Green Bond Issuance and Carbon Emissions: Can Causal Machine Learning Inform Forward-Looking Policy Decisions?

. Counties with higher concentrations of small and medium enterprises exhibit the strongest benefits. Comparisons between counties with and without prior issuance suggest that new green bonds generally reduce emissions, although magnitudes vary with local economic and infrastructure characteristics. These findings provide evidence on the effectiveness of municipal green finance, with implications for policy implementation and forecasting environmental outcomes, particularly for first-time issuers.