Description, use and calculation of the indicator

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Description of the indicators
How the indicator is used
How the indicator is calculated
Reporting units

Description of the indicators

The greenhouse gas (GHG) emissions indicator reports the trend in human-made greenhouse gas emissions at a national, provincial/territorial, and sectoral level for the six main greenhouse gases in Canada: carbon dioxide, methane, nitrous oxide, sulphur hexafluoride, perfluorocarbons, and hydrofluorocarbons.

The indicator is based on GHG emissions data taken directly from the 2006 National Inventory Report (NIR) prepared by Environment Canada, entitled National Inventory Report: 1990–2004, Greenhouse Gas Sources and Sinks in Canada.  As an Annex I Party (developed countries) to the United Nations Framework Convention on Climate Change (UNFCCC), Canada is required to prepare and submit a national inventory of anthropogenic sources and sinks of greenhouse gases on an annual basis.

Since direct measurement of emissions from all sources is not practical, the UNFCCC requires that countries develop, update, publish, and maintain national inventories using comparable emissions estimation methods.

Descriptions of the six greenhouse gases estimated and their main Canadian sources are outlined in Text table 1. Emissions from natural sources (material decay, plant and animal respiration, volcanic and thermal venting, etc.) and absorption of emissions by natural sinks (forests, oceans) are not measured by this indicator.

Text table 1 Greenhouse gas descriptions and main sources

Estimates are provided at the national level, the provincial/territorial level, and the sectoral level for five economic sectors: energy, industrial processes, solvent and other product use, agriculture, and waste. Provincial and territorial emission totals do not include emissions from consumption of halocarbons, or from fugitive refinery emissions, since the activity data associated with these sources are only available at the national level. Emission estimates for use of mineral products, such as limestone, dolomite, soda ash, and magnesite, are also not available at provincial and territorial levels. Ammonia production-related process emissions are included under “Undifferentiated Production” at the provincial level (Environment Canada, 2006).

Text table 2 provides a description of the main sources of the greenhouse gas emissions included in the indicator, broken down by economic sector.

Although the greenhouse gas emissions indicator is quite comprehensive, some emission sources have not been included as a result of exclusions within the NIR. Owing to their relatively small contributions to the total emissions, these exclusions do not significantly affect the overall completeness of the inventory. A detailed discussion of the emission sources not included can be found in Annex 5 of the NIR (Environment Canada, 2006). 

Data from the land use, land-use change and forestry sector are excluded from the national totals in the NIR and therefore are not included in the CESI report. The National Round Table on the Environment and the Economy’s Environment and Sustainable Development Indicators for Canada report recommended that the GHG indicator exclude sources and sinks from land-use change and forestry (National Round Table on the Environment and the Economy, 2003).

Text table 2  Sources of greenhouse gas emissions by sector

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How the indicator is used

The greenhouse gas emissions indicator is used to track progress in Canada’s efforts to lower emissions and reach our environmental performance objectives. Measuring the greenhouse gas emissions indicator in conjunction with economic performance indicators such as the gross domestic product (GDP) will help to support national-level decision making on sustainable development. Sectoral and geographic breakdowns have been used to inform policy development and emissions reduction plans.

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How the indicator is calculated

Data used to produce the greenhouse gas emissions indicator come directly from the NIR and do not undergo any further manipulation. The inventory follows the internationally approved methods developed by the Intergovernmental Panel on Climate Change (IPCC) to estimate emissions for the six greenhouse gases outlined in Text table 1. The IPCC guidelines (www.ipcc-nggip.iges.or.jp/public/gl/invs1.htm) are approved and developed through an international process that includes comments from national experts, testing of methods through preliminary inventory development, country studies, technical and regional workshops, and informal expert groups (IPCC, 1997).

Methods

In general, the same approach to estimating emissions is applied across the various gases and human activities. Emissions are estimated by multiplying activity data¹ by specific emission factors.²  At a simple level, the calculation is:

The IPCC guidelines provide various methods for calculating a given emission. The methods for estimating the gases are divided into “tiers” encompassing different levels of activity and technological detail. The same general structure is used, but the level of detail at which the calculations are carried out can vary. “Tier 1” methods are generally very simple, requiring less detail and expertise than the most complicated “Tier 3” methods. For example, electricity and heat generation could be measured using three different methods. A Tier 1 method would entail mass-balance calculations based on aggregated country-wide (or regional) statistics on consumption of basic fuels. A Tier 2 method would involve emission calculation by source types, based on fuel use for each industry and sector of the economy. A Tier 3 method would utilize source-specific data and could be used for only a small number of principal emission sources.

The intention of this tiered structure is to encourage countries to work at the most detailed level possible, while ensuring that for those countries that do not have detailed data, estimates can be made. The Tier 2 and Tier 3 methods are expected to produce more accurate emission estimates, but are more resource-intensive, as they usually require collection of more detailed data and a more thorough understanding of technologies.

