A new report commissioned by the Mayor of London has revealed the potentially devastating economic, social and health impacts of rising temperatures across the capital, warning that climate change could cost London up to £36 billion annually by the 2050s unless urgent adaptation measures are accelerated.
Published by the Mayor of London and London Councils, the Heat Ready London Technical Report provides the evidence base behind Heat Ready London, the capital's first city-wide strategy for adapting to extreme heat, which was launched in June.
The findings paint a stark picture of how increasing temperatures are already affecting Londoners, placing growing pressure on public services, infrastructure, businesses and healthcare systems. Without additional action, climate change could inflict annual economic damage equivalent to as much as three per cent of London's economy by the 2050s, with costs estimated at between £16 billion and £36 billion per year depending on future growth.
The projected £36 billion annual economic impact is not a direct financial liability but a measure of the widespread disruption extreme heat could impose on the capital.
The report highlights several key drivers behind these costs, including:
- Lost productivity and reduced working hours
- Increased demand on health and emergency services
- Business disruption
- Damage to critical infrastructure
- Greater pressure on water, energy and communications networks
Evidence suggests these impacts are already emerging. Productivity losses linked to high temperatures are estimated to cost London's economy £577 million every year, accounting for nearly 90 per cent of the estimated £1.5 billion cost of the capital's three heatwaves in 2022.
The 2022 heatwave also exposed vulnerabilities across essential services. Rail networks experienced cancellations and speed restrictions due to buckled tracks, while the failure of two data centres at Guy's and St Thomas' hospitals disrupted patient care and resulted in £1.4 million in unplanned expenditure. Water consumption across London surged by 50 per cent during the extreme conditions.
The warning comes after another exceptionally hot summer for the capital. London recorded new temperature highs in May, June and August, and had already entered its fifth official heatwave of 2026 by mid-August.
According to preliminary analysis from the UK Health Security Agency, 2,877 heat-associated deaths occurred across England during May and June 2026 alone.
The report emphasises that the danger extends beyond periods of extreme heat. Around 90 per cent of heat-related deaths in London occur when temperatures range between 24°C and 32°C, conditions that are becoming increasingly common.
Researchers also found evidence suggesting Londoners aged between 45 and 65 face greater heat-related mortality risks than people in the same age group elsewhere in England.
Heat Ready London identifies 37 priority actions aimed at strengthening the city's resilience to rising temperatures.
These include:
- Retrofitting homes and public buildings to cope with heat
- Expanding access to shade, drinking water and cool spaces
- Increasing urban greening initiatives
- Protecting transport, energy, water and communications infrastructure
- Improving emergency preparedness
- Supporting health and social care services during heat events
The report argues that early intervention will not only save lives but also deliver substantial long-term economic benefits.
London's parks and green spaces, for example, are estimated to generate more than £90 billion in benefits over the next 30 years, representing approximately £27 in value for every £1 invested.
To help deliver the strategy, the Mayor and London Councils are bringing together boroughs, NHS partners, emergency services, infrastructure providers, businesses, financial institutions and community organisations.
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."
Image credit: iStock
