The intense rains that fell across western and southern Germany in July were both devastating and historic. Up to eight inches of rain fell in less than 24 hours, flooding communities and causing more than 200 fatalities. In some areas, rainfall so intense was expected only once every 500 years.For hydrologist Manuela Brunner, the catastrophic flooding event was alarming for another reason.

About a year earlier, Brunner and her colleagues began investigating how flood patterns would change in a warming world in southern Germany. They found that not only will extreme precipitation events occur more often and intensely, but also extreme flooding in this area. Weeks before their paper was published, their projection came to life.

“This is totally a coincidence. We couldn’t obviously tell this was going to happen this summer,” said Brunner, a lecturer at the University of Freiburg and lead author of the study. But she said this flooding is exactly “the type of event for which we’re showing an increase in flood intensity or also flood frequency in the future.”

As global temperatures rise, researchers have been investigating how a warmer climate will affect flooding patterns. Although precipitation events have undoubtedly increased in frequency and intensity, researchers have been unable to clearly discern how flooding will change — until now.

New research by Brunner and her colleagues shows the occurrence and intensity of extreme flood events will increase, but smaller and more moderate floods will probably decline.

“There is extensive evidence that climate change is increasing the frequency and intensity of extreme precipitation events around the world, but much less evidence that flood events have increased over the same period,” wrote Daniel Swain, a climate scientist at the University of California at Los Angeles and a co-author of the paper.

“This new research demonstrates how climate change could actually have divergent effects for very large but rare floods versus smaller but more common floods,” he said.

Swain said additional work would be needed to confirm that this flooding behavior applies more broadly around the world but suspects it probably does.

Tropical Storm Ida caused flooding and power outages throughout New Jersey as the Northeast was hit by record rain and tornadoes. (Michael M. Santiago/Getty Images)

Brunner and Swain, along with colleagues at the National Center for Atmospheric Research and Ludwig-Maximilians University of Munich, looked at the relationship between precipitation and flooding for 78 watersheds in Bavaria, Germany.