Weather conditions conducive to Beijing severe haze more frequent under climate change
TL;DR: In this paper, the authors looked at how atmospheric conditions contribute and projected climate change will increase conditions favorable to severe haze events in Beijing. But they did not consider the effect of global greenhouse gas emissions.
Abstract: Severe winter air pollution events, attributed to emissions from development, have increased in Beijing in recent decades. This study looks at how atmospheric conditions contribute and projects climate change will increase conditions favourable to such events. The frequency of Beijing winter severe haze episodes has increased substantially over the past decades1,2,3,4, and is commonly attributed to increased pollutant emissions from China’s rapid economic development5,6. During such episodes, levels of fine particulate matter are harmful to human health and the environment, and cause massive disruption to economic activities3,4,7,8,9,10,11,12,13,14,15,16, as occurred in January 201317,18,19,20,21. Conducive weather conditions are an important ingredient of severe haze episodes3,21, and include reduced surface winter northerlies3,21, weakened northwesterlies in the midtroposphere, and enhanced thermal stability of the lower atmosphere1,3,16,21. How such weather conditions may respond to climate change is not clear. Here we project a 50% increase in the frequency and an 80% increase in the persistence of conducive weather conditions similar to those in January 2013, in response to climate change. The frequency and persistence between the historical (1950–1999) and future (2050–2099) climate were compared in 15 models under Representative Concentration Pathway 8.5 (RCP8.5)22. The increased frequency is consistent with large-scale circulation changes, including an Arctic Oscillation upward trend23,24, weakening East Asian winter monsoon25,26, and faster warming in the lower troposphere27,28. Thus, circulation changes induced by global greenhouse gas emissions can contribute to the increased Beijing severe haze frequency.
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TL;DR: It is highlighted that improved understanding of the emission sources, physical/chemical processes during haze evolution, and interactions with meteorological/climatic changes are necessary to unravel the causes, mechanisms, and trends for haze pollution.
Abstract: Regional severe haze represents an enormous environmental problem in China, influencing air quality, human health, ecosystem, weather, and climate. These extremes are characterized by exceedingly high concentrations of fine particulate matter (smaller than 2.5 µm, or PM2.5) and occur with extensive temporal (on a daily, weekly, to monthly timescale) and spatial (over a million square kilometers) coverage. Although significant advances have been made in field measurements, model simulations, and laboratory experiments for fine PM over recent years, the causes for severe haze formation have not yet to be systematically/comprehensively evaluated. This review provides a synthetic synopsis of recent advances in understanding the fundamental mechanisms of severe haze formation in northern China, focusing on emission sources, chemical formation and transformation, and meteorological and climatic conditions. In particular, we highlight the synergetic effects from the interactions between anthropogenic emissions and atmospheric processes. Current challenges and future research directions to improve the understanding of severe haze pollution as well as plausible regulatory implications on a scientific basis are also discussed.
586 citations
Cites background from "Weather conditions conducive to Bei..."
...In December 2016, the East Atlantic–West Russia circulation pattern in the middle troposphere strengthened the anticyclone anomaly but suppressed the vertical convection in the NCP, likely responsible for the persistent severe haze formation (125)....
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...5 concentrations during severe haze episodes in the NCP (109, 110)....
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...Field measurements have shown high light absorption capability of haze aerosols in the NCP, with the derived SSA of ∼0.9 (103–105)....
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...NPF and its subsequent growth has been shown to increase the CCN concentration (66), for example, by a factor of 5.6 to 8.7 in the NCP (63)....
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...Climate change influences several aspects of the large-scale circulations in this region, which ultimately regulates the transport and dispersion of pollutants (18, 111, 112)....
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TL;DR: In this article, the authors review the major advances in aerosol measurements, PBL processes and their interactions with each other through complex feedback mechanisms, and highlight the priorities for future studies.
