Methodological Choice – Identification of Key Categories

5.4

METHODOLOGICAL CHOICE IDENTIFICATION OF KEY CATEGORIES

5.4.1

Introduction

This chapter addresses how to identify key categories 5 in a national inventory including LULUCF.
Methodological choice for individual source and sink categories is important in managing overall inventory
uncertainty. In the decision trees in Chapters 3 and 4 of this report, specific guidance is given for each category
and each activity under Articles 3.3 and 3.4 of the Kyoto Protocol using the concept of key categories. Generally,
inventory uncertainty is lower when emissions and removals are estimated using a higher tier. However, thesegenerally require extensive resources for data collection, so it may not be feasible to use higher tier methods forevery category of emissions and removals. It is therefore good practice to make the most efficient use ofavailable resources by identifying those categories that have the greatest contribution to overall inventory
uncertainty. By identifying these key categories in the national inventory, inventory agencies can prioritise theirefforts and improve their overall estimates. It is good practice for each inventory agency to identify its national
key categories in a systematic and objective manner. Such a process will lead to improved inventory quality, as
well as greater confidence in the emission estimates that are developed.
Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories (GPG2000,
IPCC, 2000) identifies a key source category as “one that is prioritised within the national inventory systembecause its estimate has a significant influence on a country’s total inventory of direct greenhouse gases in termsof the absolute level of emissions, the trend in emissions, or both”. The concept of key sources was originallyderived for emissions excluding the LULUCF sector and as implemented in GPG2000 has enabled countries to
identify those source categories that should be estimated using higher tiers if sufficient resources are available.
In this report, the definition is expanded to also cover LULUCF emissions by sources and removals by sinks. In
this document whenever the term key category is used, it includes both sources and sinks. The inclusion of the
LULUCF categories in the key category analysis facilitates the determination of priorities across all sectors of
the national inventory and, where relevant, for Kyoto Protocol supplementary information as well.
Any inventory agency that has prepared a national greenhouse gas inventory will be able to identify key
categories in terms of their contribution to the absolute level of national emissions. For those inventory agencies
that have prepared a time series, the quantitative determination of key categories should include evaluation ofboth the absolute level and the trend of emissions and removals. Some key categories may only be identified
when their influence on the trend of the national inventory is taken into account.
The quantitative approaches to determine key categories are described in Section 5.4.2 (Quantitative Approaches
to Determining Key Categories). Both a basic Tier 1 approach and a Tier 2 approach, which takes uncertainties
into account, are described. In addition to making a quantitative determination of key categories, it is goodpractice to consider qualitative criteria, particularly when a Tier 1 assessment is performed or lower tier estimation
methods are used. These qualitative criteria are described in Section 5.4.3 (Qualitative Considerations). The goodpractice guidance provided in Sections 5.4.2 and 5.4.3 is applicable to the full inventory of emissions and removals.
For estimates prepared under Articles 3.3 and 3.4 of the Kyoto Protocol, there are additional considerations as
described in Section 5.4.4. The guidance on the application of results is given in 5.4.5. The derivation of thresholds
for the Tier 1 level and trend assessments taking the LULUCF sector into account is described in Section 5.4.7.
Finally, Section 5.4.8 gives an example of the application of the Tier 1 key category analysis.

5.4.2

5

Quantitative Approaches to Determining Key
Categories

In GPG2000 the concept was named “key source categories” and dealt with the inventory excluding the LULUCF sector.
However, because an inventory including the LULUCF sector can consist of both emissions and removals, the term "keycategory" is used here to better reflect that both sources and sinks are included. In the context of the UNFCCC inventory,
categories are land-use categories as described Table 3.1.1 in Chapter 3. In the context of the Kyoto Protocol, each activity
under Articles 3.3 and 3.4 (if elected) is a category.

IPCC Good Practice Guidance for LULUCF

5.29

Chapter 5: Cross- Cutting Issues

In each country’s national inventory, certain categories are particularly significant in terms of their contribution
to the overall uncertainty in the inventory. It is important to identify these key categories so that resources
available for inventory preparation may be prioritised and the best possible estimates prepared.
Two tiers for performing the key category analysis are described, consistent with the two-tiered quantitative
approach to identify key source categories described in Chapter 7 (Methodological Choice and Recalculations)of GPG2000. In the sections below, this approach is adapted to allow the incorporation of LULUCF categories.
The approach adapted for integrating the LULUCF categories is designed to address three objectives: (i) toenable continued assessment of key source categories without LULUCF (as is described in GPG2000); (ii) toassess the relative importance of LULUCF categories by integrating them into the overall key category analysis;and (iii) to be consistent with guidance and decisions of the Conference of the Parties to the UNFCCC and the
Kyoto Protocol regarding the identification of key categories.
With these objectives in mind, the key quantitative category analysis should be performed as follows:(i)

The key (source) categories should first be identified for the inventory excluding LULUCF (i.e., keycategories should be identified for the energy, industrial processes, solvent and other product use,
agriculture, and waste sectors) following the guidance in GPG2000, Chapter 7 (Methodological Choice
and Recalculation).

(ii)

The key category analysis then should be repeated for the full inventory including the LULUCF categories.
It is possible that some non-LULUCF categories identified as key in the first analysis will not appear as key
when the LULUCF categories are included. In this case, these categories should still be considered as key. Ina few cases, in countries with small net LULUCF emissions or removals, the integrated analysis may
identify additional non-LULUCF categories as key. In this situation, the analysis performed for the nonLULUCF sectors should be used to identify the key categories in those sectors, and the additional nonLULUCF categories identified in the combined analysis should not be considered as key.

Any agency that has developed an essentially complete greenhouse gas inventory can perform a Tier 1 Level
Assessment to identify key source or sink categories for the overall emission level. Those inventory agencies thathave developed emission inventories for more than one year will also be able to perform a Tier 1 Trend
Assessment to identify key categories that influence the trend in emissions. If national category uncertainties orparameter uncertainties are available, inventory agencies can use Tier 2 to identify key categories. The Tier 2
approach is more detailed than the Tier 1 and is likely to reduce the number of key categories identified. The
Tier 2 approach may also take into account a higher complexity, for example assessing key activity data andestimation parameters separately. If both Tier 1 and Tier 2 analysis have been performed it is good practice to
use the results of the Tier 2 analysis.
Figure 5.4.1

Decision tree to identify key categories of sources and sinks
Areinventory
data available formore than
one year?

Determine key categories
using the Tier 1 Level
Assessment and qualitative
considerations

No

Yes
Are
country- specificuncertainty estimatesavailable for eachcategory
estimate?

No

Determine key categories
using the Tier 1 Level andTrend Assessment andqualitative considerations

Yes
Determine key categories using theTier 2 Level and Trend
Assessments (incorporating national
uncertainty estimates) andqualitative considerations

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IPCC Good Practice Guidance for LULUCF

Methodological Choice – Identification of Key Categories

The decision tree in Figure 5.4.1 shown above illustrates how inventory agencies can determine which approach
to use for the identification of key categories. This figure was modified from the Figure 7.1 in Chapter 7 of
GPG2000 to make it applicable to the LULUCF sector.

