Green frontiers on the "Belt and Road": carbon policy, emission efficiency, and environmental total factor productivity across 41 economies.

As countries along the Belt and Road pursue green economic transformation, environmental total factor productivity (ETFP) has become a key indicator of green development performance, making the measurement and improvement of ETFP a pressing priority. This study evaluates the ETFP of 41 countries participating in the Belt and Road Initiative (BRI). We introduce a novel framework that combines the Green Luenberger Productivity Index with the Bi-weighted Modified Russell Model (BWMRM), treating carbon emissions as an undesirable output. The results show that although overall ETFP remains relatively low, it exhibits a clear upward trend driven primarily by technological progress and carbon emission reduction efforts. Notably, clean technology innovation contributes more to CO₂ reduction than structural energy adjustments. In addition, the input-output performance of labor exceeds that of capital and GDP, with significant regional disparities across countries. Based on these findings, we propose a four-dimensional policy framework. First, countries should establish a gradient mechanism for low-carbon transitions. Second, policymakers should optimize factor allocation to improve labor skills and the green use of capital. Third, fostering transnational green technology spillovers is essential for enhancing clean energy cooperation. Finally, governments should design differentiated, region-specific emission reduction strategies. Overall, this study provides both theoretical and practical guidance for advancing green development across BRI countries.