TRANSPORTATION - BTS - Bureau of Transportation Statistics

diseases such as malaria. Moreover, the emissions that contribute tothe greenhouse effect remain in the atmosphere for much longerperiods than do emissions affecting air quality. Most of the CO 2released in 2000 through fossil fuel combustion will still be in theatmosphere at the beginning of the 22 nd century.Carbon dioxide is the dominant greenhouse gas emitted by transportation.It is produced in approximate proportion to the amountof petroleum used, and its production can only be reduced byburning less fossil fuel (i.e., through energy efficiency or use ofalternative fuels). Transportation sources account for about 26 percentof greenhouse gas emissions, and transportation sector greenhousegas emis-sions have increased by nearly 40 percent since1975, in parallel with increases in transportation sector energyconsumption (figure 5-28) [USDOE EIA 1999e]. Contributing factorsinclude growth in travel; a significant market shift away fromautomobiles and toward trucks and sport utility vehicles (SUVs);and petroleum prices during the 1990s that, adjusted for inflation,were much lower than past levels.“Just last week, automakersunveiled cars thatget 70 to 80 miles a gallon,the fruits of a uniqueresearch partnershipbetween government andindustry. And, before youknow it, efficient productionof biofuels will giveus the equivalent ofhundreds of miles from agallon of gasoline.”President William J. ClintonState of the Union AddressJan. 27, 2000Greenhouse gas emissions from private vehicles (cars and light trucks) increased by about12 percent from 1990 to 1997 and accounted for about 70 percent of that period’s overallgrowth in transportation greenhouse gas emissions. Emissions from other trucks and busesgrew much faster—21 percent over the same period—accounting for most of the remainingoverall growth. About 95 percent of these emissions were from medium- and heavy-dutytrucks.Figure 5-28Carbon Dioxide Emissions by End-Use Sector: 1975-98(Annual totals)Million metric tons of carbon600500400300200100IndustrialTransportationResidentialCommercial01975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1998Source: U.S. Department of Energy, Energy Information Administration, Emissions of Greenhouse Gases in the UnitedStates, 1998 (Washington, DC: 1999).5-34