AGGREGATIO N LEVEL
The results of the analysis of key categories will be most useful if the analysis is done at the appropriate level ofdetail. For the LULUCF sector, the recommended level of analysis is the level of category nomenclature used in
Chapter 3, which is listed in Table 5.4.1 along with “special considerations” which provide additional
information on the key category analysis for various categories. Table 5.4.1 is adapted from Table 7.1 from
Chapter 7 of GPG2000 to include the categories of the LULUCF sector. It is reprinted with all source categories
and sectors included so as to facilitate the development of an integrated key category analysis. Each suggested
category for LULUCF activities in Table 5.4.1 comprises several subcategories and it is good practice to further
evaluate the significance of these subcategories for purposes of choosing appropriate methods and prioritisingresources. Following guidance provided in GPG2000, it is good practice to identify subcategories as key if theyaccount for 25-30 percent of the overall emissions or removals of the category. Table 3.1.3 in Chapter 3 lists thesubcategories associated with each category given in Table 3.1.1 in Chapter 3 for purposes of this analysis. For
example, carbon stock changes in soil and biomass can be distinguished within the “forest land remaining forestland” category. If a country prepares its estimates following the LUCF categories from the IPCC Guidelines,
they can map their estimates onto the categories listed in Table 5.4.1 by following the guidance given by Table
3.1.1 in Section 3.1.2 and details in the respective sections of Chapter 3.
Countries may choose to perform the quantitative analysis at a more detailed level. In this case possible
correlations should be taken into account (see the Tier 2 approach for uncertainty assessments described in
Section 5.2, Identifying and Quantifying Uncertainties). The assumptions about such correlations should be thesame when assessing uncertainties and identifying key categories. Table 5.4.1 indicates subcategories that can be
distinguished without the need to take correlations into account.
If data are available, the analysis can be performed for emissions and removals separately within a given
category. If this is not feasible it is important to apply the qualitative criteria to identify key categories insituations where emissions and removals cancel or almost cancel. See Section 5.4.3 for qualitative considerations.
TABLE 5.4.1
SUGGESTED IPCC SOURCE/SINK CATEGORIES FOR LULUCF AND NON-LULUCF a
Source/Sink Categories to be Assessed in Key Category
Analysis

Special Considerations

LULUCF
Forest land remaining forest land
Croplands remaining croplands
Grassland remaining grassland
Wetland remaining wetland
Settlements remaining settlements

Assess key categories separately for CO2, CH4 and N2O. If
the category is key, assess the significance of subcategories
by identifying those that contribute 25-30% to the total
level of emissions or removals from the category. For
information on the subcategories associated with eachcategory, see Table 3.1.1 and 3.1.3 in Chapter 3.

Conversion to forest land
Conversion to cropland
Conversion to grassland
Conversion to wetlandb

Conversion to settlements

In addition to the guidance above, assess the impact of all
deforestation occurring within the country according to thequalitative guidance provided in the sixth bullet Section
5.4.3.

Conversion to other land
ENERGYCO2 Emissions from Stationary Combustion

Disaggregate to the level where emission factors are
distinguished. In most inventories, this will be the main
fuel types. If emission factors are determined
independently for some subsource categories, these should
be distinguished in the analysis.

Non- CO2 Emissions from Stationary Combustion

Assess CH4 and N2O separately.

Mobile Combustion: Road Vehicles

Assess CO2, CH4 and N2O separately.

IPCC Good Practice Guidance for LULUCF

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Chapter 5: Cross- Cutting Issues

TABLE 5.4.1 (Continued)
SUGGESTED IPCC SOURCE/SINK CATEGORIES FOR LULUCF AND NON- LULUCF a
Mobile Combustion: Water- borne Navigation

Assess CO2, CH4 and N2O separately.

Mobile Combustion: Aircraft

Assess CO2, CH4 and N2O separately.

Fugitive Emissions from Coal Mining and HandlingIf this source is key, it is likely that underground mining willbe the most significant subsource category.

Fugitive Emissions from Oil and Gas Operations

This source category comprises several subsource categories
which may be significant. Inventory agencies should assess thissource category, if it is key, to determine which subsource
categories are most important.

INDUSTRIAL PROCESSESCO2 Emissions from Cement Production
CO2 Emissions from Lime Production
CO2 Emissions from the Iron and Steel Industry
N2O Emissions from Adipic Acid and Nitric Acid
Production

Assess adipic acid and nitric acid separately.

PFC Emissions from Aluminium Production
Sulfur hexafluoride (SF6) from Magnesium Production
SF6 Emissions from Electrical Equipment
SF6 Emissions from Other Sources of SF6SF6 Emissions from Production of SF6
PFC, HFC, SF6 Emissions from Semiconductor
Manufacturing

Assess emissions from all compounds jointly on a GWPweighted basis, since they are all used in similar fashions
in the process.

Emissions from Substitutes for Ozone Depleting
Substances (ODS Substitutes)

Assess emissions from all HFCs and PFCs used as substitutes
for ODS jointly on a GWP- weighted basis, given theimportance of having a consistent method for all ODS sources.

HFC- 23 Emissions from HCFC- 22 Manufacture
AGRICULTURE
CH4 Emissions from Enteric Fermentation in Domestic
Livestock

If this source category is key, it is likely that cattle, buffalo andsheep will be the most significant subsource categories.

CH4 Emissions from Manure Management

If this source category is key, it is likely that cattle andswine will be the most significant subsource categories.

N2O Emissions from Manure Management
CH4 and N2O Emissions from Savanna Burning

Assess CH4 and N2O separately.

CH4 and N2O Emissions from Agricultural Residue
Burning

Assess CH4 and N2O separately.

Direct N2O Emissions from Agricultural Soils
Indirect N2O Emissions from Nitrogen Used inAgriculture
CH4 Emissions from Rice Production
WASTE
CH4 Emissions from Solid Waste Disposal Sites
Emissions from Wastewater Handling

Assess CH4 and N2O separately.

Emissions from Waste Incineration

Assess CO2 and N2O separately.

OTHER

Other sources of direct greenhouse gas emissions not listed
above should also be included, if possible.

ab

In some cases, inventory agencies modify this list of IPCC source categories to reflect particular national circumstances.
Reservoirs can be distinguished in the analysis.

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IPCC Good Practice Guidance for LULUCF

Methodological Choice – Identification of Key Categories

The analysis can be performed using CO2-equivalent emissions calculated using global warming potentials(GWP) specified in the Guidelines for the preparation of national communications by Parties included in Annex
I to the Convention, Part I: UNFCCC reporting guidelines on annual inventories (UNFCCC Guidelines) and theAnnex to the Kyoto Protocol6. Each greenhouse gas from each source and sink category should be consideredseparately, unless there are specific methodological reasons for treating gases collectively. In the LULUCF
sector, for example, estimates will be prepared for emissions or removals of CO2, N2O and CH4. The key
category evaluation should be performed for each of these gases separately because the methods, emission
factors and related parameters differ for each gas.

