time series consistency.

Figure 1.1 Inventory development cycle

Start new
estimate,
building on experience of
previous inventories.
(if available)

Report inventory. Identify key categories.

(Chapter 8 and Volumes 2-5) (Chapter 4)

Select methods (Volume 2-5)

while considering data collection,
Check/Review Make necessary
uncertainty and time series
inventory through QA. revisions.(if any)
consistency good practice.
(Chapter 6) (Chapter 4)
(Volume 1 Chapters 2, 3 and 5
respectively)

QC Checking & QC Checking &

Documentation Documentation

Collect data (Volume 1 Chapter 2)

Conduct key category and estimate emissions/removals
analysis. (Volume 2-5) ensuring adequate
(Chapter 4) QA/QC and time series consistency.
(Volume 1 Chapters 5 and 6)

QC Checking &
QC Checking & Documentation QC Checking &
Documentation Documentation

Compile inventory:
Conduct uncertainty analysis: (Worksheets in Volume 2-5
Evaluate input data and or own system) considering
assess overall inventory. time series consistency and
(Chapter 3) QA/QC in Volume 1
Chapters 5 and 6.

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Box 1.1 provides an example on using the 2006 Guidelines throughout the inventory cycle when estimating
emissions from enteric fermentation.

BOX 1.1
USING THE FLOW DIAGRAM (FIGURE 1.1) AND THE 2006 GUIDELINES – LIVESTOCK EXAMPLE
Inventory compilers tasked with preparing estimates for specific emission and removal categories
need to familiarise themselves with guidance in two Volumes: the relevant guidance in a sectoral
volume (e.g., Volume 4, Agriculture, Forestry and Other Land Use), and the general guidance in
Volume 1. Along with the diagram (see Figure 1.1) this box describes how the guidance in the two
Volumes is used for estimating methane emissions from Enteric Fermentation:
Start with your previous inventory where available and prioritise categories for estimation.
• The inventory compiler can begin with the overall results of the previous national inventory,
particularly the key category assessment, as a preliminary step to selecting methods and data
(Chapter 4 of Volume 1).
Familiarise yourself with general and sector specific QA/QC requirements.
• Prior to collecting all the data and estimating emissions, the inventory compiler should consult
the general guidance in implementing Quality Control (QC) procedures in Chapter 6 of
Volume 1 (QA/QC and Verification) along with the specific QC procedures for enteric
fermentation described in Chapter 10 of Volume 4. QC procedures should be implemented at
every step of the inventory cycle. This will include regular checking and clear documentation
of data sources methods and assumptions.
Choose appropriate methods based on category importance and data availability.
• The inventory compiler should consult the decision tree and methodological guidance in
Chapter 10 of Volume 4 to select an appropriate method. In this example, enteric fermentation
is a key category, which indicates that normally Tier 2 or 3 should be selected.
• The general guidance in Chapter 2 (Approaches to Data Collection) of Volume 1 and Chapter
10 of Volume 4 will guide the inventory compiler in choosing appropriate emission factor,
activity data and other estimation parameters. This may include identifying or choosing from
existing data or collection and classification of new data.
Collect the data necessary for the latest year and a consistent time series and uncertainty
estimation.
• The next step involves collection of the needed data for all years. The availability of data may
sometimes restrict use of higher tier methods for key categories.
• Chapter 5 (Time Series Consistency) of Volume 1 should be used if preparing estimates for
more than one year. This guidance is particularly relevant if the selected method is different
from the one used in previous inventories or the sources of data or their classification have
changed. This can imply the need for recalculations of previous estimates or splicing of data
series. Chapter 10 of Volume 4 should be consulted for source-specific guidance on time-
series consistency.
• In estimating uncertainties, inventory compilers should also refer to the general guidance on
uncertainty in Chapter 3 of Volume 1 - paying particular attention to guidance on concepts
and methods – and the uncertainty section of the enteric fermentation livestock chapter for
source-specific information (for example default uncertainties). Ideally, the inventory
compiler should collect activity data, emission factors, and uncertainty information at the
same time because this is the most efficient strategy.
Estimate emissions/removals consistent with the guidance.
• The next step is to estimate methane emissions from enteric fermentation for all relevant
years. Relevant guidance for this step includes the specific guidance for enteric fermentation
in Volume 4, Chapter 10 relating to completeness, reporting and documentation, and time
series consistency sections.
• The enteric fermentation emissions and uncertainty data are used subsequently as input into
the compilation of the overall inventory, the estimation of category-specific and overall
uncertainty, and the key category assessment. The results of these steps may require changes
or revisions to the original estimate of emissions of enteric fermentation.

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BOX 1.1 (CONTINUED)

Check and review the estimates.

• Following the Quality Assurance (QA) guidance in Volume 1, the inventory compiler should
arrange for review of the estimate and documentation by technical experts not involved in the
preparation of the inventory. External reviewers may suggest improvements or identify errors
that would require a recalculation of the enteric fermentation estimate.
Report the estimates.
• The IPCC Guidelines provide guidance on reporting information on enteric fermentation in
two places: the enteric fermentation chapter of Volume 4, and the reporting tables in Chapter 8
of Volume 1. The inventory compiler should consult both chapters for a complete description
of reporting guidance.
Note: In the case of an initial inventory effort, with no previous key category analysis, a qualitative
assessment of enteric fermentation could be used. See Chapter 2 and Chapter 4 of Volume 1. In this
example, it can be concluded that methane from enteric fermentation is key in most inventories and
should therefore be considered initially key.

References
IPCC (1997). Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories: Volumes 1, 2 and 3.
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1.12 2006 IPCC Guidelines for National Greenhouse Gas Inventories