Exploring the environmental pressures in urban sectors: An energy-water-carbon nexus perspective

Rapid industrialization and urbanization has led to severe environmental issues in China. Energy, water, and CO2 are among the most important factors that influence urban sustainability. In this study, we investigated the energy–water–carbon nexus of urban sectors in Shanghai and Beijing in 2012. The energy consumption, water use, and CO2 emissions of sectors in Shanghai and Beijing were estimated by applying the environmental input–output model. Our findings indicated that the service industry, with 8.69 × 1014 kJ embodied energy, 2.60 × 109 m3 embodied water, and 41.72 Mt embodied CO2, was the largest energy and water consumer and the largest CO2 emitter in Beijing. In Shanghai, service industry ranked highest in terms of embodied energy (8.67 × 1014 kJ), embodied water (4.25 × 109 m3), and embodied CO2 (48.72 Mt). We defined the consumption (emission) coefficient and consumption (emission) index to analyze the sectoral energy–water–carbon nexus in Beijing and Shanghai, and proposed sustainable development recommendations for different sectors with various energy–water–carbon characteristics. The consumption (emission) indexes can act as a reference for each city, showing the sectors that need to be emphasized and preferentially managed. In Beijing, policymakers may need to focus on the following sectors: sector coal mining and selecting and sector electricity, gas, and water production and supply. In Shanghai, sector electricity, gas, and water production and supply and sector transport, storage and post should receive the greatest attention. For most of the studied sectors, the environmental pressures per unit output (expressed by the consumption (emission) coefficients) in Shanghai were higher than those in Beijing, indicating that Shanghai is facing greater environmental challenges in the process of urban sustainability. The energy–water–carbon nexus characteristics of each sector may offer new perspectives to tackle the environmental challenges during the achievement of urban sustainability. This approach also provides a way for other cities to determine sectors that should receive the most attention in terms of easing environmental stress during the urban sustainable development process.