5.4.2.1

T IER 1 METHOD TO IDENTIFY KEY CATEGORI ES OF
SOURCES AND SINKSThe Tier 1 method to identify key categories assesses the influence of various categories of sources and sinks on
the level, and possibly the trend, of the national greenhouse gas inventory. When the national inventory estimates
are available for several years, it is good practice to assess the contribution of each category to both the level andtrend of the national inventory. If only a single year’s inventory is available, a Level Assessment should be
performed.
The Tier 1 method can be readily completed using a spreadsheet analysis. Tables 5.4.2 and 5.4.3 illustrate theformat of the analysis. Separate spreadsheets are suggested for the Level and Trend Assessments because it isnecessary to sort the results of the analysis according to two different columns, and the output of the sorting
process is more difficult to track if the analyses are combined in the same table. Both tables use a format similar
to that described in Chapter 6 of GPG2000 (IPCC, 2000), Quantifying Uncertainties in Practice. Section 5.4.8
illustrates the application of the Tier 1 approach.

LEVEL ASSESSMENT
The contribution of each source or sink category to the total national inventory level is calculated according toEquation 5.4.1:
EQUATION 5.4.1
LEVEL ASSESSMENT (TIER 1)
Key Category Level Assessment = Source or Sink Category Estimate/ Total Contribution
Lx,t *= Ex,t* / Et*
Where:
Lx,t* = level assessment for source or sink x in year t. The asterisk (*) indicates that contributions
from all categories (including LULUCF categories) are entered as absolute values.
Ex,t*= Ex,t : absolute value of emission or removal estimate of source or sink category x in year t

Et*= ∑ E x ,t : total contribution, which is the sum of the absolute values of emissions and removals
xin year t. The asterisk (*) indicates that contributions from all categories (including LULUCF
categories) enter as absolute values.
Because both emissions and removals are entered with positive sign7, the Total Contribution
may be larger than a country’s total emissions less removals.8
Table 5.4.2 outlines a spreadsheet that can be used for the Level Assessment. This spreadsheet is to be applied inaddition to the assessment for non- LULUCF sources, as described in GPG2000, Table 7.2 in Chapter 7

6

The methodology is also generally applicable using other weighting schemes, but the threshold for the Tier 1 analysis wasderived based on the GWP concept and may be different under other weighting schemes.

7

Removals are entered with absolute values to avoid an oscillating cumulative value Lx,t as could be the case if removals
were entered with negative signs, and thus to facilitate straightforward interpretation of the quantitative analysis.

8This equation can be used in any situation, regardless of whether the national greenhouse gas inventory is a net source (asis most common) or a net sink.

IPCC Good Practice Guidance for LULUCF

5.33

Chapter 5: Cross- Cutting Issues(Methodological Choice and Recalculation). Section 5.4.8 provides an example of the application of the Tier 1
method.
TABLE 5.4.2
SPREADSHEET FOR THE TIER 1 ANALYSIS – LEVEL ASSESSMENT INCLUDING LULUCF CATEGORIESA
IPCC Source/Sink
Categories

B
Direct Greenhouse
Gas

C
Base orCurrent Year Estimateof Emissions orRemovals(absolute value)D
Level Assessmentwith LULUCF,
from column C

E
Cumulative Total of
Column D

Total

Where:
Column A : list of IPCC categories of sources and sinks (see Table 5.4.1)
Column B : direct greenhouse gas
Column C : base year or current year emissions or removals of each greenhouse gas, in CO2- equivalent
units. Removal estimates entered with absolute values (positive signs)
Column D : level assessment with LULUCF from column C, following Equation 5.4.1
Column E : cumulative total of Column D
In the table, the calculations necessary for the Level Assessment are computed in Column D, following Equation
5.4.1. Thus, the value of the Level Assessment including LULUCF should be entered in column D for eachcategory. All entries in Column D should be positive because absolute values of sinks are entered for removal
estimates in Column C. The sum of all entries in Column D is entered in the total line of this table (note that thistotal will not be the total net emission (or net removal)). Once the entries in Column D are computed, thecategories should be sorted in descending order of magnitude and the cumulative total summed in Column E.
Key categories including LULUCF are those that, when summed together in descending order of magnitude, add
up to 95 % of the total in Column D. The rationale for the choice of threshold for the Tier 1 method is explainedin the Section 5.4.7. The method builds on GPG2000 and Rypdal and Flugsrud (2001). It is also good practice toexamine categories identified between the 95 and 97 % threshold carefully with respect to the qualitative criteria(see Section 5.4.3).
The Level Assessment should be performed for all years for which inventory estimates are available. If previous
inventory estimates have not changed, there is no need to recalculate the previous years’ analysis. If any
estimates have changed or been recalculated, however, the analysis for that year should be updated. Any
category that meets the threshold in any year should be identified as a key category.

TREND ASSESSMENT
The contribution of each source or sink category to the trend in the total inventory can be assessed if more than
one year of inventory data are available, according to Equation 5.4.2.
EQUATION 5.4.29
TREND ASSESSMENT (TIER 1)
Source or Sink Category Trend Assessment =(Source or Sink Category Level Assessment) ● (Source or Sink Category Trend – Total Trend) Tx,t* = Ex,t* / Et ●  [( Ex,t – EX,0 ) / Ex,t ] – [ ( Et – E0 ) / Et] 
Where:
Tx,t*9= trend assessment, which is the contribution of the source or sink category trend to the overall
inventory trend. The Trend Assessment is always recorded as an absolute value, i.e., a negative

Norwegian Pollution Control Authority with Rypdal and Flugsrud (2001).

5.34

IPCC Good Practice Guidance for LULUCF

Methodological Choice – Identification of Key Categories

value is always recorded as the equivalent positive value. The asterisk (*) indicates that, incontrast to Equation 7.2, in Chapter 7 of the GPG2000, LULUCF sources and sinks can beevaluated using this equation.
Ex,t*= Ex,t absolute value of emission or removal estimate of source or sink category x in year t

Ex,t and Ex,0 = real values of estimates of source or sink category x in years t and 0, respectively
Et and E0= ∑ E x , t and ∑ E x ,0 total inventory estimates in years t and 0, respectively. Et and E0 differxxfrom Et* and E0* in Equation 5.4.1 in that removals are not entered as absolute values.
The Source or Sink Category Trend is the change in the source or sink category emissions or removals over time,computed by subtracting the base year (year 0) estimate for source or sink category x from the current year (yeart) estimate and dividing by the current year estimate.10
The Total Trend is the change in the total inventory emissions (or removals) over time, computed by subtracting
the base year (year 0) estimate for the total inventory from the current year (year t) estimate and dividing by thecurrent year estimate.
In circumstances where the current year emissions for a given category are zero, the expression may bereformulated to avoid zero in the denominator (Equation 5.4.3).11
EQUATION 5.4.3
TREND ASSESSMENT WITH ZERO CURRENT YEAR EMISSIONS 12

Tx,t* =  EX,0 / Et 
The Trend Assessment will identify categories that have a different trend as compared to the trend of the overall
inventory. As differences in trend are more significant for the overall inventory level for larger categories ofemissions and removals (in absolute terms), the results of the trend difference (i.e., the category trend minus total
trend) is multiplied by  Ex,t* / Et to provide appropriate weighting. Thus, key categories will be those where thecategory trend diverges from the total trend, weighted by the level of emissions or removals of the category.
Table 5.4.3 outlines a spreadsheet that can be used for the Trend Assessment. This spreadsheet is to be applied inaddition to the assessment for non-LULUCF sources, as described in GPG2000, Chapter 7, Methodological
Choice and Recalculation, Table 7.3. Section 5.4.8 provides and example of the application of the Tier 1 method.

