空气污染、温室气体与气候

Yu Zhao, Yutong Wang, Yiming Liu, Yueqi Jiang, Bo Zheng, Jia Xing, Yang Liu, Shuai Wang, and Chris Nielsen. 2023. “Sustained emission reductions have restrained the ozone pollution over China.” Nature Geoscience. Publisher's VersionAbstract
Near-surface ozone pollution, associated with complex responses to changing precursor emissions and meteorological conditions, has become one of the biggest challenges in China’s air quality management. Here, we present the spatiotemporal evolution of ozone concentrations from 2010 to 2021 using measurements of the national air quality monitoring network. We evaluate the effectiveness of the national air pollution control programme, including Phase 1 (2013–2017) and Phase 2 (2018–2021), in reducing the ozone level over China, using an optimized machine learning approach, high-resolution emission estimates and an improved air quality model. We find that while emission changes in Phase 1 increased the ozone level over the five highly developed regions, further reductions of nitrogen oxide emissions in Phase 2 have generally constrained the ozone pollution. The changing effect of emission controls on ozone pollution is due to the shift in the prevailing regime for ozone formation and the weakened effects of aerosol declines, as emission reductions continue. We further find that current emission controls have been more effective in rural locales in four of the five regions, and more effective in summer than winter. Therefore, further control of ozone pollution should consider these regional and seasonal variations to identify the most important precursors for the pollution.
Xi Yang, Chris P. Nielsen, Shaojie Song, and Michael B. McElroy. 2022. “Breaking the “hard-to-abate” bottleneck in China’s path to carbon neutrality with clean hydrogen.” Nature Energy. Publisher's VersionAbstract
Countries such as China are facing a bottleneck in their paths to carbon neutrality: abating emissions in heavy industries and heavy-duty transport. There are few in-depth studies of the prospective role for clean hydrogen in these ‘hard-to-abate’ (HTA) sectors. Here we carry out an integrated dynamic least-cost modelling analysis. Results show that, first, clean hydrogen can be both a major energy carrier and feedstock that can significantly reduce carbon emissions of heavy industry. It can also fuel up to 50% of China’s heavy-duty truck and bus fleets by 2060 and significant shares of shipping. Second, a realistic clean hydrogen scenario that reaches 65.7 Mt of production in 2060 could avoid US$1.72 trillion of new investment compared with a no-hydrogen scenario. This study provides evidence of the value of clean hydrogen in HTA sectors for China and countries facing similar challenges in reducing emissions to achieve net-zero goals.
Peter Sherman, Haiyang Lin, and Michael B. McElroy. 2022. “Projected global demand for air conditioning associated with extreme heat and implications for electricity grids in poorer countries.” Energy and Buildings. Publisher's VersionAbstract

Human-induced climate change will increase surface temperatures globally over the next several decades. Climate models project that global mean surface temperature could increase by over 2˚C by 2050 relative to the preindustrial period, with even greater changes at the regional level. These temperature changes have clear and pertinent implications for extremes, and consequentially, heat-induced health issues for people living in particularly hot climates. Here, we study future projections in the demand for AC globally in the 2050s associated with extreme heat events. To do this, we employ an ensemble of CMIP6 models under high and low emissions scenarios. We find that the increasing frequency of extreme temperatures will cause a significant portion of the global population to be exposed to conditions that require cooling. This issue will be especially pervasive in poor countries such as India and Indonesia, which at present lack the AC units required to handle rapidly growing populations and increased frequencies of extreme temperatures. The electricity needed for cooling in these countries could reach as high as 75% of the current total annual electricity demand, which could place serious strain on the electricity grid infrastructure during peak cooling hours. We conclude that demand for cooling in the future will pose a significant challenge for poorer countries whose people will require AC units to handle extreme temperatures. In some countries, the grid infrastructure is insufficient at present to meet projected AC demands, and this need must be considered in future power systems planning.

Combined solar power and storage as cost-competitive and grid-compatible supply for China’s future carbon-neutral electricity system
Xi Lu, Chris P. Nielsen, Chongyu Zhang, Jiacong Li, Xu He, Ye Wu, Shuxiao Wang, Feng Song, Chu Wei, Kebin He, Michael P. McElroy, and Jiming Hao. 2021. “Combined solar power and storage as cost-competitive and grid-compatible supply for China’s future carbon-neutral electricity system.” Proceedings of the National Academy of Sciences, 118, October, Pp. 42. Publisher's VersionAbstract
As the world’s largest CO2 emitter, China’s ability to decarbonize its energy system strongly affects the prospect of achieving the 1.5 °C limit in global, average surface-temperature rise. Understanding technically feasible, cost-competitive, and grid-compatible solar photovoltaic (PV) power potentials spatiotemporally is critical for China’s future energy pathway. This study develops an integrated model to evaluate the spatiotemporal evolution of the technology-economic-grid PV potentials in China during 2020 to 2060 under the assumption of continued cost degression in line with the trends of the past decade. The model considers the spatialized technical constraints, up-to-date economic parameters, and dynamic hourly interactions with the power grid. In contrast to the PV production of 0.26 PWh in 2020, results suggest that China’s technical potential will increase from 99.2 PWh in 2020 to 146.1 PWh in 2060 along with technical advances, and the national average power price could decrease from 4.9 to 0.4 US cents/kWh during the same period. About 78.6% (79.7 PWh) of China’s technical potential will realize price parity to coal-fired power in 2021, with price parity achieved nationwide by 2023. The cost advantage of solar PV allows for coupling with storage to generate cost-competitive and grid-compatible electricity. The combined systems potentially could supply 7.2 PWh of grid-compatible electricity in 2060 to meet 43.2% of the country’s electricity demand at a price below 2.5 US cents/kWh. The findings highlight a crucial energy transition point, not only for China but for other countries, at which combined solar power and storage systems become a cheaper alternative to coal-fired electricity and a more grid-compatible option.
Lu et al. is the cover article of this October issue of PNAS. Read the Research Brief.
Qiang Liu

