Climate change made floods in Europe at least 20% more likely

The downpour was likely made heavier by climate change as well. A day of rainfall can now be up to 19% more intense in the region than it would have been had global atmospheric temperatures not risen by 1.2 degrees Celsius (2.16 degrees Fahrenheit) above preindustrial temperatures, according to research published by the World Weather Attribution (WWA) scientific consortium.

"We will definitely get more of this in a warming climate," said the group's co-leader Friederike Otto, a climate scientist at the University of Oxford.

"Extreme weather is deadly," said Otto, recalling that she urgently contacted family members who live in the affected areas to make sure they were safe when the floods hit. "For me it was very close to home."

With extreme weather events dominating news headlines in recent years, scientists have been under increasing pressure to determine exactly how much climate change is to blame.

During the last year alone, scientists found that U.S. drought, a deadly Canadian heat wave and wildfires across the Siberian Arctic have been worsened by a warming atmosphere.

The July 12-15 rainfall over Europe triggered flooding that swept away houses and power lines, and left more than 200 people dead, mostly in Germany. Dozens died in Belgium and thousands were also forced to flee their homes in the Netherlands.

Although the deluge was unprecedented, the 39 WWA scientists found that local rainfall patterns are highly variable.

So they conducted their analysis over a wider area spanning parts of France, Germany, Belgium, the Netherlands, Luxembourg and Switzerland. They used local weather records and computer simulations to compare the July flooding event with what might have been expected in a world unaffected by climate change.

Because warmer air holds more moisture, summer downpours in this region are now 3-19% heavier than they would be without global warming, the scientists found.

And the event itself was anywhere from 1.2 to 9 times -- or 20% to 800% -- more likely to have occurred.

That broad range of uncertainty was partly explained by a lack of historical records, WWA explained, and worsened by the floods destroying equipment that monitored river conditions.