TABLE 5.4.3
SPREADSHEET FOR THE TIER 1 ANALYSIS – TREND ASSESSMENT INCLUDING LULUCF CATEGORIES
A

B

IPCC
Source/Sink
Categories

DirectGreenhouse
Gas

C
Base Year
Estimate

D
Current Year
Estimate

E
Trend
Assessment

F%
Contribution
to Trend

G
Cumulative
Total of
Column F

Total

10

Although it is common to look at growth rates in the form of (Et – E0) / E0, where the growth rate is measured from an
initial value in year 0, the functional form of Equation 7.2 in Chapter 7 of GPG2000 has been designed to minimise
occurrences of division by zero and to enable analysis of the importance of source categories with very low emissions in
the base year (e.g., substitutes for ozone depleting substances).

11

Although this equation was not shown in GPG2000, it is also generally applicable to non- LULUCF categories as it has
been derived from Equation 5.4.2.

12This results applies when Ex,t=0 is inserted into Equation 5.4.2.

IPCC Good Practice Guidance for LULUCF

5.35

Chapter 5: Cross-Cutting Issues

Where:
Column A : list of IPCC categories (see Table 5.4.1)
Column B : direct greenhouse gas
Column C : base year estimate of emissions or removals from the national inventory data,
in CO2-equivalent units. Sinks are entered with signed values (positive or negative values).
Column D : current year emissions estimate from the most recent national inventory data,
in CO2-equivalent units. Sinks are entered with signed values
Column E : trend assessment from Equation 5.4.2, recorded as an absolute value
Column F : percentage contribution to the total of assessments in column E
Column G : cumulative total of Column F, calculated after sorting the entries in Column F in descendingorder of magnitude
The LULUCF categories identified in this analysis should be considered key in addition to those identified in theanalysis that does not include LULUCF emissions and removals. If additional non-LULUCF categories are
identified as key when LULUCF is included in the analysis, these should not be initially considered key, butshould be carefully examined using the qualitative considerations.
The entries in Columns A, B and either C or D should be identical to those used in the Table 5.4.2, Spreadsheet
for the Tier 1 Analysis - Level Assessment. The base year estimate in Column C is always entered in the
spreadsheet, while the current year estimate in Column D will depend on the year of analysis. The absolute valueof Tx,t should be entered in Column E for each category of sources and sinks, following Equation 5.4.2, and thesum of all the entries entered in the total line of the table.13 The percentage contribution of each category to thetotal of Column E should be computed and entered in Column F. The categories (i.e., the rows of the table)
should be sorted in descending order of magnitude, based on Column F. The cumulative total of Column Fshould then be computed in Column G. Key categories are those that, when summed together in descendingorder of magnitude, add up to more than 95 % of the total of Column E. An example of a Tier 1 analysis for thelevel and trend is given in Section 5.4.8.

5.4.2.2

T IER 2 METHOD TO IDENTIFY KEY CATEGORI ES OF
SOURCES AND SINKS

The more sophisticated Tier 2 approach to identify key categories of sources and sinks is based on the results of
the uncertainty analysis described in Section 5.2 (Identifying and Quantifying Uncertainties) in this report, and in
GPG2000, Chapter 6 (Quantifying Uncertainties in Practice). The Tier 2 approach is consistent with, but notrequired for, good practice. Inventory agencies are encouraged to use Tier 2 if possible, because it will provide
additional insight into the reasons that particular categories are key and can assist in prioritising activities toimprove inventory quality and reduce overall uncertainty. It should be recognized that because the Tier 1 is a
simplified approach, the Tier 1 and Tier 2 approaches could result in a few differences in key categories. In suchsituations, the results of the Tier 2 approach should be utilized.
In particular, it is important to bear in mind that a LULUCF category can comprise large fluxes, and emissions
and removals may cancel out. In a Tier 2 analysis it may be possible to make the assessment at the level of evenmore detailed sub-estimates. In this case correlations need to be evaluated and modeled when appropriate. Whenthe analysis is based on Tier 1, these cases should be evaluated using the qualitative criteria as described in
Section 5.4.3.

APPLICATION OF UNCERTAI NTY ESTI MATES TO I DENTIF Y KEY
SOURCES AND SINKS CATEGORIESThe key category analysis may be enhanced by incorporating the national category uncertainty estimatesdeveloped in Section 5.2. Uncertainty estimates based on the Tier 1 approach described in Section 5.2 are
sufficient for the purpose, but estimates based on the Tier 2 uncertainty assessment approach should be used if
13

Unlike the Level Assessment, where all entries will be positive, in the Trend Assessment negative values will occur if
emissions of the source category decline by more in percentage terms than emissions in the overall inventory, or grow by asmaller amount. In this analysis the negative and positive values are considered equivalent, and the absolute values of these
are recorded in the table.

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IPCC Good Practice Guidance for LULUCF

Methodological Choice – Identification of Key Categories

available. The category uncertainties are incorporated by weighting the Tier 1 Level and Trend Assessment
results by the category’s relative uncertainty. The key category equations are shown below.

LEVEL ASSESSMENT
Equation 5.4.4 describes the Tier 2 Level Assessment including uncertainty. The results of this assessment (LUx,t)
is identical to the results of quantifying uncertainties in practice, as shown in Column H of Table 6.1 of Chapter
6 of GPG2000. So if that table has been completed, it is not necessary to recalculate Equation 5.4.4.
EQUATION 5.4.4
LEVEL ASSESSMENT (TIER 2)

Level Assessment with Uncertainty = Tier 1 Level Assessment ● Relative Category Uncertainty
LUx,t = Lx,t ● Ux,tWhere:
LUx,t =

Level assessment with uncertainty

Lx,t

=

computed as in Equation 5.4.1

Ux,t

=

relative category uncertainty in year t calculated as described in Section 5.2. The relative
uncertainty will always have a positive sign.

The key categories are identified by accounting for those that add up to 90 % of the total value of the total LUx,t.
This 90 % was the bases for the derivation of the threshold used in the Tier 1 analysis (see Section 5.4.7 andRypdal and Flugsrud (2001)).

TREND ASSESSMENT
Equation 5.4.5 shows how the Tier 2 Trend Assessment can be expanded to include uncertainty.
EQUATION 5.4.5
TREND ASSESSMENT (TIER 2)

Trend Assessment with Uncertainty = Tier 1 Trend Assessment ● Relative Category Uncertainty
TUx,t = Tx,t ● Ux,tWhere:
TUx,t =

trend assessment with uncertainty

Tx,t

=

trend assessment computed in Equation 5.4.2

Ux,t

=

relative category uncertainty in year t calculated as described in Section 5.2. The relative
uncertainty will always have a positive sign.

The key categories are identified by accounting for those that add up to 90 % of the total value of the total TUx,t.
This 90 % was the basis for the derivation of the threshold used in the Tier 1 analysis (see Section 5.4.7 andRypdal and Flugsrud (2001)).

