Estimating the impacts of urban form on CO2 emission efficiency in the Pearl River Delta, China

The improvement of CO2 emission efficiency is of great significance to realizing energy-saving and emission reduction targets and achieving low-carbon development. While it is increasingly recognized that urban form could significantly influence the CO2 emissions of urban areas, few studies have been able to quantify the implications of urban form in relation to CO2 emission efficiency. The purpose of this paper is thus to contribute to existing literature by empirically quantifying how urban form influences CO2 emission efficiency. CO2 emission efficiency in this study is presented in terms of CO2 economic efficiency (CEE) and CO2 social efficiency (CSE). Firstly, we calculated the CEE and CSE of nine cities in the Pearl River Delta (Guangzhou, Shenzhen, Zhuhai, Foshan, Jiangmen, Zhaoqing, Huizhou, Dongguan, and Zhongshan) using locally important socio-economic variables over the period 1990-2013. Then, seven landscape metrics were selected in order to quantify three dimensions of urban form (extension, irregularity, and compactness) using remote sensing data. Finally, panel data models were utilized to estimate the associations between urban form and CO2 emission efficiency. We identified a negative correlation between urban sprawl and CEE as well as CSE, a finding that indicates that urban growth decreases CO2 economic efficiency. Further, increasing irregularity in the form of cities was found to decrease both CEE and CSE-a larger degree of irregularity, in other words, results in lower CO2 emission efficiency. Conversely, urban compactness was identified as having a significant positive influence on both CEE and CSE, indicating that the compact development of cities can actually help to improve CO2 emission efficiency. The findings of this study hold important implications for building low-carbon cities in China.