刘强 Qiang Liu

清华大学能源环境经济研究所博士研究生
哈佛中国项目交流博士生
刘强是清华大学能源环境经济研究所的博士研究生。他的研究兴趣是能源和气候政策。目前,刘强的研究重点是估算中国人为甲烷排放量,并研究中国的甲烷减排途径。
Jingran Zhang, Yiliang Jiang, Yunjie Wang, Shaojun Zhang, Ye Wu, Shuxiao Wang, Chris P Nielsen, Michael B McElroy, and Jiming Hao. 2023. “Increased Impact of Aviation on Air Quality and Human Health in China.” Environmental Science & Technology, 2023, Pp. 19575–19583. Publisher's VersionAbstract
China’s civil aviation market has rapidly expanded, becoming the world’s second-largest. However, the air quality and health impacts caused by its aircraft emissions have been inadequately assessed. Here, we leverage an updated emission inventory of air pollutants with improved temporal and spatial resolution based on hundreds of thousands of flight trajectories and simulate aviation-attributable contributions to ground-level air pollution in China. We find that in 2017, the annual-average aviation-attributed PM2.5 and O3 concentrations were 0.4–1.5 and 10.6–14.5 μg·m–3, respectively, suggesting that aviation emissions have become an increasingly important source of ambient air pollution. The contributions attributable to high-altitude emissions (climb/cruise/descent) were comparable to those at low altitudes (landing and takeoff). Aviation-attributed ambient PM2.5 and O3 exposures are estimated to have caused about 67,000 deaths in China in 2017, with populous coastal regions in Eastern China suffering the most due to the dense aviation activity. We recommend that industrial and policy stakeholders expedite an agenda of regulating air pollutants harmonized with decarbonization efforts for a more sustainable aviation future.
Lu Liu, Yu Zhao, Hongyan Zhao, Yifei Wang, and Chris P Nielsen. 2023. “Impacts of Receiving International Industrial Transfer on China’s Air Quality and Health Exceed Those of Export Trade.” Environmental Science & Technology, 2023, Pp. 16989–16998. Publisher's VersionAbstract
Benefiting from international economic cooperation on income, technology diffusion, and employment, China also suffers its environmental and health impacts, from both international trade (IT), as is now widely understood, and international industrial transfer (IIT), which has been largely unrecognized. Here, we develop a comprehensive framework to estimate the impacts of exporting IT and receiving IIT. We find that China’s emissions of CO2 and almost all air pollutants associated with IIT and IT together grew after 1997 but then declined after 2010, with the peak shares of national total emissions ranging 18–31% for different species. These sources further accounted for 3.8% of nationwide PM2.5 concentrations and 94,610 (76,000–112,040) premature deaths in 2012, and the values declined to 2.6% and 67,370 (52,390–81,810), respectively, for 2017. Separated, the contribution of IIT to those impacts was more than twice that of IT. Scenario analyses suggest that improving emission controls in its less-developed regions would effectively reduce the impact of economic globalization, but such a benefit could be largely offset by strengthened international economic cooperation. The outcomes provide a scientific basis for adjusting China’s strategic roles in the international distribution of industrial production and its formulation of relevant environmental policies from a comprehensive perspective.
Jianglong Li, Jinfeng Gao, and Mun Sing Ho. 2024. “Causal effect of aviation on air pollution: An instrumental variable from faraway COVID-19 restrictions in China.” China Economic Review, 84, April 2024, Pp. 102140. Publisher's VersionAbstract
The causal impacts of aviation on local air pollution are poorly understood. Leveraging variation in aviation frequency caused by COVID-19 travel restrictions that occurred hundreds of miles away between 2020 and 2022, this study identifies the short-run effect of aviation on air pollution in Hangzhou, a Chinese megacity. The results demonstrate that a one standard deviation change in aviation is associated with 12% to 21.82% changes in ambient pollution concentrations, with even more substantial pollution effects on downwind days and flights departing from Hangzhou, respectively. These estimates also remain robust to alternative specifications, satisfy external validity beyond Hangzhou and the epidemic period, and exclude pollution spillover effects. We further quantify the welfare losses from aviation pollution and find that people are willing to pay 1.76 US dollars a day in per capita household income for reducing pollution caused by each standard deviation increase in flights (i.e., 134 flights). Further analysis reveals higher economic losses resulting from pollutants at international airports. Our results underscore the need to regulate airborne contaminants from aviation in China urgently.
2024 Feb 01

Application Deadline for Visiting Researcher or Postdoctoral Fellow Positions

(All day)

Applications are now open to join us for academic year 2024-25. Visits will typically fall between August 2024 and August 2025, although visits that fall outside of the academic year would also be considered. Click here for more information on our Visiting Researcher program. 

APPLY HERE

Components of a complete application include:

1) A...

Read more about Application Deadline for Visiting Researcher or Postdoctoral Fellow Positions

Pages