QUALITY ASSURANCE / QUALITY CONTROL
AND UNCERTAINTY MANAGEMENT PLAN FOR THE
U.S. GREENHOUSE GAS INVENTORY:
Background on the U.S. Greenhouse Gas Inventory Process
U.S. Environmental Protection Agency
Office of Atmospheric Programs (6204N)
Greenhouse Gas Inventory Program
Washington, B.C. 20460
EPA 430-R-02-007A
Version 1.0
June 2002
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How to Obtain Copies
You can electronically download this document from the U.S. Environmental Protection Agency's Global
Warming web page at www.epa.gov/globalwarming/publications/emissions.
For Further Information
Contact Mr. Michael Gillenwater, Office of Air and Radiation, Office of Atmospheric Programs, U.S.
Environmental Protection Agency, Tel: (202) 564-4092, or by e-mail at ghginventory@epa.gov
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Preface
The Inventory of U.S. Greenhouse Gas Emissions and Sinks must meet the needs of a diverse collection of
stakeholders, ranging from the general public to scientists. The Inventory is both a detailed accounting
exercise and a rigorous scientific one. In recognition of this composite of purposes, the U.S. Greenhouse
Gas Inventory Program has, since its inception, embodied the underlying principle that developing an
inventory is more than just a scientific or technical undertaking. It also requires in equal measure a
commitment to continuous improvement and quality management.
The philosophy that the inventory program has developed—as it tries to balance the needs of its diverse
audience—focuses on credibility, objectivity, and transparency. The program fosters a high level of
credibility and objectivity by striving for unbiased quantitative estimates of emissions and sinks (i.e.,
removals) and for conservative and factual qualitative findings. In turn, detailed documentation—of results,
methods, data, and evaluation of uncertainties—ensures transparency. Thus, the overall system is designed
to maximize efficiency and quality at every level.
Designing quality management processes to support the development of the inventory must recognize the
fundamental role of institutional, philosophical, managerial, and procedural subsystems. The current
structure of the inventory system, which has evolved and developed over the past decade, reflects these
principles. This document provides an overview of this system, which includes both processes for
producing the inventory and procedures to manage its uncertainty and quality.
The audience for this document includes the diverse users of the Inventory, some of whom may be
unfamiliar with the inventory process, as well as anyone else seeking background on how the U.S.
Greenhouse Gas Inventory Program functions. We hope that this document will not only serve as useful
background to these individuals, but also be of assistance to other countries, States, companies, universities,
and interested practitioners involved in conceptualizing, designing, or building a comprehensive inventory
system.
Feedback is fundamental to our quality improvement process. This document and its companion document,
Procedures Manual for Quality Assurance / Quality Control and Uncertainty Management, are intended to
be "living," in that they will continuously be updated. We encourage you to provide us with comments and
suggestions on any aspect of these documents or other products from the U.S. Greenhouse Gas Inventory
Program.
Michael Gillenwater
Greenhouse Gas Inventory Program
June 2002
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Acknowledgments
This document is the outgrowth of a decade of experience of staff at the U. S. Environmental Protection
Agency in cooperation with other supporting agencies and departments in the United States Government
and with contractors. Michael Gillenwater conceived of the project and provided overall direction and a
guiding philosophy to the development of this document from its inception in 1996. Melinda Harris took on
the daunting task of developing an early draft describing the process of producing the Inventory of U.S.
Greenhouse Gas Emissions and Sinks. However, it is Fran Sussman who is the primary author of this
document. She has added an invaluable quantity of intelligence, thoroughness, and creativity to both this
document and the U.S. Greenhouse Gas Inventory Program. Marian Martin Van Pelt and Katrin Peterson,
with their considerable knowledge of the process of developing, publishing and submitting the Inventory,
contributed greatly to the document's accuracy and completeness.
Others have also been important contributors if not to this document, then to the overall maturation of the
U.S. Greenhouse Inventory Program. Wiley Harbour directed the program with great energy and a
wonderful attitude from its early days until recently and set in place its fundamental mission. Craig Ebert of
ICF Consulting and Art Rypinski of the Energy Information Administration (EIA), at the time, were both
"inventory founders" in that they helped lead technical development of the U.S. inventory. Michael
Gillenwater established much of what has become the current U.S. greenhouse gas inventory system, and
now Marian Martin Van Pelt of ICF Consulting has furthered that effort and brought an outstanding level
of professionalism and acumen to the program. And finally, we would like to thank the rest of the staff at
EPA, EIA, ICF Consulting, and other organizations that have worked on the Inventory over the years and
helped make it such an outstanding product.
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CONTENTS
1 Introduction 1
2 Overview of the U.S. Greenhouse Gas Inventory Process 3
2.1 Uses of the National Greenhouse Gas Inventory and the Inventory Program 4
2.2 Developing the U.S. Inventory: IPCC Methodology 4
2.3 Contributors to the Inventory 5
3 Process and Organizational Structure: Developing the Inventory, Conducting QA/QC, and
Estimating Uncertainty 7
4 The Inventory Program and Process for Developing the Inventory 10
4.1 Drafting and Finalizing the Inventory Document 10
4.2 Fulfilling International Reporting Requirements 12
4.3 Cross-Cutting Activities 13
4.4 Technical and Policy Support 13
4.5 Illustrating the Inventory Development Process 14
5 QA/QC Procedures and Uncertainty Analysis 17
5.1 Goals for Inventory Quality. Implementation of QA/QC Procedures, and
Uncertainty Analysis 17
5J The U.S. Approach to QA/QC 18
5.3 The U.S. Approach to Uncertainty Analysis 20
6 References 23
Appendix A: Global Climate Protection Act of 1987: Section 1103 A-1
Appendix B: Names and Contact Information for the Inventory Team B-1
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EXHIBITS AND TEXT B OXES
Exhibits
Exhibit 3-1. Organizational Structure and Division of Responsibilities: Inventory
Development, QA/QC, and Uncertainty 9
Exhibit 4-1. U.S. Inventory Program and the Inventory Development Process 15
Exhibit 4-2. General Schedule for Completing the Annual Inventory of U.S. Greenhouse
Gas Emissions and Sinks 16
Exhibit 5-1. The Roles of Quality Assurance. Quality Control, and Uncertainty Analysis in
the I nventorv Process 21
Text Boxes
Box 5-1. Reporting Guidelines 18
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1 INTRODUCTION
Each year, the U.S. Environmental Protection Agency (EPA), in cooperation with other government
agencies, prepares the Inventory of U.S. Greenhouse Gas Emissions and Sinks (referred to here as the
Inventory). A wide range of agencies and individuals are involved in supplying data to, reviewing, or
preparing portions of the U.S. inventory—including federal and State government authorities, research and
academic institutions, industry associations, and consultants. The information reported in the Inventory
includes estimates of annual emissions and sinks and trends over time, as well as other information and
analyses on the sources of emissions and the methods by which emissions and sinks are calculated.
The Inventory—and the information it contains—serves a number of purposes, foremost of which is
fulfilling our international commitments to report under the United Nations Framework Convention on
Climate Change (UNFCCC). In addition to satisfying this formal commitment, the inventory data are
critical to monitoring and tracking the progress of the United States in meeting commitments under the
UNFCCC. The preparation of the greenhouse gas inventory is also part of a broader program of technical
and policy support, and contributes to technical, scientific, and policy research aimed at understanding the
relative contribution of different emission sources and sinks to overall emissions, the future time path of
emissions and atmospheric greenhouse gas concentrations, and the potential cost of limiting emissions from
different gases and sources. The inventory program also focuses on improving methodologies, on
developing estimates for new source categories, and on finding new and improved activity data, emission
factors, and direct measurements that go into the process of estimating the inventory.
The development of the national greenhouse gas inventory reflects a long history of U.S. leadership and
active participation in international efforts to develop credible, high quality guidance and methods for
estimating emissions and removals. The assumptions and methodologies used in the U.S. inventory are
based on guidelines and recommended good practices developed cooperatively—with the assistance of
countries like the United States—by the Intergovernmental Panel on Climate Change (IPCC/OECD/IEA
1997, IPCC 2000) on behalf of the UNFCCC. These reports are the basis of inventories produced by
diverse countries worldwide.
The official national and international prominence of the U.S. Greenhouse Gas Inventory Program and the
Inventory, as well as the program's varied audiences and uses, dictate that it meet high standards. The IPCC
inventory guidelines and good practice guidance for preparing inventories are intended to promote quality
along a number of dimensions. Foremost is the goal of reducing uncertainty in the emissions and sinks
estimates, so that countries produce inventories "that are accurate in the sense of being neither over nor
underestimates so far as can be judged, and in which uncertainties are reduced as far as practicable" (IPCC
2000). Further, an inventory program should include activities that bothpromote and check the accuracy,
completeness, consistency, transparency, and comparability of the inventory to international
methodologies, and that control other dimensions of quality. As stated in the IPCC guidance (IPCC 2000)
document,
Good practice guidance. . .supports the development of inventories that are transparent,
documented, consistent over time, complete, comparable, assessed for uncertainties,
subject to quality control and assurance, efficient in the use of the resources available to
inventory agencies, and in which uncertainties are gradually reduced as better
information becomes available.
One of the primary goals of the U.S. Greenhouse Gas Inventory Program is to work continually to improve
emission estimates. To this end, the inventory program has adopted a comprehensive and unified approach
to managing quality and uncertainty in the inventory estimates. The philosophy underlying the approach is
that methodological advances, improvements in documentation and clarity to facilitate transparency,
quality control and quality assurance, and uncertainly analysis must all be integrated into one
comprehensive greenhouse gas inventory system. Thus, quantitative uncertainly analysis is not an end in
itself; rather the method used to estimate uncertainty, and the estimated uncertainty values, are less
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important than the institutional benefits of improved communications and building quality improvement
feedback processes. As a result, the process in the inventory program of estimating uncertainty focuses on
learning and quality and is integrated with the process of improving the inventory. The uncertainty analysis
provides a mechanism for working directly with data suppliers and, thus, also provides a means by which to
build quality throughout the participants in the national system of inventory development.
In line with the philosophy underlying the inventory program, and as part of efforts to control, document,
and improve the quality of its inventory, the United States has developed a plan for conducting quality
assurance (QA) and quality control (QC) activities and estimating uncertainty. This plan is an integral part
of the U.S. Greenhouse Gas Inventory Program and has several distinct components. The first element is a
set of processes and procedures intended to control, maintain, and check the quality of the inventory. The
second element is a set of guidance material and processes, data collection and analysis, and empirical
work designed to understand the sources of uncertainty in the U.S. greenhouse gas inventory and to
estimate the magnitude of uncertainty surrounding the inventory estimates. The third element is a clear set
of organizational roles and responsibilities. The fourth element in the U. S. plan for improving the inventory
over time is the stated goal of conducting a thorough quality review and uncertainty analysis within the
next few years. The final element involves unifying the information loops and corrective actions that,
together with other feedbacks and interactions within the U. S. Greenhouse Gas Inventory Program, are
designed to improve the quality of the U.S. greenhouse gas inventory over time.
