City-level Emissions Research Articles

China's changing city-level greenhouse gas emissions from municipal solid waste treatment and driving factors

With cities’ intertwined challenges of garbage siege and climate change, it is imperative to explore the greenhouse gas (GHG) emissions from municipal solid waste (MSW) treatment and the determinants of the emissions change. However, related quantitative analysis with high spatial resolution in China has been lacking, which hinder tailored policymaking. To fill the gap, this study develops a long time-series inventory of GHG emissions (including CH4, CO2 and N2O) from MSW for 294 Chinese prefecture-level cities. The temporal and spatial logarithmic mean divisia index (LMDI) model is further used to reveal the drivers behind the emissions change and difference. Results showed that domestic GHG emissions from MSW treatment increased from 39.24 Mt CO2e in 2006 to 128.81 Mt CO2e in 2019, 63.41%-88.95% of which were CH4 emissions accounting for 8.13%-10.22% of China's total CH4 emissions. First-tier cities and new first-tier cities (6.44%) contributed 35.44% to the national emissions in 2019. Furthermore, the national increased emissions were primarily driven by economic output (66.09%), while the MSW treatment intensity per GDP caused emissions reduction by 5.23%. The spatial decomposition verified that the population size was the dominant driving factor for differences between the national average and city-level emissions. Improvements in MSW treatment structure may be the effective abatement strategy for cities in Northwestern China (e.g., Yinchuan, Xining and Lanzhou). These findings could provide insights into the GHG emission mitigation of cities’ MSW sector for a future carbon-neutral society.

A city-level comparison of fossil-fuel and industry processes-induced CO2 emissions over the Beijing-Tianjin-Hebei region from eight emission inventories

BackgroundQuantifying CO2 emissions from cities is of great importance because cities contribute more than 70% of the global total CO2 emissions. As the largest urbanized megalopolis region in northern China, the Beijing-Tianjin-Hebei (Jing-Jin-Ji, JJJ) region (population: 112.7 million) is under considerable pressure to reduce carbon emissions. Despite the several emission inventories covering the JJJ region, a comprehensive evaluation of the CO2 emissions at the prefectural city scale in JJJ is still limited, and this information is crucial to implementing mitigation strategies.ResultsHere, we collected and analyzed 8 published emission inventories to assess the emissions and uncertainty at the JJJ city level. The results showed that a large discrepancy existed in the JJJ emissions among downscaled country-level emission inventories, with total emissions ranging from 657 to 1132 Mt CO2 (or 849 ± 214 for mean ± standard deviation (SD)) in 2012, while emission estimates based on provincial-level data estimated emissions to be 1038 and 1056 Mt. Compared to the mean emissions of city-data-based inventories (989 Mt), provincial-data-based inventories were 6% higher, and national-data-based inventories were 14% lower. Emissions from national-data-based inventories were 53–75% lower in the high-emitting industrial cities of Tangshan and Handan, while they were 47–160% higher in Beijing and Tianjin than those from city-data-based inventories. Spatially, the emissions pattern was consistent with the distribution of urban areas, and urban emissions in Beijing contributed 50–70% of the total emissions. Higher emissions from Beijing and Tianjin resulted in lower estimates of prefectural cities in Hebei for some national inventories.ConclusionsNational-level data-based emission inventories produce large differences in JJJ prefectural city-level emission estimates. The city-level statistics data-based inventories produced more consistent estimates. The consistent spatial distribution patterns recognized by these inventories (such as high emissions in southern Beijing, central Tianjin and Tangshan) potentially indicate areas with robust emission estimates. This result could be useful in the efficient deployment of monitoring instruments, and if proven by such measurements, it will increase our confidence in inventories and provide support for policy makers trying to reduce emissions in key regions.

