Extreme heat and the impact of climate change could cost the capital up to £36 billion a year by the 2050s unless further action is taken, a report has said.
The Heat Ready London Technical Report, commissioned by the Mayor of London, provides the detailed evidence behind Heat Ready London – the capital’s first city-wide vision for adapting to rising temperatures.
It examines the growing impact of heat on Londoners’ health, homes, public services, infrastructure and economy. It warns without further adaptation, climate change could cause annual damage equivalent to as much as 3% of London’s economy by the 2050s – or between £16 billion and £36 billion a year, depending on economic growth
The £36 billion figure, includes lost working hours and reduced productivity, greater pressure on health and emergency services, disruption to businesses, and damage to essential infrastructure.
Such consequences were seen during the 2022 heatwave, when buckled rails caused cancellations and speed restrictions, the failure of two data centres at Guy’s and St Thomas’ hospitals disrupted patient care and required £1.4 million of unplanned spending, and London’s water consumption rose by 50%.
Lost productivity linked to high temperatures is estimated to cost London £577 million annually and accounted for almost 90% of the estimated £1.5 billion cost of London’s three heatwaves in 2022.
The danger is not limited to days of extreme heat, with the report highlighting that approximately 90% of heat-related deaths in London occur when temperatures are between 24°C and 32°C.
It also shows that acting now could save lives and avoid far greater costs in future. London’s parks and green spaces are estimated to provide more than £90 billion in benefits over 30 years—approximately £27 for every £1 spent.
The Mayor and London Councils are bringing together boroughs, health and care partners, emergency responders, infrastructure providers, businesses, financial institutions and community groups to support the delivery of Heat Ready London.
The Mayor of London, Sadiq Khan, said:
“The climate crisis is on our doorstep. It is already threatening Londoners’ lives, disrupting vital services and costing our economy hundreds of millions of pounds.
“When I unveiled Heat Ready London in June, we set out a city-wide vision for protecting Londoners and preparing the capital for a hotter future. This detailed evidence shows why that work is so urgent—and the enormous human and economic cost of failing to act.
“Without further action, climate change could cost London as much as £36 billion a year by the 2050s. We must create cooler homes and buildings, greener and shadier neighbourhoods, and infrastructure that can withstand a hotter climate.
“No organisation can do this alone. I will continue working with boroughs, government, businesses, health services and communities to protect those most at risk and build a safer, greener and more resilient London for everyone.”
Mete Coban, Deputy Mayor of London for Environment and Energy, said:
“This important report gives us the evidence and clear priorities needed to accelerate action to tackle extreme heat and the impacts of climate change . By adapting the homes and buildings most at risk, creating greener and shadier neighbourhoods and strengthening vital infrastructure, we can protect vulnerable Londoners, reduce inequalities and avoid far greater costs in the future.
“Delivering this will require sustained investment and close collaboration across government, boroughs, businesses and communities. Heat Ready London provides the city-wide framework to bring that work together and build a fairer, greener and more resilient capital for everyone.”
Professor Emma Howard Boyd CBE, Chair, National Heat Risk Commission and former Chair of the London Climate Resilience Review said:
“I welcome the Mayor’s leadership in getting ahead of climate impacts rather than simply reacting to them. Heat Ready London builds on the London Climate Resilience Review, turning evidence into action.
“But delivering it at the pace these health, economic and national-security risks demand means giving mayors statutory climate-resilience duties and funding that matches their growing powers—reaching the communities at greatest risk first.”
London Councils Executive Member for Transport and Environment, Cllr Paul Osborn, said:
“Our city’s infrastructure must adapt to a changing climate, and that means collective, coordinated action and greater investment.
“Whether it’s providing cool spaces or stepping in to keep our most vulnerable residents safe whenever the heat hits, boroughs are proud to be Heat Ready London partners, working to make sure our city’s infrastructure is ready for what’s ahead.”
Dr Tom Coffey OBE, Mayoral Health Adviser and London GP, said:
“This report sets out how by working together with our partners including Local Authorities, the NHS, emergency responders and community groups we can turn the Heat Ready London vision into action and protect Londoners’ health into the future.”
Lilli Matson, Chief Safety, Health and Environment Officer at TfL, said:
“We are working with agencies across London and beyond to develop a coordinated approach and manage the adverse impact of higher temperatures on our network, from track and road surface resilience to customer comfort and staff welfare.
“We’re already taking action to make London’s transport network more resilient, including the upcoming introduction of new air-conditioned trains on the Piccadilly line and DLR and the introduction of new air-conditioned buses. This builds on air-conditioned Tube trains covering 40 per cent of the network and every Elizabeth line and London Overground train being air conditioned.
“With more frequent and intense heatwaves likely in the future, it is vital that we help London become a more climate-resilient city and ensure that the transport network continues to operate safely and reliably.”
John Dickie, Chief Executive at BusinessLDN, said:
“This new research underscores the vital role that investment in climate resilience plays in supporting London’s economy. Rising temperatures affect businesses in a range of ways – such as disruption to travel services, reduced customer footfall or staff being unable to work effectively. It’s really positive to see the Mayor leading coordinated action to mitigate these effects and keep London growing.”
Francis Heil, Associate Director in Climate Change & Resilience at AtkinsRéalis, said:
“The evidence suggests that investing now reduces long-term costs in terms of impacts on health, productivity, infrastructure, and the environment. It also saves lives and creates opportunities for innovation and green British jobs along the way.
“It’s a really positive step to see the launch of the Technical Report that we have helped develop, working alongside the Greater London Authority, London Councils and stakeholders across London.
“Heat risk is a challenge for a globally important city like London, but we have the data, the tools, and the economic case to act.”
Image of report courtesy of Mayor of London
