February 9, 2010

• GHG Home
• Canada's GHG Inventory
  • Report Summary
  • Trends 1990-2006
  • Archives
• Facility GHG Reporting
• GHG Quantification Guidance
• GHG Verification Guidance
• Site Map
• Contact Us
• About GHG Division

Home > GHG Inventory > Archive

National Inventory Report, 1990-2004 - Greenhouse Gas Sources and Sinks in Canada

| TOC | Previous | Next |

EXECUTIVE SUMMARY

• ES.1 Greenhouse Gas Inventories and Climate Change
  • ES.1.1 Developing Canada's National Greenhouse Gas Inventory
• ES.2 Summary of National Trends in Greenhouse Gas Emissions and Removals
• ES.3 Emissions and Removals Estimates and Trends
  • ES.3.1 2004 Emissions and Removals
  • ES.3.2 Sector Trends
• ES.4 Other Information
  • ES.4.1 Emissions Associated with the Export of Oil and Natural Gas
  • ES.4.2 Provincial/Territorial Greenhouse Gas Emissions
  • ES.4.3 The International Context

ES.1 GREENHOUSE GAS INVENTORIES AND CLIMATE CHANGE

The United Nations Framework Convention on Climate Change (UNFCCC) - Article 4(1)(a), Article 12(1)(a), and Decision 3/CP.5 - requires Annex I Parties to submit an annual greenhouse gas (GHG) inventory report using UNFCCC reporting guidelines. The year 2006 marks the publication of Canada's 12th National Inventory Report (NIR). It is also the second inventory since the Kyoto Protocol to the UNFCCC, which Canada ratified in 2002, came into force. Underpinning the UNFCCC is the national GHG inventory, composed of the NIR and Common Reporting Format (CRF) tables. It is the key tool for monitoring and reporting on emissions from sources and removals by sinks and, with respect to the Kyoto Protocol, is the ultimate measure for assessing compliance with the national emissions target.

Guidelines under the UNFCCC have a number of implications on reporting and review requirements. Annex I countries are expected to estimate GHG emissions by sources and removals by sinks using agreed-upon methodologies, as outlined in the Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories (IPCC/OECD/IEA, 1997), Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories (IPCC, 2000), and Good Practice Guidance for Land Use, Land-Use Change and Forestry (IPCC, 2003). As a result, the UNFCCC now requires that countries identify, quantify, and reduce uncertainty of estimates as far as practicable. This will result in a process of continuous evaluation and improvement of methods, models, and documentation to ensure that internationally agreed upon standards are met. These activities are designed to ensure that all sources and sinks, and therefore all emission reductions and enhancements of removals, are properly accounted for.

The national inventory system includes all institutional, legal, and procedural arrangements made within a Party for estimating emissions and removals of GHGs according to the above methodologies, as well as for reporting and archiving the inventory information. This requires that a number of key inventory planning, preparation, and management functions be performed. The current report provides a short discussion (in Chapter 1) on the system that Canada has developed. A full description of the national system in accordance with guidelines under Article 5.1 of the Protocol is to be included, among other things, in Canada's initial report, due January 1, 2007, to the UNFCCC, a report that is also to facilitate the calculation of the assigned amount (emissions target) under Article 7.4.

This year's GHG inventory incorporates a number of improvements in the estimation methodologies, including the results of detailed studies on fugitive emissions from oil and gas industries. The Land Use, Land-Use Change and Forestry (LULUCF) methodologies have been entirely upgraded, and new estimation methods have been incorporated in the Industrial Processes and Waste sectors and the Agricultural Soils category. In developing the inventory, Tier 1 quality assurance/quality control (QA/QC) procedures continue to be used to formally ensure and document the quality of the estimates. In addition, some Tier 2 QA/QC has been conducted as time and resources permit.

The current report includes an inventory of anthropogenic (human-induced) emissions by sources, and removals by sinks, of the six main GHGs not controlled by the Montreal Protocol. This Executive Summary highlights some of the latest developments in the inventory, discusses underlying trends in the emissions, provides some international context, and presents provincial and territorial emissions for the period 1990-2004. Chapter 1, the Introduction, provides an overview of the most recent climate and GHG concentration trends, as well as Canada's legal, institutional, and procedural arrangements for producing the inventory (i.e., the national inventory system), a brief description of estimation methodologies and QA/QC procedures, and explanations of major changes to this year's inventory and assessments of completeness and uncertainty. Chapter 2 provides an in-depth analysis of Canada's GHG emission trends in accordance with the UNFCCC reporting guidelines.