The city-level precision industrial emission reduction management based on enterprise performance evaluation and path design: A case of Changzhi, China

Realizing precision management, which is of great importance in city-level emission reduction management, requires scientific identification of key enterprises and differentiated emission reduction measures. However, current studies have not considered the enterprises units, or have not proposed the emission reduction paths of them. To solve this problem, this study chooses Changzhi, an industrialized city in China as a case, and considers 54 enterprises from thermal-power, cement, coking, and iron and steel sectors. The pollution performances, including the indicators of energy intensity and emission intensities of SO2, NOx, and PM of the 54 enterprises are evaluated. After identifying the key enterprises, this study designs their emission reduction paths including three types of measures, and quantifies the emission reduction potential. The results show that: (1) The 54 enterprises have imbalanced pollution performances, as the values have difference of 2–4 orders of magnitude. 13, 10, and 19 enterprises are classified into level A, B, and C respectively. (2) The emission reduction paths of 24 key enterprises are designed, which can reduce 3441.21, 4507.85, and 1683.12 tons of SO2, NOx, and PM. This accounts for 29.4%, 21.2%, and 14.9% of the total emissions. Based on these results, this study puts forward some policy suggestions of precision management measures in Changzhi. In sum, this study provides a methodology into quantitative analysis of precision air pollutant emission reduction management at city level, and put forward some critical insights of cleaner and sustainable production of the enterprises.

An emissions accounting framework for industrial parks in China

China has the largest number of industrial parks in the world. These parks are not only crucial for the country to accelerate industrialization but also to achieve its climate change targets. Constructing CO2 emission inventories for industrial parks is the first step in analysing the park's emission patterns and designing low-carbon policies. However, most of the previous emission accounts for industrial parks adopted various scopes and methodologies, making them incomparable with each other. This study develops a self-consistent methodology and framework for China's industrial parks based on enterprise-level data. We consider both Scope 1 and 2 emissions and construct the inventories by 19 energy types and 39 industrial sectors, which are consistent with the existing national, provincial, and city-level emission inventories. Such sectoral-based emission inventories will be not only able to provide data support for the design of emission/energy control policies, but also help the central/local governments evaluate a park's emission reduction performance. Finally, an empirical study is applied to four industrial parks to verify the method. In addition, we review the eco-industrial park programmes in Japan and South Korea, as well as their emissions accounting framework. We find that most of the Japanese industrial parks provide Scope 1, 2 and 3 emissions, while for South Korea, parks mostly focus on Scope 1 emissions. The discussion of Japan and South Korea's eco-industrial parks have referential significance for the construction China's low-carbon parks.

Emission drivers of cities at different industrialization phases in China

As cities are the center of human activity and the basic unit of policy design, they have become the focus of carbon dioxide reduction, especially metropolitan areas that are high energy consumers and carbon dioxide emitters in countries such as China. The fact cities differ in their levels of development and stages of industrialization points to the need for tailor-made low-carbon policies. This study is the first to consider cities' different phases of industrialization when analyzing city-level emission patterns and drivers, as well as the decoupling statuses between economic growth and their emission levels in China. The results of 15 representative cities at different phases of industrialization show that various decoupling statuses, driving factors and decoupling efforts exist among cities, and that heterogeneity among these factors also exists among cities at the same industrialization phase. For further decomposition, energy intensity contributed the most to emissions reduction during the period 2005 to 2010, especially for cities with more heavy manufacturing industries, whereas industrial structure was a stronger negative emission driver during the period 2010 to 2015. Based on those findings, we suggest putting into practice a diversified carbon-mitigation policy portfolio according to each city's industrialization phase rather than a single policy that focuses on one specific driving factor. This paper sets an example on emissions-reduction experience for other cities undergoing different industrialization phases in China; it also sheds light on policy initiatives that could be applied to other cities around the world.

China city-level greenhouse gas emissions inventory in 2015 and uncertainty analysis

Accounting and understanding greenhouse gas (GHG) emissions at the city level are of great importance because cities are the focus of future mitigation and adaption activities to address climate change, especially in developing nations like China. However, existing studies have not yet provided a complete and updated emissions inventory of city-level GHGs for China in terms of city and GHG-type coverage. In this paper, we rigorously assemble a dataset that contains GHG emissions including carbon dioxide, methane, nitrous oxide, and fluorinated GHGs for 305 Chinese cities, based on a high-resolution emissions database (China High-Resolution Emission Database, CHRED 3.0) and first-hand on-site data collection and verification by 19 groups of 137 researchers using a bottom-up method, and analyze the uncertainty of the emissions. Results show that total GHG emissions are high in cities in eastern China and low in cities in west, while per capita GHG emissions are high in northern cities and low in southern cities. The emissions of four types of GHGs (CO2, CH4, N2O and fluoridated GHGs) share different spatial distributions, due to variant industrial structure, energy structure, industry point sources and agricultural surface sources, etc. The uncertainty of GHG emissions is highly related to the source data of cities. Finally, we propose policy recommendations, including improving data quality and strengthening competitions of city-level emission reduction, to improve city-level emissions data integrity and low-carbon development strategies.

