A catastrophic 2013 flood in China was probably caused, in part, by air pollution.

Credit: Imaginechina/Corbis

In July 2013, heavy rainfall resulted in a devastating flood in the mountains northwest of the Sichuan Basin in China (pictured). The basin has seen increasing industrial activity in the past few decades. Jiwen Fan at the Pacific Northwest National Laboratory in Richland, Washington, and her team modelled the region's atmospheric processes during the storm using different levels of aerosol emissions. By setting the modelled emissions at a level similar to that before China's economic boom, the team found that the rate of rainfall in the storm would have been up to 60% lower than under current emissions levels. Aerosols trapped in the basin warm the air and suppress convection, allowing excess moisture to build up and condense into rain as it rises up over the mountains.

The authors suggest that future severe floods in the region could be mitigated by reducing air pollution, particularly black carbon.

Geophys. Res. Lett. http://doi.org/5q9 (2015)