Greenhouse Gas Emissions _ Climate Change _ U.S. EPA

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					Greenhouse Gas Emissions | Climate Change | U.S. EPA                                                                         3/20/09 5:41 PM

                                                                                      Last updated on Tuesday, March 10th, 2009.
                          Climate Change - Greenhouse Gas Emissions
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    Greenhouse Gas Emissions
                                                                                                            Related Links
    Greenhouse Gas Emissions Overview | Inventories | Projections | Project
                                                                                                              Proposed Mandatory
                                                                                                        Greenhouse Gas Reporting
                                Draft 2009 Inventory of Greenhouse Gas                                  Rule
                           Emissions and Sinks                                                          U.S. Greenhouse Gas
                                                                                                        Methane to Markets
                   Prepared annually by EPA, the national greenhouse gas                                Personal Greenhouse Gas
                   inventory report presents estimates of U.S. greenhouse                               Emissions Calculator
                   gas emissions and sinks for the years 1990 through                                   Greenhouse Gas
                                                                                                        Equivalencies Calculator
    2007. This report also discusses the methods and data used to calculate
    the emission estimates.                                                                        IPCC's National Greenhouse
                                                                                                   Gas Inventories Programme

    Greenhouse Gas Overview
    Gases that trap heat in the atmosphere are often called greenhouse                                  Greenhouse Gases
    gases. This section of the EPA Climate Change Site provides information
                                                                                                        National Inventory
    and data on emissions of greenhouse gases to Earth’s atmosphere, and                                Submissions 2006
    also the removal of greenhouse gases from the atmosphere. For more
    information on the science of climate change, please visit EPA's climate
    change science home page.

    Some greenhouse gases such as carbon dioxide occur naturally and are emitted to the atmosphere
    through natural processes and human activities. Other greenhouse gases (e.g., fluorinated gases) are
    created and emitted solely through human activities. The principal greenhouse gases that enter the
    atmosphere because of human activities are:

               Carbon Dioxide (CO 2): Carbon dioxide enters the atmosphere through the burning of fossil
               fuels (oil, natural gas, and coal), solid waste, trees and wood products, and also as a result of
               other chemical reactions (e.g., manufacture of cement). Carbon dioxide is also removed from
               the atmosphere (or “sequestered”) when it is absorbed by plants as part of the biological
               carbon cycle.
               Methane (CH 4): Methane is emitted during the production and transport of coal, natural gas,
               and oil. Methane emissions also result from livestock and other agricultural practices and by the
               decay of organic waste in municipal solid waste landfills.
               Nitrous Oxide (N 2O): Nitrous oxide is emitted during agricultural and industrial activities, as
               well as during combustion of fossil fuels and solid waste.
               Fluorinated Gases: Hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride are
               synthetic, powerful greenhouse gases that are emitted from a variety of industrial processes.
               Fluorinated gases are sometimes used as substitutes for ozone-depleting substances (i.e.,
               CFCs, HCFCs, and halons). These gases are typically emitted in smaller quantities, but because
               they are potent greenhouse gases, they are sometimes referred to as High Global Warming
               Potential gases (“High GWP gases”).

    Greenhouse Gas Inventories                                                                         Page 1 of 3
Greenhouse Gas Emissions | Climate Change | U.S. EPA                                                 3/20/09 5:41 PM

    A greenhouse gas inventory is an accounting of the amount of greenhouse gases emitted to or
    removed from the atmosphere over a specific period of time (e.g., one year). A greenhouse gas
    inventory also provides information on the activities that cause emissions and removals, as well as
    background on the methods used to make the calculations. Policy makers use greenhouse gas
    inventories to track emission trends, develop strategies and policies and assess progress. Scientists use
    greenhouse gas inventories as inputs to atmospheric and economic models.

    To track the national trend in emissions and removals since 1990, EPA develops the official U.S.
    greenhouse gas inventory each year. The national greenhouse gas inventory is submitted to the United
    Nations in accordance with the Framework Convention on Climate Change                  .

