# Wang, Haikun

2022
Rong Tang, Jing Zhao, Yifan Liu, Xin Huang, Yanxu Zhang, Derong Zhou, Aijun Ding, Chris Nielsen, and Haikun Wang. 2022. “Air quality and health co-benefits of China's carbon dioxide emissions peaking before 2030.” Nature Communications, 13, 1008. Publisher's VersionAbstract

Recent evidence shows that carbon emissions in China are likely to peak ahead of 2030. However, the social and economic impacts of such an early carbon peak have rarely been assessed. Here we focus on the economic costs and health benefits of different carbon mitigation pathways, considering both possible socio-economic futures and varying ambitions of climate policies. We find that an early peak before 2030 in line with the 1.5  C target could avoid ~118,000 and ~614,000 PM2.5 attributable deaths under the Shared Socioeconomic Pathway 1, in 2030 and 2050, respectively. Under the 2  C target, carbon mitigation costs could be more than offset by health co-benefits in 2050, bringing a net benefit of $393–$3,017 billion (in 2017 USD value). This study not only provides insight into potential health benefits of an early peak in China, but also suggests that similar benefits may result from more ambitious climate targets in other countries.

2020
Haikun Wang, Xiaojing He, Xinyu Liang, Ernani F. Choma, Yifan Liu, Li Shan, Haotian Zheng, Shaojun Zhang, Chris Nielsen, Shuxiao Wang, Ye Wu, and John Evans. 2020. “Health benefits of on-road transportation pollution control programs in China.” Proceedings of the National Academy of Sciences, 117, 41, Pp. 25370-25377. Publisher's VersionAbstract
China started to implement comprehensive measures to mitigate traffic pollution at the end of 1990s, but the comprehensive effects, especially on ambient air quality and public health, have not yet been systematically evaluated. In this study, we analyze the effects of vehicle emission control measures on ambient air pollution and associated deaths attributable to long-term exposures of fine particulate matter (PM2.5) and O3 based on an integrated research framework that combines scenario analysis, air quality modeling, and population health risk assessment. We find that the total impact of these control measures was substantial. Vehicular emissions during 1998–2015 would have been 2–3 times as large as they actually were, had those measures not been implemented. The national population-weighted annual average concentrations of PM2.5 and O3 in 2015 would have been higher by 11.7 μg/m3 and 8.3 parts per billion, respectively, and the number of deaths attributable to 2015 air pollution would have been higher by 510 thousand (95% confidence interval: 360 thousand to 730 thousand) without these controls. Our analysis shows a concentration of mortality impacts in densely populated urban areas, motivating local policymakers to design stringent vehicle emission control policies. The results imply that vehicle emission control will require policy designs that are more multifaceted than traditional controls, primarily represented by the strict emission standards, with careful consideration of the challenges in coordinated mitigation of both PM2.5 and O3 in different regions, to sustain improvement in air quality and public health given continuing swift growth in China’s vehicle population.
2019
Haikun Wang, Xi Lu, Yu Deng, Yaoguang Sun, Chris P. Nielsen, Yifan Liu, Ge Zhu, Maoliang Bu, Jun Bi, and Michael B. McElroy. 2019. “China’s CO2 peak before 2030 implied from diverse characteristics and growth of cities.” Nature Sustainability, 2, Pp. 748–754. Publisher's VersionAbstract

China pledges to peak CO2 emissions by 2030 or sooner under the Paris Agreement to limit global warming to 2 °C or less by the end of the century. By examining CO2 emissions from 50 Chinese cities over the period 2000–2016, we found a close relationship between per capita emissions and per capita gross domestic product (GDP) for individual cities, following the environmental Kuznets curve, despite diverse trajectories for CO2 emissions across the cities. Results show that carbon emissions peak for most cities at a per capita GDP (in 2011 purchasing power parity) of around US$21,000 (80% confidence interval: US$19,000 to 22,000). Applying a Monte Carlo approach to simulate the peak of per capita emissions using a Kuznets function based on China’s historical emissions, we project that emissions for China should peak at 13–16 GtCO2 yr−1 between 2021 and 2025, approximately 5–10 yr ahead of the current Paris target of 2030. We show that the challenges faced by individual types of Chinese cities in realizing low-carbon development differ significantly depending on economic structure, urban form and geographical location.