This document is one of two complementary documents that together describe and provide guidance on the
overall process of preparing, submitting, and disseminating a greenhouse gas inventory that has undergone
quality control and quality assurance procedures, and that describe the procedures for both quality control
and estimating uncertainty. These documents are intended to be "living," that is, to evolve as new
information arises or as procedures or organizational structures are tested, modified, or formalized.
This Background document provides an overview of the underlying organizational structure and process by
which the Inventory and its supporting documentation are produced (including the points at which QA and
QC occur and uncertainty is estimated). The audience for the current document includes those involved in
preparing and checking the inventory and its associated documentation, as well as the general public and
other parties interested in understanding the inventory process. The companion document, Procedures
Manual for Quality Assurance / Quality Control and Uncertainty Analysis describes a comprehensive set of
procedures that the United States is implementing in order to check and continually improve the quality of
the inventory estimates and the documents in which these estimates are reported, and to estimate the
uncertainty surrounding the inventory estimates.
The remainder of this document is organized into five chapters as follows:
• Chapter 2, Overview of the U.S. Greenhouse Gas Inventory Process, provides information on the
inventory, its contributors, and the methods used to calculate emissions and sinks.
• Chapter 3, Process and Organizational Structure: Developing the Inventory, Conducting QA/QC
and Estimating Uncertainty, describes the functional responsibilities for the inventory.
• Chapter 4, The Inventory Program and Process for Developing the Inventory, describes the
process of producing and submitting the Inventory and related official documents, presents a
sample schedule for the inventory development process, and indicates other features of the U. S.
Greenhouse Gas Inventory Program.
• Chapter 5, QA/QC Procedures and Uncertainty Analysis, explains the general approach and goals
for inventory quality and uncertainty analysis, and presents the integrated process of producing the
inventory and conducting QA/QC.
• Chapter 6, References, presents source information for all chapters cited in the preceding chapters.
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2 OVERVIEW OF THE U.S. GREENHOUSE
GAS INVENTORY PROCESS
Under a decision of the Conference of the Parties: to the United Nations Framework Convention on
Climate Change (UNFCCC), Annex I parties are required to provide national greenhouse gas inventories to
the UNFCCC Secretariat each year by April 15. The information to be submitted covers annual emissions
and removals data for the year 1990 (or other relevant base-year), and subsequent years up to two years
prior to the year of submission.2 As a signatory to the UNFCCC, therefore, the United States has a
commitment to develop, update, publish, and make available a comprehensive national inventory of
anthropogenic emissions of greenhouse gases to the atmosphere (by sources) and removals from the
atmosphere (by sinks).3 The U.S. Environmental Protection Agency (EPA) works cooperatively with the
State Department and other federal agencies and departments to prepare this inventory of emissions and
removals.4
Each year, the United States estimates greenhouse gas emissions and sinks for a series of years—starting
with 1990 and ending with the most recent year for which reliable data are available (typically the calendar
year prior to the year in which the inventory is being estimated). The inventory estimates are officially
summarized and documented in the Inventory of U.S. Greenhouse Gas Emissions and Sinks (here referred
to as the Inventory). Thus, for example, the estimation process for the 1990-2000 inventory begins in 2001,
and the official Inventory for 1990 to 2000 is submitted to the UNFCCC on April 15, 2002.
The Inventory document reports annual emissions and sinks of greenhouse gases, presents emission trends
and their relationship to economic indicators, and describes the methodology and data sources used to
compute the inventory. In accordance with UNFCCC guidelines on reporting and review (adopted by the
Conference of the Parties at its fifth session), the inventory covers anthropogenic emissions by sources and
removals by sinks of all greenhouse gases not controlled by the Montreal Protocol.5 At a minimum,
inventories must include information on the following greenhouse gases: carbon dioxide (CC>2), methane
(CH/i), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride
(SF6). The Inventory also reports emissions of ambient air pollutants (specifically nitrogen oxides (NOJ,
carbon monoxide (CO), non-methane volatile organic compounds (NMVOCs), and sulfur dioxide (SO2)),
which contribute indirectly to the greenhouse effect. In accordance with the UNFCCC guidelines, the
United States reports aggregate emissions in CC>2 equivalent terms using Global Warming Potential (GWP)
values provided by the Intergovernmental Panel on Climate Change (IPCC) in its Second Assessment
Report (IPCC 1996).6
The Conference of the Parties is the supreme body of the UNFCCC, comprising more than 170 nations that have
ratified the UNFCCC. Thirty-six parties are listed in Annex I to the UNFCCC, including most countries belonging to
the Organisation for Economic Co-operation and Development (OECD).
See "Review of the Implementation of Commitments and of Other Provisions of the Convention: UNFCCC guidelines
on reporting and review. " FCCC/CP/1999/7,16 February 2000. Available at
http://www.unfccc.de/resource/docs/cop5/07.pdf.
The term anthropogenic refers to greenhouse gas emissions and removals that are the direct result of human activities
or natural processes that have been affected by human activities.
4 This role was established when Congress passed the Global Climate Protection Act of 1987 (see 15 U.S.C. Sec. 2901,
Section 1103). The Act gives the Secretary of State the responsibility of coordinating U.S. policy requiring action
through the channels of multilateral diplomacy, and also directs the Secretary of State to work jointly with the
Administrator of the EPA and other U.S. agencies. See Appendix A for the relevant language.
See "Review of the Implementation of Commitments and of Other Provisions of the Convention: UNFCCC guidelines
on reporting and review. " FCCC/CP/1999/7,16 February 2000. Available at
http://www.unfccc.de/resource/docs/cop5/07.pdf.
6 The IPCC recently published its Third Assessment Report (IPCC 2001). This report revises the global warming
potential of several gases relative to the IPCC's Second Assessment report (IPCC 1996).
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2.1 Uses of the National Greenhouse Gas Inventory and the Inventory Program
The development of the U.S. greenhouse gas inventory is part of a broader inventory program that goes
beyond preparing and disseminating the Inventory document. The objectives of this inventory program are
driven by U. S. commitments under Articles of the UNFCCC and by activities undertaken to support U. S.
policy-making.
Articles 4 and 12 of the UNFCCC require that Parties to the UNFCCC develop, periodically update,
publish, and make available to the Conference of the Parties national inventories of anthropogenic
emissions by sources and removals by sinks of all greenhouse gases not controlled under the Montreal
Protocol.7 In addition, future commitments may require estimating emissions and removals as part of
ensuring that Parties are in compliance with emission limits, that they have a national system for estimating
sources and sinks of greenhouse gases, that they submit an inventory annually, and that they formulate
national programs to improve the quality of emission factors, activity data, or methods.
The objectives of the U.S. Greenhouse Gas Inventory Program extend beyond the direct requirements of
U.S. commitments under the UNFCCC. The United States participates in international and domestic efforts
to refine and develop the methodologies used to prepare emission inventories and to advance and
incorporate scientific research, and works to foster consistent estimation approaches across domestic
agencies and programs. The EPA provides technical support and methodological information to State and
local governments for inventories and other climate change analyses. The greenhouse gas inventory, and
analyses that rely on inventory data, provide information to U.S. officials in support of international
negotiations on climate change, meetings to define and understand the implications of future provisions
under the UNFCCC, and efforts to assess progress in meeting domestic goals.
The audiences for the Inventory reflect its several roles in the broader inventory program. For example, the
international climate change community relies on the Inventory for information about U.S. emissions and
removals and evaluates the quality and consistency of the greenhouse gas inventory. Domestically,
Congress and decision makers and policy advisors rely on the Inventory and related products for
information on the U.S. contribution to global emissions and removals and on contributions by key
industries, as well as for estimating the impacts of existing and planned policies on greenhouse gas
emissions. States and localities, the general public, special interest groups, and businesses also use the
Inventory, as do scientists and researchers employed in climate and economic modeling and other climate
change issues.
2.2 Developing the U.S. Inventory: IPCC Methodology
The IPCC, working in cooperation with scientists, national experts, and inventory specialists from around
the world (including significant participation by the United States), has developed methodological
guidelines for preparing national greenhouse gas emission inventories. The IPCC guidelines are designed to
ensure that the national inventories submitted to the UNFCCC are consistent and comparable across sectors
and nations. In developing its national greenhouse gas inventory, the United States employs methods, data
sources, and analytical approaches that are consistent with the IPCC guidelines.
The most recent version of the IPCC guidelines, the Revised 1996 IPCC Guidelines for National
Greenhouse Gas Inventories (IPCC/OECD/IEA 1997, here referred to as the IPCC Revised Guidelines), is
the basis for national inventories prepared worldwide. Additional guidance on good practices in preparing
emission inventories and on improving the quality of and reducing the uncertainty in, emission estimates is
provided by a companion IPCC document, Good Practice Guidance and Uncertainty Management in
National Greenhouse Gas Inventories (IPCC 2000, here referred to as IPCC Good Practice Guidance).
The IPCC Revised Guidelines provide technical information for estimating anthropogenically-induced
emissions and removals of greenhouse gases. Both the IPCC Revised Guidelines and the IPCC Good
Practice Guidance cover six broad categories (i.e., sectors) of sources of emissions or removals (energy,
industrial processes, solvent use, agriculture, land-use change and forestry, and waste), each with multiple
7 Chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and halons (halocarbons that contain bromine) are
greenhouse gases that are also stratospheric ozone depleting substances under the Montreal Protocol.
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source categories. Because estimates of greenhouse gas emissions at the national level are generally
calculated rather than directly measured, the process of estimating emissions usually focuses on summing
the products of activity data (measures of the occurrence of activities that produce greenhouse gas
emissions in a given source category) and emission factors (the quantity of emissions per unit of the
activity).8 These products are calculated with varying degrees of complexity depending on the source
category. Removals by sinks are calculated in analogous ways.