Chapters 3-8 provide descriptions and additional analysis for each broad emissions and removals category according to UNFCCC CRF requirements. Chapter 9 presents a summary of recalculations and planned improvements. Annexes 1-7 provide a key category analysis, detailed explanations of estimation methodologies, a comparison of the sectoral and reference approaches, a more complete description of QA/QC procedures, completeness assessments, and a discussion of inventory uncertainty. Summary tables of GHG emissions tabulated by jurisdiction, sector, and gas are presented in Annexes 8 and 12. Annexes 9, 10, and 11 present additional details on the GHG intensity of electricity generation and trend analyses by industrial sector and by province/territory, respectively. Emission factors are provided in Annex 13, and a description of rounding procedures is found in Annex 14. Finally, brief summary tables showing emissions of ozone and aerosol precursors are provided in Annex 15.

ES.1.1 DEVELOPING CANADA'S NATIONAL GREENHOUSE GAS INVENTORY

On behalf of the Government of Canada, Environment Canada develops and publishes annually Canada's GHG inventory. The GHGs for which emissions and removals have been estimated in the national inventory are:

• carbon dioxide (CO₂);
• methane (CH₄);
• nitrous oxide (N₂O);
• sulphur hexafluoride (SF₆);
• perfluorocarbons (PFCs); and
• hydrofluorocarbons (HFCs).

The inventory reporting format is based on international reporting methods agreed to by the Parties to the UNFCCC, using the procedures of the Intergovernmental Panel on Climate Change (IPCC) (see above). The inventory uses an internationally agreed upon reporting format that groups emissions into the following six sectors: Energy, Industrial Processes, Solvent and Other Product Use, Agriculture, LULUCF, and Waste. Each of these sectors is further subdivided within the inventory and follows, as closely as possible, the UNFCCC category and subsector divisions.² Detailed descriptions of the methodologies used to estimate the sector emissions and removals and their respective trends are provided in Chapters 3 through 8 and Annexes 2 and 3. In keeping with UNFCCC reporting requirements for Annex I Parties, this report also contains information on the ozone precursors nitrogen oxides (NO_x), carbon monoxide (CO), and non-methane volatile organic compounds (NMVOCs), as well as on sulphur dioxide (SO₂).

ES.2 SUMMARY OF NATIONAL TRENDS IN GREENHOUSE GAS EMISSIONS AND REMOVALS

In 2004, Canadians contributed about 758 megatonnes of CO₂ equivalent (Mt CO₂ eq)³ of GHGs to the atmosphere (Figure S-1),⁴ an increase of 0.6% over the 754 Mt recorded for the year 2003. This is considerably less than the 3.9% increase that occurred between 2002 and 2003. Canada's economic GHG intensity - the amount of GHGs emitted per unit of economic activity - was 2.6% lower in 2004 than in 2003. Since 1990, emissions have increased by about 27%.

FIGURE S-1: Canadian GHG Emission Trend and Kyoto Target

Click to enlarge

Table S-1 depicts Canada's total GHG emissions from 1990 to 2004, along with several primary indicators: gross domestic product (GDP), population, energy use, energy production, and energy export. From the table, it is evident that the 27% increase in GHG emissions during the 14-year period outpaced increases in population (which totalled 15%) and approximately equalled the increase in energy use (which was 26%). However, the growth in total emissions was well short of the 47% growth in GDP between 1990 and 2004 (Statistics Canada, #13-213: millions of chained 1997 dollars).

TABLE S-1: Canada's GHG Emissions and Accompanying Variables, 1990-2004

Click here to view Table S-1

The result is that economic GHG intensity has decreased by a total of 14% over the period, an average of 1% per year. More goods were manufactured, more commercial activity occurred, and more travel took place per unit of GHG emissions. These trends are summarized graphically in Figure S-2. The indexed curves clearly show that GHG emissions per energy used remained static over the period, while economic GHG intensity decreased. This is to some extent related to energy efficiency improvements that have taken place in the Canadian economy since 1990 (NRCan, 2005).