Xi Lu, Liang Cao, Haikun Wang, Wei Peng, Jia Xing, Shuxiao Wang, Siyi Cai, Bo Shen, Qing Yang, Chris P. Nielsen, and Michael B. McElroy. 2019. “Gasification of coal and biomass as a net carbon-negative power source for environment-friendly electricity generation in China.” Proceedings of the National Academy of Sciences, 116, 17, Pp. 8206-8213. Publisher's VersionAbstract
Realizing the goal of the Paris Agreement to limit global warming to 2 °C by the end of this century will most likely require deployment of carbon-negative technologies. It is particularly important that China, as the world’s top carbon emitter, avoids being locked into carbon-intensive, coal-fired power-generation technologies and undertakes a smooth transition from high- to negative-carbon electricity production. We focus here on deploying a combination of coal and biomass energy to produce electricity in China using an integrated gasification cycle system combined with carbon capture and storage (CBECCS). Such a system will also reduce air pollutant emissions, thus contributing to China’s near-term goal of improving air quality. We evaluate the bus-bar electricity-generation prices for CBECCS with mixing ratios of crop residues varying from 0 to 100%, as well as associated costs for carbon mitigation and cobenefits for air quality. We find that CBECCS systems employing a crop residue ratio of 35% could produce electricity with net-zero life-cycle emissions of greenhouse gases, with a levelized cost of electricity of no more than 9.2 US cents per kilowatt hour. A carbon price of approximately \$52.0 per ton would make CBECCS cost-competitive with pulverized coal power plants. Therefore, our results provide critical insights for designing a CBECCS strategy in China to harness near-term air-quality cobenefits while laying the foundation for achieving negative carbon emissions in the long run.
2018
Meng Gao, Gufran Beig, Shaojie Song, Hongliang Zhang, Jianlin Hu, Qi Ying, Fengchao Liang, Yang Liu, Haikun Wang, Xiao Lu, Tong Zhu, Gregory Carmichael, Chris P. Nielsen, and Michael B. McElroy. 2018. “The impact of power generation emissions on ambient PM2.5 pollution and human health in China and India.” Environment International, 121, Part 1, Pp. 250-259. Publisher's VersionAbstract

Emissions from power plants in China and India contain a myriad of fine particulate matter (PM2.5, PM≤2.5 micrometers in diameter) precursors, posing significant health risks among large, densely settled populations. Studies isolating the contributions of various source classes and geographic regions are limited in China and India, but such information could be helpful for policy makers attempting to identify efficient mitigation strategies. We quantified the impact of power generation emissions on annual mean PM2.5 concentrations using the state-of-the-art atmospheric chemistry model WRF-Chem (Weather Research Forecasting model coupled with Chemistry) in China and India. Evaluations using nationwide surface measurements show the model performs reasonably well. We calculated province-specific annual changes in mortality and life expectancy due to power generation emissions generated PM2.5 using the Integrated Exposure Response (IER) model, recently updated IER parameters from Global Burden of Disease (GBD) 2015, population data, and the World Health Organization (WHO) life tables for China and India. We estimate that 15 million (95% Confidence Interval (CI): 10 to 21 million) years of life lost can be avoided in China each year and 11 million (95% CI: 7 to 15 million) in India by eliminating power generation emissions. Priorities in upgrading existing power generating technologies should be given to Shandong, Henan, and Sichuan provinces in China, and Uttar Pradesh state in India due to their dominant contributions to the current health risks.

2017
Haikun Wang, Yanxu Zhang, Xi Lu, Weimo Zhu, Chris P. Nielsen, Jun Bi, and Michael B. McElroy. 2017. “Trade‐driven relocation of air pollution and health impacts in China.” Nature Communications, 8, 738. Publisher's VersionAbstract
Recent studies show that international trade affects global distributions of air pollution andpublic health. Domestic interprovincial trade has similar effects within countries, but has notbeen comprehensively investigated previously. Here we link four models to evaluate theeffects of both international exports and interprovincial trade on PM2.5pollution and publichealth across China. We show that 50–60% of China’s air pollutant emissions in 2007 wereassociated with goods and services consumed outside of the provinces where they wereproduced. Of an estimated 1.10 million premature deaths caused by PM2.5pollutionthroughout China, nearly 19% (208,500 deaths) are attributable to international exports. Incontrast, interprovincial trade leads to improved air quality in developed coastal provinceswith a net effect of 78,500 avoided deaths nationwide. However, both international exportand interprovincial trade exacerbate the health burdens of air pollution in China’s lessdeveloped interior provinces. Our results reveal trade to be a critical but largely overlookedconsideration in effective regional air quality planning for China.
2016
Xi Lu, Michael B. McElroy, Wei Peng, Shiyang Liu, Chris P. Nielsen, and Haikun Wang. 2016. “Challenges faced by China compared with the US in developing wind power.” Nature Energy, 1, 6. Publisher's VersionAbstract