City-Level Features of Energy Footprints and Carbon Dioxide Emissions in Sichuan Province of China

The sustainable development of the western region of China has always been essential to the national development strategy. The Western region has undertaken an industrial transfer from the Eastern and Central regions. Therefore, the CO2 emission intensity in the western region is higher than those of the Eastern and Central regions of China, and consequently its low-carbon development pathway has an important impact for China as a whole. Sichuan Province is not only the province with the highest CO2 emissions, but also the most economically developed province in Western China in 2018. In order to promote low carbon development in the western region, it is important to understand the features of emissions in Sichuan Province and to formulate effective energy strategies accordingly. This paper uses the IPCC regional emission accounting method to calculate the carbon emissions of 15 cities in Sichuan province, and to comply with the city-level emission accounts. The results show that the total carbon emissions of Sichuan province over the past 10 years was 3258.32 mt and reached a peak in 2012. The smelting and pressing of ferrous metals, coal mining and dressing were the leading sectors that contributed to the emissions, accounting for 17.86% and 15.82%, respectively. Raw coal, cleaned coal, and coke were the most significant contributors to CO2 emissions, accounting for 43.73%, 9.55%, and 6.60%, respectively. Following the above results, the Sichuan provincial government can formulate differentiated energy structure policies according to different energy consumption structures and carbon emission levels in the 15 cities. By controlling the level of total emissions and regulating larger industrial emitters in Sichuan province, some useful information could be provided as an essential reference for low-carbon development in Western China, and contribute to the promotion of emissions mitigation from a more holistic perspective.

Carbon mitigation of China's building sector on city-level: Pathway and policy implications by a low-carbon province case study

Curbing the increasing carbon emissions from residential and commercial buildings would be of great importance for achieving China's NDC (Nationally Determined Contributions) target. However, studies on city-level emission pathways and mitigation strategies aiming at building sector are still far from sufficient, especially for regions in Central China. Considering the large potential for further building energy demand increase within this area, this study focuses on Hubei, one of the first batch low-carbon pilot provinces to investigate the possibility of earlier emission peak and reduction potentials by prefecture-level city. When downscaling provincial energy use and emissions estimated from local government plans and academic research, statistical data was applied to exploring the relationship between building energy consumption and socioeconomic variables, then spatial allocation factor could be generated after combining with projections of grid-level GDP and population. Results show that by replacing coal and natural gas (NG) that are currently the main heating & cooking energy sources with more electricity and renewable energy, emissions from the building sector would peak around 2025, which is especially true for three major big cities with higher emission growth rate due to population and urban expansions. Moreover, when considering additional improvement on building energy efficiency, provincial reductions burden would be more evenly distributed among cities. It is implied that by formulating tiered mitigation policies for cities at various economic development levels, including decarbonization of energy structure and improvement of energy efficiency, more cities would peak their emissions from the building sector before 2030. This analytical framework innovatively create a multi-city platform for the simulation of building sector mitigation pathway to facilitate cities' low-carbon development.