FIGURE S-2: Trends in GHG Emissions per Capita and per Unit GDP, 1990-2004

Click to enlarge

Another trend worth noting is the much larger growth in energy production than energy use between 1990 and 2004. This is a consequence of Canada's large fossil fuel resources and an economy geared to take advantage of them, with increasing quantities of energy being delivered to the international market. The resultant sharp growth in energy exports over the period has had a significant impact on the emission trend. (See Section ES.4.1 for more details.)

ES.3 EMISSIONS AND REMOVALS ESTIMATES AND TRENDS

ES.3.1 2004 EMISSIONS AND REMOVALS

Table S-2 details Canada's emissions and removals for 2004. On an individual GHG basis, CO₂ contributed 78% of the total emissions, while CH₄ accounted for 15%. N₂O accounted for 6% of the emissions, while PFCs, SF₆, and HFCs constituted the remaining 1%.

TABLE S-2: Canada's GHG Emissions by Gas and Sector, 2004

Click here to view Table S-2

Approximately 73% of total GHG emissions in 2004 resulted from the combustion of fossil fuels. Another 9% were from fugitive sources, with the result that 82% of emissions were from the Energy Sector. A sectoral breakdown of Canada's total emissions for 2004 is shown in Figure S-3.

FIGURE S-3: Sectoral Breakdown of Canada's GHG Emissions, 2004

As per reporting requirements, the LULUCF Sector estimates are not included in the national totals. This sector displays net overall emissions of 81 Mt for 2004. This would, if included, increase the total Canadian GHG emissions by 11%.

ES.3.2 SECTOR TRENDS

ES.3.2.1 Year-to-Year Changes

Table S-3 outlines changes in Canada's GHG emissions and removals, by sector, between 1990 and 2004. As indicated above, emissions in 2004 are estimated at 758 Mt, up 4 Mt (0.6%) from 754 Mt in 2003. Between 2003 and 2004, there were increases in some sectors (notably Industrial Processes and Agriculture), but the overall growth was minor, owing mainly to significantly reduced emissions from electricity production (less coal and more nuclear generation) and, to a lesser extent, a reduced demand for heating fuel because of a warmer winter.

TABLE S-3: Canada's GHG Emission Trends by Sector, 1990-2004

Click here to view Table S-3

Energy Sector emissions actually showed a net decrease (of about 2 Mt), the first year-to-year reduction since 1991. In 2004, although electricity demand increased, GHG emissions from electricity generation decreased by 9 Mt. This was due to a reduction in coal-fired generation. In 2003, coal supplied 18.4% of electricity generation; this was reduced to 16.5% in 2004. To fill the electricity generation gap, nuclear sources grew from 12.4% of supply to 14.8% in 2004. This trend is the result of ongoing efforts in Ontario to close that province's coal generation plants (Nyboer et al., 2006).

On average, Canadian homes and businesses required lower energy quantities for space heating in the winter of 2004 compared with the winter of 2003 due to milder temperatures. In 2004, the number of heating degree-days (HDDs), an indicator of the necessity for space heating due to the severity of cold weather, was down 2.3% on a national basis compared with 2003. Ontario, Alberta, and British Columbia all experienced 4-5% fewer HDDs in 2004 than in 2003; Quebec was down almost 1%. This fact almost certainly had an impact on fossil fuel consumption, specifically in the residential category, where emissions declined by 2 Mt from 2003.

Nevertheless, overall emissions grew in 2004. Heavy- duty diesel vehicles (HDDVs, large transport trucks) and light cars and trucks - consisting of light-duty gasoline vehicles (LDGVs), or automobiles, and light-duty gasoline trucks (LDGTs), or pickup trucks, sport utility vehicles (SUVs), and some vans - showed emission increases of 2.6 Mt and 2.1 Mt, respectively, between 2003 and 2004. This growth is a continuation of long- term trends in road transport.

Industrial Processes Sector GHG emissions grew by 4.2 Mt between 2003 and 2004. The two primary contributors were an increase in consumption of fuel for undifferentiated, non-energy uses and a maintenance- based shutdown of an N₂O emission abatement system at Canada's only adipic acid production plant. (Adipic acid is a key ingredient in the manufacture of nylon.)

Emissions from the Agriculture Sector grew by 2 Mt (4.5%) from 2003 to 2004, mainly owing to an increase in animal enteric fermentation (digestive processes that release CH₄) emissions, based primarily on an 8% increase in beef cattle population.

