Carbon estimation and urban mobility plans : opportunities in a context of austerity

Considering the constant increase of greenhouse gas (GHG) transport emissions in the past years and the consequent global warming, their reduction must be one of the most important goals in mobility planning. However, mobility plans do not always target GHG reduction for political reasons and a lack of adequate methodologies. Practically, carbon emissions are often considered secondary to mobility planning, which can be addressed indirectly by introducing measures for other purposes, but whose GHG effects are not carefully quantified. This decision is relevant when austerity is called for, when the real costs of transport measures have to be clearly expressed for consistent allocation of scarce funds. In this paper, a method is proposed to include the economic impact of GHG emissions on a mobility plan through a monetization process. The unitary value of GHG emissions has been inferred through a metaanalysis of about 700 studies and a meta-regression function. The case study proposed illustrates the concrete application and the potential of such a method. Moreover, the importance of a long-term strategy in obtaining a consistent GHG reduction and of a congruent valuation strategy to appraise its impacts is confirmed.