A major new report published today by the Mayor of London and London Councils reveals extreme heat and the continued impacts of climate change could cost the capital up to £36 billion a year by the 2050s unless further action is taken.
The Heat Ready London Technical Report, commissioned by the Mayor, provides the detailed evidence behind Heat Ready London—the capital’s first city-wide vision for adapting to rising temperatures, unveiled by the Mayor in June.
The report examines the growing impact of heat on Londoners’ health, homes, public services, infrastructure and economy. It warns that, without further adaptation, climate change could cause annual damage equivalent to as much as three per cent of London’s economy by the 2050s.
Depending on future economic growth, this could amount to annual damage of between £16 billion and £36 billion a year.
The £36 billion figure is not a single bill, but an estimate of the potential annual damage climate change could cause across London’s economy.
This includes lost working hours and reduced productivity, greater pressure on health and emergency services, disruption to businesses, and damage to essential infrastructure. The 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 per cent.
The economic impact is already being felt. Lost productivity linked to high temperatures is estimated to cost London £577 million annually and accounted for almost 90 per cent of the estimated £1.5 billion cost of London’s three heatwaves in 2022.
The warning follows another summer of record-breaking heat. London broke temperature records in May, June and August and had entered its fifth official heatwave of the year by mid-August. Preliminary UK Health Security Agency analysis estimates that 2,877 heat-associated deaths occurred across England during May and June 2026 alone.
The danger is not limited to days of extreme heat. The Mayor’s report highlights that approximately 90 per cent of heat-related deaths in London occur when temperatures are between 24°C and 32°C. Evidence also suggests that Londoners aged between 45 and 65 face a greater risk of dying during hot weather than people of the same age nationally.
Heat Ready London identifies 37 priorities across buildings, business, emergency preparedness, green space, health and care, and infrastructure. These include adapting homes and public buildings, expanding access to shade, cool spaces and drinking water, and protecting essential transport, water, energy and communications networks.
The technical report 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.”
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