INCORPORATING MONTE CARLO ANALYSISIn Section 5.2 (Identifying and Quantifying Uncertainties), Monte Carlo analysis is presented as the Tier 2
approach for quantitative uncertainty assessment. Whereas the Tier 1 uncertainty analysis is based on simplified
assumptions to develop uncertainties for each category, Monte Carlo types of analyses can handle large
uncertainties, complex probability density functions, correlations and complex emission estimation equations
among other things. The output of the Tier 2 uncertainty analysis can be used directly in Equations 5.4.4 and 5.4.5.
If uncertainties are asymmetrical, the larger difference between the mean and the confidence limit should be used.
Monte Carlo analysis or other statistical tools can also be used to perform a sensitivity analysis to directly
identify the principal factors contributing to the overall uncertainty. Thus, a Monte Carlo or similar analysis canbe a valuable tool for a key category analysis. The method can, for example, be used to analyze moredisaggregated sources categories (by modelling correlations) and emission factors and activity data separately (toidentify key parameters rather than key categories). The analysis of key parameters can be based on Equations

IPCC Good Practice Guidance for LULUCF

5.37

Chapter 5: Cross-Cutting Issues

5.4.4 and 5.4.5 above, by compiling correlations coefficients between input and output (Morgan and Henrion,1990) or on other appropriate techniques.

5.4.3

Qualitative Considerations

In some cases, the results of the Tier 1 or Tier 2 analysis of key categories may not identify all categories thatshould be prioritised in the inventory system. In GPG2000, a list of qualitative criteria was provided to address
specific circumstances that could not be readily reflected in the quantitative assessment. These criteria should beapplied to categories not identified in the quantitative analysis, and if additional categories are identified they canbe added to the list of key categories.
The qualitative considerations identified in Chapter 7 of GPG2000 have been refined slightly to reflect the
LULUCF sector:•

Mitigation techniques and technologies: If emissions from a category are being reduced or removals increased
through the use of climate change mitigation techniques, it is good practice to identify these categories as key.

•

High expected growth of emissions or removals: If the inventory agency expects emissions or removals
from a category to grow significantly in the future, they are encouraged to identify that category as key.
Some of these categories will be identified by the Trend Assessment or will be identified in the future.
Because it is important to implement a higher tier good practice method as soon as possible, however, early
identification using qualitative criteria is important.

•High uncertainty: If the inventory agency is not taking uncertainty explicitly into account by using the Tier 2
method to identify key categories, they may want to identify the most uncertain categories as key. This isbecause the largest reductions in overall inventory uncertainty can be achieved by improving estimates ofhighly uncertain categories.

•

Unexpectedly high or low emissions or removals: When emissions or removals are far higher or lower thanwould be expected using the methods in the IPCC Guidelines or those described in Chapters 3 and 4 of thisreport (for example, due to the use of a national emission factor), these categories should be designated as
key. Particular attention should also be paid to QA/QC (Section 5.5) and documentation for these categories.

•

Large stocks: When a small net flux results from the subtraction of large emissions and removals, theuncertainty can be very high. Thus, when moving from the Tier 1 to higher tier estimation methods the orderof IPCC Source Categories may change and previously insignificant categories may become significant.

•Deforestation: In the quantitative key category analysis, deforestation is spread out under the different landuse change categories (e.g., Lands converted to grassland are considered separately from Lands converted tocropland). To ensure consistency with the IPCC Guidelines, countries should identify and sum up theemission estimates associated with forest conversion to any other land category. “Deforestation” should beconsidered key if the sum is larger than the smallest category considered key in the quantitative analysis. In
this case, countries can further examine which land conversions are significant (i.e., account for more than
30 percent) of the estimate and classify them as key.

•Completeness: Neither the Tier 1 nor the Tier 2 approach gives correct results if the inventory is notcomplete. The analysis can still be performed, but there may be key categories among those not estimated.
In these cases it is good practice to qualitatively examine potential key categories applying the qualitative
considerations above. IPCC Guidelines (IPCC, 1997), GPG2000 (IPCC, 2000) and this report list potential
categories of sources and sinks. The inventory of a country with similar national circumstances can also
often give good indications on potential key categories.

For each key category identified, the inventory agency should determine if certain subcategories are particularly
significant (i.e., represents a significant share of the emissions or removals). It is good practice to identify what
subcategories are particularly important and focus efforts towards methodological improvements on thesesubcategories.

5.4.4

Identifying Key Categories under Kyoto Protocol
Articles 3.3 and 3.4

The concept of key categories can also be used for choosing the good practice estimation methods for emissions
and removals due to activities under Articles 3.3 and 3.4 of the Kyoto Protocol to the UNFCCC. The key

5.38

IPCC Good Practice Guidance for LULUCF

Methodological Choice – Identification of Key Categories

categories for Kyoto Protocol reporting can be identified following the guidance in this section. Detailed
guidance is provided in Chapter 4 on how to take the key category determination into account in methodologicalchoice for estimates prepared under the Kyoto Protocol.
Taking into consideration that there is not any experience with the preparation of these estimates under the
Kyoto Protocol, it is suggested that the basis for assessment of key categories under Articles 3.3 and 3.4 of the
Kyoto Protocol is the same as the assessment made for the UNFCCC inventory. Whenever a category is
identified as key in the UNFCCC inventory, the associated activity under the Kyoto Protocol should beconsidered as key in reporting under the Kyoto Protocol.14 The identification of key categories under the Kyoto
Protocol will also have to include some qualitative assessments as there is not always an unambiguous
correspondence between the UNFCCC categories and Kyoto Protocol activities. A country may also undertake aquantitative Tier 2 approach to identify the key categories of their inventory including the Kyoto Protocol
activities. The results of this assessment will in most circumstances result in fewer LULUCF key categories.
Table 5.4.4 can be used to establish the relationship between categories in Chapter 3 and Chapter 4 for purposesof identifying key categories under Articles 3.3 and 3.4 of the Kyoto Protocol.

TABLE 5.4.4
RELATIONSHIP BETWEEN ACTIVITIES IDENTIFIED IN CHAPTER 3 AND CHAPTER 4
AND IPCC SOURCE/SINK CATEGORIES FOR LULUCF
1Chapter 3 Categories

2
Chapter 4 Categories

3
Key category if item in Column 1
was identified as key in theanalysis of the UNFCCC
inventorya

FOREST LAND
Forest land remaining forest land (managed)

FM, GM, CM

Land converted to forest land (managed)

AR

CROPLAND
Cropland remaining cropland

CM, RVLand converted into cropland

D, RV, CM

GRASSLAND
Rangeland and grassland remaining rangelandand grassland (managed)

GM, RVLand converted to rangeland and grassland(managed)

D, RV , GM

WETLANDS
Wetlands remaining wetlands (managed)

RVLand converted to wetlands

D, RV

SETTLEMENTS
Settlements remaining settlements

RVLand converted to settlements

D, RV

ab

OTHER LAND

Other land remaining other land
Land converted to other landDa

Article 3.4 activities only when electedb
Theoretically revegetation can occur in both subcategories.
FM: forest management, AR: afforestation and reforestation, CM: cropland management, D: deforestation, RV: revegetation,
GM: grazing land management.

14This applies also when there only are partial overlaps with the UNFCCC inventory.

