Global rainstorms becoming shorter but more intense

The world's heaviest rain-bearing storms have now become shorter in duration, but their intensity has increased. This change could lead to an increase in the risk of floods and droughts. According to a report by The Guardian, nearly half of the total annual rainfall is received through these intense rain events, which have now become faster and harsher.

Chiyuan Miao and colleagues from Beijing Normal University in China analysed data between 1980 and 2022. Daily measurements from more than 19,000 rain gauges across the world were used for this study. Researchers observed that an average of nine multi-day storms, falling over a total period of 28 days, were responsible for half of the world's rainfall.

However, data since 1980 shows that the average length of intense storms has decreased by approximately 86 minutes per decade. Consequently, the total time required for half of the world's annual rainfall to fall has decreased by more than 9.5 hours. According to these findings published in 'Earth's Future', this change has been observed across all continents, although regional differences exist.

The most significant decrease in storm duration was recorded in Europe and South America, where the heaviest rainstorms shortened by up to 144 minutes per decade. The impact of this change will vary across different regions, including flash flooding, water security, agricultural productivity, soil erosion, the likelihood of forest fires, and changes in drought risk.