Structural patterns of city-level CO2 emissions in Northwest China

In Northwest China, quantifying city-level CO2 emissions is fundamental to CO2 alleviation but encounters difficulties in data availability and quality. Further, structuring city-level emissions could be conductive to CO2 reduction. This study applies a practical methodology to 16 northwestern Chinese cities to grasp their historical trajectories of CO2 emissions. Then, structuring CO2 emissions is explored in terms of industrial structure, energy mix and urban-rural disparities for 8 northwestern Chinese cities. Results show that: (1) for 16 cities (2010–2015), capital and industrial cities generated most emissions. Meanwhile, CO2 emissions were mostly incompatible with CO2 intensity, but consistent with CO2 per capita; (2) for 8 cities (2006–2015), energy producing sectors, heavy manufacturing sectors, and coal remained major drivers of emissions. Then, the interconnection between industrial structure and energy mix exerted temporally varying impacts on emissions from energy producing sectors and heavy manufacturing sectors. Besides, urban gas consumption and rural coal use continued affecting most of household consumption emissions and household consumption emissions per capita. Moreover, the interplay between emissions and population was changed when emissions by energy type were decomposed among urban and rural households; and (3) uncertainty results fall in the range of −39% to 6%. Finally, implications for CO2 reduction and future work are proposed.

An emissions-socioeconomic inventory of Chinese cities

As the centre of human activity and being under the threat of climate change, cities are considered to be major components in the implementation of climate change mitigation and CO2 emission reduction strategies. Inventories of cities’ emissions serve as the foundation for the analysis of emissions characteristics and policymaking. China is the world’s top energy consumer and CO2 emitter, and it is facing great potential harm from climate change. Consequently, China is taking increasing responsibility in the fight against global climate change. Many energy/emissions control policies have been implemented in China, most of which are designed at the national level. However, cities are at different stages of industrialization and have distinct development pathways; they need specific control policies designed based on their current emissions characteristics. This study is the first to construct emissions inventories for 182 Chinese cities. The inventories are constructed using 17 fossil fuels and 47 socioeconomic sectors. These city-level emissions inventories have a scope and format consistent with China’s national/provincial inventories. Some socioeconomic data of the cities, such as GDP, population, industrial structures, are included in the datasets as well. The dataset provides transparent, accurate, complete, comparable, and verifiable data support for further city-level emissions studies and low-carbon/sustainable development policy design. The dataset also offers insights for other countries by providing an emissions accounting method with limited data.

Low-carbon developments in Northeast China: Evidence from cities

Cities are a major source of energy use and greenhouse gases emissions, as well as being at the core of climate change mitigation. With the Revitalizing Old Industrial Base of Northeast China strategy, Northeast China has been a typical developing region with rapid industrialization and urbanization accompanied by substantial energy consumption and carbon emissions. Therefore, northeastern Chinese cities should play an important role in regional low-carbon developments. This study presents several improvements to the previous method to improve the accuracy of the results. Using the modified method, for the first time, we compile carbon emission inventories for 30 cities in Northeast China based on fossil fuel combustion and industrial processes. The results indicate that Anshan emitted the most carbon emissions annually, followed by Benxi and the vice-provincial cities (including Changchun, Shenyang, Dalian and Harbin). In 2012, the total carbon emissions of the 30 cities amounted to 973.95 million tonnes, accounting for 9.71% and 2.75% of national and global carbon emissions, respectively. Most of the CO2 emissions of these cities were from the ‘nonmetal and metal industry’ and ‘energy production and supply’. Raw coal was the primary source of carbon emissions in Northeast China, and industrial processes also played a significant role in determining carbon emissions. Additionally, both the average per capita carbon emissions and carbon emission intensity in the 30 cities were higher than the national levels. According to the differences in carbon emissions characteristics, we present several policy recommendations for carbon mitigation for northeastern Chinese cities. This study provides consistent and comparable spatial-temporal city-level emission database for further research on relationships between economic development and environmental protection in Northeast China. Simultaneously, this study provides practical reference values for other developing regions throughout the world to create low-carbon roadmaps.

A benchmark city-level carbon dioxide emission inventory for China in 2005

Year 2005 is important because it is the base year for the international carbon reduction commitment and national development plans for China. However, accurate and robust CO2 emission data for 2005 remain limited, particularly for city-level emissions. To address these gaps, we established a uniform city-level CO2 emission inventory for all the 287 prefecture-level cities in China for 2005, combining the High-Resolution Emission Gridded Database (CHRED) 2.0, statistical data and onsite survey. The results showed that Shanghai, Tangshan, Beijing, Tianjin, Jining, Handan, Chongqing, Suzhou, Shijiazhuang and Wuhan were the ten cities with greatest CO2 emissions in 2005, with total CO2 emissions of 205, 184, 145, 126, 116, 103, 96, 93, 90 and 81 Mt, respectively. These cities were either megacities or those dominated by coal, iron or steel production. However, the three cities with the highest CO2 emissions per GDP and CO2 emissions per capita were Jiayuguan, Wuhai and Shizuishan, which were dominated by industry, small- or medium-sized, and exhibited a high demand for heat and cooling. Cluster analysis revealed that industrial energy consumption was the dominant emission source for most cities, except Haikou and Lhasa, for which indirect CO2 emissions were dominant. This study will greatly contribute to the city level CO2 emission inventory and research on China.