    In addition to the U.S. inventory, greenhouse gas emissions can be tracked at the global, state and
    local levels as well as by companies and individuals:

               Many other countries also develop national greenhouse gas inventories, which can be compiled
               into global inventories. EPA works with developing and transition countries to improve the
               accuracy and sustainability of their greenhouse gas inventories. EPA has developed Greenhouse
               Gas Inventory Capacity Building templates and software tools targeting key sources, emissions
               factors, good practices, institutional infrastructure and use of the latest IPCC guidelines on
               greenhouse gas inventories.
               Many states prepare greenhouse gas inventories, and EPA provides guidance and tools to assist
               them in their efforts.
               Corporate greenhouse gas inventories provide information on the emissions associated with the
               operations of a company.
               Individuals produce greenhouse gas emissions through everyday activities such as driving and
               using air conditioning or heating. EPA provides an online calculator for estimating personal

    The Intergovernmental Panel on Climate Change (IPCC)                  publishes internationally
    accepted inventory methodologies that serve as a basis for all greenhouse gas inventories, ensuring
    that they are comparable and understandable. The 2006 IPCC Guidelines                  were completed
    and accepted by the IPCC in May 2006.

    Emission Trends & Projections

    Estimates of future emissions and removals depend in part on assumptions about changes in
    underlying human activities. For example, the demand for fossil fuels such as gasoline and coal is
    expected to increase greatly with the predicted growth of the U.S. and global economies.

    The Fourth U.S. Climate Action Report concluded, in assessing current trends, thatcarbon dioxide
    emissions increased by 20 percent from 1990-2004, while methane and nitrous oxide emissions
    decreased by 10 percent and 2 percent, respectively. The declines in methane emissions are due to a
    variety of technological, policy, and agricultural changes, such as increased capture of methane from
    landfills for energy, reduced emissions from natural gas systems, and declining cattle populations. At
    least some of the decline in nitrous oxide emissions is due to improved emissions control technologies
    in cars, trucks, and other mobile sources. (Fourth U.S.Climate Action Report, 2007)

    Many, but not all, human sources of greenhouse gas emissions are expected to rise in the future. This
    growth may be reduced by ongoing efforts to increase the use of newer, cleaner technologies and
    other measures. Additionally, our everyday choices about such things as commuting, housing,
    electricity use and recycling can influence the amount of greenhouse gases being emitted.

    The United States government prepares projections of emissions and removals of all greenhouse gases.
    The following links provide more detailed information on projections:                                                 Page 2 of 3
Greenhouse Gas Emissions | Climate Change | U.S. EPA                                                   3/20/09 5:41 PM

               Greenhouse Gas Projections, Chapter 5 of the U.S. Climate Action Report: In Chapter 5 of the
               Climate Action Report, the U.S. forecasts future emission levels using information developed
               from models.
               International Non-CO2 Greenhouse Gas Emission Projections
               Methane Projections
               Nitrous Oxide Projections
               Fluorinated Gases

    Project Methodologies

    EPA has developed several Climate Leaders Offset Project Methodologies that use a standardized
    approach to determine project eligibility, address additionality, select and set the baseline, identify
    monitoring options, and quantify reductions. This approach seeks to ensure that the GHG emission
    reductions from offset projects meet four key accounting principles—they must be real, additional,
    permanent, and verifiable.

    To be eligible as offsets, project activities must be surplus to regulation. Projects are also required to
    demonstrate additionality by achieving a level of performance with respect to emission reductions
    and/or removals that is significantly better than business-as-usual. Business-as-usual is determined
    from similar, recently undertaken or planned practices, activities or facilities in the same geographic
    region. This level of “performance” may be defined as an emissions rate, a technology standard or a
    practice standard. Data used in setting the performance standard is primarily collected from publicly
    available historic data (although planned or projected activities may be used in certain cases as well).
     The performance standard approach minimizes the risk of accepting a project that is not additional or
    rejecting a project that is additional. A performance standard approach also reduces the complexity,
    cost, and subjectivity of constructing individual project-specific reviews.

    Performance standards are available for the following project types:

               Captured Methane End Use (new project type) (PDF) (23 pp, 244K) August 2008
               Commercial Boiler (PDF) (21 pp, 233K) August 2008
               Industrial Boiler (PDF) (28 pp, 505K) August 2008
               Landfill Methane (PDF) (21 pp, 291K) August 2008
               Manure Management: Anaerobic Digester (PDF) (27 pp, 350K) August 2008
               Project accounting methodology (PDF) (22 pp, 201K) August 2008
               Reforestation/Afforestation Project Carbon Online Estimator Tool (RAPCOE)
               Transit Bus Efficiency (PDF) (21 pp, 256K) August 2008

               Fourth U.S. Climate Action Report, 2007                                                     Page 3 of 3

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