Inward foreign direct investment, outward foreign direct investment, and carbon dioxide emission intensity-threshold regression analysis based on interprovincial panel data.

Based on the panel data of 30 provinces (except for Tibet, Hong Kong, Macao, and Taiwan) in China from 2005 to 2016, a nonlinear threshold regression model and a carbon emission expansion models were constructed to empirically analyze the threshold effect of inward foreign direct investment (IFDI) and outward foreign direct investment (OFDI) on carbon dioxide emission intensity in China. The results show that (1) China's OFDI has increased carbon dioxide emission intensity while the IFDI has a significant inhibitory effect on carbon dioxide emission intensity. (2) The impact of the OFDI on carbon dioxide emission intensity gets influenced by the threshold effect of population size, economic development level, technology level, and environmental regulation. (3) The impact of the IFDI on carbon dioxide emission intensity also has threshold characteristics affected by population size, economic development level, and technological level. Hence, China should introduce more IFDI, optimize the structure of the OFDI, and exert its environmental improvement effect to satisfy the carbon emission reduction goal earlier.