Nonlinear and interactive effects of human capital skills on twin green-digital transition: Evidence from recruitment...

The twin green-digital transition (TGD) is a key pathway for firms to enhance resource efficiency, reduce pollution, and strengthen green competitiveness. However, the roles of human capital skills in TGD, particularly their heterogeneity, nonlinearities, and interactions, remain underexplored. Using recruitment data of Chinese listed firms from 2016 to 2023, this study measures firm-level investment in seven human capital skills-digital transformation, cross-cutting, soft, circular lifecycle management, technological innovation in the circular economy, clean tech and advanced materials management, and waste management-with a pre-processed large language model. A CatBoost-SHAP model examines their effects and moderating mechanisms in TGD. Digital transformation skills are the primary driver of TGD. Other skills show heterogeneous nonlinear patterns: cross-cutting and soft skills have rising positive effects; clean tech and advanced materials management follow an inverted U-shape; circular lifecycle management and technological innovation skills have modest negative effects; and waste management skills contribute little (0.44%). Interactions are observed: circular lifecycle management skills combined with cross-cutting and technological innovation skills generate positive multiplicative effects that offset standalone negatives. Soft skills show partial substitutability, and employee training strengthens the positive effects of circular lifecycle management and technological innovation, especially in large firms. These findings underscore the value of targeted human capital development and inform firms, educators, and policymakers seeking to advance TGD.