Transport and Carbon Emissions in the United States: The Long View

The following analysis traces U.S. transport CO2 emissions in combustion by mode for 1960-2008. Changes in emissions are divided into components related to overall population and economic growth, transport mode shift, changes in the ratio of fuel used to passenger or tonne-km of activity, and changes in the CO2 content of fuels. Where data permit we show how changes in vehicle utilization affected CO2 emissions. We comment on factors causing the changes in components of emissions. A Log-Mean Divisia Index and Laspeyres decompositions of the 1960-2008 changes are calculated. From this decomposition we speculate to what extent the factors associated with the increases in CO2 emissions since 1960 would be important in the future, and what other factors could reduce emissions. This thorough decomposition is imperative for the crafting of transport policy that aims to address climate change.