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agricultural and industrial activities, as well as during combustion of fossil fuels and solid waste.
<br /> Fluorinated gases, while not abundant in the atmosphere, are powerful GHGs that are emitted from a
<br /> variety of industrial processes and are often used as substitutes for 03-depleting substances (e.g.,
<br /> chlorofluorocarbons, hydrochloroflourocarbons, and halons).
<br /> All the different GHGs have various capacities to trap heat in the atmosphere, which are known as global
<br /> warming potentials (GWPs). GWPs can be expressed for several different time horizons to fully account
<br /> for the gases ability to absorb infrared radiation (heat) over their atmospheric lifetime.The BLM uses the
<br /> 100-year time interval since a majority of the climate change impacts derived from climate models are
<br /> expressed toward the end of the century. Similarly,these models are often based on 100-year emissions
<br /> projections, such that providing a 1 to 1 comparison of the emissions provides for a more meaningful and
<br /> understandable analysis. CO2 has a GWP of 1, and so for the purposes of analysis a GHGs GWP is generally
<br /> standardized to a CO2 equivalent(CO2e),or the equivalent amount of CO2 mass the GHG would represent.
<br /> Methane has a current GWP estimated to be between 28(gas alone)and 36(with climate feedbacks),and
<br /> N2O has a GWP of 298.
<br /> The EPA tracks GHG emissions in the U.S. by source sector(e.g., industrial, land use,electricity generation,
<br /> etc.), fuel source (e.g., coal, natural gas, geothermal, petroleum, etc.), and economic sector (e.g.,
<br /> residential, transportation, commercial, agriculture, etc.) (Table 2.2-6). With so many GHG emission
<br /> sources nationally, from cattle to vehicles to electric power generators, no single source is likely to
<br /> represent a significant percentage of national emissions (Table 2.2-6). Nevertheless, GHG emissions for
<br /> the U.S. are provided here in several ways. Table 2.2-6 shows GHG emissions CO2e from fossil fuel
<br /> combustion by economic sectors for 2005, 2012,and 2016.Table 2.2-7 shows total U.S. emissions in 2005,
<br /> 2012, and 2016 by gas and source and by CO2e; only the largest sources/sinks are shown for each gas.
<br /> Note that,for CO2, "Land Use, Land-Use Change, and Forestry" represents a sink rather than a source and
<br /> is therefore in parentheses.
<br /> Table 2.2-6 U.S. Greenhouse Gas Fossil Fuel Combustion Emissions Allocated to
<br /> Economic Sectors (million metric tons)
<br /> Implied Sectors 2005 2012 2016
<br /> (MMT CO2e) (MMT CO2e) (MMT CO2e)
<br /> Electric Power Industry 2,400.9 2,022.2 1,809.3
<br /> Transportation 1,855.8 1,661.9 1,782.6
<br /> Industry 855.7 812.9 809.1
<br /> Commercial 227.0 201.3 231.3
<br /> Residential 357.8 282.5 292.5
<br /> U.S.Territories 49.7 43.5 41.4
<br /> Total Emissions 5,746.9 5,024.4 4,966.0
<br /> MMT= million metric tons;
<br /> Source: EPA(2018)
<br /> equivalentshttps://www.epa.gov/sites/production/files/201801/documents/2018_complete_report.pdf.
<br /> Table ES-2.
<br /> Dunn Ranch Area LBA and Mining Plan Modification 13
<br /> Technical Resources Report
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