中美大气污染的空间交互影响--来自国家和城市层面PM2.5的经验证据

准确识别中美大气污染的空间交互影响可以为两国在大气污染治理领域开展双边合作提供科学依据。以PM 2.5浓度表征大气污染程度,采用收敛交叉映射(Convergent Cross Mapping,CCM)方法,在采集伯克利地球发布的小时数据的基础上通过算数平均得到2018年1月1日至2018年12月31日的PM 2.5浓度日均数据,从国家和城市两个层面识别了中美大气污染的空间交互影响。研究发现,中美两国的大气污染是空间交互影响的。其中,国家层面,在CCM因果检验基础上的广义同步检验表明,在1%显著性水平上,大气污染仅存在由美国指向中国的单向因果关系。城市层面,中美两国10个样本城市之间理论上共存在50个可能的因果关系(5×5×2)。研究发现,在1%显著性水平上,美国城市指向中国城市的因果关系有12个,而中国城市指向美国城市的因果关系仅有5个。在影响强度上,美国城市的大气污染对中国城市的影响强度高于中国城市的大气污染对美国城市的影响强度,如重庆的大气污染对华盛顿的影响强度为0.21,而华盛顿的大气污染对重庆的影响强度为0.35。面对大气污染的空间交互影响,中美两国可通过积极开展联合科研攻关,厘清大气污染的传输路径及其驱动因素,进行污染物的联合监测与数据管理;通过共享大气污染治理技术和建立大气污染防治基金等方式,加强在大气污染治理领域的合作。一旦中美两国成功建立起大气污染双边合作治理体系,依靠两国的国际地位和国际影响力,必将吸引越来越多的国家参与进来共同行动,大气污染全球治理体系的构建将非常值得期待。

The interaction of air pollution between China and the United States:evidence from PM 2.5 data at national and municipal levels

Accurate identification of factors concerning air pollution interaction between China and the United States could provide a scientific basis for bilateral cooperation in air pollution control.A test was conducted by obtaining the daily data of PM 2.5 between January 1 to December 31,2018 from Berkeley Earth by calculating the average of hourly data and using them as the surrogate variable of air pollution.Convergent cross mapping(CCM)was then employed to explore the interaction of air pollution between China and the United States at national and municipal levels.Test results indicated that factors of air pollution between the United States and China were interactive.At the national level,the CCM results addressing generalized synchrony showed that there existed a unidirectional causality from the United States to China at the 1%significance level.At the municipal level,50(5×5×2)possible causalities existed between the 5 American sample cities and the 5 Chinese sample cities.At the 1%significance level,the number of causality from the United States to China was 12,while the number of causality from China to the United States was 5.In the aspect of impact strength,the impact of air pollution in sample cities on Chinese sample cities was stronger than vice versa.For example,the impact strength of Chongqing on Washington D.C.was 0.21,while the impact strength of Washington D.C.on Chongqing was 0.35.Facing the interaction of air pollution between China and the United States,the two countries should implement joint research,analyze the main paths and drivers of the transboundary transport of air pollution,and launch joint monitoring and data management of air pollutants.Besides,China and the the United States should strengthen cooperation in air pollution control by taking such measures as sharing air pollution control technologies and establishing an air pollution prevention and control fund.Once the two countries successfully establish a bilateral cooperation system for air pollution control,their significant international status and influence could help motivate an increasing number of other countries to act together,which would be a promising step toward constructing a worldwide multilateral air pollution control system.