For the manufacturing subsector as a whole, energy intensity (the ratio E/Y) is a function primarily of the energy intensities of different production groups and their contributions to the total gross output mix in the subsector. The subsector’s carbon intensity of energy supply (the ratio C/E) is determined primarily by the mix of energy fuel inputs and the mix of fuel and nonfuel (sequestering) uses of the inputs. Thus, the overall carbon intensity of manufacturing (C/Y) is a combination of the energy intensity of manufacturing gross output and the carbon intensity of the energy consumed to meet manufacturing energy demand.^b

The manufacturing C/Y ratio fell by 1.4 percent per year from 1991 to 2002; however, the reduction was largely the result of a structural shift (i.e., a change in relative market shares in the subsector). The energy intensity for the “other manufacturing” category declined by 1.0 percent per year, and at the same time its gross output grew by 3.2 percent per year, from $2.0 trillion in 1991 to $2.9 trillion in 2002 (in chained 2000 dollars), as newer, less energy-intensive industries accounted for an increasing share of manufacturing activity. In 1991 the four most energy-intensive industries (petroleum, chemicals, primary metals, and paper) accounted for 29.0 percent of total manufacturing gross output, but by 2002 their share had fallen to 23.9 percent. For three of the six manufacturing categories, energy intensity increased from 1991 to 2002 (petroleum by 0.4 percent per year, chemicals 1.5 percent, and nonmetallic minerals 0.1 percent). For paper, primary metals, and other manufacturing, energy intensity declined by 2.0 percent, 0.9 percent, and 1.0 percent per year, respectively.

The mix and quantity of energy fuels consumed by manufacturers (for both fuel and nonfuel uses) affect the subsector’s aggregate carbon intensity of energy supply. Overall, manufacturing industries had C/E ratios equal to 50.92 million metric tons carbon dioxide equivalent per quadrillion Btu in 1991 and 49.53 million metric tons carbon dioxide equivalent per quadrillion Btu in 2002; however, the carbon dioxide factors of the various industries differed markedly.

The petroleum and chemical industries both transform some energy products into products that sequester carbon, such as petrochemical feedstocks, asphalt, and plastics. Because of that use, both the petroleum and chemical industries have lower aggregate C/E ratios than the manufacturing average (45.27 and 43.24 million metric tons carbon dioxide equivalent per quadrillion Btu for the petroleum industry and 45.84 and 41.47 for the chemicals industry in 1991 and 2002, respectively).

The paper industry makes extensive use of wood byproducts as an energy source. Carbon dioxide emissions from wood consumption are considered to be zero, because the carbon that is emitted has been sequestered recently, and the regrowing of trees will again sequester an equivalent amount of carbon dioxide. Consequently, the paper industry has a relatively low C/E ratio, at 37.41 and 43.35 million metric tons carbon dioxide equivalent per quadrillion Btu in 1991 and 2002, respectively. In contrast, the primary metals industry, which uses large amounts of coal and other carbon-intensive fuels (e.g., electricity), has a high C/E ratio: 68.18 in 1991 and 68.72 in 2002.

Between 1998 and 2002, manufacturing industries had decreases in carbon dioxide emissions associated with their use of electricity (20.9 million metric tons) and natural gas (49.0 million metric tons). Even so, electricity use continues to account for the largest share of manufacturers’ energy-related carbon dioxide emissions: 37.8 percent (561.6 million metric tons) in 1998 and 38.6 percent (540.7 million metric tons) in 2002.

As a result of the above changes in energy intensity, in combination with the structural shift in the subsector, the overall manufacturing energy intensity (E/Y) declined by 1.2 percent per year from 1991 to 2002. When the influence of the structural shift is removed, however, decomposition analysis suggests that the aggregate energy intensity of the manufacturing sector is virtually unchanged.^c

Carbon Dioxide Emissions from Manufacturing by Industry Group, 2002 Printer Friendly Version Industry Group NAICSa Code Carbon Dioxide Emissions (Million Metric Tons) Share of Total Manufacturing Emissions (Percent) Carbon Intensity of Energy Supply (Million Metric Tons per Quadrillion Btu of Energy Consumed) Petroleum 324    304.8   21.8 43.24 Chemicals 325    311.0   22.2 41.47 Metals 331    212.8   15.2 68.72 Paper 322    102.4     7.3 43.35 Minerals 327      91.1     6.5 68.06 Other Manufacturing    379.0   27.0 54.58 Total 1,401.2 100.0 49.53