A comprehensive city-level GHGs inventory accounting quantitative estimation with an empirical case of Baoding

Cities represent a critical source and primary unit of Greenhouse Gas (GHG) emissions. The accurate emission accounts of cities provide robust and solid data support for further emission analysis as well as the local low-carbon policy making. Restricted by the data and method lacking, there is a relative lag in city-level emission accounts. Thus, this study attempts to build an investigation-based GHG emission inventory framework for cities. We include CO2, CH4, N2O, and SF6 emissions from five sources: energy activity, industrial processes/product use, agriculture, land use change/forestry, and waste disposal. This study then uses Baoding as a case study to analyse its emission characteristics. Baoding is a low-carbon pilot city in China, which is a core and crucial city in Jing-Jin-Ji area. It is also the origin of the recently established Xiongan New Area, which has great strategic development significance. The results show that energy activity is the highest emission source followed by waste disposal processes in Baoding. Emissions induced by electricity input that brought from other provinces or cities account for another considerable emission proportion as well. Moreover, agricultural activity, which is a pillar industry in Baoding, contributes the most to methane emissions. Several emissions reduction policy recommendations are provided.

On the Impact of Granularity of Space-based Urban CO2 Emissions in Urban Atmospheric Inversions: A Case Study for Indianapolis, IN.

Quantifying greenhouse gas (GHG) emissions from cities is a key challenge towards effective emissions management. An inversion analysis from the INdianapolis FLUX experiment (INFLUX) project, as the first of its kind, has achieved a top-down emission estimate for a single city using CO2 data collected by the dense tower network deployed across the city. However, city-level emission data, used as a priori emissions, are also a key component in the atmospheric inversion framework. Currently, fine-grained emission inventories (EIs) able to resolve GHG city emissions at high spatial resolution, are only available for few major cities across the globe. Following the INFLUX inversion case with a global 1×1 km ODIAC fossil fuel CO2 emission dataset, we further improved the ODIAC emission field and examined its utility as a prior for the city scale inversion. We disaggregated the 1×1 km ODIAC non-point source emissions using geospatial datasets such as the global road network data and satellite-data driven surface imperviousness data to a 30×30 m resolution. We assessed the impact of the improved emission field on the inversion result, relative to priors in previous studies (Hestia and ODIAC). The posterior total emission estimate (5.1 MtC/yr) remains statistically similar to the previous estimate with ODIAC (5.3 MtC/yr). However, the distribution of the flux corrections was very close to those of Hestia inversion and the model-observation mismatches were significantly reduced both in forward and inverse runs, even without hourly temporal changes in emissions. EIs reported by cities often do not have estimates of spatial extents. Thus, emission disaggregation is a required step when verifying those reported emissions using atmospheric models. Our approach offers gridded emission estimates for global cities that could serves as a prior for inversion, even without locally reported EIs in a systematic way to support city-level Measuring, Reporting and Verification (MRV) practice implementation.

Advantages of a city-scale emission inventory for urban air quality research and policy: the case of Nanjing, a typical industrial city in the Yangtze River Delta, China

