Hot London Real Estate Faces High Flood Risk, Climate Change Troubles

That vision of Hackney Wick would have been ­unrecognizable on July 25 last year, when heavy rains sent flash floods through the grounds marked out with flags by property developers. Carl Edlund, who manages HWK, a coffee shop and event space, describes water coming out of nowhere and quickly seeping into the premises just as dozens of people gathered on what was the first weekend in months that social distancing rules had been lifted. The crowd was trapped by rushing waters.

“I knew it was going to rain but wasn’t expecting flooding,” Edlund says more than six months later as he unloads beer from a van in preparation for the Friday night rush at HWK.

Most of London’s 32 boroughs saw some flooding during the storm. Residents waded through knee-deep water and sewage that had washed back up through a ­centuries-old drainage system. Some people used kayaks to get around. Key infrastructure was paralyzed across the city that day. It’s a scene that’s set to play out more regularly in the British capital.

Hackney Wick’s plight is worth a closer look, because it’s both more prone to flooding than other parts of London and also one of dozens of “opportunity areas” designated by Mayor Sadiq Khan for development to alleviate a housing shortage. Developers are being encouraged to build on flood-prone areas, with some projects approved despite dire warnings of risks from more extreme weather as London’s climate changes.

At least 19 of the 28 opportunity areas contain zones that have been flagged as vulnerable to flooding in a map compiled by London’s City Hall and Bloomberg Associates, the consulting arm of Bloomberg Philanthropies. The map takes into account rainfall patterns along with 16 other metrics that affect residents’ ability to deal with flooding, including socioeconomic status and proficiency in understanding English-language warnings.

The current data used in the maps ­understate the risks from global warming in the near future. Scientists have found evidence that the atmosphere can hold 7% more moisture for every degree of warming. That means flood risks are expected to occur more often and, potentially, more intensely. The frequency of torrential rains in London in the fall and winter have increased over the past few decades and is set to rise even more over the course of the century, according to weather experts at the U.K.’s Met Office. Climate modelers at the agency’s Hadley Centre say that London, like much of the U.K., is expected to see a doubling of extreme rainfall days by 2070.

That’s what makes plans to add homes in the opportunity areas so alarming to experts. To build safely on flood plains means ensuring that resources go into flood monitoring, data collection, and protection ­measures—something they say London hasn’t invested in ­sufficiently­—as well as working closely with local communities, which often are best placed to understand where the riskiest areas are. Officials in London over the years have taken steps to mitigate flood risk, given that the city is not only the capital but also a financial hub. In February, when three successive major storms hit the U.K., London came through relatively unscathed, and overflowing rivers caused widespread destruction in the West Midlands and Yorkshire.

But the recent efforts to address the city’s ­housing shortage aren’t keeping up with accelerating global warming, says Grace Newcombe, a researcher at think tank Localis, who studies local development. “It’s instead paving the way for a collision between the housing and the ­climate crises,” she says.

But the barrier also creates a false sense of security, because it’s designed for last ­century’s climate and equipped to deal with only one type of flooding.

Rather than water spilling over from the River Thames or its tributaries, the city’s biggest flood risk in this century is from rainwater overwhelming the drainage system. Water then bubbles up from underground in random places at unexpected times. As London has expanded, in terms of both concrete and people, its 150-year-old sewer system has come under increasing strain. A lack of permeable surfaces means more rainwater ends up in the brick-lined tunnels, which have to carry both water and sewage. The system was built for only 2.5 million people, when Queen Victoria sat on the throne, not the more than 9 ­million residents who live there today. London’s population is expected to exceed 10 million by 2036.

Surface water flooding, as the phenomenon is known, is so hard to predict that many people don’t realize the danger until it’s too late. Sixty-two percent of households in the U.K. in areas at risk of flooding don’t believe it will happen to them, according to a survey conducted in February 2021 by the Environment Agency (EA). Cloud to Street, a global flood mapping company, has identified at least 15 instances of surface water flooding in London from 2002 to 2017.

“Everybody sees flooding as being an issue of the Thames, whereas in reality that’s protected,” says Paul Cobbing, chief executive officer of the National Flood Forum, a charity that helps people whose homes are at risk of flooding. “The bigger risk is surface water. It’s much more random, and it requires very, very detailed, complex, and local interventions.”

“It was devastating,” he says. “It destroyed my ­business, and it’s taken up until now to get back on my feet. I just wanted to cry.” The 30-year-old grew up around Hackney Wick and blames the area’s rapid development for the flooding. The influx of hundreds of thousands of people into the neighborhood is good for business, but they’ll also put undue pressure on an already stretched ­drainage ­system. The next time there’s a flood, more than just a party could get washed out.

