Heavy rainfall that caused once-in-a-lifetime floods in Europe, killing hundreds of people this summer, was made more likely by climate change.
The flooding caused at least 184 deaths in Germany, plus 38 in Belgium, as well as damaging houses, motorways, railway lines and bridges.
Researchers from World Weather Attribution say global warming has made rainfall events such as these nine times more likely in Western Europe.
Rainfall in the area is already 3-19% more intense due to human-caused climate change, the researchers say.
Watch: Devastating flash floods hit Germany
The researchers wrote: “The severe flooding was caused by very heavy rainfall over a period of 1-2 days, wet conditions already before the event and local hydrological factors.
“The observed rainfall amounts in the Ahr/Erft and the Belgian part of the Meuse catchment broke historically observed rainfall records by large margins.
“The likelihood of such an event to occur today compared to a 1.2C-cooler climate has increased by a factor between 1.2 and 9 for the 1-day event in the large region. The increase is again similar for the 2-day event."
Events such as the floods would previously have been once-in-400-year events, the researchers wrote, but will now become more frequent.
The researchers wrote: “All available evidence taken together… give high confidence that human-induced climate change has increased the likelihood and intensity of such an event to occur and these changes will continue in a rapidly warming climate.”
This month’s UN climate change report warned that extreme weather events like heatwaves and droughts that previously would have happened every 50 years could soon happen every four.
The report was the first to quantify the likelihood of extreme events across a wide variety of scenarios.
It also warned that other "tipping point" events are a possibility, saying: “Abrupt responses and tipping points of the climate system, such as strongly increased Antarctic ice sheet melt and forest dieback, cannot be ruled out”.
Dr Robert Rohde, lead scientist of Berkeley Earth, said: “What were once-in-50-year heat extremes are now occurring every 10 years.
“By a rise of 2C, those same extremes will occur every 3.5 years.”
The report found that (for example) once-in-a-decade heavy rain events are already 1.3 times more likely and 6.7% wetter compared with the 50 years leading up to 1900 when human-driven warning began to occur.
Droughts that previously happened once a decade now happen every five or six years.
Xuebin Zhang, a climatologist with Environment Canada in Toronto warned that as the world warms, such extreme weather events will not just become more frequent, they will become more severe.
Zhang said the world should also expect more compound events, such as heatwaves and long-term droughts occurring simultaneously.
He said: “We are not going to be hit just by one thing– we are going to be hit by multiple things at the same time.”
Watch: Deadly flash floods increasing globally with climate change