The IPCC RevisedGuidelines and IPCC Good Practice Guidance are designed to be followed by diverse
nations, each with unique national circumstances. Countries vary in the sources and sinks that are
considered "key" (i.e., contribute significantly to national emission estimates and so are high priority for
quality assurance and quality control activities), and in the availability of both the data and the resources
needed to develop a greenhouse gas inventory9 Consequently, the IPCC Revised Guidelines permits
alternative approaches to calculating an inventory of emissions and sinks, including employing relatively
simple methods that use national activity data and default average emission factors (generally referred to as
Tier 1) for use by countries where country-specific data on key variables may be unavailable or difficult to
obtain. The IPCC Revised Guidelines also provides technical information and guidance for more detailed
inventory methods (generally referred to as Tier 2 or greater).10 These methods may require a country to
develop and use emission factors and other data specific to the country.
For some emission sources, the United States uses IPCC default methodologies and factors. However, for
emission source categories that are significant sources of emissions, the United States applies a more
detailed analysis. In accordance with the IPCC Revised Guidelines, whenever the United States' approach
involves a more rigorous calculation or method than the IPCC Revised Guidelines provides, the Inventory
reports and explains the approach in a clear and transparent manner. For comparison purposes, the
Inventory also includes estimates prepared using the IPCC Reference Approach for CO2 emitted during
fossil fuel combustion.
To the extent possible, the U.S. emission estimates rely on published activity data and emission factors.
Much of the data underlying the emission estimates comes from government statistics, including published
or unpublished data supplied by agencies and departments such as the Energy Information Administration
(EIA) of the U.S. Department of Energy (DOE) and the U.S. Forest Service (USFS) of the U.S. Department
of Agriculture (USDA). State agencies and trade associations also supply important data. Some emission
estimates, such as those for nitrogen oxides (NO*), carbon monoxide (CO), and nonmethane volatile
organic compounds (NMVOCs) are taken directly from EPA estimates of emissions of ambient air
pollutant emissions, which are prepared to determine progress in meeting national standards for air
pollution promulgated under the authority of the Clean Air Act and its amendments.
2.3 Contributors to the Inventory
Developing the emission estimates and the Inventory document is an extensive effort, involving modeling
and estimation by many federal and State government agencies, research institutions, universities, and
consultants. In addition, numerous statistical and informational databases compiled by all levels of
government, by trade and research associations, and by other public and private institutions, are valuable
source of data inputs, or may supply secondary data sources, to the inventory development process.
The U.S. Greenhouse Gas Inventory Program within EPA's Office of Atmospheric Programs (OAP)
provides technical oversight, performs quality assurance on all aspects of inventory development, and
coordinates the expert and public review processes. Also within EPA, several offices coordinate in
Some sources are actually measured using direct monitoring. For example, emission factors are often developed using
measurements. For most sources, however, the U.S. inventory relies on activity based estimation methods.
9 A key source category is defined such that the estimated emissions have a "significant influence on a country' s total
inventory of direct greenhouse gases in terms of the absolute level of emissions, the trend in emissions, or both" (IPCC
1997).
1 ° Note that these Tiers should not be confused with thequality control Tiers described in Chapter 2 of ^Procedures
Manual.
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researching emission pathways and developing new procedures for estimating greenhouse gas emissions
and removals:
• The Clean Air Markets Division within OAP is home to the overall U.S. Greenhouse Gas
Inventory Program. It is responsible for reporting to the UNFCCC and publishing the Inventory of
U.S. Greenhouse Gas Emissions and Sinks each year. It also prepares fossil fuel combustion
emission estimates along with estimates from a variety of other source categories.
• The Climate Protection Partnerships Division within OAP produces annual estimates of CH4 and
N2O emissions from a variety of agricultural, waste, energy, and other source categories. They
also work with USDA and USFS to produce estimates of CC>2 fluxes from land use change and
forestry activities.
• The Global Programs Division within OAP tracks emission trends for the ozone depleting
substances and their substitutes, including hydrofluorocarbons (HFCs), perfluorocarbons (PFCs),
and sulfur hexafluoride (SFe). They also track emissions from other industrial sources of these
gases.
• The Office of Research and Development (ORD) conducts research into a variety of source
categories.
• The Office of Solid Waste and Emergency Response (OSWER) provides additional information
on landfills and solid waste management systems, as well as the fate of products in landfills. These
statistics contribute to estimates of methane emissions.
• The Office of Water (OW) provides information on domestic and industrial wastewater that is
used in calculating emissions.
• The Office of Transportation and Air Quality (OTAQ) develops emission factors and detailed
emission estimates for the transportation sector. Together with the Federal Highway
Administration, OTAQ reports vehicle miles traveled, which are used to develop methane, nitrous
oxide, and trace gas emission estimates.
• The Office of Air Quality Planning and Standards (OAQPS) provides estimates of emissions of
ambient air pollutants (including CO, NOx, and NMVOCs).
In addition to the EPA, a number of U.S. agencies and departments are important contributors to the
greenhouse gas emission inventory. A partial list of the roles of different federal government entities
supplying data for the inventory or contributing directly to its preparation includes the following:
• The Energy Information Administration (EIA) gathers and compiles detailed information on
energy production and consumption, which forms the foundation for the energy-related
greenhouse gas emission estimates. The EIA also reports on the carbon content of fossil fuels
consumed in the United States and develops emission factors that relate carbon emissions to fuel
quantity burned. Likewise, the U.S. Department of Energy (DOE) provides review and analysis.
• The U. S. Department of Agriculture (USDA) compiles and reports information on fertilizer use,
crop production statistics, and agricultural practices. The U.S. Forest Service (USFS) regularly
assembles and reports an inventory of forest and soil carbon in the United States. This forest
inventory, along with the National Resource Inventory, is used to track net CO2 fluxes from land
use change and forestry activities. The EPA works closely with the USFS to expand the analysis
of land use change, and forestry-related carbon fluxes.
• The Department of Transportation, the Federal Highway Administration, the Treasury
Department, the Federal Aviation Administration, the Department of Commerce, the Bureau of
Census, the U.S. Geological Survey, and the Bureau of Transportation Statistics are sources of
valuable information.
Private groups publish several reference materials that provide data on industrial production and chemical
use that are key to inventory development. State government agencies, academic researchers, consultants,
and others also contribute to developing inventory estimates or serve as reviewers of the final estimates.
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3 PROCESS AND ORGANIZATIONAL
STRUCTURE: DEVELOPING THE
INVENTORY, CONDUCTING QA/QC,
AND ESTIMATING UNCERTAINTY
A variety of staff contributes to the inventory process. The inventory "team" includes agency and
department staff, contractors, and other persons involved directly and indirectly in preparing or handling
the inventory estimates and the Inventory of U.S. Greenhouse Gas Emissions and Sinks (referred to here as
the Inventory) or other official documents. Inventory staffer special staff may be assigned to check the
quality of the inventory as it is developed, including routine checks to ensure data integrity, correctness,
and completeness. Staff also estimate the uncertainly surrounding the inventory estimates, and conduct
expert and public reviews associated with quality assurance (QA).
The organization of the team for inventory development and quality assurance / quality control (QA/QC)
results in supervision of all aspects of the inventory development activities, of the quality checks and
uncertainty analysis, and of the expert review process. The functional responsibilities and informal titles of
those responsible for these activities include the following (Appendix B provides contact information for
the persons directly involved in preparing the inventory):
• Agency Inventory Lead—overall director responsible for all aspects of the inventory program,
including supervising the preparation of the estimates, the uncertainty analysis, and the Inventory
document and ensuring that corrective actions are taken as needed
• Data and Document Management Coordinator—responsible for directly coordinating the
preparation of the inventory estimates and text, maintaining the electronic files, supervising the
preparation of docket and archiving materials, as assisted by staff
• Source Category Leads—responsible for preparing the inventory estimates and supporting text for
the Inventory document for a specific source category, for making key decisions and providing
critical input into the uncertainly analysis, for taking corrective action in response to QA/QC and
uncertainty results, and for supervising source category staff (sometimes referred to as inventory
analysts)
• QA/QC Officer—supervises the overall implementation of QA/QC procedures, including
overseeing the expert reviews and other components, and is responsible for ensuring the full and
adequate implementation of QA/QC and the adequate qualifications of inventory staff and
contractors
• Uncertainty Analysis Coordinator—directs the analysis of uncertainty for the inventory estimates
in coordination with the Agency Inventory Lead and Source Category Leads, and supervises
uncertainty staff (sometimes referred to as uncertainty analysts)
• Outside Experts—independent individuals who may contribute data to the inventory estimation
(i.e., data suppliers), may be involved in improving / examining the inventory methods and data
during the inventory development process, or may provide expert review of the emission estimates
or inventory document)1:
The organizational structure of the team is depicted in Exhibit 3-1. As illustrated in this exhibit, the Agency
Inventory Lead has overall leadership responsibility for all activities associated with the inventory,
including the preparation of the inventory estimates and text, QA/QC, uncertainty analysis, and the
Outside experts are not actually part of a chain of functional responsibility for producing the inventory. However,
they can be important contributors to the inventory and the uncertainty analysis, and are an essential part of the QA
process.
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centralized document and file handling and archiving. In addition to the Agency Inventory Lead, staff are
divided into four basic teams or groups. Note that QA/QC staff, data and document management staff,
uncertainty staff, and inventory staff are not necessary distinct, but may include overlap among the persons
involved.
Source Category Leads and associated staff have responsibility for preparing the inventory estimates and
document text, including obtaining all relevant data, developing methodologies, and coordinating among
government and contracting staff. QA/QC staff, under the direction of the QA/QC Officer, undertake
quality assurance activities (primarily the inventory review processes) and quality control, which includes
both of what the Intergovernmental Panel on Climate Change (IPCC), in its Good Practice Guidance and
Uncertainty Management in National Greenhouse Gas Inventories (IPCC 2000, here referred to as IPCC
Good Practice Guidance), identifies as Tier 1 checks (mostly general and computational checks) of the
inventory estimates, and as Tier 2 checks (detailed source category-specific checks of both the estimates
and the data sources). The Data and Document Management Coordinator and staff have responsibility for
synthesizing the work of the source category inventory staff, including integrating the spreadsheets across
the source categories, preparing the Inventory document and drafting language on trends and aggregate
results, synthesizing the Common Reporting Format (CRF) tables performing cross-cutting analyses (see
Chapter 4), and controlling all the facets of electronic file and document management.