The July flooding sent sewage into a ­children’s unit at one hospital, and another hospital took on 3 feet of water and closed three wards after backup generators failed. At the peak of the flood, the fire brigade received 1,500 calls and attended to almost 800 incidents. Across the London Underground, 14 stations had to close, and above-ground trains were also overwhelmed.

White Post Lane has now been classified as a flood zone, pushing up insurance costs. Still, construction in Hackney Wick continues at a rapid pace. It’s located in Olympic Park—the site of the 2012 Summer Games—where 39,000 new homes are planned for the next 20 years. Along the Hertford Union Canal, a former recycling center is being converted into a development called Wickside; it will have almost 500 apartments as well as shops, restaurants, and a microbrewery.

McGrath Group, a waste management company, secured permission two years ago to start construction despite objections from the EA, a national agency that oversees the Thames Barrier and associated flood risks. The site has a high probability of flooding, and official maps show that part of the future development lies outside the tidal flood protection zone, meaning it’s beyond the areas guarded by such infrastructure as the Thames Barrier. The EA’s warnings about the residential project go back to 2016, when the agency deemed people sleeping on the ground floor to be at deadly risk.

McGrath sold the land anyway to Galliard Homes Ltd., which is now marketing Wickside apartments, slated for completion at the end of 2024. The London Legacy Development Corp., a public-private organization in charge of regenerating the Olympic Park, approved the application. Ruth Holmes, an LLDC executive, says it has to balance flood risk and the need to build homes when assessing submissions. LLDC says Galliard promised to address the EA’s concerns, including by turning areas in one block meant for homes on the ground floor into commercial space.

Galliard is still offering apartments with rooms on the ground floor in other blocks to prospective buyers for £800,000 ($1.1 million). The company is assuming that residents are fit and agile enough to escape if flooding strikes, says Cobbing of the National Flood Forum. He paints a worst-case scenario in which residents could be asleep as a ­ground-level room starts filling up or of water rushing in at high velocity and knocking people over, with deadly consequences. Flooding could also leave lingering emotional scars: Cobbing says he still gets calls from people who were flooded a decade ago and are scared to leave their home unattended for prolonged periods. Galliard declined to comment.

In a sign of his faith in the neighborhood’s ­rejuvenation, Khan, the mayor, has moved his offices there. He’s called a shortage of homes the biggest threat facing London, one of the world’s most expensive places to live. He says the city needs at least 66,000 new homes annually for the next two decades—only about half of that was added in the last financial year. Rents fell sharply in 2020, but they’ve since risen at a record rate as lockdowns have lifted. Many young people are struggling to purchase starter homes.

The demand for new homes has pushed some officials to ignore their own local policies on flooding. Newham Council in 2019 approved plans for a four-story housing development on Albert Road, a strip sandwiched between two bodies of water, even though the EA twice objected to it because of flood risk. The authorization goes against the council’s local plan, which lays out a framework for approving building applications and where the council agreed to always adhere to EA flood advice.

The development, designed by MGL Architects, sits right outside the Thames Barrier’s protection zone, where a breach of tidal flood defenses could have “a devastating impact due to the depth and velocity of the flood water,” according to the EA. Newham Council approved the project after the architects agreed they would either refrain from building bedrooms on the ground floor or install a barrier if they did. These adjustments didn’t keep the EA from maintaining its objections. Newham Council and MGL didn’t respond to questions.

Every year, the EA publishes a sample of projects in which its advice was ignored. Looking at only 66% of applications from the past decade, the agency says councils across the U.K. granted permission for at least 6,000 homes over their protests. A couple of them were large developments such as Wickside; most were smaller projects including two-bedroom houses on single plots of land.

Local councils are under pressure to build homes even though their funds have been cut in the wake of the 2008 financial crisis, and flood prevention measures are “­desperately under-resourced,” says Julia King, deputy chair of the U.K. Climate Change Committee. Despite having some of the world’s most ambitious emissions reduction goals, the U.K. isn’t prepared to deal with the extreme weather already caused by current temperature increases, let alone future impacts, says the CCC, an independent body that advises the government on global warming.

Cities elsewhere have drastically reduced the threat of flooding while also producing a more pleasant environment. Hamburg’s HafenCity development, for ­example—which is erecting homes, offices, and businesses on a stretch of disused dockland—has made itself almost floodproof by building its streets and footpaths on a raised sandbank.

