What influences national ambition in clean transport policy? A statistical analysis of NDC climate mitigation targets and driving factors.

Current pledges in Nationally Determined Contributions (NDCs) imply emissions trajectories that do not align with the Paris Agreement. The transport sector is critically detrimental, responsible for almost a quarter of global energy-related CO₂ emissions and not-on-track for net-zero by 2050. Previous study has focussed on which domestic factors are driving economy wide emission mitigation; we bring strongly warranted focus to the transport sector. To determine whether sectoral complexities are being overlooked, we first conceptualise and quantify a novel formulation of climate policy ambition, applicable on a sectoral level for 167 countries. Second, we conduct quantitative analyses to assess the effects of a set of structural and socio-institutional domestic factors on ambition. Our findings reveal that coal rents, climate vulnerability, control of corruption, electoral democracy and GDP per capita have strong positive effects on ambition. Conversely, oil rents, climate adaptive readiness and electric-vehicle critical mineral endowments have negative effects. These results vary significantly from economy-wide findings, suggesting that sector-specific complexities have historically been overlooked. Greater resolution of transport-specific factors that influence policy ambition can contribute to maximising sectoral trade-offs and synergies to gain greater stakeholder support and reconcile political economy with ambitious clean transport policy.