The uncertainty analysis of the inventory estimates is a coordinated effort among all the groups. The
Uncertainty Analysis Coordinator and staff have primary responsibility for the statistical analysis of
uncertainty (including obtaining data inputs, eliciting expert judgments, developing the uncertainty model,
developing quantitative uncertainty estimates, and interpreting the results of the uncertainly analysis) for
entire Inventory. The Source Category Leads are responsible for making key decisions and providing key
input into the uncertainty analysis for specific source categories (such as determining the appropriate level
of disaggregation for data collection and model development, deciding which variables require enhanced
input data collection efforts, and identifying experts for elicitation). They are also responsible for reviewing
the results of uncertainty analysis, identifying corrective actions to be taken, and ensuring that a summary
of the results of uncertainty analysis is reported in the Inventory document. QA/QC staff, by conducting the
Tier 2 reviews that identify quality issues associated with secondary data, also contribute to the uncertainty
analysis.
Many of the individuals that fulfill the functions described above will be directly involved in the U.S.
Environmental Protection Agency (EPA) office supervising the development of the inventory. However,
other offices in EPA or other agencies, as well as contractors or other designated entities, may fulfill or
contribute to fulfilling portions of the functional responsibilities described above. In addition, one
individual may fulfill more than one functional role (e.g., the QA/QC Officer may be the Uncertainty
Analysis Coordinator as well). Similarly, as noted above, inventory staff may also function as QC staff, or
data and document management staff may assist in the quality assurance review processes. The specific
activities and checks that are part of QA/QC and the uncertainty analysis are discussed in the companion to
this document, Procedures Manual for Quality Assurance / Quality Control and Uncertainty Management.
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Exhibit 3-1. Organizational Structure and Division of Responsibilities: Inventory Development, QA/QC, and Uncertainty
QA staff
Tier '\ QC
check staff
LEGEND
Leads, staff
I I Activities I
Agency Inventory Lead
QA/QC officer
Tier 2 QC
check staff
Tracking,
documenting
expert reviews
Checking
inventory
estimates
and
document
flier 1)
Outside
source
category
experts
Checking
source
category
estimates
and data
(Tier 2)
Secondary
data quality
checks
suppliers
Uncertainty analysis
coordinator
Data and document
management coordinator
Uncertainty
analysis
staff
'+
Preparing
inventory
estimates
and text
r
Outside data
Prep
uncer
analys
te
V
Data and document
management staff
1
+ *
Maintaining
integrity of
electronic
inventory
files
Synthesizing
Inventory
document,
CRF, and
conducting
cross-cutting
analyses
Maintaining
current year
docket and
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4 THE INVENTORY PROGRAM AND
PROCESS FOR DEVELOPING THE
INVENTORY
The Inventory of U.S. Greenhouse Gas Emissions and Sinks (here referred to as the Inventory) is a key
component of U.S. commitments under the United Nations Framework Convention on Climate Change
(UNFCCC). The United States published the first official Inventory in 1994, covering emissions from 1990
to 1993. Prior to that year, however, inventory estimates had been prepared beginning with the year 1988.
At the first Conference of the Parties, 1990 became the base or "benchmark year;" since that time, 1990 has
been the initial year of reporting for the U.S. Inventory. The UNFCCC Common Reporting Format (CRF)
tables that depict the activity data and other information used to compile the inventory, and the national
communication, which contains a variety of technical, economic, and policy information are also part of the
U. S. commitment under the UNFCCC.
This chapter provides an overview of the components of the inventory program, focusing primarily on the
activities needed to develop the inventory and related documents—which activities are also the key focus
of the quality assurance / quality control (QA/QC) procedures and uncertainty analysis presented in the
companion Procedures Manual. Over the years, the United States has developed a structured process for
preparing its greenhouse gas emission estimates, the inventory document in which the estimates and
methodology are reported (Inventory of U.S. Greenhouse Gas Emissions and Sinks), and the official
submissions of the results to the international community. This process successfully coordinates the diverse
set of activities required to produce, review, and submit the inventory and its related activities—including
drawing on the expertise and data at the agencies and institutions described in Chapter 2. The United States
has also developed a process for conducting both public and peer reviews of the document, and for
preparing formal submissions of the inventory and CRFs to the international community.
The discussion below focuses on four distinct aspects of the inventory program: (1) preparing the inventory
and inventory document; (2) meeting international reporting requirements; (3) cross-cutting activities
associated with the inventory; and (4) technical and policy support. The discussion does not include
QA/QC and uncertainty analysis and their integration into the inventory process (see Chapter 5), with the
exception of expert review. Although expert review is technically part of the QA/QC process, it is essential
to the preparation of the inventory and so is discussed here.
4.1 Drafting and Finalizing the Inventory Document
The steps required to develop the U.S. submission are described below.
Getting Started. Initiating the annual development of the inventory requires coordinating diverse
Source Category Leads and supporting staff at the U.S. Environmental Protection Agency (EPA), Outside
Experts in the source category, such as representatives from other federal agencies, and contractors
providing technical support to the inventory. This coordination is initiated by a meeting called by the
Agency Inventory Lead in which new developments or changes to the process are highlighted. As part of
the initiation process, the Data and Document Management Coordinator distributes the text and spreadsheet
files from the previous years' inventory to the designated Source Category Leads. The Agency Inventory
Lead also distributes a "kickoff memorandum" that outlines the preparation guidelines for both the text and
the spreadsheets and includes a schedule for the upcoming year. Once files are received, Source Category
Leads begin the inventory development.
Methodology Development and Data Collection. Source Category Leads begin the process of
collecting input data and, as necessary, evaluating or developing the estimation methodology for the
individual source categories. (Chapter 2 provides additional information on the estimation methodology.)
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For most source categories, the methodology for the previous year is applied to the new "current" year of
the Inventory , and it will be necessary for inventory analysts to collect any new data or update data that
have changed from the previous year.12
If estimates for a new source category are being developed for the first time, or if the methodology is
changing for an existing source category (e.g., the United States is implementing a higher Tiered approach
for that source category), then the process is less straightforward; the Source Category Lead and staff will
need to develop the new methodology and set of spreadsheets, which also requires gathering activity data
and emission factors (or in some cases direct emission measurements) for the entire time series.13 During
methodology development and data collection, staff consult various experts throughout the federal
government, academia, and research institutions to provide both data and advice on the most appropriate
methods and data available.
Estimate Emissions and Sinks and Prepare Write-up. Once the methodology is in place and the
data are collected, Source Category Leads develop emissions and sinks estimates. Source Category Leads
and their staff update the relevant text and accompanying annexes for the Inventory. For new source
categories, new information is written. The Source Category Lead delivers all completed inventory
estimates and a well-documented analysis tool (typically Excel spreadsheets) to the Agency Inventory Lead
and the Data and Document Management Coordinator.
Compile Summary Spreadsheet. The Data and Document Management Coordinator aggregates
the estimates for the individual source categories into an inventory of emissions for the United States and
develops a summary spreadsheet to link the individual source category spreadsheets together. This
summary sheet contains all of the essential data in one central location, in formats commonly used in the
document. In addition to the data from each source category, national trend and related data is also gathered
in the summary sheet for use in the Executive Summary and Introduction.
Draft Inventory Document. The Data and Document Management Coordinator replaces the new
and updated text into the appropriate chapter in the body of the report and in the Annexes. In addition, a
brief overview of each chapter is created that summarizes the emissions from all sources discussed in the
chapters.
Also at this time, the Introduction and Executive Summary are revised to reflect the trends for the
most recent year of the current Inventory. The analysis of trends necessitates gathering supplemental data
including weather and temperature conditions, economic activity and GDP, population changes,
atmospheric conditions, and the annual consumption of electricity, energy, and fossil fuels. Changes in
these data are used to explain the trends observed in greenhouse gas emissions in the United States.
Furthermore, specific factors that affect individual sectors are researched and discussed. Many of the
factors that affect emissions are included in the inventory document as separate analyses or side discussions
in boxes within the text. There are also boxes created that look at the data aggregated in different ways than
in the remainder of the document, such as a focus on transportation activities or emissions from electric
utilities.
Expert and Public Review Periods. The entire document is sent to a select list of recipients,
generally Outside Source Category Experts, for expert review. Once comments are received and addressed,
the document is released for public review by inserting a notice in the Federal Register and posting the
document on the EPA Web site. The document will again be revised, as needed, to reflect public comments
received.
Graphical Layout and Preparation for Printing. The final step in the inventory process is to
have the document laid out in PageMaker. During this process, the Data and Document Coordinator and the
Agency Inventory Lead check the document to ensure that the final content is accurate. After layout of the
document is complete, the EPA sends the document to the Government Printing Office for printing. The
completed document is distributed by U.S. postal mail, and posted on the EPA Global Warming web page.
12 The "current" year is the year being added to thelnventory, for example, in the 1990-2000 Inventory, 2000 is the
current year.
13 In this case, Tier refers to the choice of estimation method, with Tier 1 being the most simple (often using default
data) and the higher Tiers increasing in complexity.
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4.2 Fulfilling International Reporting Requirements
Under Article 4 of the UNFCCC, the United States and other Parties to the Convention must "develop,
periodically update, publish, and make available... national inventories of anthropogenic emissions by
source and removals by sinks of all greenhouse gases not controlled by the Montreal Protocol, using
comparable methodologies." Parties also commit under Article 4 to formulate, implement and publish other
information, such as programs to mitigate emissions, and to cooperate in and promote a variety of
activities, including technology transfer, preparing for adaptation, and research. Under Article 12, Parties to
the Convention must communicate to the Conference of the Parties, through the Secretariat, a number of
elements of information, including a national inventory of emissions, steps taken to implement the
UNFCCC, and other information. These requirements have been operationalized in a number of UNFCCC
decisions and formalized in UNFCCC reporting guidelines.
The U.S. submission in fulfillment of the requirement has several components. The Inventory document
contains information on methodologies and national annual greenhouse gas inventory estimates. The
UNFCCC CRF tables aggregate the Inventory data in a format easily compared to other countries' data.
The completed Inventory document and the UNFCCC CRF tables are printed in hard copy and placed in
binders. The Agency Inventory Lead is responsible for delivering both the binders and electronic copies
(which are placed on CD-Rom and also e-mailed) to the UNFCCC Secretariat to fulfill the U.S. reporting
requirements. The final document is due to the UNFCCC Secretariat on April 15 of each year. In addition,
under the UNFCCC reporting guidelines and associated decisions, the United States is required periodically
to submit a national communication that includes a variety of information on national circumstances.
These reporting requirements, as summarized in the UNFCCC guidelines on reporting and review, are
described below.: 4
The Common Reporting Format. The UNFCCC CRF is a standardized set of tables for
reporting estimates of greenhouse gas emissions and removals and other relevant information. By using a
common format across all countries, the UNFCCC CRF presents the inventory data in a way that facilitates
improved handling, processing, and analysis of inventory information, including cross comparisons across
among submitting countries and easy identification of possible mistakes, misunderstandings, and
omissions. The completed UNFCCC CRF is submitted to the UNFCCC Secretariat.
