Greenhouse Gas Emissions and Mitigation
GHG emissions from transportation accounts for about 27% of GHG emissions in the U.S., second only to electricity generation (31%) (2013 USEPA). Within the transportation sector, light-duty vehicles were the largest category (60%) and medium- and heavy-duty trucks made up the second largest category (23%). From 1990-2013, GHG emissions in the transportation sector increased more in absolute terms than any other sector (i.e. electricity generation, industry, agriculture, residential, or commercial). (U.S. Transportation Sector Greenhouse Gas Emissions 1990-2013, U.S. EPA)
Transportation energy and climate change are closely intertwined since GHG emissions are a directly related to energy consumption. Global transportation energy demand is expected to increase substantially without implementation of aggressive policies, and could potentially be the fastest-growing end-use sector. (See p. 603 of IPCC Fifth Assessment Report WG III Chapter 8.)
For the most part, efforts to meet energy use reduction goals also will reduce transportation’s GHG emissions.