Monday’s report from the Intergovernmental Panel on Climate Change indicated that among other consequences of global warming, heavy rains fueled by warmer air will increase the number of deadly floods across the planet, a trend that many researchers say is already under way.

The recent flooding disasters in Germany, China and Afghanistan share a characteristic that is on the rise: flash flooding. It isn’t clear whether such individual events can be blamed on climate change, even though generally higher temperatures can cause more moisture to gather in the atmosphere. And other factors like the age of infrastructure and river management can contribute to death tolls from flooding.

But as intense rains have become more common across the globe, these types of rapidly moving and often deadly flood events have increased in number over the past decade, according to Robert Brakenridge, founder and co-director of the Dartmouth Flood Observatory at the University of Colorado. The observatory maintains a database of the largest floods world-wide, including information about their size, duration, causes and effects.

Three of the five deadliest floods so far this year were caused primarily by torrential rain—high intensity storms often lasting a short period of time and a major cause of flash flooding.

Flash flooding occurs within minutes or a few hours of excessive rainfall lasting generally six hours or less, according to the National Weather Service. These types of floods are particularly deadly because they rise quickly, catching people off guard and trapping them in buildings or vehicles.

Heavy-precipitation events leading to flash flooding have increased in recent decades. In the U.S., extreme rain events have been occurring more frequently across an expanding land area.

In Europe, instances of “extreme precipitation potential”—when the right ingredients are present in the atmosphere for extreme rainfall—are expected to rise dramatically by the year 2100, according to a research paper published in June in Geophysical Research Letters.

The deadly floods in Germany illustrate an additional effect of flash flooding. Many of the most heavily flooded areas were on smaller river tributaries or streams, not large, main branch rivers such as the Rhine. The torrential downpour rapidly inundated many of these smaller tributaries, destroying homes adjacent to or near the riverbanks. As heavy rainfall events increase in number, these types of smaller waterways will be even more prone to flash flooding.