The role of urban green infrastructure in offsetting carbon emissions in 35 major Chinese cities: A nationwide estimate

The carbon balance in urban areas has become a major research challenge and a principal policy concern in efforts to address anthropogenic climate change. Rapid urbanization and industrialization in China urge the search for integrated strategies to mitigate and adapt to climate change, which not only limit to traditional infrastructure sectors, but also cover urban green infrastructure, because plants and soils function as carbon sinks through biotic sequestration. This study presents a nationwide study about how urban green infrastructure could contribute to the carbon balance in 35 major Chinese cities. By the end of 2010, the total area of urban green spaces (the dominant components of urban green infrastructure) accounts for 6.38% of the total land area of these cities and represented 51.7% of the total urban green spaces of all 657 cities in China. Based on empirical data from the literature, the total amount of carbon stored in the vegetation of the urban green infrastructure of 35 cities was estimated at 18.7 million tons, with an average carbon density of 21.34 t/ha. In 2010, the amount of carbon sequestration totaled 1.90 million tons with an average carbon sequestration rate of 2.16 t/ha/year. Collectively, only 0.33% of the carbon emissions from fossil fuel combustion can be offset, ranging from 0.01% in Hohhot to 22.45% in Haikou. Nevertheless, the dominance of young vegetation stands in Chinese urban green infrastructure suggests this small carbon sequestration efficiency could become substantial in the near future, given that appropriate policies and management practices are adopted to promote urban green infrastructure for climate change mitigation and adaptation.