Carbon dioxide intensity and income level in the Chinese megacities' residential building sector: Decomposition and decoupling analyses

Carbon dioxide (CO₂) caused by residential building sector is essential for China to achieve its 2030 carbon emission peak. As the indicator to control the total CO₂ emissions, CO₂ intensity feature should be preferentially analyzed. Through the decomposition and decoupling approaches, this paper is the first to investigate whether CO₂ intensity decouples from the income level in residential building sector of China and its four megacities [Beijing (BJ), Tianjin (TJ), Shanghai (SH), and Chongqing (CQ)] from 2000 to 2016. Major findings indicate that: (1) The nationwide status was the weak decoupling during 2001-2016 excluding 2003 (the expansive coupling) and 2014 (the strong decoupling). (2) At the megacity scale, only four decoupling levels appeared and the decoupling effect rank of four megacities is as follows: CQ > TJ > BJ > SH (2001-2004), BJ > TJ > CQ > SH (2005-2008), SH > BJ > TJ > CQ (2009-2012), and SH > BJ > TJ > CQ (2013-2016). (3) Carbon Kuznets curves explained the different decoupling modes of four megacities and the increasing decoupling effects in 2001-2016 are attributable to the implementation of energy conservation strategy. Overall, this paper fills the gap of decoupling CO₂ intensity from the income level in residential building sector. Furthermore, a significant contribution is made by this paper to the carbon emission peak analysis in residential building sector of China, and our efforts will also be a case for other countries and cities to evaluate the decoupling effect in their residential building sectors.