Product and Metal Stocks Accumulation of China’s Megacities: Patterns, Drivers, and Implications

The
rapid urbanization in China since the 1970s has led to an exponential
growth of metal stocks (MS) in use in cities. A retrospect on the
quantity, quality, and patterns of these MS is a prerequisite for
projecting future metal demand, identifying urban mining potentials
of metals, and informing sustainable urbanization strategies. Here,
we deployed a bottom-up stock accounting method to estimate stocks
of iron, copper, and aluminum embodied in 51 categories of products
and infrastructure across 10 Chinese megacities from 1980 to 2016.
We found that the MS in Chinese megacities had reached a level of
2.6–6.3 t/cap (on average 3.7 t/cap for iron, 58 kg/cap for
copper, and 151 kg/cap for aluminum) in 2016, which still remained
behind the level of western cities or potential saturation level on
the country level (e.g., approximately 13 t/cap for iron). Economic
development was identified as the most powerful driver for MS growth
based on an IPAT decomposition analysis, indicating further increase
in MS as China’s urbanization and economic growth continues
in the next decades. The latecomer cities should therefore explore
a wide range of strategies, from urban planning to economy structure
to regulations, for a transition toward more “metal-efficient”
urbanization pathways.

自20世纪70年代以来，中国的快速城市化导致城市在用金属存量（metal stocks, MS）呈指数级增长。对这类金属存量的数量、质量与分布模式开展回溯研究，是预测未来金属需求、识别城市金属回收潜力、为可持续城市化战略提供决策依据的必要前提。本研究采用自下而上的存量核算方法，估算了1980年至2016年间中国10座超大城市中51类产品与基础设施所蕴含的铁、铜、铝存量。研究发现，2016年中国超大城市的金属存量已达到2.6–6.3吨/人（其中铁人均3.7吨、铜人均58千克、铝人均151千克），但仍低于西方城市的对应水平，亦未达到全国层面的潜在饱和水平（例如铁的饱和水平约为13吨/人）。基于IPAT分解分析，经济发展被认定为驱动金属存量增长的最核心因素，这意味着未来数十年随着中国城市化与经济增长的持续推进，金属存量还将进一步提升。因此，后发城市化城市应当探索从城市规划、经济结构调整到监管政策在内的多元策略，以转型走向更具“金属利用效率”的城市化发展路径。