Changes in Key Measures of Carbon Intensity in Manufacturing, 1991-2002 Printer Friendly Version Industry Group NAICSa Code 1991 2002 Annual Percent Change, 1991-2002 E/Y C/E C/Y E/Y C/E C/Y E/Y C/E C/Y Petroleum 324 29 45.27 1,310.6 30 43.24 1,312.2  0.4 -0.4  0.0 Chemicals 325 15 45.84    708.0 18 41.47    758.0  1.5 -0.9  0.6 Metals 331 25 68.18 1,688.3 22 68.72 1,532.2 -0.9  0.1 -0.9 Paper 322 19 37.41    717.9 15 43.35    668.2 -2.0  1.3 -0.6 Minerals 327 15 67.76 1,048.2 16 68.06 1,058.7  0.1  0.0  0.1 Other Manufacturing   3 56.12    150.8   2 54.58    131.2 -1.0 -0.3 -1.3 Total   8 50.92    420.4   7 49.53    358.4 -1.2 -0.3 -1.4 Total Without Structural Shift   8 NA NA   8 NA NA -0.1 NA NA

^aConsists of sales, or receipts, and other operating income, plus commodity taxes and changes in inventories.

^bThe ratios presented here are estimated as aggregations of several manufacturing industries. Specifically, 22 manufacturing industry groups were aggregated into 6 groups for calculations of industry-specified E/Y and C/Y ratios. Therefore, quantifying influences on the change in overall carbon intensity is valuable to extent that these groupings represent changes in the U.S. manufacturing sector. It should be noted, however, that these ratios are based on survey data that are subject to sampling errors and other uncertainties.

^cThere are several approaches that, based on index number theory, can be used to decompose aggregate values. The values reported here are based on a Laspeyres index.

Methane Emissions from Abandoned Coal Mines

Thousands of coal mines in the United States have been closed and abandoned during the past 100 years. The U.S. Department of Labor’s Mine Safety and Health Administration (MSHA) estimates that since 1980 more than 7,500 coal mines have been abandoned, and many continue to emit methane. In an April 2004 report,^a the U.S. Environmental Protection Agency (EPA) estimated that methane emissions from abandoned coal mines ranged between 3.0 MMTCO₂e and 4.6 MMTCO₂e in 1990, and between 4.6 MMTCO₂e and 6.4 MMTCO₂e in 2002. More recently, the EPA estimated methane emissions of 7.0 MMTCO₂e from abandoned underground coal mines in 2003, up from 6.7 MMTCO₂e in 1990 but down from a peak of 8.4 MMTCO₂e in 2000 due to a decline in the number of gassy mines being abandoned.^b Because access to abandoned mines is limited and a systematic measurement program at those sites would be time-intensive and costly, the EPA estimates rely on actual emissions data from when the mines were operating and assume a decline function in emissions based on mine and coal-seam characteristics.

The most important variable in determining the amount of methane emissions from an abandoned mine is its post-mining status—whether the mine has been sealed, flooded, or continues to be vented. Sealed and flooded mines have much lower rates of emissions than vented mines. Another variable deemed important is whether the mine was gassy (emitting more than 100,000 cubic feet per day) when it was operating. Gassy mines are estimated to emit 98 percent of all methane emissions from operating coal mines, and the EPA assumes that abandoned mines which had been gassy when operating represent a similarly predominant portion of emissions from abandoned mines. The EPA’s 2004 study thus focuses on abandoned mines that had been gassy prior to closure. Of the 364 gassy mines abandoned since 1972, the EPA has data on the status of a portion of them (i.e., whether the mines were sealed, flooded, or continue to be vented), calculates percentage shares of emissions by their respective status, and then assumes that those shares apply to mines for which it does not have data.

For abandoned mines that have been vented, the EPA derives an emissions decline curve based on three primary factors: adsorption isotherms by coal basin, coal permeability estimates, and estimates of pressure at abandonment. For mines that are flooded, the EPA assumes a decline curve equation based on measurements taken from eight abandoned mines in two basins. The EPA treats sealed mines similarly to those vented, adjusting the initial emissions rate and length of time for emissions to dissipate, given the slower release rate from sealed vents.

