Urbanization and air quality as major drivers of altered spatiotemporal patterns of heavy rainfall in China

Context: Land use/land cover change and other human activities contribute to the changing climate on regional and global scales, including the increasing occurrence of extreme-precipitation events, but the relative importance of these anthropogenic factors, as compared to climatic factors, remains unclear. Objectives: The main goal of this study was to determine the relative contributions of human-induced and climatic factors to the altered spatiotemporal patterns of heavy rainfall in China during the past several decades. Methods: We used daily precipitation data from 659 meteorological stations in China from 1951 to 2010, climatic factors, and anthropogenic data to identify possible causes of the observed spatiotemporal patterns of heavy rainfall in China in the past several decades, and quantify the relative contributions between climatic and human-induced factors. Results: Our analysis suggests that a total of 84.7–87.5% of the variance in heavy rainfall factors could be explained by large-scale climate phenomena and the local/regional anthropogenic activities. In particular, urbanization and air pollution together explained 58.5–65.5% of the variance. The spatial distribution of heavy rainfall amount and days over time shows a significant and increasing correlation with the spatial distributions of population density and annual low-visibility days. Conclusions: Our results suggest that the substantial increase in heavy rainfall across much of China during the past six decades is likely triggered by local and regional anthropogenic factors. Our results call for a better understanding of local and regional anthropogenic impacts on climate, and the exacerbated extreme climate events as a potential consequence of urbanization and air pollution.