Integrated accounting of urban carbon cycle in Guangyuan, a mountainous city of China: the impacts of earthquake and reconstruction

Approximately half of the global population resides in cities and accounts for over 80% of global carbon emissions. To improve efficiency in carbon emission reduction, and enhance adaptability of cities to climate change, it is essential to undertake accounting of urban carbon cycle. This plays a prominent role in global carbon cycle. An integrated accounting framework for urban carbon cycle was established herein to support uniform accounting and place-specific comparisons, covering natural and artificial carbon cycles, vertical and horizontal carbon flows, carbon storage and fluxes, and carbon inputs and outputs. Guangyuan, a mountainous city in China that was seriously stricken by Wenchuan earthquake in 2008, was chosen as the case to demonstrate the framework and investigate the effects of post-earthquake reconstruction on carbon cycle. The results show: 1) the proposed framework could effectively assess dynamics of carbon cycle under external disturbances, 2) there were abundant vegetation and correspondingly a large natural carbon tank and vertical carbon input, and low industrialization degree and correspondingly small horizontal and vertical carbon outputs in Guangyuan, 3) the post-earthquake reconstruction led to a series of impacts on carbon cycle, from both aspects of amount and structure, and 4) such impacts of post-earthquake construction on artificial carbon cycle were distinct with a tendency toward low-carbon development in Guangyuan. The results were helpful for investigating the effects of natural disturbance and human interference on urban carbon cycle, which in turn could improve the adaptation to climate change.