Tracing the Consumption-Based Co2 Emissions of Megacities in Multiscale Economies

Abstract

Megacities are showing heterogeneity of CO2 emission patterns under complex global trade networks. Given that megacities are closely interconnected with multiscale economies, the precise CO2 emission reduction policies require cross-boundary consumption-based CO2 emission inventories that take global supply chains into account. However, due to data availability and other issues, the CO2 flow patterns in megacities has yet to be explored deeply. Therefore, we constructed a megacity-centred CO2 emission accounting model based on the multiscale multiregional input‒output (MSIO) table and selected 10 megacities in Chinese representative city clusters to test this model. This model traced multiscale sources of megacities’ CO2 emissions driven by final demand, elucidating national and global connections with megacities. The results show that megacities exhibit diverse CO2 emission patterns, categorized into four consumption degree types (ranging from 0.96 of Chongqing to 4.10 of Chengdu), which also relate to production efficiency and consumption efficiency. Shenzhen’s consumption mainly induces emissions in other world regions while other megacities leads to CO2 emissions in mainland China regions, notably in Hebei, Shandong, Jiangsu and Inner Mongolia provinces. Construction, services and other manufacturing are the top three emission sectors. Services consumed highly from localities, while the remaining two sectors were more dependent on imports. For example, CO2 emissions of other manufacturing in Shanghai and Shenzhen were primarily imported from East Asia, while Beijing imported higher from North America. Comparing these megacities’ consumption-based CO2 emission profiles elucidates the urgent need for global carbon governance along supply chains and differentiated carbon reduction policies based on urban classification.

Keywords: Consumption-based accounting, CO2 flow, multiscale, Megacities, Nested EE-MSIO, Trans-boundary