Are exports a push or drag to China's carbon constraint targets? Evidence from the new energy technology-rare earth industry chain

China is the world's major exporter of rare earth resources and related new energy products. While exports transfer the carbon embodied in trade, they may also have an impact on the deployment of new energy. This study combines dynamic material flow with system dynamics methods to construct China's new energy technology-rare earth industry chain supply and demand model (NET-RECSD), which discusses the impact of exports in each link of the industry chain on carbon constraint targets from both production and system aspects. It also analyzes the ways to enhance the emission reduction effect of exports from the perspectives of technological progress and improvement of consumption structure. The research conclusions are as follows: From a systemic perspective, expanding the export scale of nickel-metal hydride batteries and rare earth permanent magnets are driving force for the realization of national carbon constraint goals. Expanding the export scale of wind turbines and rare earth permanent magnets and increasing the proportion of global supply downstream of the industrial chain can promote the production and carbon reduction of the rare earth industry chain from the consumption structure and industrial structure respectively. Technological innovation, adjustment of rare earth consumption structure and expansion of recycling scale can all enhance the carbon emission reduction effect of exports, but the emission reduction effect decreases in sequence. When the carbon savings per unit of new energy deployment increases by 40%, its emission reduction efficiency is the highest; when the new energy consumption of rare earths accounts for 79%, the carbon emission reduction increases by 2%. The study concludes that the government should reduct carbon in the industry chain studied by expanding the exports scale in the middle reaches of the chain, adjusting the industrial structure, improving the new energy end-use of rare earths and enhancing the efficiency of solid waste recycling.