Anthropogenic Pollution Contribution to the Catastrophic 2013 Sichuan Flood in Southwest China

IPCC AR5 report on Climate Change shows that increasing trends for many extreme weather and climate events such as heat waves, drought and floods have been observed since about 1950. The major factors responsible for the increased extreme precipitation probably vary with locations and time. Human influence is a major concern. Here we study the Catastrophic 2013 Sichuan Flood occurring on July 8-9 2013 using the improved chemistry version of the Weather Research Forecasting model (WRF-Chem). We find that anthropogenic pollution in the Sichuan Basin significantly enhances the intensity of the flooding over the windward side of the mountain regions which are located at the northwest of the Sichuan Basin. The radiative effects from the absorbing aerosols (i.e., soot) in the Sichuan Basin are responsible for the change. Detailed mechanism and significant implications will be discussed.