The CRF consists of: (a) summary and overview tables; (b) sectoral background data tables for reporting
aggregate emission factors and activity data; (c) a comparison of national estimates with estimates
obtaining using the Intergovernmental Panel on Climate Change (IPCC) reference approach for CC>2
emissions from fossil fuel combustion; and (d) tables for reporting information on a variety of items,
including recalculations, completeness, and QA/QC. To prepare the U.S. tables, the U.S. inventory
spreadsheets are linked to the appropriate location and year within the UNFCCC CRF tables. In addition,
text explanations are provided for items such as sources excluded and data changes from the previous
year's submission.
National Inventory Report. The national inventory report contains detailed and complete
information on the inventory for all years from the base year to the year of the current annual inventory
submission. The Inventory document fulfills the U.S. requirement to produce a national inventory report.
The purpose of the report is to ensure the transparency of the inventory. The national inventory report is
submitted annually to the Conference of the Parties through the UNFCCC Secretariat and must also be
published and/or maintained in its entirety on a national web site.
The national inventory report includes: (a) annual inventory information for the base year to the
year of the current submission; (b) a description of the specific methodologies and assumptions used in
each sector, including an indication of the level of complexity (IPCC tiers); (c) references or sources of
information used for the inventory estimates; (d) information on assumptions underlying the estimates and
the rationale for their selection; (e) specific information on feedstocks and bunkers; (f) information on
See "Review of the Implementation of Commitments and of Other Provisions of the Convention: UNFCCC guidelines
on reporting and review. " FCCC/CP/1999/7,16 February 2000. Available at
http://www.unfccc.de/resource/docs/cop5/07.pdf.
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recalculations, uncertainties, and quality assurance / quality control procedures; and (g) a section
identifying changes with respect to the previous years. The national inventory report
The National Communications. The purpose of national communications is to fulfill Annex I
Parties' commitments under Articles 4 and 12 of the Convention. Every three to five years, the United
States issues its National Communication on climate change. This document includes both emissions data
from the inventory, as well as projections and mitigation strategies and other data relating to the fulfillment
of commitments under the convention. The document to be submitted to the UNFCCC has several required
components: (a) an executive summary; (b) a description of national circumstances relevant to greenhouse
gas emissions and removals; (c) greenhouse gas inventory information (including summary tables and a
descriptive summary; (d) policies and measures adopted to implement commitments; (e) projected trends in
emissions and removals with policies and measures in place; (f) a vulnerability assessment; (g) details on
financial resources and technology transfer; (h) actions relating to research and systematic observation; and
(h) actions relating to education, training, and public awareness. Much of the information presented in the
national communication is supported by the technical and policy work that is done under the broader
inventory program.
4.3 Cross-Cutting Activities
The United States undertakes a number of cross-cutting analyses in conjunction with the U.S. Greenhouse
Gas Inventory Program.15 Foremost among these activities is the key source analysis. A key source is "one
that is prioritized within the national inventory system because its estimate has a significant influence on a
country' s total inventory of direct greenhouse gases in terms of the absolute level of emissions, the trend in
emissions" (IPCC 2000). The IPCC report, Good Practice Guidance and Uncertainty Management in
National Greenhouse Gas Inventories (IPCC 2000, here referred to as IPCC Good Practice Guidance),
recommends conducting a key source analysis for each year's inventory. Two quantitative approaches to
identifying key source categories are described.
The first type of key source analysis (a Tier 1 approach) identifies the contribution of individual source
categories to the absolute overall level of national emissions (called a level assessment).16 In addition, for
countries such as the United States that have a time series of emission estimates, the investigation of key
sources should also include evaluating the influence of trends in individual source categories on the overall
inventory trend (called a trend assessment). The Tier 2 approach is a more detailed analysis that builds on
the Tier 1 approach by incorporating national uncertainty estimates into the Level and Trend assessment.).
The key source analysis should also include applying qualitative criteria, such as identifying source
categories that are changing significantly because of mitigation technologies, or that have high expected-
emissions-growth.
4.4 Technical and Policy Support
Although the core of the U.S Greenhouse Gas Inventory Program is the development and preparation of the
Inventory document and associated national greenhouse gas emission and sink information, the inventory
program also fills a number of other roles. Its ability to support these other functions is a direct result of the
staff's expertise in greenhouse gas emissions and other climate change-related data analysis.
Reliable and thorough technical analysis is a crucial input to the policy making process. The Greenhouse
Gas Inventory Program supports EPA and other federal agencies, such as the State Department or the
President's Council on Environmental Quality, by providing timely support on climate change and
environmental policy issues. This support can take the form of assessing U.S. greenhouse gas emissions in
comparison to emissions globally, assessing inventories from other countries, or helping to determine
15 A number of cross cutting activities are not discussed here but are covered in the companion document,Procedures
Manual for Quality Assurance / Quality Control. These include QA/QC activities and the estimation of uncertainty,
both of which are discussed in Chapter 3 of this document. These and other activities, such as centralized archiving and
documentation procedures for the inventory, are also discussed further in the Procedures Manual.
16 Note that these Tiers are distinct from both the Tiers that represent complexity levels in the choice of the inventory
methodology and the Tier 1 and Tier 2 quality controls and checks that can be performed.
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emission trends for particular domestic sectors or industries. This latter type of analysis is also an important
input to the design of new government emission reduction (i.e., mitigation) programs and to measuring the
effectiveness of existing programs.
The UNFCCC Secretariat and the IPCC Working Groups and Technical Support Unit on greenhouse gas
inventories both depend greatly on experts from individual countries, such as the United States, which are
Parties to the UNFCCC. The U.S. Greenhouse Gas Inventory Program supports the UNFCCC process
through its participation in technical workshops and on teams charged with reviewing inventories submitted
by Parties to the UNFCCC. Support to the IPCC usually takes the form of participation in developing
improved technical guidance and supporting the broader scientific mission of the IPCC through its analysis
of emission projections and other issues. All of this support is made possible and reinforced by U.S.
leadership in developing rigorous methodologies for estimating emissions and removals of greenhouse
gases by anthropogenic activities.
The Inventory serves as an immensely valuable resource for others around the world working on their own
emission estimates for individual source categories or complete greenhouse gas inventories. In addition to
providing this resource, the United States provides bilateral and multilateral support to many developing
and Economy in Transition countries (i.e., Eastern European countries and republics from the former Soviet
Union) to improve their greenhouse gas inventories. Similarly, the technical guidance and information
provided by the inventory program is also used by many State and local governments, corporations, and
other organizations in the preparation of their own inventories. Because the Inventory serves as such an
important resource for so many, the staff of the inventory program often serves as an informal
clearinghouse for inventory-related technical information.
Finally, as part of its continual improvement process, the inventory program maintains a research and
development effort into new or improved methodologies, data sources, emission factors, and estimates for
excluded source or sink categories. This effort may be performed by inventory program staff or take the
form of directed financial support to researchers in academic or other institutions. The results of this
research are eventually reflected and documented in the published Inventory report.
4.5 Illustrating the Inventory Development Process
The above processes are depicted in flowchart form in Exhibit 4-1, and a time line of milestones for the
Inventory document and its delivery to the UNFCCC is displayed in Exhibit 4-2. The flowchart illustrates
the major stages and components of the inventory development process: estimating emissions and
developing the draft Inventory document; conducting expert and public reviews and finalizing the inventory
document; preparing associated materials (key source analysis, UNFCCC CRF, national communications);
and designing, printing, and distributing the final document. The flowchart also indicates the process of
submitting the Inventory, CRF, key source analysis, and national communication to the UNFCCC.
Exhibit 4-2 provides a timeline for key milestones in the process of developing and submitting the
inventory to the UNFCCC, for a sample inventory year. As illustrated by the Exhibit, in order to produce
the inventory by April 15 each year, the inventory team follows a highly structured process, operating
within a tight timeframe. Although the schedule indicates only the events leading up to the submittal of the
inventory, it is clear from the flowchart that a number of events are occurring concurrently with these
activities, including preparation of the CRF and key source analyses, and other activities in the inventory
program, such as support to State and local governments, outreach, and other facets of the program.
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Exhibit 4-1. U.S. Inventory Program and the Inventory Development Process
Gather Data
Source category
leads gather
published and
unpublished data
from Federal and
State agencies,
academic
institutions, and
other relevant
experts
Expert/Public Reviews
Federal and State
agencies, academic
institutions, other relevant
experts, and interested
members of the public
review the document
CRF Synthesis
When data is finalized, data
and document coordinator
prepares the CRF Tables
Key Source Analysis
The data and document
coordinator prepares the
key source analysis for
inclusion in the inventory
Layout for Printing
Data and document
coordinator supervises
graphics specialist
to prepare graphics layout
Printing
By Government
Printing Office
Upload onto Web
Document is posted
on USEPA website
Technical & Policy Support
The Agency Inventory Lead works to
provide technical and policy support to
federal agencies, state and local
governments, scientists, interest
groups, and the public. The inventory
program also has a considerable R&D
component that works to improve
methodologies and data.
Submittal of Requirements
Final document, key source
analysis, and CRF tables are
submitted to the U.S. Department
of State and the UNFCCC
Secretariat
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Exhibit 4-2. General Schedule for Completing the Annual
Inventory of U.S. Greenhouse Gas Emissions and Sinks
Date
Task
1st week Oct
1st week Oct
Oct - Mid Nov
End of Oct
Mid Nov
Mid Nov
Mid Nov - Late Dec
1st week Dec
Late Dec
Late Dec
Late Dec - Late Jan
Late Jan
Late Jan
Late Jan
Late Jan - 1st week Mar
1st week Mar
1st week Mar-1st week Apr
1st week Apr
2nd week Apr
Apr 15
Mid - Late Apr
May - June
Final estimates/spreadsheets due to Data and Document Management
Coordinator
Final write-ups, annexes, and docket/archive due To Data and Document
Management Coordinator
Prepare draft document
Expert reviewer list and transmittal letter completed
Expert review draft of Inventory document due
Distribute draft Inventor/fa expert review
Expert review period
Submit request for federal register notice
Approval of federal register notice
Expert review comments due and final date for changes!