There are also ways to safely let floodwater in, using landscaping to create basins where heavy rain can temporarily collect. This technique, dubbed the “sponge city” approach, can be worked into the fabric of new neighborhoods, creating sustainable, attractive cityscapes such as Rotterdam’s Benthemplein Water Square, where storm­water basins double as sports pitches, skateboarding rinks, and event spaces during drier weather.

Pockets of London have successfully implemented flood adaptation measures. Not far from Hackney Wick, swaths of the Olympic Park have been transformed into green and blue spaces that can absorb ­rainwater while providing a habitat for birds and other wildlife. The area was particularly vulnerable to flooding. A branch of the Thames coming from the south meets the River Lea from the north, and a tidal surge coupled with heavy rain could quickly overwhelm homes farther upstream. Planners designed a system of ponds and wetlands that can channel water back into the Lea, whose steep riverbanks are better equipped to contain it.

In Hammersmith and Fulham, which sits on the Thames in West London, concrete pavements have been replaced by permeable material made from recycled rubber, and rain gardens help slow water runoff. Homeowners throughout the city have also taken to installing seals on doors or using materials on the ground floor, such as stainless steel instead of wood, that can be easily cleaned after an inundation.

But larger-scale adaptations are mostly missing. The biggest project that needs to be done in London is expanding the ancient sewer system. Thames Water Utilities Ltd. is building a £5 billion tunnel—a super sewer of sorts—to help curb the amount of untreated sewage that’s pumped into the Thames. Still, Khan says that won’t fix flooding and other water-related problems because ­climate change, urban development, and population growth are simply happening too fast.

Since becoming mayor in 2016, Khan has put forward a series of strategies to boost London’s resilience in the face of climate change. He demanded an investigation into how to respond better after the July floods.

But Shirley Rodrigues, who’s been Khan’s deputy in charge of environment for the past five years, says City Hall’s hands are tied as long as no single organization has responsibility for surface flooding. Her office wants the government to appoint a body. If that power isn’t given to the mayor, she says, it should be handed to the EA or perhaps London Councils, which represents the city’s districts. The U.K.’s federal environment department said it’s spending £5.2 billion on flood defense, but local authorities have the main responsibility for tackling flooding.

Rodrigues says it was just luck that no one was killed in July. She’s become increasingly concerned that authorities don’t know where people are living in basements, don’t have enough data on where risk lurks, and don’t communicate well with endangered residents.

“The governance of surface water flooding is massively complicated,” she says. “We just need to know where the hell they are and to make sure the local emergency responders at least know if it happened in their patch.”

Several major cities were inundated with extreme ­rainfall last year. In July heavy rains swamped Germany as well as parts of Belgium, Luxembourg, and the Netherlands, killing more than 200 people and causing $40 billion in damage. A week later more than 400,000 people had to be evacuated from the Chinese city of Zhengzhou during a rainstorm that brought a year’s worth of precipitation in three days. Houston has seen floods with a 1-in-500-year probability three years in a row.

“London’s climate has been mild for thousands of years. Even the extremes were moderate by global standards,” says Spencer Glendon, founder of the nonprofit Probable Futures, which uses climate models to map how weather will change around the world. “The city’s infrastructure, architecture, culture, and institutions were all built assuming that this narrow, predictable range of outcomes would persist. We now know that the range is widening and the future is less predictable.”

That is the future that worries Willie Castro, who lives in Clapton, 2 kilometers north of Hackney Wick. The 49-year-old IT worker is always on high alert for flooding after experiencing one in 2014. He’s tried to protect his home by sealing windows and modifying his toilet to prevent water from coming back up.

“Every time it rains, we just panic,” he says. “If it’s a bad storm at night, I wake up and get out of bed to check the levels in the light well.”

The heavy rain that inundated Hackney Wick last July also affected Clapton, along with Barking, Dagenham, and Hounslow, all located in other opportunity areas. Castro’s wife watched as their garden filled up with water. The basement, where his children sleep, soon flooded, and a pipe burst. Six months on, Castro’s family is still living in rented accommodation, having received certification only in late January for repair work to start. That will take at least another month.

Flooding costs homeowners an average of £30,000 in repairs, and businesses often end up paying as much as £82,000, according to the mayor’s office. A February study by Zurich Insurance Group found that nearly half of all basements used by London businesses are at risk. A sharp rise in claims has made companies so reluctant to insure homes from flooding that the government and industry developed a new reinsurance system called Flood Re seven years ago; it helped 300,000 people get coverage.

Castro was able to make an insurance claim, because the damage was technically caused by a storm, not a flood. But there’s little hope he’ll be able to get flood insurance now. “Climate change is here,” he says. “We’re going to have to live with it and just build up our defenses.” — With Olivia Konotey-Ahulu and Feargus O’Sullivan