The EPA sought to calibrate its estimation methodology to field measurements, but restricted access precluded measurement at all but seven mines. Although results from those mines suggested the general accuracy of the estimation method, EIA believes the methodology has not yet been validated. EIA will reconsider including estimates of methane emissions from abandoned mines in its overall estimates of U.S. greenhouse gas emissions should additional field data confirm the EPA methodology.

^aU.S. Environmental Protection Agency, Coalbed Methane Outreach Program, Methane Emissions from Abandoned Coal Mines in the United States: Emission Inventory Methodology and 1990-2002 Emissions Estimates (Washington, DC, April 2004), web site www.epa.gov/ cmop/pdf/amm_final_report.pdf.
^bU.S. Environmental Protection Agency, Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990-2003, EPA-430-R-05-003 (Washington, DC, April 2005), web site http://yosemite.epa.gov/oar/globalwarming.nsf/content/ResourceCenterPublicationsGHG EmissionsUSEmissionsInventory2005.html.

Methane Emissions from Industrial Wastewater Treatment

When wastewater containing large amounts of organic material is treated through anaerobic decomposition, methane is emitted. The best estimate of those emissions would be based on a systematic measurement of all point sources; however, the number and diversity of U.S. industrial wastewater sources make such an approach unaffordable and impractical. As an alternative, methane emissions from industrial wastewater treatment are calculated by the following equation:

M = P ´ O ´ COD ´ A ´ EF   ,

where M = methane emissions, P = product output, O = wastewater outflow per unit of product output, COD = organic loading in outflow, A = percentage of outflow treated anaerobically, and EF = emissions factor for anaerobically treated outflow.

The Intergovernmental Panel on Climate Change (IPCC), in its Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories,^a provides default data for wastewater generation and COD on an industry-specific basis. The default data, often based on one or two literature sources, are assumed to have an uncertainty range of minus 50 percent to plus 100 percent (although no justification for the range is provided). The IPCC also provides a single default factor of 0.25 kilograms methane per kilogram of COD, premised on a general approximation of the theoretical maximum for this emission factor, and identifies an uncertainty of plus or minus 30 percent for this estimate.

There are currently no specific U.S. data that could be used to improve on the IPCC defaults, and the uncertainties make it impossible for the Energy Information Administration to provide a reliable estimate of emissions from this source. It can be noted, however, that depending on the extent to which industrial wastewater from such industries as meat and poultry processing, pulp and paper manufacturing, and vegetable, fruit, and juice processing—which is likely to have a high content of organic material—is treated anaerobically, excluding the methane emissions that would result from the U.S. emissions total will tend to produce an underestimate of U.S. methane emissions. The U.S. Environmental Protection Agency estimates that U.S. methane emissions from industrial wastewater treatment could be as high as 16.9 MMTCO₂e in 2003.^b If more comprehensive data on industrial wastewater flows become available, EIA will consider adding this source to its estimate of U.S. methane emissions.

^aIntergovernmental Panel On Climate Change, Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories (Montreal, Canada, May 2000), web site www.ipcc-nggip.iges.or.jp/public/gp/english/.
^bU.S. Environmental Protection Agency, Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990-2003, EPA-430-R-05-003 (Washington, DC, April 2005), web site http://yosemite.epa.gov/oar/globalwarming.nsf/content/ResourceCenterPublicationsGHG EmissionsUSEmissionsInventory2005.html.

Revisions in EPA Emissions Estimation Methodology

The primary source for the emissions estimates presented in this chapter is data obtained from the U.S. Environmental Protection Agency (EPA), Office of Air and Radiation. The Office of Air and Radiation also prepares an annual inventory of greenhouse gas emissions, which is published pursuant to U.S. commitments under the United Nations Framework Convention on Climate Change (UNFCCC). The UNFCCC encourages parties to revise methods regularly and to recaculate emissions affected by the revisions. The data supporting the EPA inventory, including the emissions estimates for 2004, incorporate a number of revisions to the data and estimation methodologies used for hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF₆) in its most recent emissions inventory.^a Those changes are reflected in the EPA’s historical emissions estimates, as described below:

