Decoupling transport-CO2 emissions: Mexico, Spain and The USA: A trend analysis

Existing methodologies to measure (de)coupling among economic activity, surface transport (road and rail), and CO2 emissions have not captured the complexity of decoupling. This study aims to contribute to the understanding of (de)coupling. Three groups of variables were formed (using 17 variables). By relating each variable to the others through a ratio, an indicator is obtained that corresponds to a coupling-decoupling category. In total, 36 indicators (by country) were analysed for the three countries. The results reveal that transport volume changes proportionately more than economic activity (materialization). Conversely, CO2 emissions change proportionately less than do economic activity and surface transport volume (decarbonization), although Mexico requires greater efforts. Additionally, decoupling is tangible at aggregated levels, while coupling is evident at disaggregated levels. Finally, the combination of these features contributes to the formulation of policies for achieving sustainable transport. One limitation of this study is the exclusion of air and maritime transport.