Incorporate expert comments
Public review draft of Inventory document due
Upload public review draft on EPA's Global Warming web page
Appearance of federal register notice
Public review period
Public review comments due
Incorporate public review comments
Final Inventory document due
Deliver document to UNFCCC Secretariat and State Department
Inventory due to UNFCCC Secretariat
Inventory posted on EPA's Global Warming web page
Inventory printed and distributed to mailing list
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QA/QC PROCEDURES AND
UNCERTAINTY ANALYSIS
The U.S. Greenhouse Gas Inventory Program serves a number of uses for a diverse audience, and the
quality and accuracy of the inventory estimates and analyses must be sufficient for these purposes. A key
goal of the inventory program is ensuring the transparency, consistency, comparability, completeness, and
accuracy of the inventory and the documents—such as the Inventory of U.S. Greenhouse Gas Emissions
and Sinks (referred to here as the Inventory), the United Nations Framework Convention on Climate
Change (UNFCCC) Common Reporting Format (CRF), and the national communications—in which
inventory results are reported. The U.S. inventory system is designed and operated to ensure the quality of
the inventory through planning, preparation and management of inventory activities. As part of this
approach, quality assurance (QA) and quality control (QC) procedures, coupled with uncertainty analysis,
are designed to enhance and continually to improve inventory quality over time. The United States has
developed a comprehensive greenhouse gas inventory system that combines methodological improvements,
an integrated approach to improved methodologies, transparency improvements, quality assurance / quality
control, and uncertainty analysis.
5.1 Goals for Inventory Quality, Implementation of QA/QC Procedures, and Uncertainty
Analysis
The Intergovernmental Panel on Climate Change (IPCC) has prepared Good Practice Guidance and
Uncertainty Management in National Greenhouse Gas Inventories (IPCC 2000, here referred to as IPCC
Good Practice Guidance). The IPCC Good Practice Guidance is designed as a companion to the Revised
1996 IPCC Guidelines for National Greenhouse Gas Inventories (IPCC/OECD/IEA 1997, here referred to
as the IPCC Revised Guidelines). The goal of IPCC Good Practice Guidance is to assist countries to
produce greenhouse gas inventories that are accurate (i.e., are neither over nor underestimates) and in
which uncertainties are reduced—both to the extent practicable. In addition, IPCC Good Practice Guidance
"supports the development of inventories that are transparent, documented, consistent over time, complete,
comparable, assessed for uncertainties, subject to quality control and assurance, efficient in the use of the
resources available to inventory agencies, and in which uncertainties are gradually reduced as better
information becomes available."
The IPCC (IPCC 2000) defines QA and QC as follows:
• Quality Control (QC) is a system of routine technical activities to measure and control the quality
of the inventory as it is being developed. A basic QC system should provide routine and consistent
checks to ensure data integrity, correctness, and completeness; identify and address errors and
omissions; and document and archive inventory material and record all QC activities.
• Quality Assurance (QA) comprises a planned system of review procedures conducted by
personnel not directly involved in the inventory compilation and development process.
Thus, QC includes general procedures such as checking the accuracy of data and calculations and that
standardized practices are followed in calculating emissions, estimating uncertainties, compiling and
archiving the docket, and reporting. A higher tier QC system would also include technical reviews of
source categories, activity and emission factor data, and methods.17 QA reviews, which should be
performed if possible by independent third parties, are designed to verify that data quality objectives are
met, and ensure that the inventory represents the best possible estimates of emissions and sinks given the
current state of scientific knowledge and available data. Both QA and QC refer to actions that inventory
A higher "Tier" in this case refers to source-specific QC activities, and is different from the "Tier" designation used
by the IPCC Revised Guidelines (IPCC/OECD/IEA 1997), which refers to the level of detail and specificity of the
methodology and data sources used to calculate emissions.
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agencies can take with regard to their own inventories, and not to international review or similar
procedures.
The IPCC (2000) also defines good practice in estimating and reporting uncertainties associated with both
annual estimates of emissions and emission trends over time. Two tiers are provided for combining source
category uncertainties into an uncertainty estimate for total national emissions. Tier 1 uncertainty
calculation and reporting, which relies on simple error propagation, has one line for each source category,
fuel (where appropriate), and greenhouse gas. This method does not account for correlation and
dependency between source categories that may occur because the same activity data or emission factors
may be used for multiple estimates. The Tier 2 method, which has been adopted by the United States,
estimates uncertainty by source category using Monte Carlo analysis.18
Both the IPCC Revised Guidelines and IPCC Good Practice Guidance recognize that governments do not
have unlimited resources, and so the quality of the inventory, the extent of QA and QC, and the breadth of
the uncertainty analysis may reflect these limitations, or require focusing resources on key or significant
emission sources. An integrated system for conducting QA/QC and analyzing uncertainty is part of
ensuring that the inventory meets its data quality objectives. Developing and following a plan—which
should include both quality assurance (QA) / quality control (QC) activities and a detailed analysis of
uncertainty—is itself good practice and an integral part of ensuring that good practices are followed
throughout the development, release, and archiving of the inventory.
The goal of the United States in integrating QA and QC activities into its inventory development process
and assessing the uncertainty of the resulting estimates is achieving not only high quality, but also
assessment, transparency, and credibility (see Box 5-1):
• To demonstrate—by adequate documentation, archiving, and other processes—the transparency of
the process of estimating greenhouse gas emissions and producing the inventory
• To assess (qualitatively and quantitatively)
several year process—including the '
quality of the data from suppliers
• To achieve continual improvement in
the inventory processes and products
• To ensure that the estimates produced
by the inventory apply consistent
approaches and produce comparable
numbers across the source categories,
and relative to the IPCC Revised
Guidelines and IPCC Good Practice
Guidance and the methods employed
to produce other nations' inventories
• To produce emission estimates by
sources and sinks that are complete,
reproducible, and defensible and
thereby further promote the credibility
of, and confidence in, the U.S. national
inventory.
5.2 The U.S. Approach to QA/QC
As part of efforts to achieve the stated goals for
the quality and accuracy of the inventory estimates in a
Box 5-1. Reporting Guidelines
Transparency means the assumptions and methodologies
used for an inventory should be clearly explained to facilitate
replication and assessment
Consistency means that the inventory uses the same
methodologies for the base and subsequent years, and
consistent data across sources or sinks (subject to some
exceptions.
Comparability means that estimated emissions are
comparable across Parties, i.e., that they use comparable
methodologies and formats, including the allocation of
different source/sink categories.
Completeness means that an inventory covers all sources
and sinks, as well as all gases, included in the IPCC
Guidelines.
Accuracy is a relative measure of the exactness of an
emission or removal estimate, i.e., estimates should not
systematically over- or under-estimate true emissions or
removals, and uncertainties should be reduced as far as
practicable.
Source: "Review of the Implementation of Commitments and
of Other Provisions of the Convention: UNFCCC guidelines
on reporting and review." FCCC/CP/1999/7.
18
The principle of Monte Carlo analysis is to select random values of emission factor and activity data from within
their individual probability density functions and to calculate the corresponding emission values. Repeating this process
many times results in an assessment of the statistical properties—including uncertainty—of the overall emission
estimate for a source category or for the inventory as a whole.
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inventory quality, transparency, and credibility, the United States has developed a quality assurance and
quality control plan designed to check, document and improve the quality of its inventory over time. Many
of these features have been under development over the years since the inventory was first published;
others—including the detailed Procedures Manual—are the more recent result of activities taken partly in
response to IPCC Good Practice Guidance.
In particular, key attributes of the plan or program components include:
• The plan includes specific detailed procedures (or protocols) and templates (or forms) that serve to
standardize the process of documenting and archiving information, as well as to guide the
implementation of QA/QC and the analysis of the uncertainty of the inventory estimates (see
companion document, Procedures Manual).
• The plan includes expert review as well as QC—for both the inventory estimates and the Inventory
(which is the primary vehicle for disseminating the results of the inventory development process).
In addition, the plan provides for public review of the Inventory.
• The QC process includes both Tier 1 (general) and Tier 2 (source-specific) quality controls and
checks, as recommended by IPCC Good Practice Guidance.
• Investigations of secondary data quality and source-specific quality checks (Tier 2 QC) are
conducted in parallel and coordination with the uncertainty assessment; the development of
protocols and templates provides for more structured communication and integration with the
suppliers of secondary information.
• The plan provides for a complete Monte Carlo-based assessment of uncertainty for the inventory,
including coordinated data collection and analysis, with input from virtually all the organizational
and functional roles involved in producing the inventory.
• The plan contains record keeping provisions to track what procedures have been followed, and the
results of the QA/QC and uncertainty analysis, and contains feedback mechanisms for corrective
action based on the results of the investigations, thereby providing for continual data quality
improvement and guided research efforts.
• The plan is designed so that quality control and/or assurance procedures are implemented
throughout the whole inventory development process—from initial data collection, through
preparation of the emission estimates, to publication of the Inventory.
• The plan includes a schedule for multi-year implementation, and includes checks from year to year
to ensure that all quality control findings from previous years are adequately addressed.
• The plan promotes and involves coordination, interaction, and quality control within the U. S.
Environmental Protection Agency (EPA), across Federal agencies and departments, State
government programs, and research institutions and consulting firms involved in supplying data or
preparing estimates for the inventory.
The plan—including the Procedures Manual and this Background document—is a "living" document, i.e.,
the plan is intended to be revised and reflect new information that becomes available as the program
develops, methods are improved, or additional supporting documents become necessary. For example, the
availability of new information or additional detail on techniques or procedures for checking the quality of
data inputs or emission calculations could necessitate revising the procedures in the Procedures Manual or
preparing a background paper expanding on procedures to be used. Although it is not included in the
current plan, an internally conducted or third-party review of the methodologies used to calculate emissions
could also include an assessment of the extent to which the methods conform to the IPCC Good Practice
Guidance prepared for individual sectors.
Similarly, some features of the plan—such as management functions and organization—are less developed
than others, and could be expanded over time. If the United States at some point decides to incorporate the
principles of ISO 9000, it may be necessary to expand the structure or content of the Plan. The inventory
program could, potentially in conjunction with EPA's Office of Quality Assurance, initiate a third Party
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assessment or audit of the plan—focusing on the effectiveness and appropriateness of the systems and
management established to control data quality. Such review might also result in alterations or additions to
the plan.19
The quality checking and control activities described in this QA/QC plan occur throughout the inventory
process; QA/QC is not separate from but an integral part of the preparing the inventory. As illustrated in
Exhibit 5-1, quality control—in the form of both good practices (such as documentation procedures) and
checks on whether good practices and procedures are being followed—is applied at every stage of
inventory development and document preparation. In addition, quality assurance, or expert review, occurs
at two stages. Public review, while not necessarily a significant contributor to inventory quality, is essential
to promoting the openness of the inventory development process and the transparency of the inventory data
and methods themselves.
