High-resolution Carbon Emissions Data for Chinese Cities

Executive Summary

China is currently the world’s largest energy consumer and CO₂ emitter, and its cities contribute 85% of the total CO₂ emissions in China. Given the magnitude and growth rate of Chinese cities’ carbon emissions, cities are considered to be the key areas for implementing policies designed to adapt to climate change and mitigate CO₂ emissions.

In this research, we used high-resolution CO₂ emissions data (data from China High-Resolution Emission Gridded Database (CHRED) at 1 km spatial resolution) from 288 Chinese cities. There were, in total, 9,723 million metric tons (MMT) CO₂ produced in 2012 from the 288 cities. The results show that the 288 cities had variable per capita emissions and emission intensities; both low-carbon and carbon intensive cities exist in urban China. The CO₂ per capita for these 288 cities was 11 tCO₂/person, which is lower than the US average, but higher than that of the European Union. The per capita CO₂ emissions were weakly related with the per capita GDP in the 288 cities, indicating that there was no environmental Kuznets pattern for the carbon emissions related to a city’s level of economic development in China. The research implies that urbanization may be low-carbon or carbon intensive for China. Thus, promoting a low-carbon transition for Chinese cities is critical for global greenhouse gas mitigation.

Background of CO₂ emissions data from Chinese cities

The urbanization process in China and technology developments in the United States are considered to be the main forces shaping the world in the 21st century. City development is the major driver of China’s economy, with 50% of China’s GDP growth in the past 10 years contributed by infrastructure investments associated with the urbanization process. Presently, cities account for 75% of China’s total GDP and 80% of its national energy consumption. The urbanization rate in China is expected to reach 75% in 2030, which is considered by some scholars to be the main driving force for China’s leadership in the world, after the United States, in terms of total economic volume. Urbanization in China reallocated approximately 200 million people into urban areas, and these processes are expected to relocate more than 300 million people to China’s cities over the next 15 years. Nearly 70% of the population will live in urban areas by 2035. It is expected that in the next 20 years, China will build approximately 50,000 new skyscrapers in its urban areas, which will require considerable infrastructure development and energy consumption in urban China.

The urbanization process in China is critical for protecting the global environment. China has already become the world’s top fossil fuel energy consumer and CO₂ emitter and has performed intensive studies on the features, characteristics and driving factors of its carbon emissions and mitigation actions. As the world’s largest developing country, with unprecedented urbanization, industrialization and poverty elimination processes, China has been and will continue to be the major force behind anthropogenic carbon emissions and their mitigation.

Concrete emission inventories are considered to be the cornerstone for emissions research and mitigation strategies for cities. However, challenges remain in regard to presenting comprehensive carbon emission inventories at the city level; to measuring, reporting and verifying inventories; and to minimizing the associated uncertainties. This is particularly difficult in a large country with significant geographical and social-economic diversity, such as China, because producing comprehensive carbon emission inventories requires very detailed carbon accounting for each city as well as a comprehensive understanding of local climate strategies. The methodology and associated inventories for CO₂ emissions have been developed at the national scale. Compared with nation states, cities have various definitions regarding their boundaries and non-centralized statistics as well as large discrepancies regarding the definitions of their economic development levels, which produce uncertainty for carbon emissions accounting, especially in developing countries, such as China. For example, in China, the city is the second level of an administration area (the province is the first level) and not only includes urban areas but also vast rural areas; there are 286 administration cities in China. Thus, the administrative boundary of a Chinese city is larger than that of a city in developed countries, where only urban areas are included in a city’s boundary.

In addition, cities have various definitions of the boundaries regarding emissions accounting and non-centralized statistics as well as large discrepancies in regard to defining the levels of economic development, producing uncertainty for carbon emission accounting. System scope boundaries significantly affect regional emission inventories. Researchers have generally assumed a closed system boundary when conducting regional emission inventories; however, the reality is that regions have intensive interactions across calculated boundaries (administrative boundaries), such as domestic and international transportation and purchased power supply, (generated outside the boundary). These cross-boundary activities can dramatically affect emission estimates and the distribution of associated mitigation responsibilities. The academic literature has defined the territorial direct emission boundary as scope 1, the boundary of the emission caused by purchased electricity produced outside the boundary as scope 2, and the boundary of the emission embodied in imported products and services as scope 3. By further balancing the emissions embodied in imports and exports, the emission inventory boundary, which is considered to be the emissions embodied in imports but to exclude that of exports, is defined as consumption emissions. Whether such embodied emissions are taken into account will dramatically affect the emissions inventory at the city level.

Finally, but most importantly, as a developing country, China’s statistics system is not as comprehensive as that of developed countries. Regional statistics have comparatively more uncertainty than those at the national level and lack sectoral information, making it more difficult to conduct China’s cities’ CO₂ inventories. There are a few main studies that have conducted a “bottom-up” (see methods) CO₂ emission inventory in Chinese cities; however the number of studies and sectoral information is limited.

High-resolution emission data contribute to solving such challenges. Carbon accounting from high-resolution emission data is a key research direction in the field of climate change. There is a focus on analyzing the extent, as well as the causes and effects, of CO₂ emissions at a fine scale. Understanding emissions at the city and regional levels according to high spatial resolution CO₂ emissions data has been highlighted in the carbon management literature.

In this study, we established a comprehensive and systematic city-level CO₂ emission data system in China based on the China High-Resolution Emission Gridded Database (CHRED) (1 km spatial resolution), and we further analyzed the characteristics of the total and per capita city emissions. We focused on prefecture-level cities and municipalities that are directly under China’s central government. According to the “2013 China Statistical Yearbook”, there were 285 prefecture-level cities and 4 municipalities in China in 2012. The CHRED database does not include Sansha City (founded in 2012). Therefore, this study included 288 cities covering 284 prefecture- level cities and 4 municipalities.