• Electricity Transmission and Distribution. The changes in calculations of emissions from electricity transmission and distribution are the result of incorporating more up-to-date transmission mileage data and the inclusion of additional historical partner data in the EPA’s SF₆ Emissions Reduction Partnership for Electric Power Systems for 2000, 2001, and 2002. Previously, the 2001 Utility Data Institute (UDI) Directory of Electric Power Producers and Distributors was used by the EPA to estimate SF₆ emissions for 2001 and 2002. Those numbers have been revised to account for increases in transmission mileage during 2001 and 2002, primarily as a result of growth in the U.S. transmission system. Accordingly, estimates of non-partner and non-reporting partner emissions have been recalculated in the non-reporting partner regression equations.
• Because transmission miles are highly correlated with SF₆ emissions, the EPA has used these regression equations to calculate emissions from non-partners and non-reporting partners in the SF₆ emissions reduction partnership. In addition to transmission mileage revisions, the electric power system emission estimates have also been recalculated, based on additional historical partner data. Specifically, the regression equations for each respective year of the historical partner
• submissions have been updated, resulting in new extrapolations to non-reporting partners as well. These revisions resulted in an average annual decrease in estimated SF₆ emissions from electric power systems of 0.2 percent, or less than 0.1 million metric tons carbon dioxide equivalent (MMTCO₂e) for the 2000-2002 period.
• Magnesium Production and Processing. The emissions estimates in this report have been revised to reflect new historical data supplied by the U.S. Geological Survey and participants in the EPA’s SF₆ Emission Reduction Partnership for the Magnesium Industry. This change resulted in an average annual increase in estimated SF₆ emissions from magnesium production and processing of less than 0.1 MMTCO₂e (4.1 percent) for the 2000-2002 period.
• Substitution of Ozone-Depleting Substances. The EPA has updated assumptions for its Vintaging Model pertaining to market trends in chemicals and chemical substitutes. These changes resulted in an average annual net increase in estimated HFC and PFC emissions of less than 0.1 MMTCO₂e (4.1 percent) for the 1990-2002 period.
• Aluminum Production. As the result of an EPA-funded study, facility-specific slope coefficients for three U.S. aluminum smelters have been reestimated. The new coefficients have been used by  the EPA in place of the IPCC defaults for revising the appropriate smelter-specific emission factors. The EPA provided the revised data to EIA, along with additional recently reported data concerning smelter operating parameters by participants in the EPA’s Voluntary Aluminum Industrial Partnership Program. These changes resulted in an average annual increase of less than 0.1 MMTCO₂e (0.2 percent) for the 1990-2002 period.
• HCFC-22 Production. Based on conversations with the Alliance for Responsible Atmospheric Policy, the EPA has adjusted the historical time series for HFC emissions from HCFC-22 production. These changes resulted in an average annual decrease in HFC emissions from HCFC-22 production of less than 0.1 MMTCO₂e (0.01 percent) for the 1990-2002 period.

^aU.S. Environmental Protection Agency, Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990-2003, EPA-430-R-05-003 (Washington, DC, April 2005), web site http://yosemite.epa.gov/oar/globalwarming.nsf/content/ResourceCenterPublicationsGHG EmissionsUSEmissionsInventory2005.html.

The EPA Vintaging Model: Estimation Methods and Uncertainty

The U.S. Environmental Protection Agency (EPA) uses a detailed Vintaging Model for equipment and products containing ozone-depleting substances (ODS) and ODS substitutes to estimate actual versus potential emissions of various ODS substitutes, including hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs). The model estimates the quantities of equipment and products sold each year that contain ODS and ODS substitutes, and the amounts of chemicals required for their manufacture and/or maintenance over time. Emissions from more than 40 different end uses are estimated by applying annual leak rates and release profiles, which account for the lag in emissions from equipment as it leaks over time.

For most products (refrigerators, air conditioners, fire extinguishers, etc.), emissions calculations are split into two categories: emissions during equipment lifetime, which arise from annual leakage and service losses plus emissions from manufacture; and disposal emissions, which occur when the equipment is discarded. By aggregating the data over different end uses, the model produces estimates of annual use and emissions of each compound.^a

The EPA periodically attempts to improve the model and reduce the uncertainty of emissions estimates by using more accurate data from emitting industries. The level of detail incorporated in the EPA Vintaging Model is higher than that of the default methodology used by the Intergovernmental Panel on Climate Change, although there still is some uncertainty about some of the model inputs, such as equipment characteristics and sales figures.