Abstract: Air quality is concerned with pollutants in both the gas phase and solid or liquid phases. The latter are referred to as aerosols, which are multifaceted agents affecting air quality, weather and climate through many mechanisms. Unlike gas pollutants, aerosols interact strongly with meteorological variables with the strongest interactions taking place in the planetary boundary layer (PBL). The PBL hosting the bulk of aerosols in the lower atmosphere is affected by aerosol radiative effects. Both aerosol scattering and absorption reduce the amount of solar radiation reaching the ground and thus reduce the sensible heat fluxes that drive the diurnal evolution of the PBL. Moreover, aerosols can increase atmospheric stability by inducing a temperature inversion as a result of both scattering and absorption of solar radiation, which suppresses dispersion of pollutants and leads to further increases in aerosol concentration in the lower PBL. Such positive feedback is especially strong during severe pollution events. Knowledge of the PBL is thus crucial for understanding the interactions between air pollution and meteorology. A key question is how the diurnal evolution of the PBL interacts with aerosols, especially in vertical directions, and affects air quality. We review the major advances in aerosol measurements, PBL processes and their interactions with each other through complex feedback mechanisms, and highlight the priorities for future studies.
495 citations
Cites background from "Weather conditions conducive to Bei..."
...In fact, the favorable weather conditions induced by the increases in greenhouse gas emissions or the changes in the boreal cryosphere, particularly in the global environment, are mainly responsible for the more frequent haze episodes in winter on the North China Plain [59,60]....
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...In 2014, the vertical profiles of O3 and size-resolved aerosol number concentrations were measured at a rural site on the North China Plain using an unmanned aerial vehicle [91]....
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...As a result, extensive ground measurements have been conductedduring thepast decade to characterize the chemical composition, sources and formationmechanisms of aerosol particles, with most of them taking place in the four most polluted regions, including the Pearl River Delta, the Yangtze River Delta, the North China Plain and the Sichuan Basin....
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...Based on WRF-FLEXPART simulations, it was found that the PBL air pollutants from the North China Plain can be transported by cyclones and its associated warm conveyor belts to the free troposphere over Northeast China [206]....
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...[59] developed an effective haze weather index to represent such favorable weather conditions by using observed long-term PM2....
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Abstract: Abstract. Fine particulate matter (PM2.5) is a severe air pollution
problem in China. Observations of PM2.5 have been available since 2013
from a large network operated by the China National Environmental Monitoring
Center (CNEMC). The data show a general 30 %–50 % decrease in annual mean
PM2.5 across China over the 2013–2018 period, averaging at −5.2 µg m−3 a−1. Trends in the five megacity cluster regions targeted by
the government for air quality control are -9.3±1.8 µg m−3 a−1 (±95 % confidence interval) for Beijing–Tianjin–Hebei,
-6.1±1.1 µg m−3 a−1 for the Yangtze River Delta, -2.7±0.8 µg m−3 a−1 for the Pearl River Delta, -6.7±1.3 µg m−3 a−1 for the Sichuan Basin, and -6.5±2.5 µg m−3 a−1 for the Fenwei Plain (Xi'an). Concurrent 2013–2018
observations of sulfur dioxide (SO2) and carbon monoxide (CO) show that
the declines in PM2.5 are qualitatively consistent with drastic
controls of emissions from coal combustion. However, there is also a large
meteorologically driven interannual variability in PM2.5 that
complicates trend attribution. We used a stepwise multiple linear regression
(MLR) model to quantify this meteorological contribution to the PM2.5 trends across China. The MLR model correlates the 10 d PM2.5
anomalies to wind speed, precipitation, relative humidity, temperature, and
850 hPa meridional wind velocity (V850). The meteorology-corrected
PM2.5 trends after removal of the MLR meteorological contribution can
be viewed as being driven by trends in anthropogenic emissions. The mean
PM2.5 decrease across China is −4.6 µg m−3 a−1 in the
meteorology-corrected data, 12 % weaker than in the original data, meaning
that 12 % of the PM2.5 decrease in the original data is
attributable to meteorology. The trends in the meteorology-corrected data
for the five megacity clusters are -8.0±1.1 µg m−3 a−1 for Beijing–Tianjin–Hebei (14 % weaker than in the original
data), -6.3±0.9 µg m−3 a−1 for the Yangtze River Delta
(3 % stronger), -2.2±0.5 µg m−3 a−1 for the Pearl River
Delta (19 % weaker), -4.9±0.9 µg m−3 a−1 for
the Sichuan Basin (27 % weaker), and -5.0±1.9 µg m−3 a−1 for the Fenwei Plain (Xi'an; 23 % weaker); 2015–2017 observations of
flattening PM2.5 in the Pearl River Delta and increases in the Fenwei
Plain can be attributed to meteorology rather than to relaxation of emission
controls.
