Abstract
Reducing carbon emissions is a relevant aspect that helps achieving sustainability in transport planning. However, most of the mobility plans have not yet adopted a shared methodology to internalize these emissions and to make them one of the parameters able to influence the final choices on the policies and measures to be taken. In particular, it is extremely complex to quantify and to assign a unitary economic value to GHG emissions. The present paper dwells upon this issue, presenting the methodologies currently in use and the vast degree of scientific and economic uncertainty that characterizes them. Through an extensive review of the plans and the urban strategies adopted (mostly in Europe), we analyze the current stand of transport policy for carbon emissions, drawing some conclusions and possibly inspiring some food for thought for possible future perspectives to control the effects of this issue in the long run.