^aU.S. Environmental Protection Agency, Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990-2003, EPA-430-R-05-003 (Washington, DC, April 2005), web site http://yosemite.epa.gov/oar/globalwarming.nsf/content/ResourceCenterPublicationsGHG EmissionsUSEmissionsInventory2005.html.

Millennium Ecosystem Assessment: Forest and Cultivated Systems

In 2000, United Nations Secretary-General Kofi Annan called for the Millennium Ecosystem Assessment (MA) in his report to the United Nations General Assembly. The global assessment was completed in 2005,^a and work continues on sub-global assessments. The MA was carried out under the auspices of the U.N. Environment Program and was governed by a multi-stakeholder board of representatives of international institutions, governments, businesses, non-governmental organizations, and indigenous peoples. More than 1,300 authors from 95 countries worked to prepare the global assessment, and hundreds are continuing to work on more than 20 sub-global assessments, to be published in 2006. In addition, 850 experts were involved in peer reviews of the global assessment.

The objectives of the assessment were to gauge the effects of ecosystem change on human well-being and establish a scientific foundation for enhancing the conservation and sustainable use of ecosystems. The MA responds formally to government requests for information received through four international conventions, the Convention on Biological Diversity, the United Nations Convention to Combat Desertification, the Ramsar Convention on Wetlands, and the Convention on Migratory Species. Forest and cultivated land systems were an important part of the assessment.

Forest Systems

The MA defines forest systems as areas with a canopy cover of at least 40 percent provided by woody plants taller than 5 meters, including temporarily cut-over forests and plantations, but excluding orchards and agroforests that mainly produce food crops. Forest systems regulate 57 percent of total water runoff, and they ensure all or some of the water supply for about 4.6 billion people worldwide.

According to the MA, the global area of forest systems has been halved over the past three centuries; 25 countries have lost all forests; and another 29 have lost more than 90 percent of their forest cover. Forest systems regulate 57 percent of total water runoff, ensuring some or all of the water supply for about 4.6 billion people. From 1990 to 2000, temperate forests increased by almost 3 million hectares annually; however, tropical deforestation exceeded 12 million hectares annually. About 40 percent of forest area has been lost during the industrial era, and forests continue to be lost in many regions. Some of the pressure to clear forests in the future, according to the MA, will be alleviated by the expanding role of plantations in timber supply.

Global timber production has increased by 60 percent in the past four decades. Most of the increase is attributed to plantations, which produced 35 percent of the global roundwood harvest in the year 2000. This proportion, according to the MA, is expected to increase to 44 percent by 2020. The most rapid expansion of plantations is expected to occur in the mid-latitudes, where yields are higher and costs are lower.

Under the MA scenarios, which run from 1970 to 2050, forest area is expected to increase in industrial regions and decrease in developing ones.^b Global deforestation in three of the four scenarios is projected to be approximately equal to historic rates (approximately 0.4 percent annually between 1970 and 1995). The fourth scenario projects a deforestation rate of 0.6 percent per year. Particular ecosystems, such as tropical forests, could be subject to higher than average deforestation rates.

Cultivated Systems

In the MA, cultivated systems include predominantly cropped areas, agroforestry, and aquaculture. In the past two decades, one of the areas with the greatest expansion of cropland was the U.S. Great Plains, and one of the areas with the greatest contraction of cropland was the southeastern United States. While the intensification of cultivated systems has met the increase in food needs over the past 50 years and reduced the pressure to convert natural ecosystems into cropland, this, according to the MA, has come at the cost of greater pressure on inland water ecosystems, generally reduced biodiversity within agricultural landscapes, and higher energy inputs in the form of mechanization and the production of chemical fertilizers. Although cultivated systems provide only 16 percent of global water runoff, they tend to be close to human populations, and their nutrient and industrial water runoff affects about 5 billion people.

The absence of new suitable land for cultivation and the increased productivity of agricultural lands are reducing the need for agricultural expansion. Consequently, more of the land in cultivated systems is actually being cultivated, with increased intensity of cultivation, shorter fallows, and a shift from monocultures to polycultures. Farmers in North America and other areas increasingly are adopting appropriate soil conservation practices that reduce erosion, such as minimum tillage. Since 1950, one of the areas where cropland has stabilized is North America. The table below summarizes some current characteristics of cropland and forest ecosystems as reported by the MA, including the relative proportions of potential and actual areas in each system, indicated as the “share of area transformed.”

