IPCC Fourth Assessment Report: Climate Change 2007
Climate Change 2007: Working Group III: Mitigation of Climate Change

5.4.2 Estimate of world mitigation costs and potentials in 2030

By extrapolating from recent analyses from the IEA and others an estimate can be given of the cost and potential for reducing transport CO2 emissions. This section covers improving the efficiency of light-duty vehicles and aircraft, and the substitution of conventional fossil fuels by biofuels throughout the transport sector (though primarily in road vehicles). As noted above, these estimates do not represent the full range of options available to reduce GHG emissions in the transport sector.