PNNL

Abstract

Extreme precipitation can lead to severe floods with devastating damage on the environment and society. A record-breaking flooding related to extreme rainfall struck eastern China in the summer of 2020, resulting in more than one hundred deaths and three million hectares of crop damages, with an economic loss of ten billion U.S. dollars. Understanding the mechanisms behind this event is crucial to inform prediction of future extreme precipitation. The COVID-19 pandemic rapidly spread across the globe in 2020, which disrupted human activities and resulted in substantial reductions in anthropogenic emissions. Here, we investigate the effect of the abrupt emissions reduction during the pandemic on the record-breaking precipitation in China by using an earth system model and observational data. We show that the COVID-19 emissions reductions led to a surface cooling and an associated high sea level pressure anomaly in northwestern Pacific Ocean. The latter enhanced the moisture convergence in eastern China and intensified the rainfall. The reduction in aerosols contributed to 31% of the observed extreme precipitation in summer 2020 over eastern China. We conclude that through the abrupt reduction of anthropogenic emissions, COVID-19 exerted a significant impact on extreme rainfall in China.