The impact of urban scale on carbon metabolism -- a case study of Hangzhou, China

Abstract

Urban areas are the most densely populated place. Human urban activities consume about 70% of the world’s energy and emit nearly 80% of global greenhouse gases. Studying urban carbon metabolism can provide new ideas for urban low carbon development. This paper established an urban carbon metabolism analogy model based on Kleiber’s law, and used panel data of urban construction land scale from three districts in Hangzhou, to discuss whether urban carbon metabolism was analogous to biological metabolism. We found that the β exponent of the carbon metabolism model in urban traffic land was greater than 1, indicating carbon metabolism in traffic land was not similar to biological metabolism; the β exponents in industrial land, other urban construction lands, and the overall construction land were less than 1, which indicated the existence of an analogy between carbon metabolism and biological metabolism. So urban carbon metabolism was generally similar to that of living organisms, that is, larger cities had higher energy efficiency. Coupled with the population to further control variables, we found there was a negative correlation between population size and carbon emission rate, so the benefits from the increase of construction land scale were enlarged by the effects of population size. Therefore, the government of developed cities of developing countries can build larger cities to achieve low-carbon development and pay more attention to the rationalization and adjustment of transportation land use to alleviate traffic congestion. This study provides differentiated guidance for collaboration on sustainable urban development at different levels of government. • We established an urban carbon metabolism panel model based on Kleiber’s law. • Urban carbon metabolism was generally similar to biological metabolism. • Though land urbanization increased carbon emissions, the emission rates decreased. • The effects of population enlarged decline in carbon emission rates. • Larger cities are more energy-efficient for developed cities in developing countries.