The transition to a zero-carbon society will dramatically increase the demand for copper, potentially by over 300% by 2050. This increased demand, coupled with declining ore grades and extraction in regions with weak environmental enforcement and high climate change vulnerability, necessitates a thorough assessment of the copper supply chain and the role of recycling. China, in its efforts to improve environmental outcomes, has implemented policies like the Green Fence (2013) and National Sword (2017), restricting solid waste imports. While these policies have positive local effects, they have also caused significant disruptions in various supply chains, including that of copper. Previous research has mainly focused on the impact of the ban on plastic waste, with limited studies exploring the global repercussions on the copper supply chain. This study addresses this gap by investigating how the import ban and the COVID-19 pandemic impact the global copper supply chain and its associated environmental footprint.

Existing literature emphasizes the ban's impact on plastic waste, highlighting geographical redistribution, increased landfilling, and environmental consequences. Several studies acknowledge that China's domestic secondary copper supply is insufficient to meet its rising demand, focusing primarily on changes in scrap imports and using top-down material flow analyses limited to China. However, a significant research gap remains in understanding the global supply chain reactions stemming from the import ban, the resulting environmental impacts, and strategies for maximizing environmental benefits globally. This study seeks to fill this gap by comprehensively modeling the global copper supply chain responses.

This research employs a multi-faceted approach integrating econometric time series analysis, inventory-driven price formation, dynamic material flow analysis (dMFA), and life cycle assessment (LCA). The model distinguishes between China and the rest of the world (RoW), accounting for differences in scrap composition, availability, and price. The model tracks cathode and scrap prices, refinery processing fees (TCRC), and production and consumption of copper scrap, concentrate, and refined material through 2040. Key features of the model include explicit modeling of mine-level decisions (opening, closing, capacity utilization), economic modeling accounting for cascading effects throughout the supply chain, and a cost-driven optimization model determining scrap consumption changes between China and RoW. The model architecture incorporates supply-demand imbalances for copper ore, scrap, and cathode to calculate prices and production, considering the interlinkages between different supply chain actors (mines, refineries, fabricators). The model also uses exogenous variables like GDP per capita and sectoral volume predictions to determine fabricator demand and scrap generation via material flow analysis.

The study finds that China's solid waste import ban has led to a redistribution of copper scrap trade and compositional changes. The gross weight of China's copper imports has declined, while the copper fraction has increased, maintaining a nearly constant copper content by mass. Countries like South Korea, India, Germany, Taiwan, and others have increased copper scrap imports, with some upgraded and re-exported to China. Simulations show that the ban shifts scrap availability from China to RoW, increasing prices in China and decreasing them in RoW. This leads to increased primary refining in China and decreased secondary refining, resulting in a global increase in primary refining production and a decrease in secondary refining. The study projects a cumulative global increase in CO2-equivalent emissions of up to 13 Mt by 2040, largely due to increased primary refining in China. Other environmental impacts, such as smog and respiratory effects, also increase significantly within China. Increasing China's refined copper imports could mitigate these effects, leading to a decrease in CO2-equivalent emissions in China (up to 180 Mt by 2040) and globally (up to 20 Mt). Analysis of COVID-19-related supply chain disruptions shows that the long-term environmental impacts of the solid waste import ban and refined copper import policies persist even with disruptions in mining and refining production. The impacts of these policies are largely additive to the supply chain shocks, indicating that the results are robust. The study highlights the potential for burden shifting, where emission reductions in China are partially offset by increased emissions in other regions. This emphasizes the need for responsible investment in refining capacity in regions with better environmental practices and lower-emission electricity grids.

The findings highlight the unintended environmental consequences of seemingly environmentally protective policies. The solid waste import ban, while aiming to reduce pollution within China, has shifted the environmental burden to other countries, exacerbating the global environmental impact of copper production. The study's integrated modeling approach reveals the complex interdependencies within the copper supply chain and the cascading effects of policies and disruptions. The results underscore the importance of considering global supply chain dynamics when formulating environmental policies. The effectiveness of policies depends not only on local actions but also on their global repercussions. The findings emphasize the need for international cooperation and coordinated efforts to achieve sustainable copper production.

This study demonstrates the complex interplay between environmental policy, global trade, and economic shocks in shaping the environmental impact of the copper supply chain. The China solid waste import ban, while having positive local environmental intentions, resulted in increased CO2e emissions globally, driven by a shift in primary refining to China. Increased refined copper imports to China offer a potential mitigation strategy, reducing emissions both domestically and globally. The findings emphasize the need for integrated global strategies that balance environmental protection with economic realities, and highlight the importance of considering the cascading effects of policy decisions throughout global supply chains. Future research should investigate more granular regional differences within the model to reduce uncertainty and refine projections.

The model relies on several assumptions, including constant regional distributions of mining activities and certain technological parameters. The accuracy of the projections depends on the reliability of the data used and the assumptions made about future economic growth and policy changes. The environmental impact assessment uses a specific LCA methodology (TRACI 2.1), and the results might differ with different methodologies or datasets. The model's complexity and the many interconnected variables involved make it challenging to fully isolate the independent effects of each factor.