Sir Sadiq Khan’s plan to build homes on the Green Belt will increase the risk of Londoners having their lives and homes wrecked by climate change, experts have warned.
They said building on the currently protected areas mostly in the suburbs would increase the “urban heat island” effect and result in higher risks from heatwaves and wildfires.
The intervention comes in a report published by the Grantham Research Institute on Climate Change and the Environment at the London School of Economics.
The report warns: “Without adaptation to improve London’s resilience to the impacts of climate change, growing numbers of lives and livelihoods across the capital will be damaged and lost.
“Without adaptation, London will become a riskier place to live and work, and it will find it difficult to compete for workers against other cities that are more resilient.”
The London mayor, in a major policy U-turn, announced in May that he would permit thousands of homes to be built on parts of the Green Belt, in particular areas with good transport links.
However he did not specify how many homes he had in mind, nor the locations – saying both issues were for the next edition of the London Plan, the mayor’s planning blueprint for the capital.
Sir Sadiq said he was relaxing restrictions on the Green Belt because housebuilding, which has been focused on “brownfield” sites, was “still falling way short of the needs of our city”.
Last week the London Assembly’s annual housing monitor revealed that the number of affordable homes being started with help from City Hall was at the second lowest level since Sir Sadiq became mayor in 2016.
Sir Sadiq has been given £4bn by the Government and the target of starting 17,800 affordable homes between 2021 and 2026.
However, with just a year to go, work has yet to start on more than 12,000 properties – a situation described by the assembly as helping to turn the housing crisis into a housing emergency.
In its response to the consultation on the new London Plan, the Grantham Institute said the mayor had failed to “embed” the findings of his own London Climate Resilience Review into his housebuilding vision.
This was published only a year ago and found that London was significantly exposed and vulnerable to climate change impacts, such as extreme heat.
The Grantham submission, written by Bob Ward, said: “It is somewhat disappointing that the consultation document does not make the Review’s recommendations a central theme and only explicitly mentions it twice in 76 pages.
“This failure gives the impression that implementation of the review’s recommendations is no longer a priority for the mayor. This would be extremely disappointing if it is true.”
Referring to the problems caused by building on the Green Belt, it says: “It should be noted that building on the Green Belt is likely to increase the urban heat island effect, leading to greater risks of overheating buildings and infrastructure.
“In addition, new buildings on Green Belt land may be exposed to greater risks of impacts from wildfire if they are located near to large areas of vegetation.”
Thomas Turrell, environment spokesman for the City Hall Conservatives, said: "The mayor needs to listen to the vast number of bodies and individuals warning him of the risks of concreting over the Green Belt, and back down from this disastrous policy - which his own administration acknowledges does nothing to make housing more affordable."
The next London Plan is expected to be published in 2026, with the final adoption anticipated in 2028.
City Hall sources described the intervention from the Grantham Institute as “alarmist in tone” and said many of its recommendations required Government action.
A spokesperson for the mayor said: “The climate crisis is one of the biggest threats we face, and the mayor is doing all he can to tackle this issue.
“This is why he commissioned the London Climate Resilience Review, to ensure London is better prepared to tackle the impacts of climate change.
“The consultation on ‘Towards a New London Plan’ has just closed and City Hall will be considering all the responses ahead of producing the next Plan. ”
