Nearly half of London businesses at risk of flash flooding, new research shows

Two-fifths of London’s businesses are at risk of flash flooding due to increasingly extreme weather in the capital, new analysis shows.

The research by insurance company Zurich UK showed that 42 per cent of the capital’s 301,000 commercial buildings are likely to be affected by floods in the future as climate change makes storms and torrential rain more likely.

”Extreme weather is the new normal, and businesses need to adapt,” said David Nichols, Zurich UK’s chief claims officer. “It’s crucial that firms urgently assess the flood risks they face and put in place plans to respond and recover.”

The latest report from the Intergovernmental Panel on Climate Change (IPCC) stressed that urgent adaptation around the world is needed to tackle the increase in extreme weather. 

According to the panel, adaptation means introducing measures including building sea walls, growing hardier crops and planting trees, but they warn that progress in the UK so far has been “too slow”.

Of the 301,000 commercial buildings in London, 5,692 are thought to be facing “extreme” or “high” flood risk, with the majority being basement properties.

Four storms have already hit the UK in 2022 alone, causing widespread damage due to rain and record-breaking winds. London was hit by flash floods in summer 2021 when footage shared on social media showed rivers of water running into tube stations and down busy streets. 

“Even at current levels of global warming, we saw the chaos heavy rains caused last year,” Nichols said. “More frequent and severe rainstorms could be hugely disruptive for Londoners, businesses and the city’s economy.”

Zurich named Kensington and Chelsea as the borough with the highest percentage of commercial buildings impacted by flash flooding, with 63 per cent already affected. 

This was followed by Hammersmith and Fulham (56 per cent), Merton (54 per cent), Southwark (54 per cent) and Wandsworth (53 per cent). 

The report also made reference to calculations from the MetOffice which found that the threshold for flash flooding — 30mm of rain per hour — could be two and a half times more likely in London by the 2070s compared to the 1990s. 

“London faces increasing risks from heatwaves and flash flooding: and our ageing infrastructure isn’t keeping up. The impacts will often be worse for Londoners living in inner city areas with high population density and little green space,” said Claire Harding, research director at think tank The Centre for London. 

“As well as making fast and steep cuts to our carbon emissions, governments at all levels must invest in changes which make our city more resilient: improved drainage systems, green spaces that can act as giant sponges, and trees for shade and soil stability.”

An increase of green spaces would take the pressure off London’s increasingly outdated sewage system, making way for eco-friendly alternatives for draining including porous pavements. 

“It’s not too late to prepare our towns and cities for more surface water flooding, but the pace of change is too slow. The government needs to accelerate the retrofitting of sustainable drainage in public spaces, or rainfall will increasingly overwhelm city sewers,” said David Nichols.