Greenhouse gas emissions inventory

Canada's greenhouse gas inventory is developed, compiled, and reported annually by the Pollutant Inventories and Reporting Division of Environment Canada with input from numerous experts and scientists across Canada. While the inventory is prepared in accordance with the United Nations Framework Convention on Climate Change (UNFCCC) reporting guidelines on annual inventories, Decision 24/CP.19, inventory estimates are determined by methods and models developed in-house by engineering and scientific staff, as well as from published data, data developed by industry, or methods developed by the Intergovernmental Panel on Climate Change (IPCC).

The greenhouse gases that have been estimated in the national inventory are carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), sulphur hexafluoride (SF₆), nitrogen triflouride (NF₃), perfluorocarbons (PFCs), and hydrofluorocarbons (HFCs). The inventory uses an internationally agreed to reporting format, grouping emissions and removals into the following five Sectors:

• Energy
• Industrial Processes and Product Use
• Agriculture
• Land Use, Land-Use Change and Forestry
• Waste

Inventory experts are responsible for the development, analysis and verification of activity data, methods, emission factors and the emission and removal estimates; management of the quality and archiving systems; and performance of trends analysis.

Emissions or removals are usually calculated or estimated using mass balance, stoichiometry or emission factor relationships under average conditions. In many cases, activity data are combined with average emission factors to produce a top-down national inventory. Large-scale regional estimates, based on average conditions have been used for a broad range of sources, such as transportation and emissions from landfills are determined using a simulation model to account for the long term slow generation and release of these emissions. The approach to estimating emissions and removals from manipulated biological systems such as agriculture land or forestry includes a combination of repeated measurements and modeling.

In addition, quality assurance and quality control (QA/QC) procedures are integral parts of the inventory development and submission process. These are implemented from the initial data collection stage, through the development of emission and removal estimates and publication.

Energy

The Energy Sector contributes to the bulk of Canada’s greenhouse gas emissions (about 80%) and includes greenhouse gas emissions (CO₂, CH₄, and N₂O) from stationary and transport fuel combustion activities as well as fugitive emissions from the fossil fuel industry.

Energy emissions are largely the result of the combustion of fossil fuels, which convert the carbon and hydrogen of the fuel into CO₂, water and mechanical energy or heat. CH₄ and N₂O emissions are also released in smaller quantities - CH₄ as a result of incomplete oxidation and N₂O as a result of combustion in the presence of nitrogen. Stationary fuel combustion emission sources include use of fossil fuels by the electricity generating industry, the oil and gas industry, manufacturing industry, and the residential and commercial sectors. Emissions from transport fuel combustion approach 30% of Canada’s total emissions and transportation emission sources include domestic aviation, road transportation, railways, domestic marine, off-road vehicle use and pipelines.

Fugitive emissions associated with the fossil fuel industry are the intentional (flaring) or unintentional releases (leaks or accidents) of greenhouse gases resulting from production, processing, transmission, and storage of fuels.

Industrial Processes and Product Use

The Industrial Process and Product Use Sector accounts for greenhouse gas emissions that are produced from a variety of industrial activities that are not related to energy, but that chemically or physically transform materials. During industrial processes, such as cement production, iron and steel blast furnace operation, and adipic acid production, many different greenhouse gases, including CO₂, CH₄, N₂O and PFCs can be released.

Certain halocarbons (HFCs and PFCs) and SF₆ are also consumed in industrial processes or used as alternatives to ozone depleting substances in various applications. Greenhouse gases can also be found in the manufacturing and use of products such as refrigerators, air conditioners, foams and aerosols.

Agriculture

The Agriculture Sector contributes to Canada’s greenhouse gas emissions total due to emissions released from animal production, manure management, and agricultural soils.

The emissions from livestock, or animal production, are caused by enteric fermentation. Large quantities of CH₄ are produced from herbivores during the normal digestive process as microorganisms break down carbohydrates into simple molecules for absorption and CH₄ is produced as a by-product.  Ruminant animals such as cattle generate the most methane.

Both CH₄ and N₂O are emitted during handling and storage of livestock manure.  The magnitude of the emissions depends on the quantity of manure handled, its characteristics, and the manure management system.  Generally, poorly aerated manure management systems generate more CH₄ than N₂O, whereas well-aerated system generate little CH₄, but more N₂O. Emissions of N₂O from agricultural soils consist of direct and indirect emissions as well as emissions from animal manure on pasture, range and paddock.

Land Use, Land-Use Change and Forestry

The Land Use, Land-Use Change and Forestry (LULUCF) sectors report net greenhouse gas fluxes between the atmosphere and Canada’s managed lands, as well as those associated with land-use changes. The assessment includes emissions resulting from human-induced fires and controlled burning, and conversion to cropland.

For the purpose of the inventory, managed forests are those managed for timber and non-timber resources (including parks) or subject to fire protection.

All emissions from and removals by the LULUCF sector are excluded from the national total.

Waste

The Waste Sector includes emissions from the treatment and disposal of wastes.  Sources include solid waste disposal on land (landfills), wastewater handling and waste incineration. Methane produced from the decomposition of waste in landfills is calculated using the Scholl Canyon model, which is a first-order decay model to reflect the fact that waste degrades in a landfill over many years. N₂O emissions are associated with the wastewater treatment facilities that operate anaerobically.

Quality Assurance and Quality Control

Quality Assurance and Quality Control (QA/QC) procedures ensure that Canada is able to meet the UNFCCC requirements of transparency, consistency, completeness and accuracy. Continuous data collection and improvements are integral parts of the national inventory development.

Quality Control (QC) is a system of routine technical activities to assess and maintain the quality of the inventory as it is being developed. QC activities include general methods such as accuracy checks on data acquisition and calculations, and the use of approved standardized procedures for emission and removal calculations, measurements, estimating uncertainties, archiving information and reporting. QC activities also include technical reviews of categories, activity data, emission factors, other estimation parameters and methods. Quality Assurance (QA) is a planned system of review procedures conducted by independent experts and are performed following the implementation of QC procedures. QA reviews and helps to ensure that the inventory represents the best possible estimates of emissions and removals given the current state of scientific knowledge and data availability, and supports the effectiveness of the QC program.

In addition to QA/QC, the inventory is also reviewed annually by review teams of international experts coordinated by the UNFCCC.