In the 21st Conference of the Parties to the UNFCCC held in Paris in December 2015, China pledged to peak its carbon emissions and increase non-fossil energy to 20% by 2030 or earlier. Expanding renewable capacity, especially wind power, is a central strategy to achieve these climate goals. Despite greater capacity for wind installation in China compared to the US (145.1 versus 75.0 GW), less wind electricity is generated in China (186.3 versus 190.9 TWh). Here, we quantify the relative importance of the key factors accounting for the unsatisfactory performance of Chinese wind farms. Different from the results in earlier qualitative studies, we find that the difference in wind resources explains only a small fraction of the present China-US difference in wind power output (17.9% in 2012); the curtailment of wind power, differences in turbine quality, and delayed connection to the grid are identified as the three primary factors (respectively 49.3%, 50.2%, and 50.3% in 2012). Improvements in both technology choices and the policy environment are critical in addressing these challenges.

Final Manuscript in DASH
Lu et al. is the cover article of this issue of Nature Energy. It is also subject of a "News and Views" commentary in the same issue, by Joanna I. Lewis.

Rong Xie, Clive E. Sabel, Xi Lu, Weimo Zhu, Haidong Kan, Chris P. Nielsen, and Haikun Wang. 2016. “Long-term trend and spatial pattern of PM2.5-induced premature mortality in China.” Environment International, 97, Pp. 180-186. Publisher's VersionAbstract

With rapid economic growth, China has witnessed increasingly frequent and severe haze and smog episodes over the past decade, posing serious health impacts to the Chinese population, especially those in densely populated city clusters. Quantification of the spatial and temporal variation of health impacts attributable to ambient fine particulate matter (PM2.5) has important implications for China's policies on air pollution control. In this study, we evaluated the spatial distribution of premature deaths in China between 2000 and 2010 attributable to ambient PM2.5 in accord with the Global Burden of Disease based on a high resolution population density map of China, satellite retrieved PM2.5 concentrations, and provincial health data. Our results suggest that China's anthropogenic ambient PM2.5 led to 1,255,400 premature deaths in 2010, 42% higher than the level in 2000. Besides increased PM2.5 concentration, rapid urbanization has attracted large population migration into the more developed eastern coastal urban areas, intensifying the overall health impact. In addition, our analysis implies that health burdens were exacerbated in some developing inner provinces with high population density (e.g. Henan, Anhui, Sichuan) because of the relocation of more polluting and resource-intensive industries into these regions. In order to avoid such national level environmental inequities, China's regulations on PM2.5 should not be loosened in inner provinces. Furthermore policies should create incentive mechanisms that can promote transfer of advanced production and emissions control technologies from the coastal regions to the interior regions.

2015
Y. Zhao, LP Qiu, RY Xu, FJ Xie, Q. Zhang, YY Yu, C.P. Nielsen, HX Qin, H.K. Wang, XC Wu, WQ Li, and J. Zhang. 2015. “Advantages of 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.” Atmospheric Chemistry and Physics, 15, Pp. 12623-12644. Publisher's VersionAbstract

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 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 onsite 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 inter-annual 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 9 state-opertated 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 inter-annual 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. 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.

Yanxia Zhang, Haikun Wang, Sai Liang, Ming Xu, Qiang Zhang, Hongyan Zhao, and Jun Bi. 2015. “A dual strategy for controlling energy consumption and air pollution in China's metropolis of Beijing.” Energy, 81, 1 March, Pp. 294-303. Publisher's VersionAbstract

It is critical to alleviate problems of energy and air pollutant emissions in a metropolis because these areas serve as economic engines and have large and dense populations. Drivers of fossil fuel use and air pollutants emissions were analyzed in the metropolis of Beijing during 1997-2010. The analyses were conducted from both a bottom-up and a top-down perspective based on the sectoral inventories and structural decomposition analysis (SDA). From a bottom-up perspective, the key energy-intensive industrial sectors directly caused the variations in Beijing's air pollution by means of a series of energy and economic policies. From a top-down perspective, variations in production structures caused increases in most materials during 2000-2010, but there were decreases in PM10 and PM2.5 emissions during 2005-2010. Population growth was found to be the largest driver of energy consumption and air pollutant emissions during 1997-2010. This finding suggests that avoiding rapid population growth in Beijing could simultaneously control energy consumption and air pollutant emissions. Mitigation policies should consider not only the key industrial sectors but also socioeconomic drivers to co-reduce energy consumption and air pollution in China's metropolis.