IPCC Good Practice Guidance for LULUCF

5.39

Chapter 5: Cross-Cutting Issues

The left column lists the categories of Chapter 3 that may have been used in the key category analysis of the
UNFCCC inventory15. If any of these are identified as key, the Kyoto Protocol activities in the corresponding
right column should initially be considered key. However, as in some cases several Kyoto Protocol activities
potentially can be key, it is good practice to qualitatively examine which of the possible activities actually are
key. For example, if land converted to rangeland and grassland was identified as key, this can involve
deforestation, revegetation, grassland management or land-use changes not covered by the Kyoto Protocol. The
land area affected by revegetation may be much smaller than the land area of the Chapter 3 category in which it
occurs. If this is the case, and if revegetation is identified as potentially key according to Table 5.4.4, thencountries may separately assess the importance of greenhouse gas emissions and removals in revegetationcompared to the other category (or categories). It is good practice to explain and document which of thepotential key categories are finally identified as key for Kyoto Protocol reporting.
In addition, it is good practice to take into account the following considerations in the key category
determination for estimates prepared under Articles 3.3 and 3.4 of the Kyoto Protocol:•

As shown in Table 5.4.4., several activities under the Kyoto Protocol can occur in more than one category of
the UNFCCC inventory. In such cases, it is good practice to consider the total emissions and removals fromthe activity for purposes of the key category analysis. When this approach is needed, an activity should beconsidered key if the emissions or removals from the sum are greater than the emissions from the smallest
category that is identified as key in the UNFCCC inventory (including LULUCF).

•

If, when using the quantitative methods, a category is not identified as key for the present year but it isanticipated to strongly increase in the future, it should be designated as key. This could, for example, occur
with a large-scale afforestation programme producing only small sinks in initial years, but with the
expectation of larger yields later.

•

In some cases, it is possible that the emissions or removals from an activity under the Kyoto Protocol could
exceed the emissions or removals of the associated category in the UNFCCC inventory. In such a case the
Kyoto Protocol activity should be identified as key if its emissions/removals exceed the emissions of thesmallest category that is identified as key in the UNFCCC inventory (including LULUCF).

For each key category, the inventory agency should determine if certain subcategories are particularly significant(i.e., represent a significant share of the emissions or removals). For example, if cropland management has been
elected and is identified as key, it is good practice to identify what subcategories are particularly important andfocus efforts towards methodological improvements on these subcategories. As described in Section 5.4.2.2, thequantitative key category assessment can only be made at a more disaggregated level if correlations between
input data can be taken into account.
Because there will be special requirements related to methodologies and verification for estimates for LULUCF
projects under Articles 6 and 12 of the Kyoto Protocol, projects have not been integrated into the key category
concept. Section 4.3 in Chapter 4 gives good practice guidance on how these estimates should be prepared for
the LULUCF inventories for reporting under the Kyoto Protocol.

5.4.5

Application of the Results

Identification of key categories in national inventories is important because the resources available for preparing
inventories are finite and their use should be prioritised. It is essential that estimates be prepared for all
categories, in order to ensure completeness. As far as possible, key categories should receive special
consideration in terms of two important inventory aspects. Figure 5.4.2 illustrates a decision tree to choose agood practice method, which is modified from Figure 7.4 of Chapter 7 of GPG2000 to make it applicable to the
LULUCF sector.

15

If the analysis was based on the IPCC source/sink categories (1996) the transformation will be less precise. The mapping isshown in Chapter 3, Section 3.1.

5.40

IPCC Good Practice Guidance for LULUCF

Methodological Choice – Identification of Key Categories

Figure 5.4.2

Decision tree to choose a good practice methodIsthe category
considered a key
category?

No

Choose agood practicemethod appropriate
to available data

Yes

Are thedata available tofollow category-specific goodpractice guidance related to
the key
categories?

Yes

Estimate emissions andremovals following
category-specific goodpractice guidance forkey categories

NoCan
data be collectedwithout significantly
jeopardising the resources
for other key
categories?

No

Yes

Make arrangements
to collect data

Choose a good practicemethod appropriate toavailable data anddocument why categoryspecific guidance cannot
be followed

First, additional attention ought to be focused on key categories with respect to methodological choice. As
shown in the decision tree in Figure 5.4.2, inventory agencies are encouraged to use category-specific goodpractice methods for key categories, unless resources are unavailable. For most categories, higher tier (i.e., Tiers
2 and 3) methods are suggested for key categories, although this is not always the case. For guidance on thespecific application of this principle to key categories, inventory agencies should refer to the decision trees in
Chapter 3. There may be special requirements for methodological choice when reporting under Articles 3.3 and3.4 of the Kyoto Protocol. These requirements are explained in Chapter 4 of this report.
Second, it is good practice for key categories to receive additional attention with respect to quality assurance andquality control (QA/QC). In Section 5.5, detailed guidance is provided on QA/QC for the LULUCF categories in
the inventory.

5.4.6

Reporting and Documentation

It is good practice to clearly document the key categories in the inventory. This information is essential for
explaining the choice of method for each category. In addition, inventory agencies should list the criteria bywhich each category was identified as key (e.g., level, trend, or qualitative), and the method used to conduct thequantitative key category analysis (e.g., Tier 1 or Tier 2). Table 5.4.5 can be used to document the results of the
key category analysis.

IPCC Good Practice Guidance for LULUCF

5.41

Chapter 5: Cross-Cutting Issues

TABLE 5.4.5
KEY CATEGORY ANALYSIS SUMMARY
Quantitative Method Used for Key Category Analysis:

Tier 1 ❐Tier 2 ❐

A

B

C

D

E

IPCC Source/Sink
Category

Direct Greenhouse
Gas

Key Category Flag
(Yes or No)

If C is Yes, Criteria
for Identification

Comments

Where:
Column A : list of IPCC categories – entry should be the same as column A in Tables 5.4.2 and 5.4.3
Column B : direct greenhouse gas – entry should be the same as column B in Tables 5.4.2 and 5.4.3
Column C : key category flag – enter ‘Yes’ if the category is key
Column D : criteria by which key category was identified – for each key category identified in Column
C, enter one or more of the following: ‘Level’ for Level Assessment, ‘Trend’ for Trend
Assessment, or ‘Qualitative’ for qualitative criteria
Column E : comments - enter any explanatory material

5.4.7

Derivation of Threshold for the Tier 1 Key Category
Analysis

The thresholds for the level and trend were derived using the same methodology as used in GPG2000, but with amore complete data set, longer time series and with LULUCF included. The GPG2000 method of determining
the threshold was documented in more detail in Flugsrud et al. (1999). For the level threshold, the relationshipbetween the percentage of the emissions and the sum of uncertainties of each source or sink category wascompiled for the reported greenhouse gas inventories of 30 Parties included in Annex I to the United Nations
Framework Convention on Climate Change (UNFCCC). As in GPG2000 the threshold was determined to cover
90 % of the sum of uncertainties of each category as this typically gives 10 to 15 key source categories (Rypdal
and Flugsrud 2001). The analysis is based on data received from the UNFCCC Secretariat for 1990 and 1999 (byMay 2002). The dataset used to determine the trend threshold is more limited, including only 16 countries, as
fewer countries have reported sufficiently detailed data for both years.