Text table 3 describes the methods used to estimate some of Canada’s greenhouse gas emissions. This table illustrates that the selection of IPCC method type is highly dependent on the availability of data for emission factor development.

Text table 3  Types of methods employed in estimating selected sources for Canada’s GHG emissions

To better understand the variation and complexities that arise in estimation methods, the following two sections provide examples of the methods used to calculate greenhouse gas emissions. The first example provides an overview of the methods used to estimate emissions from fuel combustion, while the second illustrates how methane gas is estimated for Canadian dairy and beef cattle.

Example of estimating emissions: fuel combustion

The energy sector includes emissions of all greenhouse gases from the production and use of fuels for the primary purpose of delivering energy. Emissions in this sector are classified as either fuel combustion or fugitive releases.³

Emissions from fuel combustion for all energy sub-sectors are estimated using the following equation:

The fuel energy-use data used to estimate the combustion emissions are taken from Statistics Canada’s annual energy supply and demand report (Statistics Canada, 2005). The fuel- and technology-specific emission factors used to estimate the emissions can be found in Annex 13 of the NIR (Environment Canada, 2006). These factors are based upon the physical quantity of fuel combusted and are subdivided by the type of fuel used.

The equation above applies to all source sectors; however, more detailed methods are often used. Fuel combustion emissions attributed to the transport sector, for example, are calculated using Canada’s Mobile Greenhouse Gas Emission Model (MGEM05). This model is used to disaggregate fuel statistics into 23 categories that represent the estimated amount of fuel consumed by vehicles of similar emission characteristics determined as a function of their model year, fuel, and vehicle type. A detailed discussion of this specific method can be found in Section 3.1.3 of the NIR (Environment Canada, 2006).

Detailed example of applying the method: methane gas from enteric fermentation

National methane gas emission estimations for dairy and beef cattle are derived using methodologies provided by the IPCC and use the following calculation:

Methane emission estimates for Canadian dairy and beef cattle
where:
CH4 =		Enteric fermentation methane emissions for all animal categories
Pl =		Animal population (P) for each specific livestock category or sub-category (l)
EFl =		Methane emissions factor for each specific livestock category (l)
Methane emission estimates for Canadian cattle are calculated using the following steps:
Step 1:	Cattle are divided into two sub-categories based on the IPCC Tier-2 methodology, along with specific information on animal sub-category, physiological status, age, gender, weight, rate of gain, level of activity, and production environment.
Step 2:	Emission factors are calculated for each cattle sub-category (dairy cows, dairy heifers, beef cows, bulls, calves <1 year, heifer replacement, heifers >1 year, and steers >1 year) by province and then combined to produce a weighted national average emission factor.
Step 3:	National enteric emissions are calculated by multiplying the emission factor with its cattle sub-category population, and by summing up estimates for all cattle sub-categories.

For more detailed information on the methods used to estimate emissions in each source category, refer to Chapters 3 through 8 and Annexes 2 and 3 in the NIR (Environment Canada, 2006).

Reporting units

The greenhouse gas emissions indicator uses the same source categories as are used in the NIR, following the same sub-sector breakdown. This reporting format is agreed upon internationally, and groups emissions into the following six sectors: energy; industrial processes; solvent and other product use; agriculture; land use, land-use change and forestry; and waste. Each of these categories is further subdivided and follows UNFCCC sector and sub-sector divisions closely, with some minor differences. As previously discussed, the indicator does not include data from the land use, land-use change and forestry category. Refer to Text table 2 for a list of all source categories for which greenhouse gas emissions are estimated by the indicator.

Greenhouse gases differ in their ability to absorb heat in the atmosphere based on their chemical properties and lifetime in the atmosphere. For example, over a period of 100 years, methane is 21 times as powerful as carbon dioxide in terms of its potential to trap heat in the atmosphere, so it is considered to have a “global warming potential” of 21. Therefore, greenhouse gas emissions are reported in terms of “carbon dioxide equivalents,” determined by multiplying the amount of emissions of a particular gas by the global warming potential of that gas. The IPCC publishes the global warming potentials for each greenhouse gas (Text table 4).

Text table 4  Global warming potentials and atmospheric lifetimes

Notes

1. Activity data refers to the quantitative amount of human activity resulting in emissions during a given period of time. The annual activity data for fuel combustion sources, for example, are the total amounts of fuel burned. In the agriculture sector, annual activity data for methane emissions from enteric fermentation are the total number of animals, by species.

2. Based on samples of measurement data, emission factors are representative rates of emissions for a given activity level under a given set of operating conditions. They are the estimated average emission rate of a given pollutant for a given source, relative to units of activity.

3. These are intentional or unintentional releases of gases from fuel production activities. In particular, they may arise from the production, processing, transmission, storage, and use of fuels and include emissions from combustion only when it does not support a primary activity, e.g., flaring of natural gases at oil and gas production facilities (Environment Canada, 2006).