Extreme rainfall and severe flooding will continue to intensify

Without urgent action, extreme rainfall and severe flooding will continue to intensify as temperatures rise. An international research team led by Newcastle University reports that efforts to mitigate global warming will help to limit the increase in extreme rainfall, but some societal adaptations will still be required.

“Climate change increases the frequency and intensity of extreme rainfall because a warmer atmosphere holds more water vapor that can rain out, sometimes over a short period. The movement of water vapor through the atmosphere, in storms, is also modified,” explained the study authors.

“Increases in extreme rainfall have been observed in many parts of the world. Extreme rainfall, in turn, can increase the chance of floods occurring and their magnitude in small and in urban catchments, severely impacting local populations and infrastructure.”

On the other hand, floods in larger, rural catchments are influenced by many different factors. These floods are less directly linked with extreme rainfall events.

The analysis of 170 scientific studies suggests that increases in daily extreme rainfall rates have been observed on continental scales throughout the 20th and early 21st centuries, and that global warming is driving increases in short-duration rainfall extremes in some regions. 

The findings show that the risk of flash flooding in urban areas has been growing in recent decades. This increase is linked to expanding impermeable landscape that causes surface runoff.

“Global warming means the atmosphere can hold more moisture and could also change the way storms behave. More intense rainfall extremes coupled with changes in other factors could increase the frequency and severity of flooding in many regions,” said study lead author Dr. Stephen Blenkinsop.

“Even if action is taken to limit the extent of global warming we will need to improve our understanding of how extreme rainfall and flooding will change in the future in order to adapt our cities and other communities to more frequent or more extreme events.”

“This is an active area of research and our review highlights that the science is becoming increasingly clear on how climate change influences extreme rainfall and how that combines with other factors to increase the chance of floods in many places,” said Adam Smith of the University of East Anglia.

The study is published in the journal ScienceBrief Review.

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By Chrissy Sexton, Earth.com Staff Writer