Data sources and methods carbon dioxide emissions from a consumption perspective indicator: chapter 5


5. Caveats and limitations

5.1 Carbon dioxide emissions from fuel combustion by industry

The carbon dioxide (CO2) emissions estimates presented in the indicator are based on CO2 emissions from fuel combustion estimates calculated by the International Energy Agency. As such, they vary from those of other indicators presented in the current set of national and global greenhouse gas (GHG) indicators from the Canadian Environmental Sustainability Indicators program, which are based on Canada's official National Inventory Report: Greenhouse Gas Sources and Sinks in Canada.

The International Energy Agency's CO2 Emissions from Fuel Combustionestimates include emissions from energy transformation (e.g., from oil refineries) which are normally included in Category 1 B in the National Inventory Report. As a result, the closest comparison between production-based CO2 emissions estimates presented in this indicator and those used in other Canadian Environmental Sustainability Indicators is the National Inventory Report's CO2 emissions from the energy sector (including stationary combustion sources, transport, fugitive sources and CO2 transport and storage). However, further differences persist between the data prepared by the International Energy Agency and the data presented in the National Inventory Report.

A key cause of the remaining differences is that the International Energy Agency estimates used for the indicator were calculated using the Intergovernmental Panel on Climate Change's (IPCC) Revised 1996 Guidelines for National Greenhouse Gas Inventories, while Canada's most recent National Inventory Report was prepared using the 2006 IPCC Guidelines for National Greenhouse Gas Inventories. Other factors listed by the International Energy Agency might also lead to differences between its estimates and those from the National Inventory Report.Footnote [1] These differences include the following:

  • The International Energy Agency uses a Tier 1 Sectoral Approach based on the 1996 IPCC Guidelines, while countries may be using a Tier 2 or Tier 3 method that takes into account different technologies. In addition, as mentioned above, Canada is now using the 2006 IPCC guidelines.
  • Energy data based on the International Energy Agency energy balances may differ from those used to prepare the National Inventory Report. In addition to different sources, the methodology used to develop national inventories may differ from that used by the International Energy Agency.
  • The International Energy Agency uses average net calorific values for fuels to transform fuel consumption data from physical units to energy units. Country experts may have more detailed data on calorific values available when calculating the energy content of the fuels. This, in turn, could produce different values from those of the International Energy Agency.
  • The International Energy Agency uses the default emission factors which are given in the 1996 IPCC Guidelines. Country experts may have better information available.
  • The International Energy Agency cannot allocate emissions from auto producers to the end-use sectors, while country experts may be doing so, according to recommendations from the IPCC.
  • Military emissions may be treated differently than in national inventories

Finally, it should be noted that the International Energy Agency CO2 emissions estimates were not developed using the International Standard Industrial Classification of All Economic Activities, Revision 3 industrial categories which are used by the Organisation for Economic Co-operation and Development to develop Inter-Country Input-Output Tables (further discussed in Development of worldwide national accounts). The Organisation for Economic Co-operation and Development thus developed a methodology to reallocate the International Energy Agency emissions estimates to these categories.Footnote [2]

5.2 Development of worldwide national accounts

In developing the Inter-Country Input-Output Tables, the Organisation for Economic Co-operation and Development converts data it receives from national agencies on a harmonized basis (a process discussed in the Inter-Country Input-Output Tables section). As a result national data presented in the Inter-Country Input-Output Tables might differ from those presented by national statistical agencies such as Statistics Canada's National Symmetric Input-Output Tables.

The level of aggregation found in the Organisation for Economic Co-operation and Development's Inter-Country Input-Output Tables (35 industries) means that the scope of potential analysis of specific products is limited. In addition, cross-country variations in data definitions mean that a specific product might not always fall under the same International Standard Industrial Classification category across all countries.

5.3 Consumption-based carbon dioxide emissions

The multi-regional input-output approach used by the Organisation for Economic Co-operation and Development to estimate consumption- and production-based CO2 emissions by country and industry combines CO2 emissions estimates by industry with Inter-Country Input-Output Tables. As a result, the accuracy of the results of the Multi-Regional Input-Output analysis is subject to the same caveats as those mentioned above in this section. In addition, the Multi-Regional Input-Output analysis does not include the impact of product disposal, and is thus a "cradle-to-gate" rather than "cradle-to-grave" analysis.Footnote [3] Furthermore, as the data from the Inter-Country Input-Output Tables are in nominal terms, emissions intensity improvements may be partly explained by changes in price levels over time.

It should also be noted that there can be a time disconnect between the Organisation for Economic Co-operation and Development's consumption-based CO2 emissions data and its production-based emissions data and other similar CO2 emissions data sources, such as Canada's National Inventory Report. This is due to the fact that the Organisation for Economic Co-operation and Development's CO2 emissions estimates are tied to Inter-Country Input-Output Tables, which include inventory movements that, by definition, can create a disconnect between the time a product is made and when it is consumed. In the National Inventory Report, the emissions are accounted for immediately when the product is made, while in the case of the consumption-based CO2 emissions estimates, changes in inventories could influence when consumption-based emissions are reported.

5.4 Data gaps

At this time, the Organisation for Economic Co-operation and Development excludes GHGs other than CO2 from its analysis due to problems with data availability and difficulties in matching non-CO2 GHG emissions with the International Standard Industrial Classification categories. In addition, all GHG emissions from international bunker (aviation and marine) fuels are excluded from the analysis (as they also are in Canada's official National Inventory Report: Greenhouse Gas Sources and Sinks in Canada), which underestimates the amount of emissions embedded in the consumption of imported products and services.

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