5.4.7.1

A SSUMPTIONS ABOUT UNCERTAINTIESThe analysis is based on the assessment of uncertainties in Table 5.4.6 . Sensitivity analysis shows the results to
be rather robust with respect to the assumptions made about uncertainties. For the sources under non-LULUCF
sectors the assumed uncertainties are: CO2 5%, CH4 25 %, N2O 100%. Non-CO2 greenhouse gases (N2O andCH4) were included for the LULUCF sector to the extent that they have been reported, assuming uncertainties as
for the non-LULUCF sector.
TABLE 5.4.6
ASSUMED UNCERTAINTIES TO DETERMINE A KEY CATEGORY THRESHOLD INCLUDING LULUCFNet CO2 emissions or removal uncertainties
Changes in forest and woody biomass

5.42± 50 %

Forest and grassland conversion- 50 to + 100 %Abandonment of managed land

- 50 to + 100 %Emissions and removals from soil

- 50 to + 100 %Other LULUCF- 50 to + 100 %IPCC Good Practice Guidance for LULUCF

Methodological Choice – Identification of Key Categories

5.4.7.2

E MISSION LEVELIn GPG2000 the threshold value was determined to be 95% of total emissions. The pattern of emission estimatesneeded to account for 90% of the sum of category uncertainties in the dataset including LULUCF is similar tothe one seen previously (as shown in Figure 5.4.3 below).
Figure 5.4.3

Cumulative uncertainty plotted against cumulative emissions

100 %Cumulative uncertainty

90 %
80 %
70 %
60 %
50 %
40 %
30 %
20 %
10 %
0%

0%

90 %

99 %
99.9 %
Cumulative emission

99.99 %Note:

The dotted lines show the division of the 95% threshold at 90% of sum of contribution from uncertainties.

Source:Data reported by Parties to the UNFCCC and assumed uncertainties.

Fraction of emissions required to reach 90% of sum of contribution fromuncertainties in different inventories. With and without LULUCF (with
LULUCF using absolute values of emissions).

Fraction of emissions required toreach 90% of uncertainty

Figure 5.4.4

99% - < 100%98% - < 99%97% - < 98%
96% - < 97%
95% - < 96%94% - < 95%
93% - < 94%
92% - < 93%
91% - < 92%
90% - < 91%
85% - < 90%
70% - < 85%

0

2

4

6

8

10

Number of inventories
Without LUCF
Source:With LUCF

Data reported by Parties to the UNFCCC and assumed uncertainties

IPCC Good Practice Guidance for LULUCF

5.43

Chapter 5: Cross-Cutting Issues

Figure 5.4.4 shows that when emissions and removals from LULUCF are included, a slightly smaller fraction of
total emissions (by absolute value) is required to account for 90% of sum of source and sink category
uncertainties. For the 30 inventories analysed, the median fraction was 97.1% without LULUCF and 96.8% with
LULUCFs. The reason is that some of emissions or removals from LULUCF are large and with high uncertainty.
The threshold would need to be very high to be able to identify all Tier 2 key categories in all inventories. It is
important to bear in mind that the Tier 2 approach is the most rigorous approach to determine key categories as
the uncertainty is taken into account. A high threshold would mean that many non-key categories according toTier 2 are defined in the Tier 1 approach. For this reason, it was determined to be most effective to set thethreshold to 95% and to advise countries to apply qualitative criteria to the categories between 95 and 97%.
The conclusion is that the previously determined threshold of 95% is also recommended for the integrated
analysis including LULUCF categories.

5.4.7.3

T REND

The threshold was set to identify 90% of the sum of Tx,t* (Equation 5.4.2) in the inventories. Figure 5.4.5 shows
the same pattern for trend as Figure 5.4.4 for the level. When emissions and removals from LULUCF are
included, a smaller fraction of total assessment (by absolute value) is required to account for 90% of the sum of
Tx,t*16. The reason is again that some of the emissions and removals from LULUCF have large contribution totrend and high uncertainty.
Fraction of emissions required to reach 90% of sum of contribution fromtrend uncertainty in different inventories. With and without LULUCF (with
LULUCF using absolute values of emissions).

Fraction of emissions required toreach 90% of trend uncertainty

Figure 5.4.5

98% - < 100%96% - < 98%
94% - < 96%92% - < 94%
90% - < 92%
88% - < 90%
86% - < 88%
84% - < 86%
82% - < 84%
80% - < 82%

0

1

2

3

4

5

6

Number of inventories
Without LUCF
Source:16

With LUCF

Data reported by Parties to the UNFCCC and assumed uncertainties

The available data did not make it feasible to include HFCs, PFCs and SF6 in the analysis. However, these gases should be
included, if possible, when the method is applied.

5.44

IPCC Good Practice Guidance for LULUCF

Methodological Choice – Identification of Key Categories

5.4.8

Example of Tier 1 Key Category Analysis

The example illustrates the application of the Tier 1 approach based on the submitted inventory for an Annex I
country. Both the level and trend assessment is shown.
TABLE 5.4.7
EXAMPLE OF A LEVEL ASSESSMENTa
A

B

Direct
IPCC Source
Greencategories
house(IPCC 1996)
Gases
Sum

Base orBase orCurrent
Current
Year
Year
Estimate
Estimate
nonLULUCF
LULUCFC
D’
E’D
E
Base or
Level
Level
Cumulative
Current Assessment
Assessment
Total of
CumulativeYear
without
with
Column D
Total of
Estimate LULUCF,
LULUCF, (additional
Column D’
Absolute from column
from column LULUCF
Value
C
C
sources)

535375- 61309643884b1

1

1.AA.3CO2138822..

138822

0.259

0.259

0.216

0.216

1.AA.4CO2102167..

102167

0.191

0.450

0.159

0.374

5.A

CO2

..

- 84861

84861

..

0.450

0.132

0.506

1.AA.2

CO2

77213

..

77213

0.144

0.594

0.120

0.626

1.AA.1

CO2

61389

..

61389

0.115

0.709

0.095

0.721

4.D

N2O

51152

..

51152

0.096

0.805

0.079

0.801

4.A

CH4

27942

..

27942

0.052

0.857

0.043

0.844

6.A

CH4

16440

..

16440

0.031

0.887

0.026

0.870

5.B

CO2

..

12540

12540

..

0.887

0.019

0.889

2.B

N2O

11093

..

11093

0.021

0.908

0.017

0.906

2.A

CO2

10371

..

10371

0.019

0.928

0.016

0.923

5.E

N2O

..

5550

5550

..

0.928

0.009

0.931

1.B.2

CO2

4006

..

4006

0.007

0.935

0.006

0.937

4.B

CH4

3644

..

3644

0.007

0.942

0.006

0.943

2.C

CO2

3443

..

3443

0.006

0.948

0.005

0.948

5.D

CO2

..

3370

3370

..

0.948

0.005

0.954

1.AA.3

N2O

3174

..

3174

0.006

0.954

0.005

0.959

4.B

N2O

3109

..

3109

0.006

0.960

0.005

0.963

1.AA.4

CH4

2817

..

2817

0.005

0.965

0.004

0.968

2.B

CO2

2723

..

2723

0.005

0.970

0.004

0.972

1.B.1

CH4

2658

..

2658

0.005

0.975

0.004

0.976

6.C

CO2

2287

..

2287

0.004

0.980

0.004

0.980

1.B.2

CH4

1906

..

1906

0.004

0.983

0.003

0.983

5.E

CH4

..

1880

1880

..

0.983

0.003

0.986

1.AA.4

N2O

1456

..

