Aluminium is one widely used metal that plays an important role in China's industrial and economic development. The life cycles of aluminium products involve high energy inputs, intensive material consumption and heavy environmental emissions. China has released its ambitious climate change targets, namely reaching carbon peak in 2030 and achieving carbon neutrality in 2060. It is therefore urgent to take appropriate actions to reduce the overall greenhouse gas emissions from aluminium production and increase resource efficiency along the entire aluminium life cycle. Under such circumstances, this study aims to explore China's aluminium recycling potential through dynamic material flow analysis for the period of 2000–2019, covering its whole life cycle and including relevant international trade activities. An entropy analysis method is also applied to identify optimal pathways to improve aluminum resource efficiency and circularity. Results indicate that China has experienced fast growth of aluminum production and consumption during the last two decades, with its output of primary aluminium increasing from 4.18 Mt in 2000 to 35.11 Mt in 2019 and its aluminium consumption increasing from 2.99 Mt in 2000 to 32.5 Mt in 2019. Such rapid growth has resulted in significant environmental impacts. For instance, environmental loss of aluminium at the production stage accounted for 46% of the total loss throughout its entire life cycle in 2000, while such a rate increased to 69% in 2019. As such, entropy analysis results reflect that at the stage of waste management, the relative entropy of aluminium is rising, which indicates that any pollutants discharged into the environment will cause significant damage. Scenarios analysis results further help to identify the optimal pathway of aluminium metabolism system. Finally, several policy recommendations are proposed to improve the overall aluminium resource efficiency.
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Circular economy is recognized as a powerful integrative framework envisioned to solve societal problems linked to environmental pollution and resource depletion. Its adoption is rapidly reforming manufacturing, production, consumption, and recycling across various segments of the economy. However, circular economy may not always be effective or even desirable owing to the spatiotemporal dimensions of environmental risk of materials, and variability of global policies. Circular flows involving toxic materials may impose a high risk on the environment and public health such that overemphasis on anthropogenic circularity is not desirable. Moreover, waste flows at a global scale might result in an uneven distribution of risks and costs associated with a circular economy. Among other benefits, circular economy needs to generate environmental advantages, energy savings, and reductions of greenhouse gas emissions. Recent attempts to implement the carbon neutrality strategy globally will likely push the circular economy further into more economic sectors, but challenges remain in implementing and enforcing international policies across national boundaries. The United Nations Basel Convention on the Transboundary Movement of Hazardous Waste and their disposal is used here as an example to illustrate the challenges and to propose a way forward for anthropogenic circularity.