The likelihood of such downpours would increase by up to 40% if the world warms by more than two degrees above pre-industrial levels, scientists said.
Extreme rain conditions similar to those linked to a fatal train derailment five years ago will become more common due to climate change, according to a new study.
Researchers found that intense deluges like one that preceded a derailment at Carmont near Stonehaven, Aberdeenshire, which claimed three lives in August 2020 are between 15% and 20% more likely in future due to the warming environment.
Experts said that should the world warm by more than two degrees above pre-industrial levels, the likelihood of such downpours would increase by 30 to 40%.
Train driver Brett McCullough, 45, conductor Donald Dinnie, 58, and passenger Christopher Stuchbury, 62, died following the derailment on August 12 2020 while six people were injured.
A criminal prosecution saw Network Rail fined £6.7 million in 2023 after it admitted health and safety failings over the crash, which happened on a day of torrential rainfall.
Climate scientists from the University of Edinburgh’s school of geosciences and school of physics and astronomy and the Met Office examined data from weather radars and climate models to calculate the extent to which global warming changed the intensity, frequency and distribution of rainfall at and near Carmont.
The team discovered that on the morning of August 12 2020, a huge burst of rainfall lasting for around four hours landed close to the crash site, followed by another severe downpour just one hour prior to the derailment on the Aberdeen to Glasgow line.
A Rail Accident Investigation Branch (RAIB) report published in March 2022 found errors in the construction of a drainage system installed by Carillion meant it was unable to cope with heavy rain which fell in the area on the morning of the crash.
Carillion went into compulsory liquidation in January 2018.
Professor Simon Tett, chairman in earth system dynamics, school of geosciences, University of Edinburgh, said: “Climate change is not only increasing the risk of heatwaves but also extreme rainfall.
“Scotland would be wise to prepare for heavier summer deluges as the climate continues to warm.”
The researchers found more frequent extreme rainfalls will increase the risk of flash floods in urban areas and cause more damage to infrastructure.
Previous research has shown the earth’s atmosphere and oceans are currently 1 to 1.5 degrees warmer compared to conditions in the late nineteenth century.
Scientists said a warmer atmosphere holds more water and extreme rain happens when all the water in the atmosphere falls out.
The paper, published in the journal Environmental Research Climate, was funded by the University of Edinburgh and the Met Office Hadley centre climate programme, funded by the UK Department of Science, Innovation and Technology (DSIT).
A fatal accident inquiry is to be held into the train derailment.
Network Rail previously said it is determined to build on the “significant changes” it has made since the incident, which have “helped us to manage the risk of severe weather to the network”, and it has invested millions to improve the resilience of the railway.