ES.3.2.2 Long-Term Trends

Although the long-term (1990-2004) sectoral emission trends showed declines and increases (Figure S-4), the increases were well ahead of the declines, for a net growth of 159 Mt, or 27%. The largest portion of the growth is observed in the Energy Sector, where the Energy Industries (Fossil Fuel Industries plus Electricity and Heat Generation), Road Transportation, Commercial & Institutional, and Mining categories made the greatest contributions.

FIGURE S-4: Change in GHG Emissions from 1990 Baseline, 1992-2004

Click to enlarge

Note:

Mining excludes that portion of emissions associated with the oil sands industry (included in Energy Industries). Energy Industries includes both the Fossil Fuel Industries and Electricity and Heat Generation.

The activities of the Energy Industries' Fossil Fuel Industries include both combustion sources (Fossil Fuel Industries and Pipelines) and fugitive sources (Coal Mining and Oil and Natural Gas). There is also some overlap with Mining, which (as a result of categorizations by the Alberta Energy Utilities Board and Statistics Canada) includes a portion of oil sands production activities.

Oil and gas activities, representing by far the largest portion of the fossil fuel industries, registered a net increase of about 52 Mt of GHG emissions from 1990 to 2004 (51% growth).⁵ These emissions are related to the production, transmission, processing, refining, and distribution of all oil and gas products.

Over the period, total production of crude oil and natural gas increased by 65% (see Section ES.4.1), with an attendant 55% increase in subsector GDP.⁶ Increasing demand in both Canada and the United States drove these trends, with the export market growing by far the most rapidly (see Section ES.4.1). Although increasing demand provides a portion of the explanation for the emission trend, it does not paint the complete picture.

Since well before 1990, easily removable reserves of conventional crude have been falling. Thus, energy consumption per unit of conventional oil produced has been increasing (Neitzert et al., 1999). In fact, between 1990 and 2000, the energy requirements per barrel of conventional light/medium oil extracted nearly doubled (Nyboer and Tu, 2006). At the same time, highly energy- and GHG-intensive⁷ synthetic oil production (i.e., from oil sands) has become increasingly competitive with conventional oil extraction. These trends then also contribute significantly to the rapidly rising emission increases in the oil and gas industry over the 1990-2004 period.

Electricity and Heat Generation, representing the other portion of the Energy Industries, also saw large increases. Rising demand for electricity, exacerbated by the increasing use of fossil fuels in the generation mix, drove GHG emissions up by almost 35 Mt between 1990 and 2004. In 2004, electricity demand was 109 terrawatt-hours (TWh) above the 1990 level. Although this increased demand was supplied in part by greater hydroelectricity and nuclear generation, fossil fuel generation rose even more. The result was that by 2004, hydropower's share of the generation mix had fallen from 63% to 59%, while fossil fuels' had risen from 21% to 25%, worsening the average GHG intensity of production. The end result was that from 1990 to 2004, generation rose 23%, while GHG emissions increased 37%, about 1.5 times the generation increase.

Of note in these trends is that coal's portion of electricity generation, which had been increasing since the mid-1990s, dropped off to about 16.5% in 2004, a level about the same as it was in 1990. As mentioned above, it appears as if this is largely the result of Ontario's program to reduce coal generation within the province.

Emissions from Road Transportation rose by 38 Mt (36%) between 1990 and 2004. Of particular interest in this subsector is a 22 Mt increase in emissions from LDGTs. This was partially offset by 4 and 1.3 Mt emission reductions from gasoline-fuelled cars (LDGVs) and alternatively fuelled cars (Propane & Natural Gas Vehicles).

The primary source of this net trend of rising emissions is the increase in the number of passenger-kilometres travelled (more people drove further) (NRCan, 2005). However, it was light trucks' passenger-kilometres that increased, while cars' showed reductions. Substantiating this is the fact that the number of light trucks on the road doubled between 1990 and 2004, while the number of automobiles contracted slightly. Since light trucks have higher emissions per kilometre than automobiles, the rising popularity of SUVs and pickups worsened the emission impact of increasing numbers of people driving further.

Research suggests⁸ that, over the period, about 10% of the emission increase from automobiles and light trucks can be attributed purely to the shift in the type of private vehicles being driven. Perhaps of greater concern is the overall trend towards increasing horsepower, which has negated the rather substantial efficiency improvements made in power plants for all classes of passenger vehicles.

