AN expert warned flash flooding seen in Edinburgh last week when half the rainfall in July was recorded in one hour will begin to happen more regularly with climate change. 

Research shows 50mm of rainfall in a day is a one in 100-year event in Edinburgh, yet on Monday, July 5, 40mm fell in just an hour at the Botanical Gardens.

The capital recorded half the rainfall in July in just one hour on Sunday (July 4), with residents describing it as “biblical” as streets were underwater.

A climate change researcher has warned extreme events like this are going to become common as the climate crisis unfolds, and could even get worse if action is not taken. 

Homes and business premises were flooded and the city’s newly-opened 
St James Quarter was flooded as the thunderstorm struck on Sunday afternoon and persisted on to Monday. 

Dr Kate Crowley, co-director of the Edinburgh Climate Change Institute, said: “We are going to see more of these extreme events, so we need to take some action.
“We are likely to experience more of this kind of intense, extreme event due to climate change in the future.”

“That amount of rain in a period of time causes the problem, especially in cities where we have tarmac-ed everything so it’s very difficult for rain to seep into the ground.

“You get surface water flooding when it rapidly flows off, there’s almost too much water for the drainage systems to manage. 

“They’re not designed to absorb so much of this water so quickly. It just runs through the streets.”

Dr Crowley points to research by one of her students, Shane O’Neil, who is studying extreme precipitation risk in the Edinburgh area.

His research found that rainfall levels during events like this could potentially increase by 20 to 50 per cent in the Greater Edinburgh region in the future.

Autumn and winter seasons cause the most concern, where Edinburgh could see extreme rainfall events increase by greater than 50 per cent  in the 2030s through to the 2070s. Strong, intense downpours could also become more prevalent in summer months due to a warming atmosphere.

Dr Crowley added: “We need to see if we can adapt our city to manage these kinds of events.

“But also we need to make sure new builds take into account these possible changes due to climate change.

“We know that these events are going to happen again in the future, so it’s about preparing as best as you can now.”

She said more financial support is needed to local authorities to fight these events. 

Dr Crowley said: “That needs to come from central government and big political change.”

“It’s about changing how we behave and how we prepare and respond to the impacts of climate change we are likely to see in the future.

“It’s things like educating the public not to walk through floodwaters as it’s very dangerous. 

“We need flood defences to reduce the risk from these kinds of hazards.

“I have worked in adaptation for a long time and never before have I seen the appetite that we have at the moment to get stuff done.

“Never before have we had politicians on board and everyone saying we have a serious problem and we need to address it.

“I’m no longer having to persuade people that it’s important. 

“I feel quite hopeful.”

According to a recent study, reported earlier this week, human-caused climate change has already changed the world, making it wetter, snowier, and potentially more hazardous. 

Scientists from the University of California in Los Angeles used machine learning methods to prove that human-caused climate crisis has already intensified extreme precipitation occurrences, both rain and snow, in recent decades, as published in the journal Nature Communications.

If left uncontrolled, it is also likely that human activities will continue to contribute to extreme wet weather occurrences in the future, it warned.