5.3 The U.S. Approach to Uncertainty Analysis
Both the QC and uncertainty analyses are part of a learning process. While the uncertainty analysis
provides a standalone quantitative assessment of the inventory, its primary function in the U.S. Greenhouse
Gas Inventory Program is as an integral component of efforts to understand what produces uncertainty and
how to improve inventory quality. Conversely, the outcome of the QC evaluation may result in a
reassessment of inventory or source category uncertainty. In addition, the quality checks of the data
suppliers and the methodologies they use not only provides information on the quality of the data
underlying the inventory estimates, but more importantly creates lines of communication with suppliers and
opportunities for understanding and improving the quality of the data and the quality control activities used
by suppliers. Thus, by identifying potential areas of improvement in the estimates, procedures to check
quality, the uncertainty analyses, and the review processes can all work to reduce the uncertainty of the
estimates over time.
The IPCC Good Practice Guidance recommends treating uncertainty estimates as an essential element of a
complete inventory of emissions and sinks. Uncertainty information is not intended to dispute the validity
of the inventory estimates, but to help set priorities across efforts to improve the accuracy of inventories in
the future and guide decisions on methodological choice. Even an inventory that is carefully prepared
following accepted inventory methods will be subject to uncertainty; national inventories will typically
contain a wide range of emission estimates, varying from carefully measured and demonstrably complete
data on emissions of certain engineered chemicals, to order of magnitude of estimates of highly variable
nitrous oxide (TS^O) fluxes from soils and waterways (IPCC 2000).
Uncertainty arises when the emissions and removals in the inventory are quantified. This type of
uncertainty—referred to as estimation uncertainty—has several sources. First, the estimates can be subject
to random or statistical uncertainty; this uncertainty results from variations in the underlying data (such as
the activity data or emission factors). This variation can be the result of naturally occurring variation (e.g.,
emission rates vary over a given time period) or variations in human reactions or in the measurement
equipment. In some cases, information may be available that quantifies the statistical properties of
measured data. Second, the estimates can be subject to non-random uncertainty, or bias; if estimates are
biased, the average of the measured or estimated value is always less or greater than the true value. Bias
can arise, for example, because emissions factors are constructed from samples are non-representative, or
the use of faulty equipment. Uncertainty arising from bias cannot easily be quantified based on measured
data, but must rely on expert judgment.
Estimating uncertainty is as much an art as a science. The pragmatic approach to producing quantitative
uncertainty estimates for the greenhouse gas inventory estimates is to combine the available measured data
with expert judgments of the magnitude of the estimation uncertainty that cannot be measured. Even given
this flexible approach, not all forms of uncertainty can be captured in a quantitative estimate. For example,
uncertainty does not only arise during estimation; rather, scientific uncertainty—which is not amenable to
quantification—arises when the science of actual emission and/or removal processes is not completely
understood. Research conducted by the United States, by the IPCC and by other Parties to the UNFCCC,
19 See EPA QA/QMP materials, which can be downloaded at: http://www.epa.gov/quality/
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Exhibit 5-1. The Roles of Quality Assurance, Quality Control, and Uncertainty
Analysis in the Inventory Process
1 ~l
| Work with experts to collect |^ »>
1 data, improve methods, i
1 gather information on •
secondary data
Gather data for emission
estimates and uncertainty
analysis and
review/assess inventory
methodo ogy
-&~
i
Conduct quality checking 1
and quality control activities 1
on the inventory estimates |
as they are developed and [^ »
throughout the year; |
coordinate Tier 2 checks i
with the uncertainty i
estimates . . .
1
Develop inventory
emission est mates
^CL
1 Develop uncertainty
estimates
^Check quality of uncertainty
X ^^ estimates
-G. \
Prepare inventory
estimates for expert
review
^L
Conduct expert review of
emission est mates
^CL
Revise estimates in
response to comments
and prepare draft
Inventory document
Conduct quality checking '
and quality control activities 1
on the Inventory document^
for each major iteration of | \
the document \
I fr\
t!
Check content of final
1 document for accuracy, 1^ ^
| conformity with inventory |
| results, layout, etc. |
Check the contents of thej
' archive and the current '^ ^
1 docket 1
ZLJ~
Conduct expert review of
draft. Inventory document
^CL
Revise document to
ncorporate expert review
comments and prepare
public review draft
— *J3L
Conduct public review
period
J3L
ncorporate public review
comments
» 1 1
*-LJ-
Prepare final document
and deliver Inventory and
CRF tables to UNFCCC
Prepare graphics layout;
posting to USEPA
website, and print and
distribute final Inventory
document
^ru
Archive all materials and
create a docket
LEGEND:
^Opportunities j Steps in the
ifor QA/QC [ Inventory process
^ 1 Use the uncertainty results i
• to improve inventory quality
>
\ - The expert reviews provide
J quality assurance
t
\ Check content of CRF
| against final inventory and
|_ perform other QC
\
A — I — | Prepare CRF tables based
C | on final inventory estimates
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seeks to improve the sources of data and methodologies used to calculate emissions inventories. Analyzing
uncertainty is a part of this effort to understand and reduce the uncertainty associated with inventory
estimates. Uncertainty for the inventory can be analyzed both qualitatively and quantitatively. Uncertainty
can be assessed qualitatively—i.e., as high, medium, or low. The United States is engaged in a multi-year
effort to assess uncertainty quantitatively for the inventory. This effort has several components:
• a centralized approach to developing uncertainty estimates, to ensure consistency in the approach
used across source categories and consistency with IPCC recommended methods
• the development of a Monte Carlo model for estimating uncertainties, based on (1) the
mathematical models used for estimating source category-specific estimates, (2) source category-
specific input parameters, (3) the statistical properties of the source category-specific parameters,
and (4) other statistical relationships across the inventory source categories
• the use of statistical data to quantify uncertainty where possible, and careful and detailed methods
for eliciting expert judgment in cases where statistical data are unavailable
• coordination between the uncertainty analysis and the detailed checks conducted on source
category estimates as part of QC procedures, including the use of quality check information in the
uncertainty analysis (such as the information obtained on the quality of data supplied by outside
sources)
• using the uncertainty analysis to inform directions for methodological and data development,
including working with data suppliers to improve the quality of information
Procedures, templates, and other information on the workings of the uncertainty analysis are part of the
overall QA/QC and Uncertainty Management Plan for the U.S. Greenhouse Gas Inventory. As with
QA/QC procedures and the templates and other documents designed to support the procedures, the
uncertainty analysis plan—including its procedures and templates—is a "living" document, that is,
intended to be revised and reflect new information that becomes available as procedures are implemented
and tested, as methods are improved, or additional supporting documents become necessary.
Despite the careful procedures being undertaken under the U.S. Greenhouse Gas Inventory Program to
develop both the inventory and the uncertainty estimates, the uncertainty estimates must themselves be
considered highly uncertain. Types of uncertainty, such as scientific uncertainty or the uncertainty
associated with estimates of global warming potential, which are omitted from the quantitative uncertainty
estimates, contribute to the uncertainly surrounding the uncertainty estimate. In addition, the process of
estimating uncertainty surrounding the emissions estimate for a number of the greenhouse gas source
categories (or the estimated sinks) will, of necessity, have many elements that are highly subjective. In
many cases, expert judgment will be required to quantify the statistical properties of the variables
underlying the inventory values. Such judgment is not only uncertain, but also difficult to obtain in a
comparable and consistent manner across source categories and across inventories prepared by different
countries.
Consequently, the uncertainty analysis is most useful as a qualitative measure of uncertainty and as part of
an educatory process and feedback loop that allows us to improve the inventory estimates over time. For
example, collecting the information needed to determine the statistical properties of the activity data and
emission factors underlying the emission estimates forces the researcher to ask hard questions and to
carefully and systematically investigate data quality. Similarly, the uncertainty analysis provides a vehicle
for setting priorities in research into alternative data sources and methodologies, and for communicating
with data suppliers and initiating a dialogue that can ultimately provide a clearer understanding of the
quality of the data underlying the inventory estimates and potentially improve that data over time.
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6 REFERENCES
IPCC (1996) Climate Change 1995: The Science of Climate Change. Contribution of Working Group I to
the Second Assessment Report of the Intergovernmental Panel on Climate Change [Houghton, JT, LG
Meiro Filho, BA Callander, N Harris, A Kattenberg, and K Maskell (eds.)]. Intergovernmental Panel
on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY.
IPCC (2000) Good Practice Guidance and Uncertainty Management in National Greenhouse Gas
Inventories [J Penman, D Kruger, I Galbally, T Hiraishi, B Nyenzi, S Emmanul, L Buendia, R
Hoppaus, T Martinsen, J Meijer, K Miwa, and K Tanabe (eds)]. Intergovernmental Panel on Climate
Change. Download at
IPCC (2001) Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third
Assessment Report of the Intergovernmental Panel on Climate Change [Houghton, JT, Y Ding, DJ
Griggs, M Noguer, PJ van der Linden, X Dai, K Maskell, and CA Johnson (eds.)]. Intergovernmental
Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York,
NY.
IPCC/OECD/IEA (1997) Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories. The
Reference Manual. [JT Houghton, LG Meira Filho, B Lim, K Treanton, I Mamaty, Y Bonduki, DJ
Griggs, and BA Callander (eds.)]. Intergovernmental Panel on Climate Change, Organisation for
Economic Co-operation and Development, and International Energy Agency.
Download at
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APPENDIX A: GLOBAL CLIMATE PROTECTION ACT OF 1987: SECTION 1103
The Global Climate Protection Act of 1987 is codified as 15 U.S.C. Sec. 2901. Section 1103 states the
responsibilities of the State Department and the U.S. Environmental Protection Agency with regard to
inventories.
"SEC. 1103. MANDATE FOR ACTION ON THE GLOBAL CLIMATE.
"(a) Goals of United States Policy. - United States policy should seek to -
"(1) increase worldwide understanding of the greenhouse effect and its environmental and health
consequences;
"(2) foster cooperation among nations to develop more extensive and coordinated scientific
research efforts with respect to the greenhouse effect;
"(3) identify technologies and activities to limit mankind's adverse effect on the global climate by -
"(A) slowing the rate of increase of concentrations of greenhouse gases in the atmosphere
in the near term; and
"(B) stabilizing or reducing atmospheric concentrations of greenhouse gases over the long
term; and
"(4) work toward multilateral agreements.
"(b) Formulation of United States Policy. - The President, through the Environmental Protection Agency,
shall be responsible for developing and proposing to Congress a coordinated national policy on global
climate change. Such policy formulation shall consider research findings of the Committee on Earth
Sciences of the Federal Coordinating Council on Science and Engineering Technology, the National
Academy of Sciences, the National Oceanic and Atmospheric Administration, the National Science
Foundation, the National Aeronautic and Space Administration, the Department of Energy, the
Environmental Protection Agency, and other organizations engaged in the conduct of scientific research.
