LONDON — Brian May is best known as the songwriter and guitar god who backed Freddie Mercury in the British band Queen. He has a doctorate in astrophysics and studies asteroids as a hobby. But lately, Mr. May has gotten attention for the kind of earthbound problem that plagues ordinary mortals: a flooded basement.
When a torrential downpour on July 12 inundated London, dumping a month’s worth of rain in a single day, sewage backed up into Mr. May’s basement, soiling his carpets with a “stinking sludge” and wrecking photo albums, scrapbooks and other treasured mementos, he recounted on his Instagram account.
“It’s disgusting, and actually quite heartbreaking,” Mr. May wrote, likening the ordeal to being “invaded” and “desecrated.”
There was an especially cruel poignancy to the floodwaters finding Mr. May’s cellar, which is standard size and came with his gracious house in moneyed Kensington. For years, he has been a withering critic of wealthy neighbors who tunneled deep into the ground to install multistory basements, complete with swimming pools, wine cellars, movie theaters and exotic-car showrooms.
To Mr. May, these vast subterranean complexes are not only a symbol of wretched excess but also an abuse of their neighbors, who had to suffer through years of head-pounding noise as excavators clawed the London clay. Now he has added a climate-related charge: oversize basements obstruct underground aquifers and interfere with natural drainage, causing sewage overflows of the kind that hit him.
With his homeowner’s howl, Mr. May has managed to knit together two politically resonant issues: the escalating threat from extreme weather, which scientists broadly agree is a manifestation of climate change, and the environmental impact of years of extravagant building projects by London’s superrich.
“Digging down can be seen as environmentally bad or environmentally good, depending on your perspective,” said Tony Travers, an expert in urban affairs at the London School of Economics. “But if you’re building a basement and you’re rich, you’d be well advised to install a pump.”
Mr. May’s rock-star fame and scientific credentials, Professor Travers said, guaranteed that his warnings would register with people, certainly more than another academic paper or a Cassandra-like politician. The musician’s story has focused attention on London’s vulnerability to the effects of climate change, which are real, if less obvious than in low-lying coastal cities like Miami or Mumbai.
The problem, Professor Travers said, is that London’s weather is usually so moderate and predictable that no single weather episode, however damaging, is likely to galvanize politicians into taking major action to climate-proof the city.
Alarmist reactions to bad weather are a well-worn London tradition: Heat waves bring warnings of buckled railroad tracks; a light coating of snow paralyzes the streets. But they tend to wash away with the return of clouds and drizzle.
Even if there was a climate reckoning, the most obvious remedy — rebuilding London’s Victorian-era sewage system, which was built to serve a city less than half the size it is today — would be prohibitively expensive. The city is currently digging a giant tunnel system, the Thames Tideway, to carry sewage that flows into the river when it rains. The cost of that alone is nearly $7 billion.
“There’s no question that this Victorian infrastructure is not capable of handling that much water,” said Roger Burrows, a professor of cities at Newcastle University. “Poor Brian May’s basement is merely an example of that.”
Professor Burrows, who has written about the proliferation of megabasements in London, said it was a stretch to blame them for overflowing sewers. After all, the city already sits on a vast amount of excavated underground space, most recently the Elizabeth line, a new 60-mile railway that currently connects Paddington Station and Liverpool Street Station and will ultimately link Heathrow Airport in the west with Essex in the east.
But, Professor Burrows added: “The very fact that the superrich and merely wealthy have extracted 12 times the mass of St. Paul’s Cathedral from under London is bound to have an effect. The water is going to go somewhere.”
He predicted a noisy era of “subterranean politics,” with critics who have derided megabasements as playthings for oligarchs now able to brand them as climate villains, the rich-neighborhood equivalent of coal-burning power plants.
Mary Dhonau, a consultant who advises on flood risks, said that large basements were only one of several factors that conspired to make London more susceptible to flooding. Homeowners had also paved over the equivalent of about 22 Hyde Parks — or around 10 Central Parks — in their gardens to create parking spaces. That makes the ground less permeable to rainwater, which is then forced into their homes, she said, “almost like a waterfall.”
“When you remove that much earth in any given location, you’re losing places for the water to percolate through and seep away naturally,” Ms. Dhonau said. “There are a lot of things happening in London that when you put them together, it makes the flooding so much worse.”
As a city that sits on a floodplain, London has already taken some important steps. In addition to the Thames Tideway, scheduled for completion in 2025, the city in 1982 built a gargantuan retractable barrier in the Thames River to hold back water from storms and from tidal surge flowing up from the North Sea. In its first decade of operation, it was closed 10 times; in the past decade, it has been closed 80 times.
Now, city officials are talking about installing three-foot-high glass barriers along a stretch of the Thames to prevent the river from bursting over the existing barricades. They also say they will have to upgrade or retrofit other floodgates. And some parts of London are restricting development in flood-prone areas.
The market for sprawling basements has cooled anyway, in part because the local authorities are stingier in approving their construction. Homeowners must submit costly hydrology, geology and soil-testing reports, according to Paul Schaaf, a partner in the Basement Design Studio, which has designed more than 2,000 of them.
Mr. Schaaf disputes the contention that other people’s basements caused the flooding in Mr. May’s house. Water, he says, finds a way to flow around such obstacles. As for the basements he designs, technological advances now allow homeowners to install sophisticated pumps to keep their premises dry, he noted. At some point, however, Mr. Schaaf conceded, it is a simple matter of physics.
“If the water level is one foot above the manhole outside your house,” he said, “there’s nothing you can do.”
For his part, Mr. May seems to be trying to move on. Asked to elaborate further on his views about basements and flooding, his publicist declined, saying Mr. May was busy preparing for the reissue of his 1992 album — aptly named in these stormy times — “Back to the Light.”
Anna Joyce contributed reporting.