Emissions from HDDVs (large freight trucks) rose by about 20 Mt between 1990 and 2004, an 83% increase. Spurred on by free trade and the deregulation of the trucking industry, the amount of freight shipped grew rapidly over the period. In addition, the quantity shipped by truck (as opposed to other modes of transport, such as rail) increased as a result of customer requirements for just-in-time delivery and cross-border freight (NRCan, 2005).

The Commercial & Institutional category displayed a 12 Mt (47%) growth in GHG emissions between 1990 and 2004. Driving this trend was a significant increase in the floor space (25% between 1990 and 2003) of commercial and institutional buildings (e.g., offices, schools, stores, and government edifices), a result of Canada's growing economy over the period (NRCan, 2005). Energy demand in commercial buildings is also influenced by weather. In terms of HDDs, 2004 was 8% colder than 1990, so this contributed to the emission growth; however, its impact was considerably less than that of increased floor space.

Mining showed a large increase in emissions between 1990 and 2004 - 9.2 Mt (about 149%), when excluding the portion related to oil sands activities - on the basis of a 48% growth in sector GDP.

Another sector that contributed, although to a lesser extent than Energy, to the longer-term growth in GHG emissions is Agriculture. This sector showed a 10 Mt increase (23%) between 1990 and 2004, resulting primarily from the expansion of the beef cattle, swine, and poultry industries, as well as an increase in synthetic nitrogen fertilizer consumption.

In addition to the already-mentioned reduction in emissions from automobiles, two subsectors, both within the Industrial Processes Sector, contributed towards counteracting 1990-2004 emission growth - Adipic Acid Production (Chemical Industry) and Aluminium Production (Metal Production).

While output increased at the sole adipic acid production plant in Canada, the installation of an emission abatement system in 1997 resulted in significant reductions of N₂O emissions. Despite being temporarily off-line in 2004, this system reduced GHG emissions by 7.6 Mt (71%) over the 1990-2004 period.

In the aluminium industry (which emits both CO₂ and PFCs), PFC emissions were reduced as a result of better control of anode events in smelters by increasing use of electronic monitoring and automated emission controls. As a result, between 1990 and 2004, total GHG process emissions from the aluminium industry decreased by 2.03 Mt (22%), while primary aluminium production increased by more than 60%.⁹

Although it does not contribute to national totals, it is of interest to consider the trends in the LULUCF Sector. The net flux, calculated as the sum of CO₂ emissions and removals and non-CO₂ emissions, displays high interannual variability over the reporting period. In fact, there is no discernible trend, with the flux ranging from net emissions of 190 Mt (in 1995) to net removals of 130 Mt (in 2000). Bracketing the period is a net removal of 82 Mt in 1990 and a net emission of 81 Mt in 2004. The interannual swings are primarily a consequence of the large and variable impact of emissions from wildfires, which are inventoried under the LULUCF Sector.

ES.4 OTHER INFORMATION

ES.4.1 EMISSIONS ASSOCIATED WITH THE EXPORT OF OIL AND NATURAL GAS

Canada is rich in fossil fuel resources. The fossil fuel industry, with a GDP of $33 billion¹⁰ in 2004, contributes significantly to the economy. A much greater quantity of Canada's oil and gas production is sold internationally now than in the past.

Growth in oil and gas exports, almost all to the United States, contributed significantly to emissions growth¹¹ between 1990 and 2004. In this period, net oil exports (exports minus imports) grew by 513% to 1572 petajoules (PJ)¹² (almost 10 times the rate of growth of oil production) (Table S-4), while net exports of natural gas increased 138% to 3600 PJ (almost twice the rate of growth of natural gas production) (Table S-5). Over the period, the sum total of net oil and gas energy exports increased by 192% (Table S-6).

Note:

N/A = not available

Note:

N/A = not available

Note:

N/A = not available

The portion of emissions from all oil and gas production, processing, and transmission activities that is attributable to net exports¹³ rose from about 22 Mt in 1990 to 48 Mt in 2004 (a 123% increase; Table S-6).¹⁴ This 26 Mt increase is half of the total 52 Mt growth in emissions from the oil and gas industry, which is in turn about one-third of the 159 Mt national emission growth over the period.

