Table 17. U.S. Methane Emissions from Mobile Sources, 1990-1998
(Thousand Metric Tons of Methane)

Item 1990 1991 1992 1993 1994 1995 1996 1997 P1998
Motor Vehicles  
  Passenger Cars 142 132 131 126 117 109 107 105 104
  Buses 1 1 1 1 1 1 1 1 1
  Motorcycles 4 4 4 4 4 4 4 4 4
  Light-Duty Trucks 63 63 63 75 85 99 92 91 92
  Other Trucks 12 12 12 13 14 14 15 15 16
     Total 222 212 212 219 221 228 219 217 217
  Other Transport 23 23 24 22 22 23 23 21 21
Total Transport 245 235 235 241 243 251 242 238 238
P = preliminary data.
Sources: Calculations based on vehicle miles traveled from U.S. Department of Transportation, Federal Highway Statistics, various years, Table VM-1. Vehicle emissions coefficients from Intergovernmental Panel on Climate Change, Greenhouse Gas Inventory Reference Manual: Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories, Vol. 3 (Paris, France, 1997), pp. 1.65-1.75, web site www.iea.org/ipcc/invs6.htm. Distribution of passenger car and light duty truck fleet model years for 1983, 1985, 1988, 1991, and 1994 according to data in the Energy Information Administration's "Residential Transportation Energy Consumption Surveys" for those years. Distribution for passenger cars and light duty trucks in other years computed by interpolation. Distribution of bus and other truck fleet according to model year computed assuming 10-percent attrition per annum of pre-1983 fleet for each year after 1984.

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