Transport infrastructure and CO₂ emissions in the OECD over the long run

A gap in the transportation-environment literature is the absence of studies analysing the effect of transport infrastructure on carbon dioxide (CO₂) emissions, controlling for other factors correlated with CO₂ emissions. We address this gap by providing parametric and non-parametric estimates of the effect of transport infrastructure on CO₂ emissions for a panel of OECD countries over a period of almost 150 years. We also examine economic growth and population as channels through which transport infrastructure influences CO₂ emissions. Our point estimates suggest that a 1% increase in transport infrastructure is associated with an increase in CO₂ emissions of about 0.4%, although dependent on the long-run estimator used. Our non-parametric estimates suggest a time-varying relationship between transport infrastructure and CO₂ emissions, which was positive during the first wave of globalisation, World War II and for most of the period since 1950. We find that economic growth and population mediate the transport infrastructure CO₂ emissions relationship.