398 citations
Cites background from "Weather conditions conducive to Bei..."
...5 identified in previous studies (Wang et al., 2014; Cai et al., 2017; Shen et al., 2017; Leung et al., 2018; Song et al., 2019; Zou et al., 2017)....
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...5 wintertime pollution events in the North China Plain because northerly winds (negative V850) ventilate the region with clean dry air (Cai et al., 2017; Pendergrass et al., 2019)....
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TL;DR: In this article, a detailed bottom-up emission inventory over Beijing, the MEIC regional emission inventory and the WRF-CMAQ (WeatherResearch and Forecasting Model and Community Multiscale Air Quality) model was used to evaluate the effectiveness of clean air actions in Beijing and its surrounding regions.
Abstract: . In 2013, China's government published the Air Pollution Prevention and
Control Action Plan (APPCAP) with a specific target for Beijing, which aims
to reduce annual mean PM 2.5 concentrations in Beijing to
60 µ g m −3 in 2017. During 2013–2017, the air quality in
Beijing was significantly improved following the implementation of various
emission control measures locally and regionally, with the annual mean
PM 2.5 concentration decreasing from 89.5 µ g m −3 in 2013
to 58 µ g m −3 in 2017. As meteorological conditions were more
favourable to the reduction of air pollution in 2017 than in 2013 and 2016,
the real effectiveness of emission control measures on the improvement of air
quality in Beijing has frequently been questioned. In this work, by combining a detailed bottom-up emission inventory over
Beijing, the MEIC regional emission inventory and the WRF-CMAQ (Weather
Research and Forecasting Model and Community Multiscale Air Quality) model, we
attribute the improvement in Beijing's PM 2.5 air quality in 2017
(compared to 2013 and 2016) to the following factors: changes in
meteorological conditions, reduction of emissions from surrounding regions,
and seven specific categories of local emission control measures in Beijing.
We collect and summarize data related to 32 detailed control measures
implemented during 2013–2017, quantify the emission reductions associated
with each measure using the bottom-up local emission inventory in 2013,
aggregate the measures into seven categories, and conduct a series of CMAQ
simulations to quantify the contribution of different factors to the
PM 2.5 changes. We found that, although changes in meteorological conditions partly explain
the improved PM 2.5 air quality in Beijing in 2017 compared to 2013 (3.8 µ g m −3 ,
12.1 % of total), the rapid decrease in
PM 2.5 concentrations in Beijing during 2013–2017 was dominated by local
(20.6 µ g m −3 , 65.4 %) and regional (7.1 µ g m −3 ,
22.5 %) emission reductions. The seven categories of
emission control measures, i.e. coal-fired boiler control,
clean fuels in the residential sector, optimize industrial structure,
fugitive dust control, vehicle emission control,
improved end-of-pipe control, and integrated treatment of VOCs,
reduced the PM 2.5
concentrations in Beijing by 5.9, 5.3, 3.2, 2.3, 1.9, 1.8, and 0.2 µ g m −3 ,
respectively, during 2013–2017. We also found
that changes in meteorological conditions could explain roughly 30 % of
total reduction in PM 2.5 concentration during 2016–2017 with more
prominent contribution in winter months (November and December). If the
meteorological conditions in 2017 had remained the same as those in 2016,
the annual mean PM 2.5 concentrations would have increased from
58 to 63 µ g m −3 , exceeding the
target established in the APPCAP. Despite the remarkable impacts from
meteorological condition changes, local and regional emission reductions
still played major roles in the PM 2.5 decrease in Beijing during
2016–2017, and clean fuels in the residential sector, coal-fired boiler control,
and optimize industrial structure were the three most effective local measures
(contributing reductions of 2.1, 1.9, and 1.5 µ g m −3 ,
respectively). Our study confirms the effectiveness of clean air actions in
Beijing and its surrounding regions and reveals that a new generation of
control measures and strengthened regional joint emission control measures
should be implemented for continued air quality improvement in Beijing
because the major emitting sources have changed since the implementation of
the clean air actions.
275 citations
Cites background or methods from "Weather conditions conducive to Bei..."