Synergies

The MA approach attempts to look beyond the confines of particular systems and stresses a broad interconnected view of the costs and benefits of ecosystem conversions. Because of the connections among ecosystems, the degradation of one can have negative synergistic effects on others; however, the same connections can be harnessed through properly designed human interventions to produce positive synergistic effects. According to the MA, increasing food production in cultivated systems can have negative effects on biodiversity and water regulation, as well as increasing agricultural pollutants in the runoff; however, the interactions between human and natural systems can also have positive synergies. Agroforestry systems, if properly designed, can provide food and fuel, restore soils, and contribute to biodiversity conservation.

Characteristics of Forest Systems and Cultivated Systems Worldwide Printer Friendly Version System and Subsystem  Area (Million Square Kilometers)  Share of Terrestrial Surface of Earth (Percent)  Mean Net Primary Productiona (Kilograms Carbon per Square Meter per Year)  Share of System Covered by Protected Areasb (Percent)  Share of Area Transformedc (Percent) Forest/Woodland 41.9 28.4 0.68 10 42   Tropical/Subtropical 23.3 15.8 0.95 11 34   Temperate   6.2   4.2 0.45 16 67   Boreal 12.4   8.4 0.29   4 25 Cultivated 35.3 23.9 0.52   6 47   Pasture   0.1   0.1 0.64   4 11   Cropland   8.3   5.7 0.49   4 62   Mixed (Crop and Other) 26.9 18.2 0.60   6 43

^aFor an overview of the Millennium Ecosystem Assessment, see web site www.millenniumassessment.org/en/about.overview.aspx. At the time this chapter was written, subglobal assessments were not available. This summary is based on the synthesis report, with an emphasis on the United States.

^bScenarios are story lines that envision different future worlds. As with climate change analysis, models are run, and their outputs are described for several possible future scenarios. Each scenario encapsulates a broad set of socioeconomic, political, and ecological assumptions. The four scenarios used in the assessment focused on global conditions in 2050. For more details on the scenarios analyzed, see Millennium Ecosystem Assessment, Ecosystems and Human Well-being: Synthesis (Washington, DC: Island Press, 2005), web site www.millenniumassessment.org/en/Products.Synthesis.aspx.

Accounting for Harvested Wood Products in Future Greenhouse Gas Inventories

Harvested wood products (HWP) are defined as “goods manufactured or processed from wood, including lumber and panels for end uses such as housing and furniture, and paper and paperboard for uses such as packaging, printing and writing, and sanitary applications.”^a HWP are an important part of the overall carbon cycle and are thus integral to any greenhouse gas accounting system or inventory.

Preparation of the 2006 guidelines of the Intergovernmental Panel on Climate Change (IPCC) for preparing national greenhouse gas inventories under the United Nations Framewrk Convention on Climate Change (UNFCCC)—including methods for estimating and reporting of HWP—is underway. The issue of accounting for HWP, however, is a complex one, and involves the consideration of factors such as international trade (import-export) of wood products, timing of emissions accounting, determining whether emissions include those from existing wood product pools or solely from harvesting, and establishing how complex or simple the accounting approach should be so as not to create barriers to participation.^b

Three approaches—stock-change, production, and atmospheric-flow—have been developed and debated, and all three were discussed at a UNFCCC-sponsored workshop held in Norway on August 30 through September 2, 2004.^c At the Eleventh Conference of the Parties to the UNFCCC in December 2005, the parties agreed to return to this issue at the 24th meeting of the Subsidiary Body for Scientific and Technical Advice.^d

The first approach under consideration for HWP is the stock-change approach. This approach accounts for changes in carbon stock in forests in the country in which the wood is grown, deemed the producing country. Changes in the products pool are accounted for in the country where the products are used, deemed the consuming country. These stock changes are counted within national boundaries, where and when they occur.^b Under this approach, the HWP stock change in a country may be estimated considering either transfers into and out of the HWP pool, or the difference between HWP carbon stocks at two different set points in time.