1456

0.003

0.986

0.002

0.988

3.A

CO2

823

..

823

0.002

0.987

0.001

0.989

1.AA.2

N2O

796

..

796

0.001

0.989

0.001

0.990

1.AA.1

N2O

683

..

683

0.001

0.990

0.001

0.991

6.B

N2O

665

..

665

0.001

0.991

0.001

0.992

3.D

CO2

658

..

658

0.001

0.993

0.001

0.993

IPCC Good Practice Guidance for LULUCF

5.45

Chapter 5: Cross-Cutting Issues

TABLE 5.4.7 (CONTINUED)
EXAMPLE OF A LEVEL ASSESSMENT FOR AN ANNEX I COUNTRYa
A

B

Direct
IPCC Source
Greencategories
house(IPCC 1996)
Gases

Base orBase orCurrent
Current
Year
Year
Estimate
Estimate
nonLULUCF
LULUCFC
D’
E’D
E
Base or
Level
Level
Cumulative
Current Assessment
Assessment
Total of
CumulativeYear
without
with
Column F
Total of
Estimate LULUCF,
LULUCF, (additional
Column D
Absolute from column
from column LULUCF
Value
C
C
sources)

2.D

CO2

656

..

656

0.001

0.994

0.001

0.994

3.D

N2O

613

..

613

0.001

0.995

0.001

0.995

4.D

CH4

482

..

482

0.001

0.996

0.001

0.996

6.C

N2O

402

..

402

0.001

0.997

0.001

0.997

6.C

CH4

368

..

368

0.001

0.997

0.001

0.997

6.D

CH4

359

..

359

0.001

0.998

0.001

0.998

1.AA.3

CH4

312

..

312

0.001

0.999

0.000

0.998

6.B

CH4

282

..

282

0.001

0.999

0.000

0.999

5.B

CH4

..

236

236

..

0.999

0.000

0.999

4.C

CH4

163

..

163

0.000

0.999

0.000

0.999

3.B

CO2

136

..

136

0.000

1.000

0.000

1.000

1.AA.2

CH4

81

..

81

0.000

1.000

0.000

1.000

2.B

CH4

55

..

55

0.000

1.000

0.000

1.000

5.C

CO2

..

- 48

48

..

1.000

0.000

1.000

1.AA.1

CH4

28

..

28

0.000

1.000

0.000

1.000

5.B

N2O

..

24

24

..

1.000

0.000

1.000

1.B.2

N2O

0

..

0

0.000

1.000

0.000

1.000

a

Shaded cells of the table show values for cumulative assessment that identifies key categories for the level.

bThis sum differs from the sum of the two columns to the left because removals are summed up as absolute values.

5.46

IPCC Good Practice Guidance for LULUCF

Methodological Choice – Identification of Key Categories

TABLE 5.4.8
TREND ANALYSIS WITH LULUCFSa
A

B

C

D

E

F

G

IPCC Source
Categories(IPCC 1996)

DirectGreenhouse
Gas

Base Year
Estimate

Current Year
Estimate

Trend
Assessment% Contribution
to Assessment

Cumulative
Total of
Column F

486002474066

0.162226

1Sum
1.AA.3CO21191561388220.046486

0.28655

0.28655

2.B

N2O

27775

11093

0.03292

0.202928

0.489477

5.A

CO2- 75330- 84861

0.023418

0.144352

0.63383

1.AA.4CO294375

1021670.020804

0.128239

0.762069

1.AA.1

CO2

65495

61389

0.005139

0.031676

0.793745

2.A

CO2

13016

10371

0.004784

0.029492

0.823237

1.AA.2

CO2

76919

77213

0.004491

0.027681

0.850918

1.AA.3

N2O

1208

3174

0.004106

0.025310.876228

1.B.1

CH4

4331

2658

0.003225

0.019882

0.896109

4.A

CH4

30058

27942

0.002834

0.017467

0.913576

5.B

CO2

11710

12540

0.00230.014175

0.927751

6.A

CH4

17917

16440

0.002134

0.0131520.940903

2.C

CO2

4550

3443

0.002046

0.012613

0.953516

5.D

CO2

4051

3370

0.001197

0.007376

0.960892

4.D

N2O

52898

51152

0.000918

0.005659

0.966551

1.B.2

CH4

2199

1906

0.000493

0.003041

0.969592

2.B

CO2

3007

2723

0.000433

0.002667

0.972259

6.C

CO2

2133

2287

0.000425

0.002620.974879

1.B.2

CO2

4306

4006

0.000398

0.002456

0.977336

4.B

CH4

3537

3644

0.000398

0.002453

0.979789

5.E

N2O

5494

5550

0.000394

0.002428

0.982217

1.AA.4

CH4

3043

2817

0.000313

0.001927

0.984143

1.AA.4

N2O

1338

1456

0.000310.001913

0.986056

1.AA.1

N2O

561

683

0.000278

0.001714

0.98777

1.AA.3

CH4

453

312

0.000267

0.001648

0.989418

6.D

CH4

246

359

0.000245

0.001513

0.990931

3.B

CO2

252

136

0.000226

0.001394

0.992325

1.AA.2

N2O

731

796

0.000170.001049

0.993374

3.A

CO2

920

823

0.000153

0.000943

0.994317

6.B

N2O

612

665

0.000140.000861

0.995178

5.E

CH4

1861

1880

0.000134

0.000824

0.996002

4.B

N2O

3249

3109

0.000124

0.000766

0.996768

6.C

CH4

320

368

0.000115

0.000708

0.997477

6.C

N2O

357

402

0.000112

0.000689

0.998166

3.D

N2O

596

613

6.56E- 05

0.000404

0.99857

IPCC Good Practice Guidance for LULUCF

5.47

Chapter 5: Cross-Cutting Issues

TABLE 5.4.8 (CONTINUED)TREND ANALYSIS WITH LULUCFSa
A

B

C

D

E

F

G

IPCC Source
Categories(IPCC 1996)

DirectGreenhouse
Gas

Base Year
Estimate

Current Year
Estimate

Trend
Assessment% Contribution
to Assessment

Cumulative
Total of
Column F

6.B

CH4

259

282

5.91E- 05

0.000365

0.998935

5.B

CH4

221

236

4.27E- 05

0.000263

0.999198

1.AA.1

CH4

46

28

3.52E- 05

0.000217

0.999415

4.D

CH4

482

482

2.6E-05

0.000160.999575

4.C

CH4

180

163

2.57E- 05

0.000159

0.999733

2.D

CO2

681

656

1.65E- 05

0.0001010.999835

3.D

CO2

681

658

1.12E- 05

6.92E- 05

0.999904

2.B

CH4

53

55

6.85E- 06

4.22E- 05

0.999946

5.B

N2O

22

24

4.42E- 06

2.72E- 05

0.999974

5.C

CO2

- 48

- 48

2.43E- 06

1.5E-05

0.999989

1.AA.2

CH4

82

81

7.13E- 07

4.39E- 06

0.999993

1.B.2

N2O

..

0

5.74E- 07

3.54E- 06

0.999996

1.B.2

N2O

..

0

5.74E- 07

3.54E- 06

1aAdditional LULUCFs identified are shaded.

5.48

IPCC Good Practice Guidance for LULUCF