Abstract. With most eastern Chinese cities facing major air quality challenges, there is a strong need for city-scale emission inventories for use in both chemical transport modeling and the development of pollution control policies. In this paper, a high-resolution emission inventory (with a horizontal resolution of 3 × 3 km) of air pollutants and CO2 for Nanjing, a typical large city in the Yangtze River Delta, is developed, incorporating the best available information on local sources. Emission factors and activity data at the unit or facility level are collected and compiled using a thorough on-site survey of major sources. Over 900 individual plants, which account for 97 % of the city's total coal consumption, are identified as point sources, and all of the emission-related parameters including combustion technology, fuel quality, and removal efficiency of air pollution control devices (APCD) are analyzed. New data-collection approaches including continuous emission monitoring systems and real-time monitoring of traffic flows are employed to improve spatiotemporal distribution of emissions. Despite fast growth of energy consumption between 2010 and 2012, relatively small interannual changes in emissions are found for most air pollutants during this period, attributed mainly to benefits of growing APCD deployment and the comparatively strong and improving regulatory oversight of the large point sources that dominate the levels and spatial distributions of Nanjing emissions overall. The improvement of this city-level emission inventory is indicated by comparisons with observations and other inventories at larger spatial scale. Relatively good spatial correlations are found for SO2, NOx, and CO between the city-scale emission estimates and concentrations at nine state-operated monitoring sites (R = 0.58, 0.46, and 0.61, respectively). The emission ratios of specific pollutants including BC to CO, OC to EC, and CO2 to CO compare well to top-down constraints from ground observations. The interannual variability and spatial distribution of NOx emissions are consistent with NO2 vertical column density measured by the Ozone Monitoring Instrument (OMI). In particular, the Nanjing city-scale emission inventory correlates better with satellite observations than the downscaled Multi-resolution Emission Inventory for China (MEIC) does when emissions from power plants are excluded. This indicates improvement in emission estimation for sectors other than power generation, notably industry and transportation. A high-resolution emission inventory may also provide a basis to consider the quality of instrumental observations. To further improve emission estimation and evaluation, more measurements of both emission factors and ambient levels of given pollutants are suggested; the uncertainties of emission inventories at city scale should also be fully quantified and compared with those at national scale.

Aircraft mass budgeting to measure CO2 emissions of Rome, Italy

Aircraft measurements were used to estimate the CO2 emission rates of the city of Rome, assessed against high-resolution inventorial data. Three experimental flights were made, composed of vertical soundings to measure Planetary Boundary Layer (PBL) properties, and circular horizontal transects at various altitudes around the city area. City level emissions and associated uncertainties were computed by means of mass budgeting techniques, obtaining a positive net CO2 flux of 14.7 ± 4.5, 2.5 ± 1.2, and 10.3 ± 1.2 μmol m(-2) s(-1) for the three flights. Inventorial CO2 fluxes at the time of flights were computed by means of spatial and temporal disaggregation of the gross emission inventory, at 10.9 ± 2.5, 9.6 ± 1.3, and 17.4 ± 9.6 μmol m(-2) s(-1). The largest differences between the two dataset are associated with a greater variability of wind speed and direction in the boundary layer during measurements. Uncertainty partitioned into components related to horizontal boundary flows and top surface flow, revealed that the latter dominates total uncertainty in the presence of a wide variability of CO2 concentration in the free troposphere (up to 7 ppm), while it is a minor term with uniform tropospheric concentrations in the study area (within 2 ppm). Overall, we demonstrate how small aircraft may provide city level emission measurements that may integrate and validate emission inventories. Optimal atmospheric conditions and measurement strategies for the deployment of aircraft experimental flights are finally discussed.

Establishment of City Level Carbon Dioxide Emission Baseline Database and Carbon Budgets for Developing Countries with Data Constraints

One of the major constraints of developing countries in controlling carbon dioxide emissions is the limited availability of an emission database. Since there is no city level emission database in Malaysia, the authors have made the first attempt in the country to establish city level carbon dioxide emission data for different sizes of city using the System Dynamics based FML Model. From the results, it was found that the carbon dioxide emission of a city has a positive correlation with population size and GDP value, and an increasing emission trend is taking place in Malaysia regardless of the size of city. Projections of emission trends up to 2050 showed that if no aggressive actions were taken to cap emissions from the cities, there would be an extreme increase of emissions by as much as more than seven times of the current level. Hence, the authors have proposed three alternative approaches to set a city level carbon budget, i.e. equal share, population and GDP approaches. The study also demonstrated the capability of the present model in estimating present and future city level carbon dioxide emissions. The model can be used for establishment of a city level carbon dioxide emission database for the whole of Malaysia and in future may be applied to other developing countries.