Haikun Wang, Yanxia Zhang, Xi Lu, Chris P Nielsen, and Jun Bi. 2015. “Understanding China's carbon dioxide emissions from both production and consumption perspectives.” Renewable and Sustainable Energy Reviews, 52, Pp. 189-200. Publisher's VersionAbstract

China is now the largest emitter of CO2 in the world, having contributed nearly half of the global increase in carbon emissions between 1980 and 2010. The existing literature on China’s carbon emissions has focused on two dimensions: the amount of CO2 emitted within China’s geographical boundaries (a production-based perspective), and the drivers of, and responsibility for, these emissions (a consumption-based perspective). The current study begins with a comprehensive review of China’s CO2 emissions, and then analyzes their driving forces from both consumption and production perspectives, at both national and provincial levels. It is concluded that China’s aggregate national CO2 emissions from fossil fuel consumption and cement production maintained high growth rates during 2000-2010. National emissions reached 6.8–7.3 billion tons in 2007, nearly 25% of which were caused by net exports (i.e., exports minus imports) to other countries. However, emission characteristics varied significantly among different regions and provinces, and considerable emission leakage from the developed eastern regions to inland and western areas of the country was found. The objectives of China’s policies should therefore be broadened from continued improvement of energy efficiency to accelerating regional technology transfer and preventing mere relocation of carbon-intensive economic activities from developed coastal regions to less developed, inland provinces. To rapidly and effectively cut down China’s carbon emissions, moreover, its energy supply should be aggressively decarbonized by promoting renewable and low carbon energy sources.

2014
Yanxia Zhang, Haikun Wang, Sai Liang, Ming Xu, Weidong Liu, Shalang Li, Rongrong Zhang, Chris P Nielsen, and Jun Bi. 2014. “Temporal and spatial variations in consumption-based carbon dioxide emissions in China.” Renewable & Sustainable Energy Reviews, 40, Pp. 60-68. Publisher's VersionAbstract

China’s CO2 emissions have sharply increased in recent years with soaring economic development and urbanization. Consumption-based accounting of CO2 emissions could provide new insights for allocating regional mitigation responsibility and curbing the emissions. A multi-regional input–output model is used to study the trends and disparities of consumption-based emissions from Chinese provinces during the period 2002–2007. Results show that China’s consumption-based CO2 emissions grew from 3549 Mt in 2002 to 5403 Mt in 2007 with an annual average growth rate of 8.8%. The annual growth rate in the richer eastern region was over 10% because of a rapid increase in capital investment and the growth of urban consumption. Consumption-based CO2 emissions embodied in interprovincial trades contributed only 10% (351 Mt) to the national total of such emissions in 2002, but 16% (864 Mt) in 2007. Given low per capita emissions currently, China’s consumption-based emissions have much room to grow because of further development of urbanization and stimulation of domestic demand. The government should pay greater attention to controlling CO2 emissions from a consumption-based perspective.

1998
R.C. Peng, L.H. Wang, H. Wang, K.B. He, and X.P. Xu. 1998. “Indoor air pollution from residential energy use in China.” In Energizing China: Reconciling Environmental Protection and Economic Growth, edited by M.B. McElroy, C.P. Nielsen, P. Lydon, and eds.. Cambridge, MA: HUCE/Harvard University Press. Publisher's VersionAbstract

As China develops its booming, fossil fuel-powered economy, is it taking lessons from the history of Western industrialization and the unforeseen environmental harms that accompanied it? Given the risks of climate change, is there an imperative, shared responsibility to help China respond to the environmental effects of its coal dependence? By linking global hazards to local air pollution concerns—from indoor stove smoke to burgeoning ground-level ozone—this volume of eighteen studies seeks integrated strategies to address simultaneously a range of harmful emissions. Counterbalancing the scientific inquiry are key chapters on China’s unique legal, institutional, political, and cultural factors in effective pollution control.

Energizing China, the stage-setting publication of an ongoing program of Harvard–China research collaboration, is distinguished by its conceptual breadth and spirit of exchange. Its contributors include twenty-two Western and seventeen Chinese scholars with a disciplinary reach that includes science, public health, engineering, economics, public policy, law, business, and China studies.