"(c) Coordination of United States Policy in the International Arena. - The Secretary of State shall be
responsible to coordinate those aspects of United States policy requiring action through the channels of
multilateral diplomacy, including the United Nations Environment Program and other international
organizations. In the formulation of these elements of United States policy, the Secretary of State shall,
under the direction of the President, work jointly with the Administrator of the Environmental Protection
Agency and other United States agencies concerned with environmental protection, consistent with
applicable Federal law.
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APPENDIX B. NAMES AND CONTACT INFORMATION FOR THE INVENTORY TEAM
Organizational Function
Agency Inventory lead
Data and Document Management
Coordinator
QA/QC Officer
Lead Staff
Michael Gillenwater
EPA
Marian M. Van Pelt
ICF Consulting
Adam Chambers
USEPA
Phone
202-564-4092
202-862-1129
202-564-3999
E-mail address
gillenwater.michael@epa.gov
mvanpelt@icfconsulting.com
chambers.adam@epa.gov
UncertaintyAnalysis Coordinator
Kamala R. Jayaraman
ICF Consulting 703-934-3331 kjayaraman@icfconsulting.com
SOURCE CATEGORY LEADS AT THE U.S. ENVIRONMENTAL PROTECTION AGENCY
Energy
Carbon Dioxide Emissions from Fossil Fuel
Combustion
Carbon Stored in Products from Non-
Energy Uses of Fossil Fuels
Stationary Source Fossil Fuel Combustion
(excluding CCb)
Mobile Source Fossil Fuel Combustion
(excluding CCb)
Coal Mining
Natural Gas Systems
Petroleum Systems
Natural Gas Flaring and Ambient Air
Pollutants from Oil and Gas Activities
International Bunker Fuels
Wood Biomass and Ethanol Consumption
Indirect CCb from ChU Oxidation
Municipal Solid Waste Combustion
Michael Gillenwater
Michael Gillenwater
Michael Gillenwater
Veronika Pesinova
Elizabeth Scheehle
Elizabeth Scheehle
Elizabeth Scheehle
Michael Gillenwater
Michael Gillenwater
Michael Gillenwater
Michael Gillenwater
Michael Gillenwater
202-564-4092
202-564-4092
202-564-4092
202-564-9415
202-564-9758
202-564-9758
202-564-9758
202-564-4092
202-564-4092
202-564-4092
202-564-4092
202-564-4092
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
pesinova.veronika@ epa.gov
scheehle.elizabeth@epa.gov
scheehle.elizabeth@epa.gov
scheehle.elizabeth@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
Industrial Processes
Titanium Dioxide Production
Aluminum Production (CO2)
Aluminum Production (PFCs)
Iron and Steel Production
Ferroalloy Production
Ammonia Manufacture
Cement Manufacture
Lime Manufacture
Limestone and Dolomite Use
Soda Ash Manufacture and Consumption
Carbon Dioxide Consumption
Petrochemical Production
Silicon Carbide Production
AdipicAcid Production
Nitric Acid Production
Michael Gillenwater
Michael Gillenwater
Deborah Schaeffer
Michael Gillenwater
Michael Gillenwater
Michael Gillenwater
Michael Gillenwater
Michael Gillenwater
Michael Gillenwater
Michael Gillenwater
Michael Gillenwater
Michael Gillenwater
Michael Gillenwater
Elizabeth Scheehle
Elizabeth Scheehle
Substitution of Ozone Depleting Substances Dave Godwin
HCFC-22 Production
Semiconductor Manufacture
Electrical Transmission and Distribution
Magnesium Production and Processing
Industrial Sources of Ambient Air Pollutants
Solvent Use
Deborah Schaeffer
Deborah Schaeffer
Deborah Schaeffer
Deborah Schaeffer
Michael Gillenwater
Michael Gillenwater
202-564-4092
202-564-4092
202-564-9149
202-564-4092
202-564-4092
202-564-4092
202-564-4092
202-564-4092
202-564-4092
202-564-4092
202-564-4092
202-564-4092
202-564-4092
202-564-9758
202-564-9758
202-564-3517
202-564-9149
202-564-9149
202-564-9149
202-564-9149
202-564-4092
202-564-4092
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
ottinger.deborah@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
scheehle.elizabeth@epa.gov
scheehle.elizabeth@epa.gov
godwin.dave@epa.gov
ottinger.deborah@epa.gov
ottinger.deborah@epa.gov
ottinger.deborah@epa.gov
ottinger.deborah@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
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Version 1.0
PageB-2ofB-3
Organizational Function
Lead Staff
Phone
E-mail address
Agriculture
Enteric Fermentation
Manure Management
Rice Cultivation
Agricultural Residue Burning
Agricultural Soil Management
Joseph Mangino
Joseph Mangino
Tom Wirth
Tom Wirth
Tom Wirth
202-564-9481
202-564-9481
202-564-9108
202-564-9108
202-564-9108
mangino.joseph@epa.gov
mangino.joseph@epa.gov
wirth.tom@epa.gov
wirth.tom@epa.gov
wirth.tom@epa.gov
Land-Use Change and Forestry
Changes in Forest Carbon Stocks
Changes in Carbon Stocks in Urban Trees
Changes in Agricultural Soil Carbon Stocks
Changes in Yard Trimming Carbon Stocks
in Landfills
Tom Wirth
Tom Wirth
Tom Wirth
Michael Gillenwater
202-564-9108
202-564-9108
202-564-9108
202-564-4092
wirth.tom@epa.gov
wirth.tom@epa.gov
wirth.tom@epa.gov
gillenwater.michael@epa.gov
Waste
Landfills
Wastewater Treatment
Human Sewage
Waste Sources of Ambient Air Pollutants
Elizabeth Scheehle
Elizabeth Scheehle
Elizabeth Scheehle
Michael Gillenwater
202-564-9758
202-564-9758
202-564-9758
202-564-4092
scheehle.elizabeth@epa.gov
scheehle.elizabeth@epa.gov
scheehle.elizabeth@epa.gov
gillenwater.michael@epa.gov
Other Sections
Executive Summary
Introduction
Emissions by Economic Sectors
Potential Emissions of MFCs, PFCs, and
SF6
Carbon Intensity Box
Common Reporting Format Tables
Michael Gillenwater
Michael Gillenwater
Michael Gillenwater
Dave Godwin
Michael Gillenwater
Michael Gillenwater
202-564-4092
202-564-4092
202-564-4092
202-564-3517
202-564-4092
202-564-4092
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
godwin.dave@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
Annexes
A. Methodology for Estimating Emissions of
CO2 from Fossil Fuel Combustion
B. Methodology for Estimating Carbon
Stored in Products from Non-Energy
Uses of Fossil Fuels
C. Methodology for Estimating Emissions of
ChU, NhO, and Ambient Air Pollutants
from Stationary Combustion
D. Methodology for Estimating Emissions of
ChU, NbO, and Ambient Air Pollutants
from Mobile Combustion
E. Methodology for Estimating ChU
Emissions from Coal Mining
F. Methodology for Estimating Chk
Emissions from Natural Gas Systems
G. Methodology for Estimating ChU
Emissions from Petroleum Systems
H. Methodology for Estimating CCb
Emissions from Municipal Solid Waste
Combustion
I. Methodology for Estimating Emissions
from International Bunker Fuels used by
the U.S. Military
J. Methodology for Estimating HFC and
PFC Emissions from Substitution of
Ozone Depleting Substances
K. Methodology for Estimating CH4
Emissions from Enteric Fermentation
L. Methodology for Estimating Chk and N2O
Emissions from Manure Management
M. Methodology for Estimating NbO
Emissions from Agricultural Soil
Management
Michael Gillenwater
Michael Gillenwater
Michael Gillenwater
Veronika Pesinova
Elizabeth Scheehle
Elizabeth Scheehle
Elizabeth Scheehle
Michael Gillenwater
202-564-4092 gillenwater.michael@epa.gov
202-564-4092 gillenwater.michael@epa.gov
202-564-4092 gillenwater.michael@epa.gov
202-564-9415 pesinova.veronika@epa.gov
202-564-9758 scheehle.elizabeth@epa.gov
202-564-9758 scheehle.elizabeth@epa.gov
202-564-9758 scheehle.elizabeth@epa.gov
202-564-4092 gillenwater.michael@epa.gov
Michael Gillenwater 202-564-4092 gillenwater.michael@epa.gov
Dave Godwin 202-564-3517 godwin.dave@epa.gov
Joseph Mangino 202-564-9481 mangino.joseph@epa.gov
Joseph Mangino 202-564-9481 mangino.joseph@epa.gov
Tom Wirth 202-564-9108 wirth.tom@epa.gov
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Quality Assurance/Quality Control and Uncertainty Management Plan for the U.S. Greenhouse Gas
Inventory: BACKGROUND ON THE U.S. GREENHOUSE GAS INVENTORY PROCESS
Filename: Background Document (v 1.0).doc
| June 16, 2002
Version 1.0
PageB-3ofB-3
Organizational Function Lead Staff
N. Methodology for Estimating Net Changes -,- ,.r JU
• i- i ^ L. 01 i Tom Wirth
in Forest Carbon Stocks
O. Methodology for Estimating CH4 Fli7ahPth SrhPPhlP
Emissions from Landfills Elizabeth Scheehle
P. Key Source Analysis Michael Gillenwater
Q. Global Warming Potential Values Michael Gillenwater
R. Ozone Depleting Substance Emissions Dave Godwin
S. Sulfur Dioxide Emissions Michael Gillenwater
T. Complete List of Source Categories Michael Gillenwater
U. IPCC Reference Approach for Estimating
CO2 Emissions from Fossil Fuel Michael Gillenwater
Combustion
V' ^xclu^e? Greenh°USe GaS Emissions Michael Gillenwater
W. Constants, Units, and Conversions Michael Gillenwater
X. Abbreviations Michael Gillenwater
Y. Chemical Symbols Michael Gillenwater
Z. Glossary Michael Gillenwater
Phone
202-564-9108
202-564-9758
202-564-4092
202-564-4092
202-564-3517
202-564-4092
202-564-4092
202-564-4092
202-564-4092
202-564-4092
202-564-4092
202-564-4092
202-564-4092
E-mail address
wirth.tom@epa.gov
scheehle.elizabeth@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
godwin.dave@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
gillenwater.michael@epa.gov
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