Linking Climate Finance to Mitigation Outcomes in Indonesia’s Transportation Sector: Evidence from Verified Emission Reduction and Its Cost

Decarbonizing the transportation sector depends not only on the scale of mitigation programs but also on whether financing systems are capable of generating measurable emission reductions. In Indonesia, climate finance allocation remains substantially below the level required to achieve the transportation-sector target under the Enhanced Nationally Determined Contribution (ENDC). At the same time, mitigation planning rarely establishes a clear relationship between financial expenditure and verified greenhouse gas (GHG) reduction outcomes, making policy effectiveness difficult to assess. This study examines the relationship between climate finance and mitigation outcomes in Indonesia’s transportation sector using verified emission reduction data and realized mitigation expenditures during 2018–2022. A cost-based assessment approach was applied to estimate the financing required to reduce one ton of CO2 equivalent (tCO2-e) across direct and indirect mitigation actions. The analysis identified 33 mitigation actions categorized under the Avoid–Shift–Improve (ASI) framework and evaluated their contribution to sectoral emission reduction. The results indicate substantial variation in mitigation costs among intervention types. Direct mitigation actions, particularly mass public transportation expansion, are linked to larger emission reductions at relatively lower costs than enabling or indirect measures. On average, reducing 1 tCO2-e in Indonesia’s transportation sector requires approximately USD 184–1000 (IDR 3–16.4 million), using a standardized exchange rate of approximately IDR 16,400 per USD. Based on the transportation-sector ENDC target, the estimated financing requirement by 2030 ranges from USD 2.5–13.8 billion (IDR 42–226 trillion). The findings suggest that climate finance policies should move beyond expenditure-oriented approaches toward financing frameworks that explicitly connect investment allocation with verified mitigation performance.