...…province, also implemented the APPCAP, and the air quality of the whole region has attained marked improvements, which have also been confirmed by satellite-based and ground-based observations (Liu et al., 2016; S. Cai et al., 2017; Zhao et al., 2017; J. Wang et al., 2017; Y. Zheng et al., 2017)....
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...Based on emission inventories and air quality models, existing studies have established a mature sensitivity decomposition framework to assess the contributions of emission control to air quality improvements (Zhao et al., 2013; W. Cai et al., 2017)....
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...…2013–2017, the industry and the power and heating sectors made the most prominent contributions to SO2 emission reductions, which decreased SO2 emissions by 3021 and 2000 kt, respectively, indicating that the SO2 emissions control measures were quite effective (Cai et al., 2017; Shao et al., 2018)....
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TL;DR: The authors show that from 2013 to 2017, the plan has achieved substantial public health benefits and more ambitious policies are required to reduce the health impacts of air pollution by 2030 and meet the United Nation’s Sustainable Development Goal 3.
Abstract: Air pollution kills nearly 1 million people per year in China. In response, the Chinese government implemented the Air Pollution Prevention and Control Action Plan (APPCAP) from 2013 to 2017 which had a significant impact on reducing PM2.5 concentration. However, the health benefits of the APPCAP are not well understood. Here we examine the spatiotemporal dynamics of annual deaths attributable to PM2.5 pollution (DAPP) in China and the contribution from the APPCAP using decomposition analysis. Despite a 36.1% increase in DAPP from 2000 to 2017, The APPCAP-induced improvement in air quality achieved substantial health benefits, with the DAPP in 2017 reduced by 64 thousand (6.8%) compared to 2013. However, the policy is unlikely to result in further major reductions in DAPP and more ambitious policies are required to reduce the health impacts of air pollution by 2030 and meet the United Nation’s Sustainable Development Goal 3. Chinese government has implemented the air pollution control measure-the Air Pollution Prevention and Control Action Plan in 2013, whose effects have not been fully studied. Here the authors show that from 2013 to 2017, the plan has achieved substantial public health benefits.
225 citations
References
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TL;DR: The NCEP/NCAR 40-yr reanalysis uses a frozen state-of-the-art global data assimilation system and a database as complete as possible, except that the horizontal resolution is T62 (about 210 km) as discussed by the authors.
Abstract: The NCEP and NCAR are cooperating in a project (denoted “reanalysis”) to produce a 40-year record of global analyses of atmospheric fields in support of the needs of the research and climate monitoring communities. This effort involves the recovery of land surface, ship, rawinsonde, pibal, aircraft, satellite, and other data; quality controlling and assimilating these data with a data assimilation system that is kept unchanged over the reanalysis period 1957–96. This eliminates perceived climate jumps associated with changes in the data assimilation system. The NCEP/NCAR 40-yr reanalysis uses a frozen state-of-the-art global data assimilation system and a database as complete as possible. The data assimilation and the model used are identical to the global system implemented operationally at the NCEP on 11 January 1995, except that the horizontal resolution is T62 (about 210 km). The database has been enhanced with many sources of observations not available in real time for operations, provided b...
28,145 citations
TL;DR: The fifth phase of the Coupled Model Intercomparison Project (CMIP5) will produce a state-of-the- art multimodel dataset designed to advance the authors' knowledge of climate variability and climate change.
Abstract: The fifth phase of the Coupled Model Intercomparison Project (CMIP5) will produce a state-of-the- art multimodel dataset designed to advance our knowledge of climate variability and climate change. Researchers worldwide are analyzing the model output and will produce results likely to underlie the forthcoming Fifth Assessment Report by the Intergovernmental Panel on Climate Change. Unprecedented in scale and attracting interest from all major climate modeling groups, CMIP5 includes “long term” simulations of twentieth-century climate and projections for the twenty-first century and beyond. Conventional atmosphere–ocean global climate models and Earth system models of intermediate complexity are for the first time being joined by more recently developed Earth system models under an experiment design that allows both types of models to be compared to observations on an equal footing. Besides the longterm experiments, CMIP5 calls for an entirely new suite of “near term” simulations focusing on recent decades...
12,384 citations
TL;DR: A comprehensive evaluation of the research findings provides persuasive evidence that exposure to fine particulate air pollution has adverse effects on cardiopulmonary health.