The next alternative—the atmospheric-flow approach— accounts for emissions or sequestration of carbon to and/or from the atmosphere within national boundaries, both where and when emissions and sequestration occur. The producing country accounts for sequestration of carbon attributed to forest growth, while the consuming country accounts for emissions of carbon to the atmosphere from oxidation of HWP.^b Under this approach, it is the net flow of carbon dioxide from the pools to the atmosphere that would be reported as the equivalent emission, and the net flow in the opposite direction as the equivalent amount of carbon sequestration.^c

The third approach for accounting for HWP is the production approach. While this approach also reports changes in carbon stock, it is the producing country that reports the stock changes in HWP regardless of the location of the stock (i.e., whether within country boundaries or exported).^c This approach thus accounts for domestically produced stocks only; that is, stock changes are counted when they occur, regardless of where the stock change occurs.^b

An additional method that was proposed by one Annex I country—the simple decay approach—effectively falls under the production approach. This method assumes that HWP remain a part of the forest in which they were produced until decomposed.^c This approach is therefore similar to the production approach in that it also estimates the stock changes in HWP when, but not where, they occur if wood products are exported or traded. Both sequestration of carbon from the atmosphere due to forest growth and emissions resulting from harvesting are accounted for in the producing country.^b

^a”United States Submission on the Views Related to Carbon Accounting and Wood Products,” in United Nations Framework Convention on Climate Change, Issues Relating to Harvested Wood Products, Paper No. 7 (May 10, 2004), pp. 42-43, web site http://unfccc.int/ resource/docs/2004/sbsta/misc09.pdf.

^bM. Ward, “Harvested Wood Products, A Beginning Guide to Key Issues,” Senior Counsel to the Government of New Zealand (July 2004).

^cK. Pingoud et al., "Approaches for Inclusion of Harvested Wood Products in Future GHG Inventories Under the UNFCCC, and their Consistency with the Overall UNFCCC Inventory Reporting Framework," IEA Bioenergy (July 13, 2004).

^dInternational Institute for Sustainable Development, “Summary of the Eleventh Conference of the Parties to the UN Framework Convention on Climate Change and First Conference of the Parties Serving as the Meeting of the Parties to the Kyoto Protocol: 28 November – 10 December 2005,” Earth Negotiations Bulletin, Vol. 12, No. 291 (December 12, 2005), web site www.iisd.ca/vol12/ enb12291e.html.

Global Forest Resources Assessment 2000

The Food and Agriculture Organization of the United Nations (FAO) is the main intergovernmental source of data on global forests. FAO’s global forest assessments date back to 1948, with the most recent assessment— Global Forest Resources Assessment 2000—published in 2001. The 2000 assessment was the first to include a uniform definition of forests for all regions of the world—that is, areas with at least 10 percent of canopy cover (excluding stands of trees primarily used for agricultural production). Using this new definition, FAO estimated the world’s forested area in 2000 at 3.9 billion hectares.

The 2000 assessment reported that the world’s forests showed average net annual losses of 9.4 million hectares from 1990 to 2000, with annual losses of 14.6 million hectares due to deforestation and annual gains of 5.2 million hectares due to reforestation, afforestation, and the natural expansion of forests. Net losses for tropical forests were 12.3 million hectares annually, and net gains for non-tropical forests were 2.9 million hectares annually.^a

The FAO Global Forest Resources Assessment 2000 draws its forest data for the United States from U.S. Forest Service periodic forest inventories, which cover all forest land in the United States for more than 70 years. The Forest Inventory and Analysis (FIA) traditionally sampled on a 5- to 10-year cycle with an accuracy of ±1 percent per million hectares for forest area estimates. Since 1996, however, the FIA has involved annual sampling in many States. Currently, 46 States are sampled annually. The FAO Assessment for 2000 cites total U.S. forest area at 226 million hectares. The change in U.S. forest area from 1990 to 2000 was 0.4 million hectares per year.^b

A revised assessment is currently being prepared and will be published in early 2006. Global Forest Resources Assessment 2005 will involve more sophisticated datasets that result from satellite remote sensing.^c At the time this chapter was written, the assessment had not yet been published.

^aFood and Agriculture Organization of the United Nations, Global Forest Resources Assessment 2000, “Executive Summary,” web site www.fao.org/DOCREP/004/Y1997E/y1997e05.htm#bm05.

^bFood and Agriculture Organization of the United Nations, Global Forest Resources Assessment 2000, Chapter 34, “North America, Excluding Mexico,” web site www.fao.org/DOCREP/004/Y1997E/y1997e13.htm#bm39.

^cT. Parris, “Global Forest Assessments,” Environment, Vol. 45, No. 10 (2003), p. 3.