It should be noted that natural gas exports fell between 2002 and 2003; although growth resumed between 2003 and 2004, it was relatively small. In fact, it has been forecasted that since the reserves in Canada's largest natural gas reservoir (the Western Sedimentary Basin) are reaching their limit, the country's natural gas production will not increase significantly in the future (Nyboer and Tu, 2006). As a result, gas exports may show very little growth from this point on.

ES.4.2 PROVINCIAL/TERRITORIAL GREENHOUSE GAS EMISSIONS

It is important to note that Canada's GHG emissions vary from region to region. This is linked to the distribution of natural resources and heavy industry within the country. While the use of natural resources and industrial products benefits all regions of North America, emissions from their production tend to be concentrated in particular geographic regions. Thus, particular jurisdictions in Canada tend to produce more GHG emissions because of their economic and industrial structure and their relative dependence on fossil fuels for producing energy. Figure S-5 illustrates the provincial/territorial distribution of emissions and the change in these emissions between 1990 and 2004.

FIGURE S-5: Total Provincial/Territorial GHG Emissions, 1990 and 2004

Click to enlarge

ES.4.3 THE INTERNATIONAL CONTEXT

Canada contributes about 2% of total global GHG emissions. It is one of the highest per capita emitters, largely the result of its size, climate (i.e., energy demands), and resource-based economy. In 2004, Canada emitted about 24 t of GHGs per capita, which represents a 10% growth since 1990 (see Table S-1).

In terms of total anthropogenic GHG emissions, Canada ranks sixth among the nine Annex I Parties whose emissions increased more than 20% over the 1990-2003 period¹⁵ and first among the G8 nations. Canada's +24% growth (-6% Kyoto target) compares with Spain's +42% growth (-8% target), Greece's +26% rise (-8% target), and Japan's +13% increase (-6% target). Parties whose emissions decreased by 2003 include the European Union, by -1% (-8% target), the United Kingdom, by -13% (-8% target), and Germany, by -18% (-8% target).

² Minor differences exist between the UNFCCC and Canada's national inventory sector designations. These are explained in footnotes throughout this report. More details can be found in Chapters 3-8, where the methodology used in Canada's inventory is described.

³ Each of the GHGs has a unique average atmospheric lifetime over which it is an effective climate-forcing agent. The concept of global warming potential (GWP) has been introduced to equate this climate forcing for different GHGs to that of CO₂. A more detailed explanation is provided in Section 1.1.5 of this document.

⁴ Unless explicitly stated otherwise, all emission estimates given in Mt represent emissions of GHGs in Mt CO₂ equivalent.

⁵ Relative to the categorizations of Table S-3, the oil and gas industry emissions discussed here include Petroleum Refining, Fossil Fuel Production (minus coal), Transportation – Pipelines, all Oil and Natural Gas fugitives, and that part of Mining representing the oil sands. Since the industry also produces CO₂ from certain chemical processes, a portion of Industrial Processes Sector emissions (about 4 Mt of those categorized under Other and Undifferentiated Production) is included as well. See the analysis presented in Annex 10.

⁶ Source for all sector economic growth figures: Informetrica Limited.

⁷ Nyboer and Tu (2006) estimate that, per unit of output, GHG emissions from oil sands mining and upgrading are about five times greater than those from conventional light/medium crude oil production.

⁸ Adapted from NRCan (2005).

⁹ Source: Aluminum Association of Canada. Data provided to Greenhouse Gas Division, Environment Canada.

¹⁰ Constant 1997 dollars (source: Informetrica, January 2006).

¹¹ The source for all export and energy production data is Statistics Canada, #57-003. The 1990-1995 GHG emissions associated with net exports are taken from a report prepared for Environment Canada (McCann, 1997), while the 1996-2004 estimates were extrapolated from this report.

¹² A petajoule (PJ) is a measure of the energy content of fuels.

¹³ Net export emissions are the Canadian emissions associated with extracting, processing, and transporting exported fuel minus the Canadian emissions associated with transporting and processing imported fuels.

¹⁴ Absolute emissions attributable to net exports are rough approximations. The long-term trends are considered to be more accurate.

¹⁵ These aggregate estimates are based on the most recent data from 39 Parties that submitted inventories to the UNFCCC in 2005 (Table 5 in UNFCCC, 2005).