Abstract: Efforts to understand and mitigate the health effects of particulate matter (PM) air pollution have a rich and interesting history. This review focuses on six substantial lines of research that have been pursued since 1997 that have helped elucidate our understanding about the effects of PM on human health. There has been substantial progress in the evaluation of PM health effects at different time-scales of exposure and in the exploration of the shape of the concentration-response function. There has also been emerging evidence of PM-related cardiovascular health effects and growing knowledge regarding interconnected general pathophysiological pathways that link PM exposure with cardiopulmonary morbidity and mortality. Despite important gaps in scientific knowledge and continued reasons for some skepticism, a comprehensive evaluation of the research findings provides persuasive evidence that exposure to fine particulate air pollution has adverse effects on cardiopulmonary health. Although much of this research has been motivated by environmental public health policy, these results have important scientific, medical, and public health implications that are broader than debates over legally mandated air quality standards.
5,547 citations
TL;DR: The results suggest that, in addition to mitigating primary particulate emissions, reducing the emissions of secondary aerosol precursors from fossil fuel combustion and biomass burning is likely to be important for controlling China’s PM2.5 levels and for reducing the environmental, economic and health impacts resulting from particulate pollution.
Abstract: Rapid industrialization and urbanization in developing countries has led to an increase in air pollution, along a similar trajectory to that previously experienced by the developed nations. In China, particulate pollution is a serious environmental problem that is influencing air quality, regional and global climates, and human health. In response to the extremely severe and persistent haze pollution experienced by about 800 million people during the first quarter of 2013 (refs 4, 5), the Chinese State Council announced its aim to reduce concentrations of PM2.5 (particulate matter with an aerodynamic diameter less than 2.5 micrometres) by up to 25 per cent relative to 2012 levels by 2017 (ref. 6). Such efforts however require elucidation of the factors governing the abundance and composition of PM2.5, which remain poorly constrained in China. Here we combine a comprehensive set of novel and state-of-the-art offline analytical approaches and statistical techniques to investigate the chemical nature and sources of particulate matter at urban locations in Beijing, Shanghai, Guangzhou and Xi'an during January 2013. We find that the severe haze pollution event was driven to a large extent by secondary aerosol formation, which contributed 30-77 per cent and 44-71 per cent (average for all four cities) of PM2.5 and of organic aerosol, respectively. On average, the contribution of secondary organic aerosol (SOA) and secondary inorganic aerosol (SIA) are found to be of similar importance (SOA/SIA ratios range from 0.6 to 1.4). Our results suggest that, in addition to mitigating primary particulate emissions, reducing the emissions of secondary aerosol precursors from, for example, fossil fuel combustion and biomass burning is likely to be important for controlling China's PM2.5 levels and for reducing the environmental, economic and health impacts resulting from particulate pollution.
3,372 citations
01 Jan 2006
TL;DR: The 2006 A&WMA Critical Review on Health Effects of Fine Particulate Air Pollution: Lines that Connect documents substantial progress since the 1997 Critical Review in the areas of short-term exposure and mortality and time scales of exposure.
Abstract: INTRODUCTION Herein is the discussion of the 2006 A&WMA Critical Review1,2 on “Health Effects of Fine Particulate Air Pollution: Lines that Connect.” In the review, Drs. C. Arden Pope III and Douglas Dockery addressed the epidemiological evidence for the effects of particulate matter (PM) on human health indicators. The review documents substantial progress since the 1997 Critical Review3 in the areas of: (1) short-term exposure and mortality; (2) long-term exposure and mortality; (3) time scales of exposure; (4) the shape of the concentration-response function; (5) cardiovascular disease; and (6) biological plausibility. Invited and contributing discussants agree and disagree with points made in the review. Each discussion is self-contained and adds information relevant to the topic. Joint authorship of this article does not imply that a discussant subscribes to the opinions expressed by others. Commentaries are the opinions of the author only and do not necessarily reflect the positions of their respective organizations. In particular, Dr. Costa’s comments have not been reviewed by U.S. Environmental Protection Agency (EPA) and do not reflect official positions or policies of the agency. CRITICAL REVIEW DISCUSSION ISSN 1047-3289 J. Air & Waste Manage. Assoc. 56:1368–1380
2,011 citations