City Hall says London's 2026 heatwaves cost about £2.5bn in lost work and could cost over £25bn in ten years. Sadiq Khan takes the figures to COP31 today.
London’s heatwaves this summer cost the capital around £2.5 billion in lost productivity, and if summers like it become normal the bill could pass £25 billion over the next ten years, City Hall estimated on Wednesday 11 November. That is more than the Mayor’s entire annual budget for London.
The Mayor of London, Sadiq Khan, is taking the figures to COP31, the United Nations climate conference in Antalya, Türkiye. City Hall says he will be the first Mayor of London to speak at the World Leaders’ Summit, a slot usually kept for heads of state and government leaders.
Why it matters in Bromley
Heat has already reached the council chamber here. Ahead of the Full Council meeting on 12 October, six Bromley councillors, led by Councillor Chloe-Jane Ross, asked for a statement on how the council coped with this summer’s heatwaves, covering the pressure on adult social care, highways, parks, waste collection and public health (our report on that meeting, and the councillors’ request).
City Hall says it is working with the boroughs to prepare for hotter summers. Its plan, Heat Ready London, was produced with London Councils and published this summer. It sets out priorities including reducing overheating in homes and essential public buildings, protecting frontline workers and creating more shade, and brings together health services, emergency responders, transport providers and utilities.
What the heat cost
City Hall’s estimate draws on research into London’s 2022 heatwaves, updated with this summer’s temperature data and adjusted for inflation. High temperatures make it harder for people to work effectively, which is where the lost productivity comes from.
Families felt it too. Earlier research found that heat-related school closures during the 2022 heatwaves cost parents nearly 60,000 working days and an estimated £9.4 million in lost earnings, according to the Mayor’s office.
The emergency services had their busiest summer on record:
- London Ambulance Service crews attended 300 heat-exposure incidents between June and August, more than three times the five-year summer average.
- London Fire Brigade firefighters and control officers responded to nearly 100,000 emergency calls between May and August.
The health toll was wider still. Research from Imperial College London and the London School of Hygiene & Tropical Medicine estimates that more than 50,000 people died from heat-related causes in European urban areas this summer, around two-thirds of those deaths attributed to human-induced climate change. Imperial College London also estimates there were more than 4,000 excess deaths across 135 urban areas in the UK this summer.
What London has done so far
City Hall points to early warning systems for heat and air quality, more than 640,000 trees planted across the capital under the current Mayor, and more than 2,000 football pitches’ worth of green space created or improved. It says making buildings cooler will need public money, private investment and support from national government.
In his speech, the Mayor is expected to say: “The climate sceptics argue that these investments are unaffordable. But the only thing we cannot afford is to do nothing. Because, even if you can see past the devastating implications for human health, the long-term economic impact of extreme heat alone will be astronomical. If the scenes we saw this summer became the standard, it could cost London’s economy more than £25 billion over the next ten years.”
He is also expected to say: “Climate disaster is no longer the stuff of some distant dystopia. It’s killing people, harming communities and impacting our economies right now. And failing to protect ourselves from the perils we face, or prepare ourselves for worse to come, would be a dereliction of duty.”
As co-chair of the C40 network of almost 100 cities, he says members are working to make sure all of them have early warning systems by the end of 2027.
What the fire, ambulance and health chiefs said
London Fire Commissioner Jonathan Smith said: “In preparation for the heatwaves of 2026, we built on lessons learned from previous years to strengthen our resilience and improve our response. Thanks to investment from the Mayor of London, we have introduced new training and equipment to help us better predict, prevent and tackle wildfires.
“As the impacts of climate change become more frequent and severe, the risk of wildfires across the capital will continue to grow. It is critical that the fire and rescue service is adequately resourced to enable us to continue to respond and keep our communities safe.”
Jason Killens, chief executive of London Ambulance Service, said crews responded to more 999 calls and Category 1 incidents than in any previous summer. “We are now preparing for winter and already planning for next summer, including how we put additional ambulance crews on the road to respond to the surge in demand that extreme weather brings and ensure the sickest patients continue to get the care they need.”
Dr Tom Coffey, the Mayor’s health adviser and a London GP, said: “Extreme heat now presents the greatest risk to health from climate change in the UK, and as a GP, I’ve seen first-hand that its impacts are widespread, not just on those we traditionally think of as vulnerable, such as those with mental and physical health conditions, but any of us.”
Emma Howard Boyd, chair of the National Heat Risk Commission, said: “The capital has shown what practical preparation looks like, but no city can do this alone. The UK needs a heat ‘circuit breaker’: a national response that protects people now and invests in homes, workplaces and public buildings fit for a hotter future.”
The figures come from the Mayor of London’s press office.
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