Mayor warns heatwaves could cost London over £25bn in a decade

A City Hall release, created on 11 November 2026 (the page shows that date, not 12 November), says London's 2026 heatwaves cost about £2.5 billion in lost productivity. If the next ten summers are as hot, the cost could pass £25 billion. City Hall says that figure is the annual estimate multiplied by ten and does not account for inflation. Mayor Sadiq Khan, co-chair of the C40 cities network, is representing London at COP31 in Antalya, Türkiye. He is to be the first Mayor of London to speak at the World Leaders' Summit. The release cites London Ambulance Service figures of 300 heat-exposure incidents between June and August, more than three times the five-year summer average. London Fire Brigade responded to nearly 100,000 emergency calls between May and August. Imperial College London modelling estimates over 4,000 excess deaths across 135 UK urban areas; these are modelled estimates, not registered counts. City Hall says more than 640,000 trees have been planted and the Heat Ready London plan was published in June 2026 with London Councils. C40 aims to have early warning systems in all member cities by the end of 2027. Khan said: "the only thing we cannot afford is to do nothing."