Abstract: The enhancement of human capital stock in China is a crucial guarantee for firms to achieve improvements in carbon productivity and, subsequently, to elevate the quality of green product exports. This study explores how the dynamic changes in the structure of human capital and its synergistic effects with carbon productivity facilitate the enhancement of firms' green product export quality. The findings indicate that the synergistic effect between human capital and carbon productivity significantly improves the quality of green product exports. Moreover, the conclusion remains robust after conducting a series of tests for robustness and endogeneity. Additionally, the positive influence of the synergistic effect on the quality of green product exports is particularly pronounced among private firms, processing trade firms, firms with a high degree of differentiated product, and firms exporting to high-income countries. The synergistic interaction between human capital and carbon productivity enhances the export quality of green products in firms through two mechanisms: research and development facilitation and technological absorption capacity building. Further research reveals that the advanced human capital structure synergistically interacts with carbon productivity across temporal and spatial dimensions, which serves as a critical driver in enhancing the export quality of green products at the firm level. Consequently, firms should prioritize the improvement and synergistic development of human capital and carbon productivity to provide sufficient impetus for enhancing the quality of green product exports.

Key words: human capital, carbon productivity, quality of green product exports, technology absorption